GREEN CHEMISTRY AND SUSTAINABLE

Environmental Engineering and Management Journal, October 2006, Vol.5, No.4, 545-558

http://omicron.ch.tuiasi.ro/EEMJ/

_______________________________________________________________________

ICEEM/03 – ENVIRONMENTAL ENGINEERING SECTION

Environmental Pollution and Monitoring

GREEN CHEMISTRY AND SUSTAINABLE DEVELOPMENT

Valentin Popa*, Irina Volf

“Gh. Asachi” Technical University of Iasi, Faculty of Chemical Engineering, Departments of Pulp

and Paper and Environmental Engineering and Management, 71 D. Mangeron Blvd., 700050 Iasi, Romania

Abstract “Green chemistry” is chemistry for environment and is really a philosophy and a way of thinking what can help chemists in research and production to develop more eco-friendly and efficient products and processes. The biosynthesis processes are known as inducing accumulation – in Nature – of some significant amounts of chemical compounds, most of them being indispensable for normal evolution of human society. Our studies lead us to the conclusion that phytomass could be processed to assure a suitable resource not only for chemical compound and energy (biodiesel production, ethanol, landfill gas or biogas, Btu gas) but also for biological compounds or forerunners for them. Thus by using different kinds of phytomass we have demonstrated the possibilities to separate and to utilize natural aromatic products (lignins or its derivatives and polyphenols) in nonmodified and modified forms in several biological systems. The biological activity of these products was tested in experiments of plant development. Keywords: green chemistry, biomass, phytomass, energy, biofuel, biological compounds 1. Introduction

“Green chemistry” is chemistry for environment and is really a philosophy

and a way of thinking what can help chemists in research and production to develop more eco-friendly and efficient products and processes. The term “Green Chemistry” describes an area of research arising from scientific discoveries about pollution and from public perception in much the same way as the identification and understanding of a deadly discuss stimulates the call for a

* Author to whom all correspondence should be addressed: Phone: +40-232-278683, e-mail: [email protected]

“Gh. Asachi” Technical University of Iasi, Romania

Popa and Volf/Environmental Engineering and Management Journal 5 (2006), 4, 545-558

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cure. The term represents the assumption that chemical processes that carry environmental negatives can be replaced with less polluting or nonpolluting alternatives. Green Chemistry is utilization of a set of principles that reduce or eliminates the use or generation of hazardous substances in the design, manufacture and application of chemical products. Green chemistry involves the design and redesign of chemical syntheses and chemical products to prevent pollution and thereby solve problems. In the past, chemistry has caused many environmental problems but chemical industry is now trying to address some of these issues by applying the Twelve Principles of Green Chemistry:

1. Prevention – it is better to prevent waste than to treat or clean up waste after it has been created.

2. Atom Economy – synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.

3. Less Hazardous Chemical Syntheses – wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment.

4. Designing Safer Chemicals – chemical products should be designed to affect their desired function while minimizing their toxicity.

5. Safer Solvents and Auxiliaries – the use of auxiliary substances (e.g. solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used.

6. Design for Energy Efficiency – energy requirements of chemical processes should be recognized for their environmental and economic impacts and should be minimized. If possible synthetic methods should be conducted at ambient temperature and pressure.

7. Use of Renewable Feedstock – a raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.

8. Reduce Derivatives – unnecessary derivatization (use of blocking groups, protection/deprotection, and temporary modification of physical/chemical processes) should be minimized or avoided if possible, because such steps require additional reagents and can generate waste.

9. Catalysis – catalytic reagents are superior to stoichiometric reagents. 10. Design for Degradation – chemical products should be designed so that

at the end of their function they break down into innocuous degradation products and do not persist in the environment.

11. Real-time Analysis for Pollution Prevention – analytical methodologies need to be further developed to allow for real-time in-process monitoring and control prior to the formation of hazardous substances.

12. Inherently Safer Chemistry for Accident Prevention – substances and the form of a substance used in a chemical process should be chosen to minimize the potential for chemical accidents, including releases, explosions and fires.

Considering the pressures of environmental regulations and the growing awareness of the negative impacts produced by the processes and technologies the chemical industry is facing greater restrictions related to discharges of their

Green chemistry and sustainable development

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wastewater and associated penalties. However, there are alternatives that may be chosen, depending on the

scale of the chemical industrial production facility and the pollutant loads that are identified.

The objectives of this study envisage the possibilities that biomass/phytomass could be processed to assure a suitable resource not only for energy (biodiesel production, ethanol, landfill gas or biogas, Btu gas) but also for chemical and biological compounds or forerunners for them. 2. Sources of biomass/phytomass and evaluation of resources

All sorts of biomass are suitable for sustainable energy. The most important are: organic household, industrial and public wastes, agricultural residues, garden and road side chippings, clean residues of all sorts of wood and from forests, energy crops (energy plantations such as poplar and willow, oilseed crops, latex bearing plants – Asclepias syriaca a.s.o.). At present on a world-wide basis 55% of all wood consumed is for fuel, 30% for paper and 15% for solid wood products. From an environmental perspective, wood is preferable to fossil fuels for energy, to agricultural fibers for paper, and to steel or plastics for material applications. It is a huge potential to increase world wood growth through use biotechnology and modern silvicultural practices such as culture of hardwood species and annuals, rotating crops, double crops, control of the harvesting/planting ratio, integral utilization of tree or plant, utilization of forestry resources, selection of vegetal species for generating a high biomass production, annual plantations with a high yield of solar energy conversion and s.o. It was estimated that the products resulted from photosynthesis represents 150x109 t/year. At European level a quantity of 24x106 t/year of wheat straw could be taken into account.

In the case of resources evaluation it is necessary to estimate the removable phytomass (green mass dried basis) but also the energy content, the energy potential and the cost of biomass production at the forest road sides and the biomass user gate too, including harvesting, skidding, comminuting of biomass and transportation (Table 1).

Table 1. Products resulted from completely upgrading forest resources

(Rozmarin and Popa,1982)

Wood used for pulp obtaining 65 % Wood for chemical conversion or used as fuel 10 % Bark 15 % Leafage 10 % 3. Biomass/Phytomass for energy

It is well known that if current energy consumption trends and structural

changes in the global economy continue, the world’s energy consumption will


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be doubled over the next thirty years. Having in mind that in 2030, 90% of energy consumption will based on fossil resources, the use of biomass/phytomass for energy can be one way to reduce the ever-increasing emissions of carbon dioxide, one of the main gases responsible for global warming.

Phytomass for energy uses presents the folowing important advantages: - it is mainly an indigenous source and therefore reduces dependency on

energy imports and increase security of supply; - like the other renewable, it has an enormous potential for job creation

predominantly in agriculture and forestry and in small and medium sized enterprises;

- technologies for renewable energy carriers of European industries offer promising business opportunities, because world wide energy consumption is expected to grow;

- in many industries, biomass (phytomass) is a by-products of industrial processes, so its utilization solves both a waste and energy problem;

Moral responsibility for future generation forces the industrial nations to aspire to sustainability. Sustainability, in the long term, cannot rely on finite resources and phytomass as renewable raw material could correspond to this concept. In a summary presentation the most important energy technologies based on biomass are:

- Direct combustion – it is a thermo- chemical conversion process type that utilized as major biomass feedstock wood, agricultural, waste municipal solid and waste residential fuels for heat, steams or electricity (Fig. 1).

- Gasification – it is also a thermo-chemical conversion process type in wich wood, agricultural, waste municipal or solid waste are used for low or medium Btu producer gas (Fig. 1).

Fig.1. Combustion, gasification and pyrolysis. Process and identification of emissions


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- Pyrolysis - it is a thermo -chemical conversion process type that

utilizes as major biomass feedstock wood, agricultural, waste municipal and waste solid for synthetic fuel oil (biocrude) and charcoal (Fig. 1).

- Anaerobic digestion – a biochemical (anaerobic) conversion that process animal manure, agricultural, waste landfills and waste water for biogas obtaining (Fig. 2).

- Ethanol production - a biochemical conversion that could transform sugar or starch, crops, wood waste, pulp sludge and grass straw into ethanol (Fig. 3).

- Biodiesel production - a chemical process that transforms rapeseed, soy bean waste, vegetable oil and animal fats into biodiesel (Fig. 4).

- Methanol production - it is a thermo-chemical conversion process type that utilizes as major biomass feedstock wood, agricultural, waste municipal and solid waste for methanol obtaining.

Fig.2. Technological process and identification of emissions in anaerobic digestion

4. Phytomass for integral and complex processing

The biosynthesis processes are known as inducing accumulation – in the Nature – of some significant amounts of chemical compounds, most of them indispensable for normal evolution of human society. On the other side, the development of sound industry based on synthesis reactions, assures a large


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range of micro- and macromolecular compounds for most diverse utilization.

Fig.3. Technological process and identification of emissions in ethanol production

Fig. 4. Technological process and identification of emissions in biodiesel production

On considering the both the rich existing resources of natural

compounds and their environmental compatibility, the concerns have been


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mainly concentrated on the latter direction of interest (Simionescu et al., 1987, Rusan and Popa, 1992).

All these considerations have determined new directions of study, too: - direct utilization of the individual chemical compounds isolated from biosystems; - chemical processing of biomass and its components by destruction, thus assuring raw materials, for synthesis of polymers and chemical or energy resources; - chemical or biochemical transformation of both components and integral biomass (functionalization or functionality), for specific uses; - elucidation of structures and functions of the natural compounds in biosystem aiming at utilizing them in structures with advanced properties and at simulating their behaviors against physical, chemical and biological agents; -in vitro simulation of natural chemical compounds synthesis. 5. Results and discussion

Studies carried out starting several years ago lead to the

conclusion that phytomass could represent a convenient resource of chemical compounds and energy, if the processing of raw materials, having in view their different sources and different composition, had taken place following a technology allow to separate each compound as a function of the accessible resource. Thus using different kinds of phytomass, both in laboratory and in the pilot plant conditions, various possibilities of biomass complex processing were experimented (Fig. 5).

From the obtained data, it is important to discuss some results concerning isolation, modification and application of lignin and polyphenols products.

As is known the plants have the property to synthesize some micro and macromolecular compounds with aromatic rings, classified in 12 main groups, function of the carbon atoms number existing in structural units (Rusan and Popa, 1990), (phenols, phenolic acids, phenyl acetic acids, hydroxycinnamic acids, naphtoquinone, xanthone, stilbens, flavonoids, lignans, neolignans, biflavonoids, melanins condensed tannins and lignin.

Among these, lignin representing up to 25 % from biomass being the second as importance after cellulose, may be used in different fields (Tudose et al., 2003; Popa and Volf, 2005) (Fig. 6).

By using wastes resulted from wood processing (spruce wood bark) and other grades of biomass (vine stems, grape seeds, Asclepias syriaca herb) it was separated polyphenolic compounds and established a number of important utilizations (Simionescu, 1988, Rotinberg, 1991), (Fig. 7). Lignocellulose resulted after polyphenols extraction may be used as substrate for microorganism cultivation with the aim to obtain proteinaceous materials.


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Fig. 5. Scheme of complex processing of vegetable biomass

Fig. 6. Some possibilities of alkalilignin utilization


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The polyphenols (from spruce bark, beech bark, oak bark) and lignins (lignosulfonates, alkali lignins), non-modified or modified have been used in the experiments of germination, plant cultivation, grafting of vine and vegetal tissue cultures. Some results will be presented as follows (Abaecherli and Popa , 2005; Popa, et al.,1996; Simionescu, 1998).

In the case of plants seeds germination it has been experimented a lot of variants (Figs. 8-11). From the obtained data result that the germination is improved both by polyphenols and lignin samples. The influence on this property depends on the kind of products and their degree of modification. On having in view that lignin plays an important role on humus formation and in these transformations some products are involved in redox plant cell reactions, one can assess that this natural aromatic polymer along with polyphenols might represents a possible source of valuable compounds for plant growth.

Fig. 7. Some possibilities of polyphenols utilizations

To obtain more information about the role played by polyphenols in

the biosynthesis processes it was carried out another series of experiments using tissue culture of Daucus carota. The comparison from the point of view of morphological elements evidenced the positive influence of polyphenols separated from different sources (Simionescu, 1991), (Table 2).


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Fig. 8. Germination capacity of bean seeds treated with: 1-ammonium lignosulfonate; 2-polyphenols from spruce bark; 3- polyphenols from oak bark; 4-polyphenols from

beech bark

020406080

100

0 0.25 0.5 1

Concentration, [g/L]

Ger

min

atio

n, [%

]

1234

Fig. 9. Germination capacity of bean seeds treated with 1-ammonium lignosulfonate; 2-oxidized polyphenols from spruce bark; 3- oxidized polyphenols from oak bark;

4-oxidized polyphenols from beech bark

0

50

100

150

200

0 0.25 0.5 1


Bio

mas

s, [%

]

1234

Fig. 10. Biomass variation for millet seeds treated with nonmodified polyphenols and lignosulfonates: 1-ammonium lignosulfonate; 2-polyphenols from spruce bark;

3- polyphenols from oak bark; 4-polyphenols from beech bark


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050

100150200

0 0.25 0.5 1


Bio

mas

s, [%

]

1234

Fig. 11. Biomass variation for millet seeds treated with oxidized polyphenols and lignosulfonates: 1-ammonium lignosulfonate; 2-oxidized polyphenols from spruce bark;

3- oxidized polyphenols from oak bark; 4-oxidized polyphenols from beech bark

Table 2. Influence of polyphenolic compounds from various types of bark, and of the raw extract from softwood bark on the development of carrot callus

Variant of medium Inoculating

agent developed

on:

Development 2,4-D

0.5 mg/L

OPPH 0.51 mg/L

BPPH 0.43 mg/L

SPPH 0.51 mg/L

SPPH +

BPPH +

OPPH

SBE 2.56 mg/L

SBE 0.84 mg/L

B5 + 2,4-D Callus Adventitious

Shoots Roots

+ - -

++ - -

++

+++ -

+

+++++ +++++

++ - -

++ - -

+

+++++ -

B5 + 2,4-D + OPPH

Callus Adventitious

Shoots Roots

++++ - -

++++ - -

++++ - -

++++ - -

++++

+++++ -

B5 + OPPH Callus Adventitious

Shoots Roots

++

++++ -

++

++++ -

+++ - -

++

+++++ -

++

+++++ -

Estimation of development was made in conventional units from 1 to 5. In the blank spaces, the samples have been removed as infected. OPPH-Polyphenols from oak bark. BPPH-Polyphenols from beech bark. SPPH-Polyphenols from spruce bark. SBE-Alkaline extract from spruce bark.

Further, the action of polyphenols was compared with that of some simple model compounds such as hydroquinone and galic acid in the experiments of tissue cultures (Table 3).

The callus in the control variant did not evolve, it has remained unchanged. The callus grown in the presence of hydroquinone or galic acid, and polyphenols displayed a better caulogenesis and root formation (normally, individuals with roots, shoots and leaves were obtained). The


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photosynthetising pigments content is variable depending on light intensity. The highest values of chlorophyll (a and b) were registered under continuous illumination conditions and on the medium supplemented with polyphenols. The positive influence of polyphenols could be correlated with differentiation of the callus.

Table 3. The variability of some chemical and biochemical traits in vegetative

organs and callus of Daucus carota L

The source and the analised trait

% dry substance

% organic

substance

% mineral

substance

% d.w. a chlorophyll

% d.w. b chlorophyll

Beta-caroten

Callus/control 11.00 72.02 27.98 0.032 0.014 0.0135 Callus/polyphenols 12.00 86.73 13.27 0.065 0.040 0.020

Callus/hydroquinone 12.48 87.95 12.05 0.040 0.018 0.0148 Callus/galic acid 11.75 - - 0.031 0.015 0.022

Leaves, Shoots/polyphenols

8.18 71.24 28.76 0.850 0.550 0.326

Leaves, Shoots/hydroquinone

7.06 82.34 17.66 0.052 0.031 0.028

Leaves, Shoots/gallic acid

6.64 83.82 16.18 0.027 0.017 0.018

The accumulated data (Popa et al., 2000; Popa et al., 2005; Tudose

and Popa, 2000) certifies that polyphenols participate as bioregulators in biosyntesis process from plants (Fig. 12).

From presented data it is obvious that are sufficient arguments to state that polyphenols and lignin derivatives can regulate biosynthesis processes in plants. The action of these compounds depends on their nature, composition, concentration, procedure and degree of modification. Nevertheless, it is necessary to improve our information by developing a research program keeping in mind the following problems which could be of interest:

- the improvement of extraction procedures taking into account the susceptibility of lignin and polyphenols toward the chemical agents and oxidation;

- the complete characterization of extracted products and their derivatives with the aim to establish the compounds which are active in biological systems;

- the elucidation of action mechanism of natural aromatic compounds tested in biological systems following the transmission of information to the nucleic acids level and enzymes involved in biosynthesis processes.


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Fig. 12. Influence of bioregulators on essential physiological processes in plants

6. Conclusions

From the data obtained results that phytomass represents a renewable raw

material which could be used as energy source or processed by biorefinery principles with the possibilities to separate both secondary and main components with chemical and energetical value. The application of chemical and biotechnological processes allow us obtaining compounds which are compatible with environment and which could substitute a lot of chemicals resulted from synthesis.

At the same time it is evident that permanent improvements will be needed in biomass/phytomass management, process and product technology, product standards and performance, and even public education if these materials are to play a key or even significant role in society in coming centuries. Research, technology transfer, and education in the field of green chemistry will be important in determining the future of raw materials in the context of sustainable development.


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Environmental Engineering and Management Journal, 4, 273-292. Popa A.M., Volf I., (2005), Short assessement on the non toxicity and other antioxidant

properties of some compounds with polyphenolic structure, RSCC Magazine, 5, 29-34.

Popa V.I., Beleca C., Popa M., Bodarlau R., Bara I., Truta E., (1996), Studies regarding the behaviour of some individual biological systems under polyphenolic products action, Bol.Soc.Brot., Sec.2, 67, 245-255.

Popa V.I., Volf I., Anghel N., Dumitru M., (2005), Lignin and polyphenols as allelochemicals, In: Proceedings of the 7th International Lignin Institute Forum, Barcelona, 67-71.

Popa V. I., Tudose I., Anghel N., (2000), Influence of polyphenols and lignin products on the biosynthesis processes, In: Proceedings of Annual Meeting and 5th International International Lignin Institute Forum, Bordeaux, 220-228.

Rozmarin G., Popa V.I., (1982), Options concerning the valorification of some lignocellulosics materials, In: Proceedings of New possibilities of reintegrating byproducts in the economic cycle, Piatra Neamt, Romania, April, 23, vol.I, p.207-216.

Rotinberg P., Simionescu Cr.I., Kelemen S., Rusan V., Nuta V., Popa V.I., (1991), Cytostatic and antitumor activity of the polyphenolic preparation pA2, Rev Roum. Biol.-Ser.Biol.Anim., 36 (1-2), 67-71.

Rusan V., Popa, V.I., (1992), Correlations between the chemical components of wood and synthetic polymers, Cellulose Chem. Technol., 26 (5), 591-606.

Rusan V., Popa V.I., (1990), Functional natural polymers with aromatic structure, Celuloza si Hartie, 39 (4), 99-112.

Simionescu Cr.I., Rusan V., Popa V.I., (1987), Options concerning phytomas valorification, Cellulose Chem.Technol, 20 (1), 3-16.

Simionescu Cr.I., Bulacovschi J., Popa V.I., Popa M., Nuta V., Rusan V., (1988) New possibilities of using alkaline extracts from vegetal biomass in adhesive systems for wood industry, Holzforsch. u Holzverwert., 40 (6), 136-140.

Simionescu Cr.I., Popa V.I., Rusan M., Rusan V., (1988), Biodegrdation of vegetal materials under the action of some mixed culture of microorganisms, Cellulose Chem.Technol. 22 (3), 293-301.

Simionescu Cr.I., Popa V.I., Rusan V., Colf V., Zanoaga C.V, Marinescu C., Bara I.,.Vintu S, (1991), Study on the action of some wood bark polyphenolic compounds upon plant growth, Cellulose Chem.Technol. 25 (3-4), 187-195.

Tudose I., Popa A.M., Popa V.I., (2003), Separarea si caracterizarea unor extracte din seminte de struguri rosii cu proprietati antiradicalare , RSCC Magazine, 2, p. 25-28.

Tudose I., Popa V.I., (2000), Plants regulators from stems of Vitis Vinifera, In: Proceedings of Sixth European Workshop on Lignocellulosics and Pulp, Bordeaux, 79-96.

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