The book edited by Haibo Xie and Nicholas
Gathergood focuses on one of the most important
scientific issues of the 21 century which is the
replacing fossil fuel with sustainable alternatives such
as biomass. Fossil fuels are conventional raw
materials for many industrial sectors including
chemical and energy production. Usage of fossil fuel
is limited by their availability, price and carbon
footprint. Biomass is a renewable resource globally
available, cheaper and carbon sequestering. Step by
step shifting towards biomass processed products
usage in all industrial areas including transportation
increases their sustainability and reduces overall
environmental impact.
The first chapter of the book is dedicated to
the familiarization of the reader with the biomass and
biorefinery concepts which are both defined in larger
means. The chapter also stands as a justification of
the research need in the field of replacing of
petroleum and coal based supply chains with
biobased ones is particularly emphasized. The
biorefinery technologies and biorefinery systems are
discussed in general but concise terms together with
critical look over the economic profitability and
environmental aspects. A secondary book chapter
provides information on the general green chemistry
issues. The principles of green chemistry are
enounced, commented and exemplified, by thus
providing a more complete understanding of their
importance, in chapter two. The principles of green
engineering, which are derived from the green
chemistry ones, are also highlighted.
The third chapter gathers information on
ionic liquids (IL) as important emerging new agents
(solvents and catalysts) for fractionation of the
lignocellulosic biomass. The concept of a possible IL
technological approach is illustrated together with the
mechanism of biomass polymers dissolution. These
are further usable as feedstock into different chemical
processing facilities to obtain different sustainable
materials or fuels. Toxicity of IL is an important issue
therefore an important range of microbial and other
living organisms are generally used for testing. Most
of the studies have evidenced a negative
environmental impact of most of the potentially
useful ionic liquids. These are reasons that lead to the
need of sustainable management strategies for IL use,
recovery, recycling or final disposal. Moreover,
research should focus on finding lower toxicity IL.
Searching for solutions to water use as a
biorefinery agent is justified by reasons like safety
and environmentally friendliness. One important
advantage of water use is that water contained by
biomass can be removed in liquid state without
vaporization. Chapter four is mostly dedicated to
lignocellulosics water treatment. The final targets of
these pretreatments are the liberation of sugars, pulp
fibers and lignin derived chemicals. Water biomass
pyrolysis and gasification target on transformation of
solid materials into liquid forms easier to transport.
Such processes have been developed and studied by
different laboratories all over the world. An important
part of this chapter is dedicated to the mechanisms
involved in supercritical water conversion processes.
Chapter five reviews the most promising
Carbon dioxide biomass converting technologies. An
example of such a process is the production of
ethanol by fermentation processes. These CO2 should
be considered on collection and storage since it’s
purity it’s rather high. CO2 has interesting properties
Book Review/Environmental Engineering and Management Journal 12 (2013), 3, 613-615
614
as extraction solvent in certain conditions and has
potential to replace fossil fuel derived solvents.
Supercritical CO2 may be used for extraction of much
valued flavors and aromas from spices and for food
and pharmaceutical industry. Waxes and resins may
be also extracted from wood and further valued in
cosmetics, lubricants, coatings or other applications.
The major impediment in CO2 usage seems to be
linked to direct or indirect costs such as labor or
financing costs. Biomass pelletizing promises the
reduction of volume of investments.
Cellulose is the most abundant natural
polymer, but an important milestone in its
valorization was the lack of its solubility in common
solvents. Dissolution of cellulose, discussed in
chapter six, opens multiple paths towards its
processing. NaOH/urea aqueous solution is a new
solvent system of lower cost and better environmental
performance. In this way, chapter 6 of the book
reviews the most recent advances on the mechanism
of cellulose dissolution in aqueous NaOH/urea system
and solutions properties. Materials such as novel
cellulose fibers, films, gels or derivatives are possible
to be obtained by regeneration of cellulose from these
new solvent solutions.
Organosolv biomass treatment methods
described in chapter seven include interesting new
ways of organic solvent (with or without presence of
catalysts) separation of wood or nonwood
lignocellulosics components. Altough conventional
technologies such as kraft, soda or sulphite are still at
great spread in pulping industry, organosolv methods
promise a higher environmental compatibility
combined with increased economic and technological
potential. Most of organosolv processes utilize
alcohols (especially ethanol), organic acids, phenols
and amines. The employed catalysts are alkalis, acids
and salts. The products should be high quality
cellulose, lignin as well as other chemicals such as
furfural and organic acids. The chapter also provides
important insights on the chemistry of lignin and
polysaccharides reactions during organosolv pulping.
Interesting aspect such as mass balance, enzymatic
digestibility of the obtained cellulose substrate and
properties of the obtained lignins are also included.
Pyrolysis of biomass is regarded as its thermal
decomposition in absence of oxygen, and is presented
in chapter eight. Thermal treatment at temperatures
up to 450-500°C generates products such as solid
char, liquids and gases. The chemical composition of
liquids includes products such as water, organic acids,
aldehydes and ketones, phenols. The liquid phase,
also called bio-oil, may be furthered distilled or
extracted to recover valuable components. Other
ways of adding value to the bio-oil are hydrogenation,
cracking, steam reforming or emulsification. The
generated gas phase is rich in methane, carbon
monoxide and carbon dioxide as well as other
chemical compounds and may be used as fuel or
synthesis gas.
Using of microwave energy in chemistry is
attractive due to the high efficiency of energy
transfer, selectivity or significant reduction of
reaction time. This subject is covered by chapter nine.
By treating wood or nonwood biomass with
microwaves, its enzymatic digestibility is improved.
Adding catalysts, such as peroxomolybdates, to the
process further enhances biomass pretreatment
efficiency. The major obstacle in industrial
applicability of microwave based technology is the
cost of the irradiation equipment.
The tenth chapter of the book discusses the
possibility of “harvesting” the products of microbial
growth on different biomass substrates. Different
microorganism species may be employed to produce
bioethanol, biobutanol or biodiesel mainly by yeasts.
Commodity chemicals such as lactic acid and
succinic acid may be produced by different bacteria.
The main obstacles in microorganisms’ may be
overcome by genetic engineering or adaptation
techniques.
Catalysts have long been recognized as green
chemistry agents. The eleventh chapter describes the
potential applications of the heterogeneous catalysis
in biomass conversion and includes the recent
advances in the field. Heterogeneous catalysis may be
a suitable route for conversion of lignocellulosic
components to polyols or for the production of
biodiesel. The continuity of subject is ensured by the
presence of the twelfth chapter dedicated to catalytic
conversion of glycerol as a byproduct of soaps, fatty
acids and biodiesel industry. Glycerol is valued as the
raw material in the production of diols, acrylic acid,
acrolein and syngas.
Ultrasonic energy utilization in biodiesel
production is described in the thirteenth chapter. High
frequency high energy ultrasounds are responsible of
cavitation, heating, acoustic streaming, cavitation and
free radical generation. These effects may be used to
facilitate the biomass processing by size reduction,
increase in specific surface and better mass transfer.
The complexity of the mixtures obtained by
different treatment methods requires similar
complexity in separation o valuable products.
Membrane technologies offer immediate solutions for
a wide range of product separation needs. Membrane
technologies have already proven their advantages
over conventional separation methods. Chapter
fourteen reviews the most important advances in the
field of membrane application in accomplishing
biorefinery needs. Ethanol separation or inhibitor
removal using membrane filtration units are just two
of the most important application examples provided
by authors.
The last chapter provides a more complete
analysis on the ecotoxicological and environmental
effects of biomass processing to obtain fuels,
chemicals, and other materials. Since the chemical
composition of biomass processing streams is rather
complex, most of the research is focused on the
identification of the potentially harmful components
or on the synergistic effects. In this context, different
assays are to be performed to evaluate toxicity or
mutagenic action of different biomass derived
The role of green chemistry in biomass processing
615
substances. The authors conclude that knowledge
would further contribute on the optimization of the
existing processes.
The book edited by Haibo Xie and Nicholas
Gathergood sets the newest trends in environmental
chemistry applications such as biomass conversion to
energy, fuels, chemicals and materials.
By providing interesting outlooks on a subject
of such high debate and importance in both industry
and research, the work of the editors sets itself as
foundation for all those interested in development of
new and sustainable means of bioresources
processing.
Adrian Cătălin Puiţel
Dan Gavrilescu
Department of Natural and Synthetic Polymers
Faculty of Chemical Engineering and
Environmental Protection
“Gheorghe Asachi” Technical University of
Iasi, Romania