sustainable chemistry in wood transformation

Sustainable Chemistry in Wood Transformation

Tatjana Stevanovic, Professor

Wood Sciences and Forestry Department, Laval

University, Quebec City, Canada

55th International Convention of Society of Wood Science and Technology, Beijing, 27-

31 August 2012

Sustainable Chemistry

• “Green chemistry also known as sustainable chemistry, is the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances. Green chemistry applies across the life cycle of a chemical product, including its design, manufacture, and use.”

• 12 principles of sustainable chemistry are defined • Inspired by these the 12 principles of green engineering

into which wood engineering is perfectly integrated • We shall be exploring some of them through the case

study of two selected wood transformation processes


31 August 2012

Prevention Instead of Treatment of Waste Principle and role of wood chemistry

• Sustainable chemistry principle : • It is better to prevent waste than to treat or clean it up after

it is formed – part of wood transformation practices for a long time – Word waste replaced by “residue”

• Use of sawdust, shavings, small diameter wood etc. as feedstock for wood panels and pulp and paper manufacture is a long time practice


31 August 2012

Wood engineering practices and biorefinery concept

• Biorefinery concept of wood transformation as a holistic approach to forest biomass transformation

• Sustainable engineering principle: Integrate Material and Energy Flows: – Design of products, processes, and systems must

include integration and interconnectivity with available energy and materials flows

55th International Convention of Society of Wood Science and Technology, Beijing, 27-31

August 2012

Examples of biorefinery concept in wood transformation

• The co-generation of energy by combustion of the residues within the same mill is a common practice

• the multiple projects on cellulosic ethanol are proposed • production of nano-cellulose from highly purified

chemical pulp under development • pyrolysis of forest biomass for production of biofuels

– The good knowledge of wood chemistry is essential for all further developments and design of innovative wood products within the biorefinery concept


August 2012

Renewable rather than depleting: wood as raw material

• Sustainable chemistry principle: • Material and energy inputs should be renewable rather than depleting

– Obviously applied by wood industry which is dealing with a renewable material

– Should secure its favorable position in all future developments • Two innovative wood transformation processes and how the sustainable

(green) chemistry and engineering principles apply to them will be reviewed

– NWFP based on phenolic extractives from bark – Innovative technology of welding solid wood without

adhesives.


31 August 2012

Extraction of bioactive molecules from bark and forest bioefinery

• Sustainable engineering principle: – Design for Separation and Purification Operations: should be

designed to minimize energy consumption and materials use

• Green (sustainable) chemistry principle: – Atom Economy: Design methods to maximize the incorporation

of all materials used in the process into the final product, are applied in the processes of the forest biomass extraction

• Contribution to atom economy by saving the bioactive molecules from residues of wood transformation, such as bark, most readily and abundantly available – Polyphenols from bark


August 2012

Bark extractives from Canadian species • bark extractives available from commercial wood species

of Canada • real potential to integrate the extraction as part of the

biorefinery concept into primary transformation of wood • extraction with green solvents (primarily water and

ethanol) of residual bark • The extracted bark still available as source of fibers or for

energy production • sustainable chemistry principles by saving the atoms in

the molecules so ingeniously synthesized by nature


August 2012

Selection criteria Ethnopharmacological data

Commercial importance


August 2012

Hot water extract from black spruce bark

• Important antioxidant and anti-inflammatory properties – NWFP- Antioxidants of natural (plant) origin – High content of total phenols and flavonoids – low toxicity on normal human keratinocytes – adequate chemical reactivity towards different free radicals

involved in psoriasis, a skin disorder affecting up to 2 % of the world’s population

• Potential of very high value pharmaceutical application of the hot water extract of black spruce bark and its fractions


August 2012

Ethyl-acetate fraction of hot water extract of black spruce Picea mariana bark composed of lignans, neolignans,

cinnamic acids, flavonoids and stilbene resveratrol, along with minor quantities of other phenols and terpene

derivatives

3'2'

4'1'

5' 6'

β′

α′ 1

3

4

2

56

OH

OH

OH

Trans-resveratrol


August 2012

12

Black spruce bark- new source of resveratrol

Source Resvératrol (µg.g-1)

Dark chocolate** 0.4

Raisins variety Thompson

40.61

Peanuts 0.03-0.14

Black spruce bark 104.19

http://astronutrition.com

3'2'

4'1'

5' 6'

β′

α′ 1

3

4

2

56

OH

OH

OH

Commercial extracts

Resveratrol (mg/100 g

extrait)

Red wine 337

Red grape skin** 60-75

White grape skin** 63

Red grape seeds** 27

White grape seeds** 25

Polygonum cuspitatum** 19719

Purified black spruce bark extract

502.95

**Counet et al (2006). Food Chemistry 98 : 649-656


August 2012

Forest and agricultural resources belong to the same world- better synergy needed

• Trans-resveratrol concentration in black spruce bark 109 mg/g, while in grapes only 40 mg/g – Black spruce bark an interesting alternative source of this

valuable bioactive molecule

• Further study: Crude water extract of black spruce bark obtained on a larger scale – same chromatographic profile and the comparable

contents of the total phenols constituents


August 2012

Black spruce bark water extract and its fractions

• The crude water extract examined in form of powder on rats: does not have any adverse effects as demonstrated by acute toxicity tests

• real potential of innovative bio-products based on hot water extract of black spruce bark and of its fractions – natural health products, – antioxidants – food supplements – pharmaceuticals – Ingredients of novel cosmetic products.


August 2012

ECO-CONCEPTION OF LAMINATED WOOD PANELS

Sustainable production of laminated wood panels by rotational dowel welding


August 2012

Rotational wood-dowel welding

• produces wood joints of considerable strength without any adhesive, an opportunity to – increase productivity – reduce costs of the furniture production – eliminate need for synthetic adhesives of

petrochemical origin – significantly reduce (eliminate) the time required for

the gluing process


August 2012

Sustainable chemistry and engineering principles involved in wood welding

• Use of Renewable Feedstocks • Maximize Efficiency:

– maximize mass, energy, space, and time efficiency

• Minimize Material Diversity – Material diversity in multicomponent

products should be minimized to promote disassembly and value retention


August 2012

Sugar maple (Acer saccharum) and Yellow birch (Betula alleghaniensis)

• investigated parameters : – grain orientation, rotational speed and insertion speed

on specially designed welding machine in CRIQ

• Temperature profile measurements at the interface -the maximum temperature – applied in the study of the gases which are released in

form of fume during wood welding. • Optimal welding parameters based on mechanical

properties of the welded products determined from the dowel withdrawal


August 2012

Optimal welding parameters - machine designed for the project • rotational speed of 1000 RPM for both species • A 25 mm s-1 insertion speed for sugar maple • 16.7 mm s-1 insertion speed for yellow birch • Peak welding temperatures with optimal parameters:

– 244˚C for sugar maple and 282˚C for yellow birch

• To prepare panel specimens, 25x30x225 mm slats of sugar maple and yellow birch wood were cut from clear wood material.


August 2012

Scheme of a dowel-welded panel


August 2012

Rotational dowel-welding

• dowels : 9.68 mm in diameter and 96 mm • welded by insertion into pre-drilled holes (7.67 mm in

diameter and 50 mm deep into two adjacent slats as illustrated

• Same species for each dowel –slat combination • Friction between the dowel and substrate during insertion

(less than 3 s) combined with high-speed dowel rotation: – temperature rise, thermochemical transformations of lignin and

carbohydrates, “molten” material which upon the release of pressure solidifies and ultimately induces the wood to weld


August 2012

Advantages of rotational wood dowel-welding

• The usual adhesive in hardwood panelling polyvinyl acetate (PVA), requires long curing time (up to 24 hours) and multiple handling

• These constraints limit the production flow and flexibility required for customized production

• Dowel wood welding – improves the efficiency of production, reduces the use

of petrochemicals, lowering of production costs


August 2012

Adhesion mechanisms in wood-to-wood welding

• Material collected from the welding zone analysed by Py-GC-MS, XPS and FT-IR

• The results obtained reveal that the thermochemical changes can be related to the mechanisms involved in fast pyrolysis, characterized by high pressures applied which are limiting the availability of the oxygen at the interface.


August 2012

Study of gases released during wood welding

• VOCs studied by Pyr-GC-MS – no harmful gases • valuable information for air safety inspections important

for future implementation of wood-welding technology • The composition of the non-condensable gases (NCG)

was close to that found in pure air, – CO was not detected, traces of CO2 and hydrogen

• The wood-welding technology developed by our team with a specially designed machine by CRIQ can be applied to the eco-conception of wood-welded panels for furniture and other indoor appearance applications


August 2012

100% sugar maple

No adhesive

66 cm wide (26’’)

46 cm high (18’’)

36 cm deep (14¼’’)

228 wood dowels

Small-scale crib

Potential of wood welding technology in green construction

• Our preliminary results with dowel-welding of black spruce indicate a potential of applying this technology in green (sustainable) construction

• Same line with the results published on manual dowel welding of Norway spruce (Bocquet et al., 2007 a,b).


August 2012

Conclusions

• Black spruce bark extract with hot water – contributes to saving atoms in molecules recovered by extraction

with green solvent – Extracted bark remains available as source of fibres or energy

• Wood welding -assembling wood slats into laminated panels – relies on wood chemistry and implicates several sustainable

chemistry and engineering principles – ecological panels fully recyclable at the end of service life

• The public awareness of environmental and health implications of wood transformation -a shift towards sustainable wood

transformation based on principles of green chemistry and sustainable engineering.


August 2012

Acknowledgments and partners

55th International Convention of Society of Wood Science and Technology, Beijing,

27-31 August 2012

Acknowledgments to project participants

• Martha Estrella Garcia Perez, Ph.D student • Benoit Belleville, Ph.D student • Gina Rodriguez, M.Sci student • Ying Sun, M.Sci student • Papa Niokhor Diouf, postdoctoral fellow • Mariana Royer, postdoctoral fellow • Maria Prado, M. Sci student • Sanja Erakovic, Ph.D student


August 2012

sustainable chemistry in wood transformation

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