DEVELOPMENT OF NANO WATER FILTER

Submitted by

Asha DaraAshwin S NathHiba AbdullaM. Ziyad Sayed

Under the guidance of Mr K.HARI BABU

Water: The Building Block of Life

• Most important substances on earth.

• All plants and animals must have water to survive.

• If there was no water there would be no life on earth.

• Also essential for the healthy growth of farm crops and farm stock and used in the manufacture of many products.

• Pure water does not exist naturally on our planet; water is the universal solvent, and most other substances present on Earth dissolve in it to different degrees

INTRODUCTION

Drinking water availability around the world

Over 70% of our Earth's surface is covered by water.

97.5% of all water on Earth is salt water, leaving only 2.5% as fresh water, nearly 70% of that fresh water is frozen in the icecaps of Antarctica and Greenland

Only ~1% of the world's fresh water is accessible for direct human uses

As a result, some 1.1 billion people worldwide lack access to water, and a total of 2.7 billion find water scarce for at least one month of the year

Reasons for drinking water shortages

Water pollution: many sources including pesticides and fertilizers that wash away

from farms untreated human wastewater industrial waste Even groundwater is not safe from pollution, as many pollutants

can leach into underground aquifers toxic substances from industrial processes leaky irrigation systems inefficient application methods

Major Variable to be tested in Indian Surface water

Role of water purifier in the present scenario

It provides clean drinking water in the regions of pure water shortage

It is also helpful in disaster struck areas It can be used by hikers

WORLD STANDARD AVAILABLE PRODUCTS

Conventional methods available and methods selected

Disinfection : Available methods: Chlorine UV Boiling Distillation

Method Selected: UV

Advantages of UV over the other methods No known toxic or significant nontoxic byproducts environmentally friendly Unlike chlorine, are effective against both Cryptosporidium and Giardia Destroys 99% of microbes Disinfect water faster than chlorine No micro-organisms known to be resistant to UV, (hepatitis virus and Legionella pneumophila

are some of the microbes resistant to chlorine ) 

Conventional methods available and methods selected contd...

Membrane Filtration 

Available methods: Ceramic membranes Polymeric membranes

Method selected: Polymeric membrane(polypropylene membrane)

Advantages of Polymeric Membranes: far less prone to adsorption effects resulting in higher measurable flux rates and

longer service life of the respective filtration modules. Also it is more elastic and can be used for wide variety of purposes

  

Conventional methods available and methods selected contd...

Adsorption

Available methods: Activated carbon Activated alumina

Method selected: activated carbon

Photo catalytic oxidation by nanoparticles

Available techniques: zno2 tio2 

Conventional methods available and methods selected contd...

Method selected: TiO2

Advantages of tio2 over the other method: ZnO is unstable with respect to incongruous dissolution of yield

(OH) on the ZnO particle surfaces and thus leading to catalyst inactivation over time.

Compared to other available semiconductor photo catalysts, TiO2 is unique in its chemical and biological inertness, photo stability , high oxidation efficiency, no toxicity, environmentally friendly nature.

Low cost of production owing to the abundance of Ti (0.44% of Earth’s crust).

Principles of Methods Used

Activated Carbon

works by the process of adsorption. full of pores. This network of connected pores inside the

carbon gives it a large

surface area (approx.

1000 sq M per gm of carbon)

for adsorption

Activated Carbon contd...

The efficiency of the adsorption process is influenced by carbon characteristics (particle and pore size, surface area, density and hardness) and the contaminant characteristics (concentration, tendency of chemical to leave the water, solubility of the contaminant, and contaminant attraction to the carbon surface).

A particle of activated carbon

Granulated Activated Carbon Isotherm

used by carbon manufacturers to characterize the ability of a particular GAC to remove a specific contaminant .

describes the equilibrium relationship between the adsorbate, adsorbent, and the equilibrium concentration of the adsorbate in water.

are typically shown graphically on log-log plots. On such plots, more adsorbable compounds have higher and flatter lines than less adsorbable compounds

most common mathematical expressions used to relate the adsorption isotherm are the Freundlich equation and the Langmuir equation.

The Freundlich equation has the following form: qe = KCe1/n and can be

linearized as log qe = log K +1/n *log Ce

Granulated Activated Carbon Isotherm contd...

where: qe = equilibrium loading on the GAC (mg chemical/g GAC)

Ce = equilibrium concentration in the water (mg chemical/L)

K = adsorption capacity at unit concentration (mg/g)(L/mg)1/n

1/n = strength of adsorption (dimensionless) The Langmuir equation has the following form:

qe = (qmaxbCe)/(1+bCe)

and can be linearized as follows:

1/qe = 1/(qmaxbCe + 1/qmax

where: qmax = ultimate adsorption capacity (mg chemical/g GAC)

b = relative energy of adsorption (L/mg)

An isotherm is typically determined by running several batch reactors, typically bottles, in parallel

Figure: a typical GAC isotherm

Contaminants Removed by Activated Carbon

remove many volatile organic chemicals (VOC), pesticides and herbicides, as well as chlorine, benzene, trihalomethane (THM) compounds, radon, solvents and hundreds of other man-made chemicals found in tap water.

Some are moderately effective at removing some heavy metals.

In addition, densely compacted carbon block filters mechanically remove particles down to 0.5 micron, including Giardia and Cryptosporidium, turbidity and particulates.

some iron, manganese, and hydrogen sulfide will be removed by these higher quality activated carbon filters.

Contaminants Not Removed by Activated Carbon

Not generally successful at removing dissolved inorganic contaminants or metals such as minerals/salts (hardness or scale-causing contaminants), antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, copper, fluoride, mercury, nickel, nitrates/nitrites, selenium, sulfate, thallium, and certain radio nuclides.

GAC does not remove sediment / particulate material very well, so they are often preceded by a sediment filter.

 

Titanium dioxide

TiO2 is a semi conductive material is a photo catalyst under ultraviolet (UV) light during illumination acts as a strong oxidizing agent lowering the

activation energy for the decomposition of organic and inorganic compounds.

The illumination of the surface of the TiO2 induces the separation of two types of carriers: (1) an electron (e−) and (2) a hole (h+).

The recombination of holes and electrons is relatively slow in TiO2 compared to electrically conducting materials, i.e., metals where the recombination occurs immediately. 

Figure : Action of TiO2 on organic pollutants

Modification of activated carbon by coating it with TiO2 nanospindles

one main drawback of the TiO2 nanostructures is their easy loss during the process of water treatment, resulting in low utilization rate and high cost.

the immobilization of TiO2 nanoparticles onto some supports such as carbon nanotube , glass , ceramic , and activated carbon can improve the reuse efficiency of TiO2,

The TiO2 nanospindle coating on the surface of AC indicated excellent capability in photo catalytic degrading organic compounds.

capable of prolonging the separation lifetime of photogenerated e−/h+, resulting in the increasing rate of ∙OH radical generation by the photo catalyst.

Therefore, the synergistic effect between AC and TiO2 nanospindles indicates greater degradation rate than pure TiO2 nanospindles.

This also reduces bacterial growth on activated carbon in the long run since TiO2 nanoparticles have antimicrobial activities

Polymeric membrane (polypropylene membrane) liquid containing two or more components comes into contact with a membrane

that permits some components to pass through the membrane (the permeate), while the other components cannot pass through it (the retentate)

based on the component particle size. may have a relatively uniform pore structure throughout the thickness; such

symmetrical structures act as depth filters. Alternatively, the membrane may consist of a thin layer with fine pores (active layer or “skin”) overlaying a thicker layer with larger pores to provide mechanical support but little resistance to water flow

The mass flux, n, of a solution of density, ρ, and viscosity, μ, through pore flow membranes with a porosity, ε, can be modeled as flow through a circular tube of radius, R, and length, L, using the well-known Hagen-Poiseuille equation

  n=(ɛ ρ R^2/(8 μ L))*(PO-PL)

where the pressure difference between the entrance of the pore and the exit of the pore [p0 − pL] drives the flow.

Figure : membrane filtration

Figure : SEM image of polypropylene membrane

Ultra violet radiation

UV can be separated into various ranges, with short-wavelength UV (UVC) considered “germicidal UV”. 

At certain wavelengths, UV is mutagenic to bacteria, viruses and other microorganisms. Particularly at wavelengths around 250–260 nm, UV breaks molecular bonds within microorganismal DNA, producing thymine dimers that can kill or disable the organisms.

Microorganisms have less protection from UV and cannot survive prolonged exposure to it.

UV disinfects water containing bacteria, viruses, and Giardia lamblia and Cryptosporidium cysts.

Effect of UV rays on bacterial and virus DNA

Modified membrane using TiO2 coating A number of approaches are available to reduce the membrane fouling. An increase in membrane hydrophilicity improves the membrane resistance to

fouling. A recently established method to improve the membrane anti-fouling properties is the usage of TiO2 nanoparticles on the membrane surface.

When TiO2 nanoparticles are irradiated by a ray equal to or greater than the band gap energy in ordinary conditions, a pair of holes and electrons is created on the surface of particles.

The photo-generated electrons tend to reduce Ti(IV) cations to the Ti(III) state and the holes oxidize O2

− anions. In this process, the oxygen atoms are thrown out, and a group of oxygen vacancies are produced on the surface.

The water molecules in the environment can occupy the empty sites, and adsorbed (OH) groups are created on the surface which considerably increase the hydrophilicity of the surface

In this work, the role of the increasing of hydrophilicity was studied as an effective factor on the anti-fouling performance of membranes..

EXPERIMENTAL SECTION

Materials  Titanium oxide sulphate, sodium oxalate, hydrogen peroxide, titanium tetra

isopropoxide,2-propanol,nitric acid ,ammonium hydroxide and ammonia solution which were used for the synthesis of titanium dioxide nanospindles and titanium oxide nanoparticles were purchased from Krishna Agencies, Calicut and were used without further purification. Polypropylne membrane(.2 micron) , activated carbon and Ultra violet light used in this project was supplied by Green Water Concepts, Feroke

Experimental procedure

Preparation of Titanium dioxide Nanospindles 3.00 g TiOSO4 powders dissolved into

350 mL de-ionized water by a vigorous

stirring for 0.5 h.

then aqueous solution of NH3 .H2O

with a concentration of 10 wt% was added

drop-wise into the above solution.

Solution of TiSO4 in water

Preparation of Titanium dioxide Nanospindles contd..

the white precipitation was obtained by

a centrifugal separation which was mixed

with 250 mL de-ionized water with a vigorous

stirring again a mixture solution involving 2 g of sodium

oxalate and 150 mL de-ionized water was

added slowly into the above solution. After a vigorous stirring for 0.5 h, the

precipitation was separated by a centrifuge.

Precipitation due to the addition

of NH3OH to the TiOSO4 solution

Preparation of Titanium dioxide Nanospindles contd..

Finally, the mixture including 4 g of H2O2 and 250 mL deionized water was used as the react reagent, which was reacted with the obtained products from step 2 for 12 h until a brown transparent solution was produced .

then it was kept heating at 100°C for 6 h.

The large scale of TiO2 Nano spindles was formed and uniformly distributed in the water

Preparation of TiO2/Activated Carbon Composite

1 g of granular AC particles (average diameter of 4 mm) was suspended in the TiO2 suspension prepared by continuous slow stirring for 1 h and then kept at room temperature for 10 h.

the AC granular particles with the TiO2 coating were obtained after a simple vacuum filtration process and then dried at 70°C for 12 h

Preparation of TiO2 nanoparticles The starting solution used is a mixture of 5 ml titanium isopropoxide,

TTIP and about 15 ml of 2-propanol . A 250 ml solution of distilled water with various ph was used as the

hydrolysis catalyst. The desired pH value of the solution was adjusted by adding HNO3 or NH4 OH.

The gel preparation process started when both solutions were mixed together under vigorous stirring.

Hydrolysis of TTIP produced a turbid solution which was heated up to 60–70˚C for almost 18–20 h (peptization).

After peptization process, the volume of the solution decreases to 50 cm3 and a suspension was produced. The prepared precipitates were washed with ethanol and dried for several hours at 100˚C. After being washed with ethanol and dried at 100˚C in a vacuum system for 3 h, a yellow-white powder is obtained.

Finally, the prepared powder was heated at temperatures ranging from 200 to 800˚C for 2 h.

Preparation of TiO2 nanoparticles

After peptization process, the volume of the solution decreases to 50 cm3 and a suspension was produced. The prepared precipitates were washed with ethanol and dried for several hours at 100˚C. After being washed with ethanol and dried at 100˚C in a vacuum system for 3 h, a yellow-white powder is obtained.

Finally, the prepared powder was heated at temperatures ranging from 200 to 800˚C for 2 h

Impregnation of Ceramic membrane with titanium oxide nanospindles(sol gel method)

A solution of TTIP in isopropanol (0.45 M) was added drop wise into a solution of isopropanol (4.5 M) in distilled water under vigorous stirring.

After the hydrolysis reaction was complete, the remaining white precipitate of titanium hydroxide (Ti (OH) 4) was filtered and washed with water to remove the alcohol.

The filtrate was then dispersed in distilled water (Ti4+) and nitric acid was added to achieve a 0.5 molar ratio of acid/alkoxide (H+/Ti4+).

Next, the solution was peptized for 2 h at 70 °C. A closed beaker was used to enhance the rate of peptization.

The final product was a blue, semi-opaque colloidal dispersion at a concentration of 0.325 M. A dilute concentration of the dispersion was produced by dilution with distilled water.

Then the membrane is immersed in this solution for 6 hrs at 60 °C .Then the membrane is dried and calcined at 200 °C for 2hrs

Evaluation of Photo Catalytic Activity of TiO2

This was performed with the help of an experimental set up called peristaltic pump that facilitates the continuous flow of water through the prepared experimental filter set up. This set up consists of a peristaltic pump, a filter cartridge , a silicon tube and a sample source.

The experimental set up involving peristaltic pump and filter cartridge

Individual elements of the experimental set up

Peristaltic pump a type of positive displacement pump used for pumping a variety of fluids. based on alternating compression

and relaxation of the hose or tube

drawing the contents into the hose

or tube, operating in a similar way

to our throat and intestines

Fig : a peristaltic pump

Peristaltic pump contd...

A rotating shoe or roller passes along the length of the hose or tube totally compressing it and creating a seal between suction & discharge side of the pump, eliminating product slip.

Upon restitution of the hose or tube a strong vacuum is formed drawing product into the pump.

The medium to be pumped does not come into contact with any moving parts and is totally contained within a robust, heavy-duty hose or a precision extruded tube.

This pumping action makes the pump suitable for accurate dosing applications and has a pressure rating up to 16 bar (hose) and 2 bar (tube).

The high pressure hose has inner layer of 2-6 reinforcement layers and an outer layer, which allow higher working pressures and generate higher suction lifts than non re-enforced tubing

Silicone tubing It is important to select tubing with appropriate chemical resistance

towards the liquid being pumped. Types of tubing commonly used in

peristaltic pumps include (PVC), Silicone

rubber, Fluoropolymer and PharMed. Silicone rubber is an elastomer (rubber-

like material) composed of silicone—itself

a polymer —containing silicon together

with carbon , hydrogen and oxygen. generally non-reactive, stable, and

resistant to extreme environments and

temperatures from -55 °C to +300 °C while

still maintaining its useful properties

Filter cartridge column

A filter cartridge used for filtration

is embedded within the column. It consists of an outer layer of granulated

activated carbon coated with titanium

dioxide nanospindles , an inner layer of

a .2 micron pore size polypropylene

membrane coated with titanium

nanoparticles.

Filter cartridge column contd...

The experiment is carried out in the presence of UV light. The milk sample was allowed to pass through the filter for

sometime. After fixed intervals of time, the product that is coming through

the filter column is collected and tested for various properties . The values obtained were tabulated for various cases like

activated carbon with and without the TiO2 coating, polymeric membrane with and without coating etc.

The operational mode was cross flow batch concentration, i.e. the concentrate was recycled to the feed tank. The feed is pumped into the cell and the volumetric flux of liquid which passes through the membrane is measured every 15 min.

The change in flow rate after filtering for a long time( around 3hrs) was also measured and membrane fouling was determined

Sample

1

Sample

2

Sample

3

Sample

4

Sample

5

Sample

60

150ACTIVATED CARBON TREATMENT 6g

UntreatedTreated

SAMPLES

TOTA

L D

IS-

SOLV

ED S

OLI

DS

(ppm

)

Sample

1

Sample

2

Sample

3

Sample

4

Sample

5

Sample

60

204060

UntreatedTreated

SAMPLESTURB

IDIT

Y (N

TU)

RESULTS

Sample

1

Sample

2

Sample

3

Sample

4

Sample

5

Sample

60

50100150200 MICRON FILTER -6mm

UntreatedTreated

SAMPLES

TOTA

L D

ISSO

LVED

SO

LID

S (p

pm)

Sample

1

Sample

2

Sample

3

Sample

4

Sample

5

Sample

60

1020304050

UntreatedTreated

SAMPLESTURB

IDIT

Y (N

TU)

Sample

1

Sample

2

Sample

3

Sample

4

Sample

5

Sample

60

50100150200

MICRON FILTER-9mm + 6g Activated Carbon

UntreatedTreated

SAMPLES

TOTA

L D

ISSO

LVED

SO

LID

S (p

pm)

Sample

1

Sample

2

Sample

3

Sample

4

Sample

5

Sample

60

1020304050

UntreatedTreated

SAMPLESTURB

IDIT

Y (N

TU)

1 5 3 0 4 5 6 0 7 5 9 0 1 0 5 1 2 0 1 3 5 1 5 0 1 6 5 1 8 0 1 9 5 2 1 0 2 2 5 2 4 00

1

2

3

4

5

6

7

8

9 Membrane coated with TiO2 nanoparticles (0.01wt%) with UV radiation

Membrane coated with TiO2 nanopaticles (0.03wt%) with UV radiation

Membrane without coating under UV radiation

Membrane without coating

Membrance coated with TiO2 nanoparticles (0.01wt%) without UV radiation

time (mIn)

Flux

(l/m

2 hr

)

1 5 3 0 4 5 6 0 7 5 9 0 1 0 5 1 2 0 1 3 5 1 5 0 1 6 5 1 8 0 1 9 5 2 1 0 2 2 5 2 4 00123456789

10

Membrane coated with TiO2 nanoparticles (0.01wt%) with UV radiation while immersed in water for 5min

Membrane coated with TiO2 nanoparticles (0.01wt%) with UV radiation

Membrane coated with TiO2 nanoparticles (0.03wt%) with UV radiation while immersed in water for 5min

Membrane coated with TiO2 nanoparticles (0.03wt%) with UV radiation

Membrane without coating

Uncoated membrane with 5min immersion in water before usage

time (min)

flux

(l/m

2 hr

)

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 1800

0.2

0.4

0.6

0.8

1

1.2

Adsorption rate for different ratios of Ti02 / AC

0% 0.50% 2% 1% 1.50%

Irridiation time (min)

Nor

mal

ised

con

c C/

Co

Sample

1

Sample

2

Sample

30

4080

120

ACTIVATED CARBON TREATMENT 6g

UntreatedTreatedTreated with TiO2 impregnated

SAMPLES

TOTA

L D

ISSO

LVED

SO

LID

S (p

pm)

Sample 1 Sample 2 Sample 3010203040

UntreatedTreatedTreated with TiO2 impregnatedSAMPLES

TURB

IDIT

Y (N

TU)

Sample 1 Sample 2 Sample 30

50

100

150 MICRON FILTER -6mm

Untreated Treated Treated with TiO2 impregnated

SAMPLESTOTA

L D

ISSO

LVED

SO

LID

S (p

pm)

Sample 1 Sample 2 Sample 3010203040

UntreatedTreatedTreated with TiO2 Impregnated

SAMPLES

TURB

IDIT

Y (N

TU)

Sample 1 Sample 2 Sample 3050

100150

MICRON FILTER-9mm + 6g Activated Carbon

Untreated

Treated

Treated with TiO2 Impregnated

SAMPLES

TOTA

L D

ISSO

LVED

SO

LID

S (p

pm)

Sample 1 Sample 2 Sample 30

10

20

30

40

Untreated Treated Treated with TiO2 ImpregnatedSAMPLESTU

RBID

ITY

(NTU

)

0 50 100 150 200 250 3000

1

2

3

4

5

6

7

8

9

f(x) = − 0.0186176470588235 x + 7.4925

Flux Vs Time

Time (mins)

Flux

(L/m

2 h

r)APPROXIMATE MINIMUM LIFE EXPECTANCY

CONCLUSION

Different methods are employed in purification of water in different regions as depending upon the impurities present

Major Comparison to the Existing methods

1. It is a techniques which uses TiO2 to oxidize and kill microorganism. Other methods

include ionization of water or reduction of pore size etc.

2. The minimum theoretical value for capacity for our cartridge would be 200 litre.

Whereas market provides products which can serve for a capacity of 300-400litres

3. Increases lifetime of the cartridge as it reduces fouling .

4. TiO2 is a potential compound which can serve for high purification in the future