Overview of modified and non- modified biomass to remove...
Transcript of Overview of modified and non- modified biomass to remove...
Overview of modified and non-
modified biomass to remove
toxic metals from polluted waters
Mehmet Yaman Firat University, Sciences Fac. Chem. Dep.
Elazig-Turkey
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Prof.
Yaman
Editor-in-Chief: Inter. J. Pure and
Appl. Chem
Member of consultative
committee of TÜBİTAK (the Scientific and Social
Research Council of Turkey).
Between 2010-2013.
Supervised: 11 PhD:
9 complet, 2 cont.
22 M.Sc. 20 complet,
2 cont.
Int. Book Chapter:
Air Pollution-
Monitoring,
Modelling, Health
and Control,2012
110 articles in SCI,
more than 1900 cita.
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Collaboration partners (14 Universities)
• Univ. of Canakkale 18 Mart, Science Fac. (Prof. Yusuf Dilgin)
• University of Kirklareli, Science Fac. (Dr. Cemile Ozcan)
• University of Kilis, Science Fac. (Assoc. Prof. Halim Avci)
• University of Bozok, Science Fac. (Assoc. Prof. Ismail Akdeniz)
• Univ. of Firat, Medicine Fac. (Prof. Mehmet Simsek)
• Univ. of Firat, Health Science. Fac. Assoc Prof. Gokce Kaya)
• Univ. of Firat. Engineer. Fac. (Prof. Ahmet Sasmaz, Halil Hasar, and others)
• Univ. of Tunceli, Chem. Engineering Fac. (Dr. Nagihan Karaaslan,
Muharrem Ince and Olcay Kaplan)
• Univ. of Yildiz Technic, Science Fac. (Assoc. Prof. Sezgin Bakirdere)
• Univ. of Istanbul Technical, Science Fac. (Prof. Dr. Filiz Senkal)
• Univ. of Bingol, Agricultural Fac. Prof. Mehmet Aycicek
• Univ. Of Gaziantep, Medicine Fac. Assoc. Prof. Nese Kizilkan)
• Univ. of Mardin Dep. Chem. Assoc. Prof. Ersin Kilinc
• Univ. Of Karaman, Science Fac. Prof. Dr. Fevzi Kilicel
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• Outline of the presentation In this lecture,
• An overview of analytical and environmental
applications of biosorbents will be presented, by
focusing on the mechanisms involved.
- Among types of biomaterial species, it will be
focused on modified and non-modified
agricultural wastes to be considered in removing
of toxic metals from waste waters.
- The major points to consider in this study are
removing of toxic metals such as lead, cadmium,
and nickel from waste water and metal recovery
interests.
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Problem ? and solution -To solve the water pollution problem by toxic metal
resulting from anthropogenic and industrial activities
has for long time a most important popularity.
-Biosorption can be a part of the solution.
-Some types of biosorbents such as seaweeds, molds,
yeasts, bacteria or crab shells have been more studied
examples of biomass for metal biosorption with very
encouraging results.
-New biosorbents can be developed for better
efficiency (up to 50% of the biomass dry weight) and
multiple re-use to increase their economic
attractiveness.
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Tendency • A large amount of researches on metal biosorption
have been published to elucidate the principles of
the effective metal-concentration phenomenon
during the past 30 years.
• Thousands of publications show that materials of
biological origin including biosorbents can be
considered as effective material to remove different
substances.
• Hovever, there have been few investigations on
determining the compatibility of the biosorbent for
real industrial effluents.
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(biosorption or biosorbent or
biosorbents) AND TOPIC: (removing or
remove or bioremediation or purification or
purifying or cleaning)
What is biosorption ? • Biosorption is the process of sorption of a dissolved
substance using a biomaterial/biomass.
• In other words, biosorption is a physical-chemical process,
simply defined as the removal of substances from solution by
biological material.
• Among biomaterials including microorganisms (such as
bacteria, fungi, yeast, algae) and plants, use of hyper-
accumulator plants opens a new branch of bioremediation for
polluted water as well as preconcentration in trace element
determinations.
This is an ecofriendly and scientific approach to remove, extract
and/or determine metal ions.
-This technique has also a strong potential for recovery of
precious metals as well as removal of toxic metals from
waters.
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Why Biosorption? The use of biosorbents is one of the alternative
options, when traditional wastewater treatment
methods, such as biological treatment or chemical
precipitation, cannot be used because of:
-the high costs;
-low removal efficiency;
-large amount of chemicals used or sludge produced.
In other words, biosorption offers the advantages of
low cost and good efficiency and thus is a recently
raising and attractive technology.
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Sources of biomass
• Biomass can come from
• (i) Agricultural and industrial wastes which should
be obtained free of charge;
• (ii) organisms easily available in large amounts in
nature; and
• (iii) organisms of quick growth, especially cultivated
or propagated for biosorption purposes.
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Why metal should be removed There are at least three major points to consider,
when choosing the metal for biosorption studies:
metal toxicity (Direct health threat)
metal costs (Recovery interests)
Scientific studies (how representative the metal may be in
terms of its behavior)
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Factors influencing sorption performance
• The factors that influence the biosorption process
can be classified as:
• 1.Physical and chemical properties of metal ions
(e.g., molecular weight, ionic radius, oxidation state)
• 2.Properties of the biosorbent (e.g., the structure of
the biomass surface)
• 3.The experimental conditions (e.g., pH,
temperature, concentration of biosorbent, the
concentration of sorbate, contact time, etc.)
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- Basic of Biosorption
• Metals can be removed from solution only when
they are appropriately immobilized.
- In most of the applications, the element species
interact with functional groups including amine,
amide, carboxylate, hydroxyl, imidazol, phosphate,
thioethers, and thiols on the material surface.
- Based on the understanding of metal uptake
mechanism, engineered technologies including the
cell surface display technology, have been used to
improve the performance of biomass in metal
removal from aqueous solution.
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Selectivity and maximum sorption capacity can be
achieved by suitable adjustment of the expr. conditions
such as pH, the contact time, ionic strength, particle
size, temperature, and concomitant species and
concentrations.
The functional groups present in biomass molecules
acetamido, carbonyl, phenolic, structural
polysaccharides, amido, amino, sulphydryl carboxyl
groups alcohols and esters.
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These groups have the affinity for metal
complexation. Some biosorbents are non-selective
and bind to a wide range of metals with no specific
priority, whereas others are specific for certain types
of metals depending upon their chemical
composition.
In order to understand how metals bind to the
biomass, it is essential to identify the functional
groups responsible for metal binding.
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Amino and amidoxime groups
• Amino (-NH2) groups have a lone pair of
electrons on the nitrogen and may form a
covalent bond with a metal.
• The amidoxime group is a bidentate
ligand and has both an acidic group which
loses a proton and a basic lone pair of
electrons on the nitrogen which can
coordinate with the metal ion (Liu et al., 2002; Lutfor
et al., 2000).
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Imidazole group
• Imidazole has also been used as a
binding agent on a glycidyl methacrylate grafted
cellulose adsorbent (O’Connell et al. 2006a,b,c).
• The imidazole is a five-membered ring
molecule containing two nitrogen atoms. The
imidazole group has the ability to impart
rigidity to the ligand system, due to its
aromatic ring system.
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• Agricult-materials are usually composed of lignin
and cellulose as major constituents and may also
include other polar functional groups of lignin, which
includes alcohols, aldehydes, ketones, carboxylic,
phenolic and ether groups [21].
• These groups have also the ability to bind some
metals by donation of an electron pair from those
groups to form complexes with the metal ions [11].
• In conclusion, metal biosorption is a rather
complex process affected by several factors.
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Biosorption Mechanism
• Mechanisms involved in the biosorption process
include chemisorption, complexation, adsorption–
complexation on surface and pores, ion exchange,
microprecipitation, heavy metal hydroxide
condensation onto the biosurface, and surface
adsorption [155–157].
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• Most of the functional groups involved in the binding
process are found in cell walls.
• Plant cell walls are generally considered as
structures built by cellulose molecules, organized in
microfibrils and surrounded by hemicellulosic
materials (xylans, mannans, glucomannans,
galactans, arabogalactans), lignin and pectin along
with small amounts of protein [68,158,159].
• The behavior of cellulose as a substrate is highly
dependent upon the crystallinity, specific surface
area, and degree of polymerization of the fibers
being studied [160]
Mechanisms controlling metal biosorption
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There is a relatively strong interaction between neighbouring
cellulose molecules in dry fibres due to the presence of the
hydroxyl (–OH) groups, which stick out from the chain and form
intermolecular hydrogen bonds. Regenerated fibres from
cellulose contain 250–500 repeating units per chain. This
molecular structure gives cellulose hydrophilicity, chirality and
degradability. Chemical reactivity is largely a function of the high
donor reactivity of the OH groups (Klemm et al., 2005).
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There are one primary hydroxyl group and two
secondary hydroxyl groups in the cellulose chain.
Functional groups may be attached to these hydroxyl
groups through a variety of chemistries.
The principle and main routes of direct cellulose
modification (with the introduction of chelating or metal
binding functionalities) in the preparation of adsorbent
materials are esterification, etherification, halogenation
and oxidation.
Alternative approaches have focused on grafting of
selected monomers to the cellulose backbone
either directly introducing metal binding capability or
with subsequent functionalisation of these grafted
polymer chains with known chelating moieties.
Untreated wastes
• Most of the adsorption studies have been focused on
untreated plant/agricultural wastes such as
• papaya wood (Saeed et al., 2005),
• maize leaf (Babarinde et al., 2006),
• teak leaf powder (King et al., 2006),
• lalang and rubber leaf powder (Hanafiah et al., 2007 and 2006b,c ),
• Coriander (Karunasagar et al., 2005),
• peanut hull pellets (Johnson et al., 2002),
• sago waste (Quek et al., 1998),
• saltbush leaves (Sawalha et al., 2007a,b),
• tree fern (Ho and Wang, 2004; Ho et al., 2004; Ho, 2003),
• rice husk ash and neem bark (Bhattacharya et al., 2006),
grape stalk wastes (Villaescusa et al., 2004), etc. 44
Solution or sample digest (about 100 mL)
Adjust pH
Addition of buffer and read just pH
Addition of biomass
Stirring
Filtration and drying
Elution (desorption)
Measurement
Typic scheme of adsorption by untreated wastes
Modification of biosorbents
• Biosorbents can be modified in order to reduce
several deficiencies, which are:
• -Low sorption capacity
• -Poor chemical stability
• -Low mechanical strength
• -Tendency of biosorbent particles to expand or shrink
• It should be noted that the modification reagents
or equipment used leads to additional costs.
However, it should be strongly emphasized that
the costs of modification are never mentioned in
research papers, as well as cost evaluation in
general. 47
Modification of biomass
• Particular functional groups on the biosorbent
surface can be substituted through different
chemical pretreatment methods.
• The introduction of new binding sites to the
biosorbent surface can enhance the sorption
capacity.
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Esterification
• The citric acid (CA) modification on the wood involved an
esterification reaction process of the carboxyl groups in
citric acid and the hydroxyl groups on the wood surface.
• Chemical treatment with CA at high temperature
produced condensation product and CA anhydride.
• The reactive CA anhydride can react with cellulosic
hydroxyl groups to form an ester linkage and
introduce carboxyl groups to the cellulose (Marshall et al., 1999).
• The esterification process increases the carboxylic acid
content of the wood surface and leads to an increase in
the sorption of metal cations (101.16 mg Cd g1 by
treated, and 48.33 mg Cd g1 by untreated orange
waste). 52
Etherification
• In order to add cyano groups to the cellulose
structure, sawdust was modified chemically
with amidoxime groups by reacting
acrylonitrile with the sawdust, through an
etherification reaction (Saliba et al. (2005).
• These cyano groups were then amidoximated
by reaction with hydroxylamine.
• This amidoximated sawdust had a high
adsorption capacity of 246 mg g1 for Cu(II)
and of 188 mg g1 for Ni(II).
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The biosorption commercialization
• Although some commercial biosorbents
(Vitrokele 573 for Hg, The biosorbent BIO-FIX
for Al3+>Cd2+>Zn2+>Mn2+,) were reported,
biosorption has not been commercially
successful and its traditional direction as a low-
cost and environmentally-friendly pollutant
treatment method should be re-considered.
• Attempts to improve biosorption (capacity,
selectivity, kinetics, re-use) by physicochemical
and biotic manipulations increase cost and may
raise environmental issues. 64
• Pretreatment of plant wastes can extract soluble
organic compounds and enhance chelating
efficiency (Gaballah et al., 1997).
• For this purpose, different kinds of modifying agents that
are commonly used;
• Base solutions (sodium hydroxide, calcium hydroxide,
sodium carbonate),
• Mineral and organic acid solutions (hydrochloric acid,
nitric acid, sulfuric acid, tartaric acid, citric acid,
thioglycollic acid), organic compounds (ethylenediamine,
formaldehyde, epichlorohydrin, methanol),
• Oxidizing agent (hydrogen peroxide), etc. for increasing
efficiency of metal adsorption have been performed (Dewayanto, 2010).
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Biosorbent selection and assessment
• The selection of a proper sorbent for a given
separation is a complex problem.
• How to select the suitable biosorbent among a
large quantity of biomass tested?
• The predominant scientific basis for sorbent
selection is the equilibrium time.
• Diffusion rate is generally secondary in importance.
From the viewpoint of practical application, availability
and economy is a major factor to be taken into account
for selecting the biomass for clean-up purposes
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OPAA was prepared from hydrolysis of the grafted copolymer, which was
synthesized by interacting methyl acrylate with crosslinking orange peel. 71
Removing Interfering Sorption Sites
The natural biomass of biosorbents has many surface
functional groups, some of which could interfere with
the sorption of target metal species.
For instance, -N-H groups have a role as sorption
sites for anionic metal removal by electrostatic
interaction, whereas negatively charged -COOH
groups could repel anionic metals.
Thus, elimination of interfering binding sites from the
biomass surface could result in more efficient
biosorbents (Vijayaraghavan and Yun, 2008).
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The manipulation of interfering sites has been
reported previously as the
(1)methylation of –N-H groups,
(2) acetylation of –N-H and -OH groups,
(3) esterification of -COOH groups, and
(4) esterification of phosphonate groups.
Gong et al. (2005) removed -COOH groups from
peanut hulls by methylation of the –N-H group,
esterification of the -COOH group, and acetylation of
the –N-H and -OH groups. Therefore, the addition of
positively charged –N-H groups and elimination of
-COOH groups is a highly attractive strategy for
developing more effective biosorbents to recover
negatively charged Precious Ms and positively
charged heavy metals in water and wastewater. 73
Coating With Ionic Polymers Coating the biosorbents and biochars with ionic
polymers could be an efficient way to enhance the
recovery of PMs ions (Fig. 7.3C). For example, the
combination of an ethanolamine molecule with the
biomass can create amine sites on the material
surface.
In addition, the association of polyethyleneimine (PEI)
with the biosorbent and biochar biomass can result in
the generation of a large number of amine groups. PEI
is made of several primary and secondary –N-H
groups and can lead to a significant increase in
sorption capacity for negatively charged PM ions (Mao
et al., 2011). 74
In contrast to methylation pretreatment, in which
residual methanol needs to be removed after
biosorbent and biochar preparation, PEI-coated
biosorbents and biochars can provide a low-cost and
more environmentally friendly solution for metal
removal and recovery.
Yu et al. (2007) synthesized poly(amic acid)-grafted
baker’s yeaste derived biomass by reacting with
pyromellitic dianhydride and thiourea. The authors
reported 15- and 11-fold increases in Cd and Pb
removal, respectively.
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The OP collected from a local plantation field was cut into
small pieces, washed several times with distilled water and
dried at 80 ◦C. The product was crushed and sieved to obtain
a particle size lower than 0.45 mm. 5.0 g of OP was mixed
together with 25 mL of saturated calcium hydroxide and 25
mL of 0.1 mol L−1 NaOH solutions for 20 h and occasionally
stirred. After filtered, the residue was rinsed several times with
distilled water and thereafter cross-linked with
epichlorohydrin. The obtained sample is abbreviated as COP.
Preparation OPAA
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COP was added to 100 mL of HNO3 solution (2.5×10-2 mol L-
1) in a three-necked flask, then stirred and purged by passing
nitrogen for 30 min. Ceric ammonium nitrate (5.0×10−3 mol L-
1) was then added in the reaction mixture and allowed to
interact with substrate. After 30 min, 15 mL of methyl acrylate
was added to the reaction flask to start polymerization.
Polymerization was allowed to proceed for 60 min in N2
atmosphere and the reaction was stopped by the addition of 2
mL of 5% (w/v) quinone solution.
Preparation OPAA
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The polymerization product was filtered, washed several times
with distilled water, and dried in an oven at 60 ◦C to constant
weight.
Finally, removal of the homopolymer from the grafted samples
was carried out with a Soxhlet extractor, using acetone as a
solvent, for 24 h.
The grafted product was then dried in an oven at 60 ◦C for 12
h, hereafter this obtained sample is abbreviated as OPMA.
The grafted copolymer (OPMA) together with 300 mL of 0.5
mol L−1 sodium hydroxide solution was put in a three-necked
flask and the mixture was stirred under reflux at 60 ◦C for 10 h.
Preparation OPAA
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After cooling dawn to room temperature, the pH of the
reaction mixture was adjusted to ∼6.5 by adding
hydrochloric acid. The residue was filtered off and washed
with ethanol. It was then dried in vacuum, hereafter this
obtained sample is abbreviated as OPAA. The product was
crushed and sieved to obtain a particle size lower than 0.45
mm and used in this study.
Preparation OPAA
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Effect of pH
• Variation in pH can affect the surface charge of
the adsorbent and the degree of ionisation and
speciation of the metal adsorbate. At very low
solution pH, the binding sites on the modified
cellulose materials are likely to be protonated
resulting in poor metal binding levels.
• An optimum pH range usually between pH 4.0
and pH 6.0 leaves the binding sites unprotonated
and metal binding is maximised.
• At pH’s above this optimum range, most metals
tend to precipitate out of solution in the hydroxide
form. 93
Solution or sample digest (about 100 mL)
Adjust pH
Addition of buffer and read just pH
Addition of biomass Stirring
Filtration and drying
Elution (desorption)
Measurement
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0
300
600
900
1200
1500
1800
2100
0 1 2 3 4 5 6 7
Pb
c
on
c. p
pb
pH
Willow-Pb-pH Biomass Pb conc.(ppb)
(filtrate Pb conc. (ppb)
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In CONCLUSION The performance of biosorbents could be
enhanced through different surface
pretreatment methods, and among them,
coating with ionic polymers appears to be the
most effective pretreatment method.
However, there is a lack of understanding
about how chemical surface pretreatment
coupled with polymer coating can further
increase the metal sorption capacity for
maximum recovery. 129
Evaluation of Sorption performance
• The optimum pH should be about 7 when a
biomass will be used to remove toxic
elements from vast amount of municipial
waste water, because it is not practice the
use of chemicals for adjustment of pH of a
such large sample.
• Economic analyses are required to
obtain the overall cost of the sorbent and
biosorption process
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Future directions
• One efficient way to introduce
functional groups on the biomass
surface is the grafting of long polymer
chains onto the biomass surface via
direct grafting, or the polymerization
of the monomer [20].
• Cooperation between scientists would
be advisable, as multidisciplinary
skills are needed
133
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