study and characterization of polyphenolic compounds from black liquor of kraft pulping
TRANSCRIPT
Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
1. INTRODUCTION:
The focus of this project is to study the lignin yield after precipitation
of lignin in the wood and bagasse Kraft spent black liquor (chemical pulp
mill 1 &2 liquor) by acidification. The pulp mill of today produce an energy
surplus occurring from the combustion of wood residuals in the recovery
boiler. At the sometime, the recovery boiler is the battle neck of the process
at many mills. One way to utilize the energy surplus at the same time as a
production increase is obtained is to extract lignin from Kraft spent black
liquor before the combustion in the recovery boiler to produce a biofuel.
Extraction of lignin can be done by fractionation of Kraft spent black liquor
in a lignin rich and a lignin-depleted stream by ultrafiltration, another way is
to precipitate the lignin in the spent black liquor by acidification. The
precipitate is separated by filtration followed by a washing step. Both
methods involve problems. The fuel produced by ultra-filtration contains too
high an ash content. The ash contains high amounts of spent cooking
chemicals, i.e. sulphur and sodium, which would cause problems during
combustion of the fuel. By precipitation, the ash content is lower but
problems during combustion of the fuel. By precipitation, the ash content is
lower but problems are induced at the mills occurring from the need of after-
treatment of the filtrate and the wash liquid.
Fundamental research aimed at improving pulping and bleaching
processes almost invariably requires an understanding of the structural
details of residual Kraft lignin. For such endeavors it is essential that the
lignin remaining on the fiber be isolated from the black liquor in high yield
and purity, unaltered and in the absence of contaminants. Isolation of lignin
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
can be done many methods in that of acid hydrolysis using hydrochloric
acid, sulphuric acid and hydrofluoric acid. Currently, a sulphuric acid
method is use for the isolation of residual lignin from black liquor. Despite
extensive research efforts, aimed at obtaining residual lignin that it would
completely comply with the above criteria both of these methods have
limitations that need to be addressed. The acid hydrolysis technique, while it
offers a residual lignin preparation of high purity, is plagued with relatively
low yields and the possibility of structural alterations induced during the
acidic treatment.
The Kraft process was developed by Carl.F.Dahl in 1879,with the
name of the process coming from the German word “Kraft”, meaning
strength/power. The Kraft process describes a technology for conversion of
wood into wood pulp consisting of almost pure cellulose fibres.The first
Kraft mill in the United States was not built until 1911 and was located in
Pensacola, Florida. Today, the process is used in approximately 80% of
paper production. Those companies using the Kraft process are easy to
recognize by their strong, offensive smell. This is because one of the
byproducts of the process is hydrogen sulfide gas and other sulfur gas
compounds. The Kraft pulping process involves the digesting of wood chips
at elevated temperature and pressure in “white liquor”, which is a water
solution of sodium sulfide and sodium hydroxide. The white liquor
chemically dissolves the lignin that binds the cellulose fibers together.
The invention of the recovery boiler by G.H.Tomlinson in the early
1930s was a milestone in the advancement of the Kraft process. Most Kraft
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
pulp mills adopted this technology to recover and burn much of the black
liquor, generating steam and recovering the “cooking chemicals” (sodium
hydroxide and sodium sulfide used to separate lignin from cellulose fibers
needed for papermaking).In fact this enhancement not only managed to deal
with pollution load reduction and chemical recovery increase but also made
it possible for Kraft pulp mills to become self-sufficient energetically. In
efficient recovery boiler mills the amount of energy is more than necessary
to run the process and the surplus can be sold. Approximately 7 tonnes of
black liquor (15%solids by weights of which 10% is inorganic).
Lignin is a complex chemical compound most commonly derived,
from wood, and an integral part of the secondary cell walls of plants and
some algae. The term was introduced in 1819 by De-Candolle and is derived
from the Latin word lignum, meaning wood. Lignin polymers are mostly
made of phenylpropanoid units linked to each other through different kinds
of bonds. As a biopolymer, lignin is unusual because of its heterogeneity and
lack of a defined primary structure. Its most commonly noted function is the
support through strengthening of wood (xylem cells) in trees and improves
water transport.
Resin is a natural or synthetic compound which begins in a highly
viscous state and hardens with treatment. Typically, resin is soluble in
alcohol, but not in water. There are a number of different classes of resin,
depending on exact chemical composition and potential.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
WOOD CHEMISTRY:
1.1 TYPES OF WOOD:
Wood is the hard, fibrous substance found beneath bark in the stems
and branches of trees and shrubs. Practically all commercial wood, however,
comes from trees. It is plentiful and replaceable. Since a new tree can be
grown where one has been cut, wood has been called the world's only
renewable natural resource.
Two most important properties of any papermaking cellulosic raw
material are, how much cellulose fiber it has and how long the fibers are.
The amount of cellulose fiber in wood determines the pulp yield, ease of
pulping and cost of pulp produced. The importance of fiber length is
explained in pulp properties. The maximum average fiber length pulp will
have is that of wood because whatever pulping method, full chemical to full
mechanical, fiber is going to damage. In mechanical pulping the damage is
physical (cutting, bruising etc.) and in chemical pulping it is chemical
degradation (lower degree of polymerization).It has been estimated that
based on a mixture of softwoods and hardwoods 12 meters (40 ft) tall and
15-20 centimeters (6–8 in) in diameter, it would take an average of 24 trees
to produce 0.9 tonne (1 ton) of printing and writing paper, using the Kraft
process (chemical pulping).
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
CHEMICAL COMPOSITION OF WOOD:
Average chemical contents of wood:
Element
s
Share, % of dry matter weight
Carbon 45-50%
Hydroge
n
6.0-6.5%
Oxygen 38-42%
Nitrogen 0.1-0.5%
Sulphur max 0.05
Wood is mainly composed of cellulose, Hemicellulose, lignin and
extractives. The following table provides main chemical components of
some wood species.
Constituents Scot Pine Spruce Eucalyptus Silver Burch
Cellulose (%) 40.0 39.5 45.0 41.0
Hemicellulose (%) 28.5 30.6 19.2 32.4
Lignin (%) 27.7 27.5 31.3 22.0
Total Extractive (%) 3.5 2.1 2.8 3.0
Wood Components Hardwood (%) Softwood (%)
Cellulose 40 - 50 40 - 50
Hemicellulose 25 - 35 25 - 30
Lignin 20 - 25 25 - 35
Pectin 1 - 2 1 - 2
Starch Trace Trace
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
PHYSICAL PROPERTIES OF WOOD:
ASH CONTENT:
Ash is a solid particulate, inorganic combustion residue left after the
wood is burnt.
Ash content varies with different components of trees.
Stem wood: 0.4-0.6%
Stem bark: 2.0-5.0% & 1.0-2.0%
As a mean value wood can be expected 1-2% ash content.
MOISTURE CONTENT:
Wood may contain 50% moisture. Wood moisture provides
lubrication to ground stone & keep the temperature low in grinding zone.
Wood moisture help better chemical penetration during cooking due to
diffusion.
1.2 PULPING:
Pulp is a dry fibrous material prepared by chemically or mechanically
separating fibers from wood or fiber from wood or fiber crops. Pulp can be
either fully or formed into thick sheets. The latter form is used if the pulp
must be transported from the pulp mill to a paper mill. Pulp which is shipped
and sold as pulp is referred to as market pulp. When suspended in water the
fibers disperse and become more pliable. This pulp suspension can be laid
down on a screen to form a sheet of paper, and this is the primary use for
wood pulp. Wood pulp is the most common material used to make paper.
The timber resources used to make wood pulp are referred to as pulpwood.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Wood pulp comes from softwood trees such as spruce, pine, fir, larch, and
hemlock and hardwoods such as eucalyptus,aspen,and birch.
1.3 BLACK LIQUOR
Black liquor is a byproduct of the Kraft process, during the production
of paper pulp. Wood is decomposed into cellulose fibers, hemicelluloses and
lignin fragments. Black liquor is an aqueous solution of lignin residues,
hemicellulose, and the inorganic chemicals used in the process. The black
liquor contains more than the half of the energy content of the wood fed into
the digester. Early Kraft pulp mills discharged black liquor to watercourses.
Black liquor is quite toxic to aquatic life, and causes a very dark “Coca-
Cola” color in the water. In chemical pulping a large part of the wood is
dissolved during digestion. The dry matter content of the generated black
liquor is typically 12 to 18 wt. %.In the case of Kraft liquors four main
groups of organic constituents are present,30-45wt% ligneous material,25-
35wt% saccharinic acids, about 10wt% formic acid and acetic acid, and 3-
5wt% extractives. It also contains about 1wt% methanol and many inorganic
elements, mainly sodium(17-20wt %) and sulphur (3-5wt%).The exact
composition of the black liquor varies considerably between different mills
depending on the cooking conditions and feedstock. The vast majority of
lignin in the spent liquors of pulp mills is used as in house fuel for the
recovery of chemicals.
2. VISION:
Million tonnes of black liquor generation in a small scale will be
money saving, time and energy.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
3. MPM AT A GLANCE:
Mysore paper mill was established in the year 1936. It is one of largest
mill in India. MPM is located on the banks of Bhadra River. This mill used
bamboo, euca, acacia, pine and bagasse as raw material for paper making.
This mill has three pulping plant, out of 3, two are chemical pulp
mills that is CPM2 for hard wood and other one is for bagasse pulp plant
called CSRMP ( cold soda refiner mechanical pulp plant ) this pulp is used
to news print like papers.
Raw materials are used in MPM required mainly two sources
1. Captive sources
2. Privative sources
Captive plantation sources are requires mainly in 4 areas like
1. Tirathahalli
2. Sagara
3. Hosanagar
4. Bhadravathi
Hear all the activities are controlled by forest officer weighed woods
are stored in the different stocks based on their quality, size & durability. it is
very essential homogenize the different type of RM in the form 5-7 feet logs
& diameter in 5-6 inch & those logs are made free roots, barks, knots &
other undesirable impurities, which are not useful for paper making.
According to the need of for chipper house. The stored RM is issued.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Chipper house means the RM that is logs are cut in to small pieces
(chips) with the help of chipper, & the pieces are stored in a tank called
“SILO”. The materials rich in cellulosic fiber are used as RM. chipper are
classified Into 2 types MPM based on the wood. Each chipper contains two
types of blades for chipping. One is dead knife & other one is fly knife. Fly
knife rotates with the help of motors. Chipping converts heterogeneous type
of chipper into homogeneous & uniform type of chips.
1. Gsualiar chipper: - 5 chipper is working.
2. Pallmann chipper: - 2 chipper is working.
Gsualiar Chipper: - It is also called disk chippers. It is used to cut the hard
wood like euca and acacia. In this chipper fly knife are added to big disc
which is rotating with the help of motors.
Pallmann Chipper: - It is also called drum chipper. It is used to chip the
soft wood like bamboo. Here the fly knife is adjusted to drum which is
rotating with the help of motor. In pallmann chipper “Feed roller” are used to
crust the RM.
The chips will conveyed to chip screener for separating the dust &
oversized chips from accepted chips. The accepted chips are stored in SILO.
The dust is sent to boiler as a source of energy. The oversized chips will go
re chipper for making small chips.
Chipper size: - Very important to maintain the size of chips. Because in
CPM the liquor should penetrate easily.
Length ----------13 to 25 mm
Breadth ------------ 10 to 12 mm
Width --------------- 06 to 05 mm
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
SILO: - SILO is a big tank for storing the chips. This comes from the
chipper house. It has the capacity to store 700 tones of chips. It is classified
into 3 different chambers.
1. Bamboo storage.
2. Euca storage.
3. Acacia & bamboo mix storage.
PULPING TECHNOLOGIES AT MPM:
In MPM 3 varieties of pulp is producing. They are.
1. CSRMP: - (cold soda refiner mechanical pulping) for euca &
Acacia.
2. CPM 1: - Chemical pulp mill for bagasse
3. CPM 2: - Chemical pulp mill for bamboo & wood.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
4. HISTORY OF LIGNIN:
For many years wood was considered to be uniform chemical
compound. In 1811, Gay Lussac and Thenard carried the elementary analysis
of wood and found its components consists entirely of carbon, hydrogen and
oxygen and that no other elements, and that no other elements, such as sulfur
and nitrogen, or only traces of the latter, are present. At about the same time,
Prout reported same analysis of wood fibers which he called “fibres
ligneux.” These chemists believed that wood is a chemical entity.
With the development of the organic chemical experimental technique
over a hundred years ago, however, chemists succeeded in separating wood
into individual components. About 1815, Raspail expressed the opinion that
wood may consists of several components and he suggested that the cell wall
is buildup of gum and lime. That wood is not a uniform chemical compound
was shown in 1819 by Braconnot and three years later by Authenrieth and
Bayer hammer, when they found that wood gives glucose in boiling with
dilute sulfuric acid. None of them, however, mentioned any other reaction
products.
In 1834, Runge discovered that wood gives a green color reaction with
phenol and hydrochloric acid, and a yellow color with aniline hydrochloride,
but he did not realize the significance of these reactions.
The first serious attempt to study the chemical composition of the cell
wall of lignified plants was made in 1838 by Anselme Payen by the
intelligent applications of different reagents; he succeeded in isolating a
uniform compound which he called Cellules. He treated wood alternatively
with nitric acid and caustic soda and in this way obtained cellulose fibres
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
which are considered as the basic substance of cell membrane. From the
elementary analysis of wood and their celluloses, from the lignin it uses to be
55.6% carbon, 5.8% hydrogen and 38.6% oxygen.
From this he arrived at a formula, C19H24O10, for lignin. The carbon
content he calculated ifs considerably lower than that he found for lignin’s
isolated by newer methods. This is not surprising because the lignin content
found by Schulze is much too high and includes a considerable portion of
carbohydrates which lowers the carbon content. All attempts by Schulze to
isolate lignin as such for a direct analysis failed. An attempt to isolate it by
alkali fusion and acidification of alkaline solution resulted in very small
amount of precipitate which had been altered chemically.
That interest in chemistry of lignin has continued to increase is shown
by the fact during that decade since 1948, when the manuscript for “The
Chemistry of Lignin” was completed, the amount of research carried out and
the numbers of reviews written on the subject have exceeded those of any
previous decade.
The brief history revives shows that the problem of lignin is an old
one. Although a tremendous work had been carried out, particularly during
the last quarter century, we are still remote from the final solution of its
constitution.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
4.1 HISTORY OF RESIN:
Plant resins have a very long history that was documented in ancient
Greece by Theophrastus, in ancient Rome by Pliny the Elder, and especially
in the resins known as frankincense and myrrh, prized in ancient Egypt.[1] These were highly prized substances, and required as incense in some
religious rites. Amber is a hard fossilized resin from ancient trees. The
English word originates from the late 14th century Old French resine, from
L. resina "resin," from Greek rhetine "resin of the pine," of unknown earlier
origin.
The first commercial attempts to prepare resins from epichlorohydrin
were made in 1927 in the United States. Credit for the first synthesis of
bisphenol-A-based epoxy resins is shared by Dr. Pierre Castan of
Switzerland and Dr. S.O. Greenlee of the United States in 1936. Dr. Castan's
work was licensed by Ciba, Ltd. of Switzerland, which went on to become
one of the three major epoxy resin producers worldwide. Ciba's epoxy
business was spun off and later sold in the late 1990s and is now the advance
materials business unit of Huntsman Corporation of the United States. Dr.
Greenlee's work was for the firm of Devoe-Reynolds of the United States.
Devoe-Reynolds, which was active in the early days of the epoxy resin
industry, was sold to Shell Chemical (now Momentive Specialty Chemicals,
formerly Hexion, Resolution Polymers and others).
Early varnishes were developed by mixing resin, like pine sap, with a
solvent and applying them with a brush to get the golden and hardened effect
one sees in today's varnishes.[1] The ancient Egyptians were well acquainted
with the art of varnishing, but its origin appears to be far east of there
in India, China and Japan, where the practice of lacquer work, a species of
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
varnish application, was known at a very early date. It has been claimed that
Japan was acquainted with the art of lacquering by 500 or 600 B.C., but the
majority of authorities place its first usage there to the 3rd century AD, as an
art acquired from their neighbors, the Koreans. The Chinese and Indian
peoples probably knew the art much earlier than the Japanese. Varnish and
lacquer work are, however, generally treated in the arts as separate and
distinct.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Pulp is a lignocellulosic fibrous material prepared by chemically or
mechanically separating cellulose fibres from wood, fibre crops or waste
paper. Wood pulp is the most common raw material in papermaking. Pulp
can be manufactured using mechanical, semi-chemical or fully chemical
methods (Kraft and sulfite processes). The finished product may be either
bleached or non-bleached, depending on the customer requirements. The aim
of pulping is to break down the bulk structure of the fibre source, be it chips,
stems or other plant parts, into the constituent fibers.
Chemical pulping achieves this by degrading the lignin and
hemicellulose into small, water-soluble molecules which can be washed
away from the cellulose fibers without depolymerizing the cellulose fibres.
Pulp category Production [M ton]
Chemical 131.2
-Kraft 117.0
-Sulfite 7.0
-Semi chemical 7.2
Mechanical 37.8
4.1.1 TYPES OF PULPING
There are a number of different processes which can be used to
separate the wood fibres.
Thermo mechanical pulp
Thermo mechanical pulp is pulp produced by processing wood
chips using heat (thus thermo) and a mechanical refining movement (thus
mechanical). It is a two stage process where the logs are first stripped of
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
their bark and converted into small chips. These chips have a moisture
content of around 25-30% and a mechanical force is applied to the wood
chips in a crushing or grinding action which generates heat and water vapor
and softens the lignin thus separating the individual fibers. The pulp is then
screened and cleaned, any clumps of fiber are reprocessed. This process
gives a high yield of fibre from the timber (around 95%) and as the lignin
has not been removed, the fibres are hard and rigid.
Chemithermo Mechanical Pulp
Wood chips can be pretreated with sodium carbonate, sodium
hydroxide, sodium sulfite and other chemicals prior to refining with
equipment similar to a mechanical mill. The conditions of the chemical
treatment are much less vigorous (lower temperature, shorter time, less
extreme pH) than in a chemical pulping process since the goal is to make the
fibres easier to refine, not to remove lignin as in a fully chemical process.
Pulps made using these hybrid processes are known as chemithermo
mechanical pulps (CTMP).
Chemical pulp
Chemical pulp is produced by combining wood chips and chemicals
in large vessels known as digesters where heat and the chemicals break down
the lignin, which binds the cellulose fibres together, without seriously
degrading the cellulose fibres. Chemical pulp is used for materials that need
to be stronger or combined with mechanical pulps to give product different
characteristics. The Kraft process is the dominant chemical pulping method,
with process being second. Historically soda pulping was the first successful
chemical pulping method.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Bleaching
The pulp produced up to this point in the process can be bleached to
produce a white paper product. The chemicals used to bleach pulp have been
a source of environmental concern, and recently the pulp industry has been
using alternatives to chlorine, such as chlorine dioxide, oxygen, ozone and
hydrogen peroxide.
4.2 KRAFT PULPING:
The kraft process (also known as kraft pulping or sulfate process)
describes a technology for conversion of wood into wood pulp consisting of
almost pure cellulose fibers. The process entails treatment of wood chips
with a mixture of sodium hydroxide and sodium sulfide, known as white
liquor, that break the bonds that link lignin to the cellulose.
The kraft pulping process involves the digesting of wood chips at
elevated temperature and pressure in "white liquor", which is a water
solution of sodium sulfide and sodium hydroxide. The white liquor
chemically dissolves the lignin that binds the cellulose fibers together.
There are 2 types of digester systems, batch and continuous. Most
Kraft pulping is done in batch digesters, although the more recent
installations are of continuous digesters. In a batch digester, when cooking is
complete, the contents of the digester are transferred to an atmospheric tank
usually referred to as a blow tank. The entire contents of the blow tank are
sent to pulp washers, where the spent cooking liquor is separated from the
pulp. The pulp then proceeds through various stages of washing, and
possibly bleaching, after which it is pressed and dried into the finished
product.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Fig: Kraft pulping process
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
4.3 AIM AND OBJECTIVES
AIM:
Identification and Utilization of value added polyphenolic
compounds from pulp mill waste.
(Extraction of lignin from CPM-1 and CPM-2, wood and bagasse
Kraft spent black liquor which is a ‘byproduct of pulp mills, Kraft process
and yield obtained and IR characterization of the lignin.)
Objective:
Small scale Pulp mills generate a million tons of black which is
sewered. Where as large scale industries are installing chemical
recovery units to recover the chemicals. Due to environmental facts
utilization of value added products like polyphenols from black liquor in
bagasse Kraft pulping method could saves environment, energy and
money.
Is to extract the lignin present in the bagasse Kraft spent liquor which
is a bit expensive process but it is worth putting money for all the advantages
we are going to get from it. By doing so instead of only burning it in boiler
which is the bottle neck process for pulp industries for only power purpose it
can also be employed in many use full ways. Where pulp industries are
producing much more power than they are required to sustain, which can be
sold out, but along with that it is necessary to use part of it to extract lignin
which can be used in many ways. Lignin can be used to synthesize many
alternatives like, an alternative to plastic, vanillin, agricultural chemicals and
many more and also raw materials for several chemicals and high quality
bleached paper. Create new projects using lignin as raw material and in the
field of lignin characterization.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
5. CHARACTERIZATION OF BLACK LIQUOR:
The Kraft black liquor used in this study was supplied by Mysore
Paper Mills, Bhadravathi, and Shimoga Dist. The Monsteras paper mill is
situated on the edge of the Bhadra River in the east of the Bhadravathi town.
The Monsteras pulp mill uses a continuous digester. The cooking
temperature is about 165-170°C and delignification is done to a kappa
number of 29-3 . The liquor was withdrawn between digester and pre-
impregnation as softwood pulp was being processed.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
5.1 METHODOLOGY:
Production of Black liquor:
The Kraft pulping process involves the digesting of wood chips at
elevated temperature and pressure in “white liquor” which is a water solution
of sodium sulfide and sodium hydroxide. The white liquor chemically
dissolves the lignin that binds the cellulose fibers together.
There are 2 types of digester systems, batch and continous.Most Kraft
pulping is done in batch digesters, although the more recent installations are
of continuous digester. In MPM (Mysore Paper Mills) the batch digester
process is done, in a batch digester, when cooking is complete, the contents
of the digester are transferred to an atmospheric tank usually referred to as a
blow tank. The entire contents of the blow tank are sent to pulp washers,
where the spent cooking liquor is separated from the pulp. The pulp then
proceeds through various stages of washing, and possibly bleaching, after
which it is pressed and dried into the finished product. The “blow” of the
digester does not apply to continuous digester systems.
The balance of the Kraft process is designed to recover the cooking
chemicals and heat. Spent cooking liquor and the pulp wash water are
combined to form weak black liquor which is concentrated in a multiple-
effect evaporator system to about 55% solids. The black liquor is then
further concentrated to 65% solids in a direct-contact evaporator, by bringing
the liquor into contact with the flue gases from the recovery furnace, or in an
indirect-contact concentration. The strong black liquor is then fired in a
recovery furnace. Combustion of the organics dissolved in the black liquor
provides heat for generating process steam and for converting sodium sulfate
to sodiumsulfite.Inorganic chemicals present in the black liquor collect as a
molten smelt at the bottom of the furnace.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
The smelt is dissolved in water to form green liquor, which is
transferred to a caustic zing tank where quicklime (calcium oxide) is added
to convert the solution back to white liquor for return to the digester system.
A lime mud precipitates from the caustic zing tank, after which it is calcined
in a lime kiln to regenerate quick lime.
The characteristic odor of the Kraft mill is caused by the emission of
reduced sulfur compounds, the most common of which are hydrogen sulfide,
methyl mercaptan,dimethyl sulfide, and dimethyl disulfide, all with
extremely low odor thresholds. The major source of hydrogen sulfide is the
direct contact evaporator, in which the sodium sulfide in the black liquor
reacts with the carbon dioxide in the furnace exhaust. Indirect contact
evaporators can significantly reduce the emission of hydrogen sulfide. The
lime kiln can also be a potential source of odor, as a similar reaction occurs
with residual sodium sulfide in the lime mud. Lesser amounts of hydrogen
sulfide are emitted with the non-condensable of off gases from the digesters
and multiple-effect evaporators.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
5.2 LIGNIN ISOLATION FROM BLACK LIQUOR:
Several different enzymatic, chemical and mechanical methods have
been developed for the isolation of lignin from black liquor.however,due to
the heterogeneity that exists between individual fibres,no method is currently
available for the quantitative isolation of native or residual lignin without the
risk of structural changes during the isolation. Even if the perfect isolation
technique could be found, the product would at best represent the average
structure of native or residual lignin components. However, the information
gained about the chemical reactivity and structure of isolated lignin is
valuable. Thus, the three most commonly employed methods for isolating
residual lignin are described below.
Lignin can be isolated currently, by two methods they are isolation of
residual lignin from Kraft pulp that of enzymatic hydrolysis using
cellulolytic enzymes, and that of acid hydrolysis of black liquor using a
solution of hydrogen chloride and sulfuric acid in dioxane/water.
5.4 EXPERIMENTAL PROCEDURE:
Bagasse Kraft Spent Liquor obtained after production of paper, which
is highly dilute in nature is passed and stored in the CPM-2 processor plant
to evaporate to some extent. And then it is passed to CPM-1 plant to
evaporate it to much more extent than in the CPM-2 evaporator plant and
then it is passed to evaporator where it is evaporated to larger extent to get a
highly concentrated black liquor which is passed to boiler for combustion to
produce steam which in turn to produce power. The black liquor taken for
our project to isolate lignin is from the CPM-2 is highly dilute in nature and
its solid content is about 14-18%.Out of the three types of black liquor CPM-
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
2 is the better one to isolate lignin in good yield. Other than that CPM-1 and
evaporator black liquor are having concentration and solid content.
Precipitation:
About 1litre of Dilute Bagasse Kraft Black Liquor (CPM-2liquor) is
taken in a beaker and it is treated with 70% sulfuric acid which is added
slowly, the whole set up is kept in ice water bath, constant stirring is done to
prevent spilling. Constant pH is maintained in between 2-3 with the help of
the pH-meter. A gelatinous solution of dark blackish brown in color is
obtained. It allowed for 24hours settling down.
And then it is filtered using vacuum pump the filtrate is washed with
dilute sulfuric acid of 3% and washed with hot distilled water until the
sulfuric acid content is removed completely and also the sulphates and
chlorides. The sulfuric acid lignin often contains 2-5% sulfur which is
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
mostly removed by heating with 1litre 0.5%hydrochloric acid for about 8-10
hours. The cake is reddish brown in color, waxy in nature, dried in open hot
air drier at 60C a luster yellowish brown of lignin separates. A technical
sulfuric acid lignin is known as “Scholler Lignin”.
5.5 METHODS OF PREPARATION OF LIGNIN:
In order to isolate lignin from lignified substance, a carefully selected
starting material must be used like when woods are utilized knots, bark, and
resin are used, but when coming to industrial products or by products pulp,
bagasse, and Kraft spent liquor may be used. In our project We are using
Wood & Bagasse Kraft Spent Liquor as the starting material for the isolation
of lignin. Lignin can be isolated from black liquor by many methods they are
as follows,
Sulfuric Acid Lignin or Klason Lignin:
The isolation of lignin by means of sulfuric acid is based on a
discovery of Braconnot in 1819. In spite of earlier reports, Klason in198O
was the first to propose the use of 64 — 72% sulfuric acid for the hydrolysis
of the carbohydrates in the isolation of lignin. This method is therefore
generally associated with his name in the literature and the product obtained
is referred to as “Klason Lignin or Sulfuric Acid Lignin.” The conditions he
recommended for quantitative lignin determination can also be applied to the
preparation of lignin on a large scale.
5.6 GENERAL PROPERTIES OF LIGNIN:
It is a resinous material.
Soluble in Water, coagulates, colloidal solution.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Melting Point is 18000.
Lignin is co-precipitated with natural GRS and Nitrile Elastomers.
It provides sufficient formaldehyde reactants.
It follows condensation reaction due to polyhydroxy groups.
Inhibiting properties of lignin:
Inhibitory efficacy has been determined by the method of the weight
losses of steel in acid with native lignin, hydrolysis lignin, ammoniated
native lignin, chlorinated hydrolysis lignin, and ammoniated hydrolysis
lignin, and Without these additives. It has been established that the efficacy
of lignin and its modifications as inhibitors of acid corrosion increases with a
rise in the number of carboxyl groups in the macromolecule, and therefore
the ammoniated hydrolysis lignin is the most effective. It is capable of
forming water proof bonds and wood derivatives/substrates after hydroxyl
methylation.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
5.7 GENERAL PROCEDURE:
5.8 CALCULATIONS:
Black liquor initial PH:
CPM 1 =13.27
CPM 2 =13.06
Black liquor +sulphuric acid:
CPM 1 =4
CPM 2 =4
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
CPM 1:
Weight of empty sintered glass crucible( W1) =50.170g
Weight of sintered crucible + precipitate (W2) =50.198g
CPM 1 (W) =W2-W1
=50.198 -50.170
=0.028g
CPM 1 =2.8g/liter
CPM 2:
Weight of empty filter paper (W1) =1.543g
Weight of filter paper + precipitate (W2) =1.721g
CPM 2 (W)= W2-W1
=1.721-1.543
=0.17g
CPM 2=1.78g/lite
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
6. GENERAL PROPERTIES OF RESIN:
High tensile strength,
Heat distortion temperature,
Low water absorption,
Mould shrinkage,
High surface hardness,
Volume resistance
Excellent mechanical properties over temperatures from below -40°C (-
40°F) to above 148°C (300°F)
Self-extinguishing, non-dripping characteristics
Excellent dimensional stability and low water absorption
Resistance to aqueous chemical environments
Excellent impact strength
The practical melting point varies with different specimens, some being
semi-fluid at the temperature of boiling water, others melting at 100°C to
120°C.
It is very flammable, burning with a smoky flame, so care should be
taken when melting it. It is soluble in alcohol, ether, benzene and
chloroform.
STRUCTURE OF RESIN:
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6.1 PREPARATION OF RESIN:
ALCOHOL BENZENE SOLUBILITY METHOD:
Reagent: Alcohol benzene Mixture: Mix one volume of
approximately 95 % Ethanol and two volumes of Benzene.
Sulphuric acid 72 % carefully pour 665 ml of concentrated sulphuric
acid into about 300 ml of water and after cooling, dilute to one liter.
Standardize against standard NaOH solution using methyl orange as
indicator.
Adjust the acid to strength of 72 +/- 0.1 % by addition of water or
concentrated sulphuric acid as may be found necessary.
6.2 METHODOLOGY:
Weigh the oven dried test specimen of approximately 10-g to the
nearest 0.01 g in tarred extraction thimbles.
Clean, and then dry the sox let- extraction flask. Place the extraction
flask with 150 cm of the required solvents. Connect the flask to the
extraction apparatus and start water flow to the condenser section. Adjust the
extraction apparatus and start water flow to the condenser section. Adjust the
heaters to provide a boiling rate, which will cycle the specimens for not less
than 24 extractions over a 4-5 hour period. Remove the flask from the
apparatus and partially evaporate the solvent in the extraction flask to a
volume 20-25 cm.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Transfer the extract to the tarred weighing dish by washing with small
amounts of fresh solvent. Handle the weighing dish with forceps or tongs. If
using benzene, evaporate the solvent to near dryness, while in the chemical
fume hood. Dry the dish and contents in an oven for 1 hr at 105degree c cool
in a desiccators, and weigh to the nearest 0.1- milligram. Run a blank
determination with the solvent used in the test. Evaporate 150 cm of the
solvent to dryness, and weigh the residue to the nearest 0.1 milligram.
Correct the weigh the residue to the nearest 0.1 – milligram. Correct the
weight of the dried extract by the weight of residue found.
6.3 CALCULATION:
Weight of thimbles+ concentrated sample=15.788g
Weight of concentrated moisture less thimbles=14.498g
Difference in Weight of concentrated sample=1.29g
Weight of thimbles + firing sample=15.880g
Weight of firing moisture less thimbles =14.748g
Difference in Weight of firing sample=1.132g
AFTER THE PITCH PROCESS:
FOR CONCENTRATED BLACK LIQUOR:
Weight of round bottom flask( W1)=179.776g
Weight of round bottom flask + Resin (W2)=180.901g
W=W2-W1
= 180.901-179.776
=1.125g
Percentage for concentrated liquor:17.33%
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
FOR FIRING BLACK LIQUOR:
Weight of round bottom flask(W1)=115.253g
Weight of round flask + Resin(W2)=116.338
W=W2-W1
= 116.338-115.253
=1.085g
Percentage of firing liquor =17.78%
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
7. CHARACTERIZATION
At Infrared -spectroscopy:
Infrared (IR) radiation is electromagnetic radiation whose wavelength
is longer than that of visible light (400-700 mn), but shorter than that of
terahertz radiation (100 um - l mm) and microwaves (~30,000 um). Infrared
radiation spans roughly three orders of magnitude (750nm and 100 pm).
Common Applications:
Identification of compounds by matching spectrum of unknown
compound with reference spectrum (fingerprinting).
Identification of functional groups in unknown subtend the light our
eyes see is but a small part of a broad spectrum of electromagnetic
radiation. On the immediate high energy side of the visible spectrum
lies the ultraviolet, and on the low energy side is the infrared. The
portion of the infrared region most useful for analysis of organic
compounds is not immediately adjacent to the visible spectrum, but is
that having a wavelength range from 2,500 to 16,000 nm with a
corresponding frequency range from 1.9*10‘3 to 1.2*10“‘ Hz.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Simplified optical layout of typical FTIR spectrometer.
A Fourier transform is a mathematical operation used to translate a
complex curve into its component curves. In a Simplified optical layout of
typical FTIR spectrometer.(Reprinted by Fourier transform infrared
instrument, the complex curve is an interferogram, or the sum of the
constructive and destructive interferences generated by overlapping light
waves, and the component curves are the infrared spectrum. The standard
infrared spectrum is calculated from the Fourier-transformed interferogram,
giving a spectrum in percent transmittance (%T) vs. light frequency (cm-1).
IR spectroscopy regions have been classified in to three regions,
Near IR (12,500 - 4000¢m")
Mid IR (4000 0- 4400¢m")
Far IR (400 - 10cm")
The mid region IR is fundamental IR region which is more useful
region for organic compounds and inorganic compounds. IR spectra of the
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
compounds were recorded by KBr pellet technique in the range of 4000 —
550 cm-1.
Structure of lignin:
A. Ketonic Structure of Lignin.
Lignin is a cross-linked racemic macromolecule with molecular
masses in excess of 10,000 amu. It is relatively hydrophobic and aromatic in
nature. The degree of polymerization in nature is difficult to measure, since it
is fragmented during extraction and the molecule consists of various types of
substructures which appear to repeat in a haphazard manner. Different types
of lignin have been described depending on the means of isolation. There are
three monolignol monomers, methoxylated to various degrees: p-coumaryl
alcohol, coniferyl alcohol, and sinapyl alcohol. These lignols are
incorporated into lignin in the form of the phenylpropanoids p-
hydroxyphenyl (H), guaiacyl (G), and syringal (S) respectively. Molecular
fonnula of Protolignin is C92H108O38.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
B is the structure of on-Lignin and C is the B-Lignin.
7.1 CONSTITUENTS GROUPS OF LIGNIN:
Lignin structure consists of following constituents like methoxyl
group, hydroxyl group, carbonyl group, carboxylic group, double bonds.
Which are conformed as follows bellow,
i. Methoxyl Groups;
A qualitative test for alkoxide groups in lignin was developed by
Kratzl and Osterberger. In this method the alkoxide iodide as obtained in the
Zeisel determination is allowed to react with thiourea, and the alkyl thiourea
is isolated as its picrate. Kratzl and Gruber separated and determined
quantitatively the methoxyl and ethoxyl groups in lignin preparation by
means of gas-liquid chromatography [3].Lignin mainly contains methoxyl —
OCH3; which show a very little affinity towards water molecule. It cannot
participate in the hydrogen with the available electronegative atoms or
groups either in the water or cellulosic fibers.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
ii. Hydroxyl Groups;
The hydroxyl groups, there differentiation and quantitative
determination have played an important role in recent lignin chemistry.
There is no doubt that lignin contains phenolic and aliphatic hydroxyl groups
and, since some them may be etherified and form either alkyl ether or
heterocyclic (furan or pyran) rings, their quantitative determination may
contribute to the elucidation of structure of lignin molecule.
iii. Carboxyl Groups;
The presence of carboxyl groups in lignin and lignosulphonic acids
has been the subject of controversy for many years. While it is generally
believed that protolignin does not contain any carboxyl group, Regestad and
Samuelson and Freudenberg and co Workers reported that they had found
such groups in lignosulphonic acid; Kullgren also reported their presence in
the lignosulphonic acid in unbleached sulfite pulp.
iv. Double Bonds;
The presence of aliphatic double bonds in lignin is still doubt.
According to Aulin Erdtman, ultraviolet absorption analysis show that
spruce protolignin contains less than 0.03 to 0.04, double bond, conjugated
with a phenolic ring, per methoxyl groups.
Alder and Ellmer believed they have definitely proven the presence of
coniferyl aldehyde groups in lignin by the phloroglucinol-hydrochloric acid
color reaction given by lignosulphonic acid after treatment with sodium
hydroxide. This treatment splits off not only the sulfurous acid which is
loosely combined to the aldehyde group but also the sulfonic acid which is
attached to the oi carbon atom of the coniferyl aldehyde side chain in
lignosulphonic acid and thus regenerates the double bond in this side chain.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Weather this double bond is present in protolignin is still debatable, since a
hydroxyldihydriconiferyl structure with a hydroxyl group at or position may
occur in protolignin and this hydroxyl would be replaced by a sulfonic acid
group in the lignosulfonic acid. In protolignin and soluble native lignin, the
hydroxyl group may be split off as water by the action of the mineral acid in
the Wiesner reagent.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
8. APPLICATIONS OF LIGNIN:
1. Lignin in Wood Adhesives:
Lignin-based wood adhesives are obtained that satisfy the
requirements of relevant international standards for the manufacture of
exterior-grade wood particleboard, They are prepared and tested for
application to wood panels such a particleboard. The adhesives yield good
internal bond strength results for the panels which are good enough to
comfortably pass relevant international standard specifications for exterior-
grade panels. The adhesives also show sufficient reactivity to yield panels in
press times comparable to that of formaldehyde-based commercial
adhesives.
In the manufacture of certain types of water soluble glues and
adhesive lignosulfonates is due partly to their sugar content. Adhesive of
superior performed and with a wide range of applications are made from
lignosulfonates in solution of high viscosity. Typical examples are glues
from mixture of lignosulphonates with polyvinyl alcohols and
polyacrylamide.
2. Agriculture:
Lignosulfonate from suspension or dispersion in variety of stable
insecticide, fungicide, or herbicide. They are compactable with other anionic
tension active and are frequently used in conjunction with wetting agents,
improving the action of lost.
By precipitating their black liquor with acid or acids evolved gases
like CO2 are sustentions used in conjunction with wetting agents Agricultural
pesticides. Generally, agricultural pesticides are manufactured in the form of
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
dilute suspension or dispersions for doing so, it is necessary to incorporate a
high active dispersant lignosulfonates act as grinding acids, as well as
dispersants.
The suspension should not only from spontaneously but should also be
maintained during the period of application, zinc, copper, iron, magnesium
etc. complexes of lignosulphonates be incorporated in the composition of
fertilizers t supplement micro nutrients to the plants.
3. Lignin in biodegradable composites:
Composites from alkali lignin and wheat gluten, modified with
different percentages of sodium silicate, were prepared and characterized.
Moreoreover, the addition of silica to the aforementioned composites was
studied with the aim of improving the thermal and mechanical properties.
The effect of wheat gluten percent and the extent of its modification on the
blends properties were investigated via diametric tensile strength, thermo
mechanical analysis (tma), scanning electron microscope (SEM), thickness
swelling and thermo gravimetric analysis (tga). The results showed
significant improvement in the diametric tensile strength, thickness swelling,
uniformity in the fracture surface, and the shift of glass transition
temperature (tg) toward higher values with increasing wheat gluten percent
and its modification extent.
4. Engineering plastics from lignin:
Hydroxypropylation of lignin in a batch reactor under alkaline
conditions at 180°C was studied using propylene oxide (PO) by itself and
PO in combination with several lignins like model compounds and with
Kraft lignin.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
5. Lignin based paint:
A method is provided for producing a painted article comprising: (a)
preparing a lignin solution comprising lignin and a dye or pigment; (b)
mixing the lignin solution with a phenol oxidizing enzyme; (c) incubating
the mixture from said step (b) under conditions and for a time sufficient to
form a solution of a desired viscosity; (d) contacting or spreading the
mixture from the step (c) on an article to be painted; and
6. Fire Extinguishers:
Lignosulfonates have as applications as foam stabilizers for the
extinguishing foams (such as in airports, oil refiners etc) lignosulfonate
stabilized foams are prepared from hydrolyzed protein extracts.
7. The Biological application of Lignin-Contained Compounds:
The investigation of biological properties of lignin-contained
compounds (LCC) as multitonnage wastes of woodworking industry is very
actual from the viewpoint of estimation of their treatment on ecosystems.
The purpose of this work was to study the relationship between
macromolecular, mutagenic and growth-regulating properties of LCC. LCC
in water medium and in swelling state (at moisture 3 60%) behave as
polyanions and/or neutral molecules according to value of pH, whose action
on biological objects is connected with competition mechanisms. They
disturb the structural-functional systems of cells: genetical, membraneous,
ferment-protein.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
8.1 APPLICATION OF RESIN:
1. Wood Protection:
Hydrocarbon resins are widely used in wood protection coatings
because of their water-repellant and fixing properties, i.e. fixing fungicides,
insecticides and helping to prevent "blooming" of wood preservatives.
2. Agriculture:
Most recent studies point out that resin is a good inducer for defense
mechanisms in plants. It has also been assessed as a fertilizer that can
improve overall crop yields. The EPA regulates chitin for agricultural use
within the USA. Chitosan is prepared from chitin by deacetylation.
3. Industrial:
It used in industry in many processes. It is used as an additive to
thicken and stabilize foods and pharmaceuticals. It also acts as a binder
in dyes, fabrics, and adhesives. Industrial separation membranes and ion-
exchange resins can be made from chitin. Processes to size and strengthen
paper employ chitin.
Also, there is potential for applications in solar cells and cell phone
screens; when chitin is treated in hydrochloric acid, sodium hydroxide and
ethanol to strip the material of minerals, proteins, lipids, fats and pigments,
and supplemented with acrylic resin monomer, a clear product results.
Crushed and spread into a nanocomposite film it forms a useful component
for solar cell and cell phone screens.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
4. Paints and Varnishes:
Many traditional solvent based coatings contained a so-called hard
resin. These resins are used to improve hardness, gloss, dry time and
improve water repellency and resistance to saponification. Hydrocarbon
resins with softening points of 100 -120 °C are often used in the formulation
of aluminum and bronze paints, aerosol paint, primers and alkyd paint
modifiers.
5. Temporary Rust Protection Coatings:
In steel construction as well as other applications, temporary rust
prevention is very important. Hydrocarbon resins are commonly used along
with waxes, anticorrosion agents and a low KB solvent such as mineral
spirits.
6. Floor Tiles:
Hydrocarbon resins are commonly used in the manufacture of floor
tile based on PVC or SBR rubber. They are mainly used as processing aids.
A wide range of resins may be used with choice depending mainly on price
and end use requirements.
7. Medicine:
Resins are flexible and strong material make it favorable as surgical
thread. Its biodegradability means it wears away with time as the wound
heals. Moreover, it has some unusual properties that accelerate healing of
wounds in humans.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
9. RESULTS:
Characterization of the lignin is an extremely difficult task because of
their diversity in respect with both sources and extraction methods. The
heterogeneity of lignin is due to the changes in polymer composition, size of
morphological units, crosslinking, nature of the functional groups, linkage
types between various moieties such as phenylpropanoic.p-hydroxylphenyl,
guaicyl, siryngyl,etc. Lignins from Black liquor with different chemical
composition and properties can be obtained by use of several extraction
methods. Commercial chemical pulping processes produce lignosulfonates
and Kraft lignin’s as residues. Recently commercialized alkaline pulping-
precipitation process supply sulfur-free, free-flowing lignin.
Department of Chemistry, Govt.SC, Bommankatte Page 45
Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Figure 1: FT-IR Spectrum EBL-M
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Department of Chemistry, Govt.SC, Bommankatte Page 47
Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
10. DISCUSSION:
The result given by the IR spectra shows and confirms the lignin
present in the bagasse Kraft spent liquor. With this result we can say that
using black liquor only for power purpose is not the only use it can be used
to isolate lignin for commercial purpose which can be used in alternative for
many products, in the alternative form of lignin. In this method of isolation
of lignin is easy and there is not much complicated or risk it can be adapted
in pulp mills as an additional plant which helps in converting the spent liquor
not only to produce power but also to isolate lignin. From that lignin many
derivatives can be synthesized which can be used in many fields, like
Agriculture, paint industries, adhesives, and many more.
Lignin can undergo many reactions which give derivatives of lignin in
which one of the important derivative is the sulfonated lignin and vanillin.
Some of the reactions which lignin undergo are as follows,
Sulfonation of lignin.
Nitration of lignin
Alkylation of lignin
Amination
Methylation
Compost formation.
Synthetic Vanillin is one of the most important derivative which is
synthesized from the lignin which is a flavoring agent used in the
alternative for the natural lignin.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Lower molecular weight compounds and polymer products are
synthesized from the lignin.
Low molecular compounds are,
Vanillin
Phenolic compounds
The Polymer products are,
Lignin Sulfonates
Cement and Concrete.
Binders and Adhesives
Rubber Additives
Emulsifier and Stabilizers
Department of Chemistry, Govt.SC, Bommankatte Page 49
Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
11. CONCLUSION:
In small scale ,Its better usage of lignin from black liquor
Small scale Pulp mills generate a million tons of black liquor, which is
sewered.
Where as large scale industries are installing chemical recovery units
to recover the chemicals. Due to environmental facts utilization of
value added products like polyphenols from black liquor in bagasse
Kraft pulping method could saves environment, energy and money.
Using better quality raw material to achieve desired brightness,
Manipulation of raw material quality enables use of lesser quantity of
bleaching chemicals, hence requires less water quantity of bleaching
and washing.
Black Liquor spills can be collected in tank and recycled back to the
system. This reduces fresh water consumption required for floor
washing.
All native lignins are heterogeneous biopolymers linked to
polysaccharides
Alkaline or acidic processes result in both lignin degradation and re-
polymerisation
The up-grading of technical lignins require purification steps
Several options exist for an increased lignin use
Increased pulp production in small scale.
Reduced thermal load in the recovery boiler.
Reduced oil consumption – Go Green
Excess energy can be avoided.
IR data showed that lignin particles are present in the black liquor in
their altered form.
Department of Chemistry, Govt.SC, Bommankatte Page 50
Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Lignin was precipitated successfully from black liquor at
different pH values, precipitates of good quality
It is very difficult to elucidate the structure of lignin because of
different structure of lignin is present in different wood.
Instead of using lignin for only combustion to produce power but it
can be used to isolate lignin which is commercially demanded.
Not all the lignin produced from black liquor is used for power
production, some of it is treated and let to water recourses.
Lignin can be used to synthesis many alternatives like, an alternative
to plastic, vanillin, agricultural chemicals and many more and also raw
materials for several chemicals and high quality bleached paper. From
which we can conserve our natural resources from getting vanished
from the face of the earth and preventing pollution of our
environment.
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
PHOTOS:
Fig: Semisolid Black Liquor.
Fig: Wood Barks
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Fig: Wood chips
Fig: black liquor
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Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
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The institute of paper chemistry, Appleton, Wisconsin.
Wood and Cellulosic chemistry by, David N.S.Hon.Nobuo shiraishi-
Marcel Dekker 2001.
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BEST AVAILABLE TECHNIQUES FOR THE PULP AND PAPER
INDUSTRY,CEMBUREAU 2000
http://www.cembureau.be/Documents/Publications/
CEMBUREAU_BAT_Reference_Document_2000-03.pdf
Department of Chemistry, Govt.SC, Bommankatte Page 54
Study and Characterization of Polyphenolic compounds from Black Liquor of Kraft Pulping
Energy and Cost Reduction in the Pulp and Paper industry – A
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