Sorbents For Heavy Metal Ions Research Articles

Selective Sorption of Heavy Metals by Renewable Polysaccharides.

Renewable and biodegradable polysaccharides have attracted interest for their wide applicability, among them their use as sorbents for heavy metal ions. Their high sorption capacity is due mainly to the acidic groups that populate the polysaccharide backbone, for example, carboxylic groups in alginate and sulfate ester groups in the iota and lambda carrageenans. In this study, these three polysaccharides were employed, alone or in different mixtures, to recover different heavy metal ions from aqueous solutions. All three polysaccharides were capable of adsorbing Eu3+, Sm3+, Er3+, or UO22+ and their mixtures, findings that were also confirmed using XPS, TGA, and FTIR analyses. In addition, the highest sorption yields of all the metal ions were obtained using alginate, alone or in mixtures. While the alginate with carboxylic and hydroxyl groups adsorbed different ions with the same selectivity, carrageenans with sulfate ester and hydroxyl groups exhibited higher adsorption selectivity for lanthanides than for uranyl, indicating that the activity of the sulfate ester groups toward trivalent and smaller ions was higher.

USING TANGERINE PEEL AS A SORPTION MATERIALS TO REMOVING POLLUTANTS FROM WATER ENVI-RONMENTS

The literature data on the use of agricultural waste, mandarin peel (Citrus reticulata) as a sorption material for the removal of various pollutants, mainly metal and metalloid ions and dyes from aqueous media, are summarized. The review, based on the analysis of various literary sources, provides information on the volume of waste generation from the processing of citrus fruits, including tangerines. Information is given on the content of various chemical compounds in the composition of tangerine peel. Ways of using mandarin peel in various branches of industrial production are shown. Information on the values ​​of the maximum sorption capacity of the peel of tangerines for pollutants is given. It has been determined that adsorption isotherms of various pollutants by tangerine peel are in most cases described by the Langmuir model, and the kinetics of the process in most cases corresponds to a pseudo-second order model. The possibility of obtaining carbonizates and activated carbons from the peel of Citrus reticulate and the use of the latter as sorbents of heavy metal ions and dyes from aqueous media is shown. It is shown that it is possible to increase the sorption parameters of tangerine peel powder and carbonizates for various pollutants by chemical modification with various reagents.

Hydrogel Beads of Amidoximated Starch and Chitosan as Efficient Sorbents for Inorganic and Organic Compounds.

The synthesis of hydrogel beads involving natural polymers is, nowadays, a leading research area. Among natural polymers, starch and chitosan represent two biomolecules with proof of efficiency and low economic impact in various utilization fields. Therefore, herein, the features of hydrogel beads obtained from chitosan and three sorts of starch (potato, wheat and rise starches), grafted with acrylonitrile and then amidoximated, were deeply investigated for their use as sorbents for heavy metal ions and dyes. The hydrogel beads were prepared by ionotropic gelation/covalent cross-linking of chitosan and functionalized starches. The chemical structure of the hydrogel beads was analyzed by FT-IR spectroscopy; their morphology was revealed by optical and scanning electron microscopies, while the influence of the starch functionalization strategies on the crystallinity changes was evaluated by X-ray diffraction. Molecular dynamics simulations were used to reveal the influence of the grafting reactions and grafted structure on the starch conformation in solution and their interactions with chitosan. The sorption capacity of the hydrogel beads was tested in batch experiments, as a function of the beads’ features (synthesis protocol, starch sort) and simulated polluted water, which included heavy metal ions (Cu2+, Co2+, Ni2+ and Zn2+) and small organic molecules (Direct Blue 15 and Congo red).

Rational Design of Polyamine-Based Cryogels for Metal Ion Sorption.

Here we report the method of fabrication of supermacroporous monolith sorbents (cryogels) via covalent cross-linking of polyallylamine (PAA) with diglycidyl ether of 1,4-butandiol. Using comparative analysis of the permeability and sorption performance of the obtained PAA cryogels and earlier developed polyethyleneimine (PEI) cryogels, we have demonstrated the advantages and disadvantages of these polymers as sorbents of heavy metal ions (Cu(II), Zn(II), Cd(II), and Ni(II)) in fixed-bed applications and as supermacroporous matrices for the fabrication of composite cryogels containing copper ferrocyanide (CuFCN) for cesium ion sorption. Applying the rate constant distribution (RCD) model to the kinetic curves of Cu(II) ion sorption on PAA and PEI cryogels, we have elucidated the difference in sorption/desorption rates and affinity constants of these materials and showed that physical sorption contributed to the Cu(II) uptake by PAA, but not to that by PEI cryogels. It was shown that PAA cryogels had significantly higher selectivity for Cu(II) sorption in the presence of Zn(II) and Cd(II) ions in comparison with that of PEI cryogels, while irreversible sorption of Co(II) ions by PEI can be used for the separation of Ni(II) and Co(II) ions. Using IR and Mössbauer spectroscopy, we have demonstrated that strong complexation of Cu(II) ions with PEI significantly affects the in situ formation of Cu(II) ferrocyanide nanosorbents leading to their inefficiency for Cs+ ions selective uptake, whereas PAA cryogel was applicable for the fabrication of efficient monolith composites via the in situ formation of CuFCN or loading of ex situ formed CuFCN colloids.

Production of Magnetically Controlled Biosorbents Based on Fungi Pleurotus ostreatus

Background. Biogenic magnetic nanoparticles (BMN) have been found in representatives of all three superkingdoms of living organisms: bacteria, archaea and eukaryotes (including fungi). At the same time, it was established that the mechanism of biomineralization of BMN is unique for all living organisms. The search for sorbents of biological origin has become one of promising ways of addressing the problem of environmental pollution by heavy metals. Heavy metals are elements of transport emissions and many factories in various industries. These metals getting into the human body cause significant disruption of metabolism and vital functions of the body. Many macromycetes are known to be natural sorbents for heavy metal ions. Laboratory tests use a method of filtering spent sorbent through a paper filter, which is long enough and inefficient. Therefore, it is important to find a more effective way of removing biosorbent from the solution. Such a cheap and efficient method is high-speed magnetic gradient separation. Objective. The aim of the paper is to obtain a magnetically controlled biosorbent based on a fungus Pleurotus ostreatus , to determine the fraction of the magnetically controlled phase of the fungus biomass when added to the substrate of the magnetic fluid, and to investigate the efficiency of extraction of Fe 3+ ions by the fungus biomass of the fungus Pleurotus ostreatus . Methods . The standard method of cultivation of the fungus Pleurotus ostreatus , the method of high-grade magnetic separation and the method of biosorption of ferric ions were used. Results. The process of biosorption of ferric ions by a Pleurotus ostreatus grown on substrates with the addition of magnetic fluids of different concentrations was carried out. It is shown that the dry biosorbent based on the biomass of the Pleurotus ostreatus has a high sorption capacity with respect to Fe 3+ ions since the efficiency of their extraction for 30 minutes of sorption in the samples grown on the substrate with the addition of magnetite is more than 95%. It is proved that when using biomass of ordinary fungus grown on a magnetic fluid, complete saturation occurs 6 times faster (for 5 minutes), compared to 30 min for biosorbent based on biomass of mushroom grown without magnetic fluid. Conclusions. Addition of magnetite (concentration 0.1 and 1 mg/ml) to the substrate in the cultivation of fungi Pleurotus ostreatus significantly increases the efficiency of the sorbent. When using the fungus biomass of Pleurotus ostreatus without adding magnetite for 5 minutes, the efficiency of extraction of iron ions is 70%, for 30 min – 80%. When used to grow the magnetic fluid at a concentration of 0.1 mg/ml and 1 mg/ml for almost 5 minutes, almost complete removal of heavy metal ions occurs.

Preparation and properties of polyimides having porphyrin moieties for heavy metals removal

A tetramine monomer containing porphyrin moiety is prepared in high purity by the propionic acid-mediated condensation of pyrrole with 4-cyanobenzaldehyde and then reduction in the tetracyano intermediate. The thermally stable porphyrin-based polyimides (PI)s are prepared using tetramine and four aromatic tetracarboxylic dianhydrides via a two-step method in quantitative yields with inherent viscosities of 0.34–0.63 dL/g. The PIs are soluble in some organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide and dimethyl sulfoxide. The resultant PIs had high glass transition temperatures and displayed outstanding thermal stability up to 500 °C. The resulting polymers revealed strong UV–Vis absorption band around 422 nm in DMF. Wide-angle XRD measurements exhibited that the PIs were amorphous. The polymer films had tensile strengths 101–128 MPa, elongates at break of 7–11% and tensile moduli of 2.0–2.2 GPa. One of the PIs was applied to examine the adsorption properties of two heavy metal ions (Cd2+ and Hg2+) at pH 7. The results revealed that the applied PI was an outstanding sorbent for heavy metal ions. The goal of this study is the preparation of hydrophobic PIs for ion-selective membranes and chemical sensors to adsorb of toxic heavy metals.

Моделирование процесса адсорбции в системе жидкость – твердое тело: регрессионный анализ извлечения меди из водных растворов цеолитом Холинского месторождения, модифицированным серосодержащим полимером

This article describes the formation of an effective sorbent for heavy metal ions by modifying natural zeolite (clinoptilolite type, Kholinskoye deposit). The modification was carried out by applying the network of a sulphur-containing polymer on the zeolite surface. For the formation of a polymer network, elemental sulphur was dissolved in the hydrasine hydrate–monoethanolamine system to generate polysulphide anions (in particular, S2 2- ). During the contact of the obtained sulphur solution with zeolite, polysulphide anions and the monoethanolamine entering the zeolite pores were concentrated on the surface. Further polycondensation of S2 2- anions with 1,2,3-trichloropropane (epichlorohydrine production waste) resulted in the formation of a reticulated sulphur-containing polymer covering the zeolite surface. Such a sorbent provides immediate solution to the problems concerned with utilisation of organochlorine wastes and purification of technological media containing heavy metals. Extraction of metals by the obtained sorbent was studied using model solutions with a metal concentration of 5000 mg/L. Encouraging results were obtained for five metals. Detailed information on the extraction of copper ions from aqueous solutions is presented. Experimental data was obtained on the effect of pH on the sorption efficiency of copper ions, as well as on the thermodynamic and kinetic characteristics of adsorption under static and dynamic conditions. The complex coordination mechanism of Cu (II) sorption by modified zeolite was confirmed using IR-spectroscopy. Since the thermodynamic and kinetic dependencies frequently deviate from the classical laws during sorption by the complex coordination mechanism, regression analysis was used to process the experimental data. As the result, nonlinear models were obtained fairly accurately describing experimental data on the extraction of copper ions by modified zeolite. The obtained regression models can be applied in further research of the new sorbent and in designing installations for extracting copper compounds from technological media.

Role of surface functionalization of ZnO nanoparticles as sorbents for heavy metal ions

ABSTRACT The surface functionalization of ZnO nanoparticles (ZnO NPs) was carried out by a simple one pot co-precipitation method followed by a facile ligand introduction onto the surface. This technique allows for tailoring of the surface chemistry to impart the specificity and affinity toward the target analytes (heavy metal ions like Pb and Hg) depending on the ligand incorporated on the surface resulting in highly selective sorbents. The functionalized ZnO NPs were characterized using different techniques. Elemental, IR, and thermal analysis studies confirm the presence of functional groups. X-ray diffraction (XRD) shows functionalization does not result in change of ZnO NPs but reduces their crystallinity. The average crystallite size of the nanoparticles is not affected by functionalization indicating that the process is restricted to the surface only. Surface area measurements reveal that functionalization results in mesoporous structures as can be deduced from the average pore diameter. Functionalization resulted in enhanced uptake of Pb and Hg, and the kinetics were very fast. Different models were used to understand the sorption behavior. The Langmuir uptake capacity values for lead and mercury using the thiol-functionalized ZnO NPs were found to be 78 and 145 mg/g, respectively. The role of interfering ions on the sorption was evaluated to get an idea of the selective nature of the sorbent.

Sawdust-kaolinite composite as efficient sorbent for heavy metal ions

The improvement of the adsorption capacity of clay minerals using chemicals though effective is expensive, results in secondary contamination and noxious to the environment. This study was therefore aimed at the development of a new sawdust clay modified adsorbent (SDKC) as an alternative means of improving the adsorption capacity of kaolinite. The adsorbents were characterized by the Fourier transform infrared spectroscopy and X-ray diffraction analysis. Batch sorption was employed to determine the effect of pH, metal concentration, sorbent dose, time and temperature on the removal of Pb (II) and Cd (II) ions from solution by the adsorbents. Optimum operating conditions of pH 6.0, metal concentration 200mg/L, sorbent dose 0.1g was obtained. Equilibrium isotherm analysis indicated the Langmuir, Temkin and Flory-Huggins models to be more suitable than the Freundlich, Dubinin–Radushkevich (D-R). The kinetic data were analyzed using the pseudo-first order, pseudo-second order, the Elovich and intraparticle diffusion models. The analysis revealed that the adsorption process followed pseudo second order model. The calculated thermodynamic parameters showed an endothermic, spontaneous and a physisorption process between both metal ions and the adsorbents. The obtained result of the experiment indicated a significant improvement in the uptake of Pb (II) and Cd (II) ions on the sawdust modified kaolinite adsorbent than the untreated kaolinite clay. This could be utilized as an alternative to chemical treatment methods
 Bangladesh J. Sci. Ind. Res.54(1), 99-110, 2019

Ionic liquid grafted polyamide 6 as porous membrane materials: Enhanced water flux and heavy metal adsorption

The design and preparation of new membrane material are of great importance. In this work, a hydrophilic ionic liquid (IL) grafted polyamide 6 (PA6) (IL-g-PA6) porous membrane materials were designed and prepared via radiation induced grafting method. The improved hydrophilicity, solubility and the unique ion structure of IL-g-PA6 made it suitable to prepare porous membrane using simple immersion precipitation phase inversion method. SEM images showed opened sponge-like pores for both PA6 and IL-g-PA6 porous membranes, while the pore size decreased and porosity increased as ionic liquid was grafted on PA6. It is believed that the mass transfer process was slowed down by enhanced hydrophilicity and solubility of IL-g-PA6, which lead to a different porous structure from that of PA6. Besides, even though the pore size of 2%-50 K membrane was much smaller, the water flux of which was 2.6 times higher than that of PA6 membrane. Moreover, the chromate sorption on 8%-50 K membrane was 2.7 times higher than that of PA6 membrane, which implies that the IL-g-PA6 porous membranes are good sorbent for heavy metal ions. The special interaction between grafted ionic liquid and heavy metal ions would account for the excellent adsorption property.

Synthesis and characterization of mesoporous polymeric microspheres of methacrylic derivatives of aromatic thiols

The paper presents the synthesis and characterization of mesoporous microspheres of derivatives of three aromatic thiols: S-phenyl 2-methylprop-2-enethioate (PSM), S,S′-thiodi-4,1-phenylenebis(thiomethacrylate) (DMSPS), and bis[4(2-hydroxy-3-methacryloyloxypropoxy)phenyl]sulfide (BES.DM) with divinylbenzene (DVB). The microspheres were obtained by the emulsion-suspension polymerization procedure. The chemical and porous structure, morphology, and properties of the microspheres were analyzed by attenuated total reflection-Fourier transform infrared (ATR/FT-IR) spectroscopy, low-temperature nitrogen adsorption data, optical microscope MORPHOLOGI G3, differential scanning calorimetry (DSC), and wavelength dispersive X-ray fluorescence (WD-XRF). Moreover, studies on the Pb(II) ions sorption process were carried out on the above mentioned compounds. The sorption kinetics and mechanism were described by the pseudo-first order, pseudo-second order, and intraparticle diffusion models. The sorption equilibria were described by the Langmuir and Freundlich isotherms. The PSM-DVB, DMSPS-DVB, and BES.DM-DVB microspheres exhibit high thermal resistance and good adsorption properties of Pb(II) ions. The best adsorption properties for the examined microspheres were obtained at pH 5. The highest monolayer adsorption capacity determined by Langmuir isotherm was obtained for the DMSPS-DVB microspheres and was equal to 22.54 mg/g. The preliminary studies show that the synthesized microspheres can be used as heavy metal ion sorbents from aqueous solutions.

Research into quality of pectins from pea seed coats

For the first time, the complete set of quality indicators and sorption properties was studied in pectins extracted from the seed coats of peas, using standard and modified methods. It is established that organoleptic and physico-chemical indicators of pectins from pea seed coats meet the requirements of GOST 29186-91; moreover, safety and microbiological indicators conform to both GOST 29186-91 and SanPiN 2.3.2.1078-01. According to the main analytical characteristics, pectins from pea seed coats are highly esterified and meet the requirements for industrial pectins. The sorption properties of the studied pectins are the most pronounced when exposed to lead, cadmium and copper ions, and to a lesser extent, zinc ions. The obtained data allows us to recommend pectins from pea seed coats as structure-forming agents and sorbents of heavy metal ions in the production of functional foods.

Efficient Removal of Lead, Copper and Cadmium Ions from Water by a Porous Calcium Alginate/Graphene Oxide Composite Aerogel.

In this study, we fabricated a porous calcium alginate/graphene oxide composite aerogel by using polystyrene colloidal particles as sacrificial template and graphene oxide as a reinforcing filler. Owing to the excellent metal chelation ability of calcium alginate and controlled nanosized pore structure, the as-prepared calcium alginate/graphene oxide composite aerogel (mp-CA/GO) can reach the adsorption equilibrium in 40 min, and the maximum adsorption capacity for Pb2+, Cu2+ and Cd2+ is 368.2, 98.1 and 183.6 mg/g, respectively. This is higher than most of the reported heavy metal ion sorbents. Moreover, the mp-CA/GO can be regenerated through simple acid-washing and be used repeatedly with little loss in performance. The adsorption mechanism analysis indicates that the mp-CA/GO adsorb the heavy metal ions mainly through the ion exchange and chemical coordination effects.

Modified magnetic nanoparticles with catechol as a selective sorbent for magnetic solid phase extraction of ultra-trace amounts of heavy metals in water and fruit samples followed by flow injection ICP-OES

A simultaneous and fast method was explored for extraction of heavy metal ions from aqueous samples based on magnetic solid phase extraction (MSPE). Fe3O4@catechol nanoparticles were successfully fabricated to coat catechol onto super paramagnetic iron oxide. Using a polymerization reaction the Fe3O4@catechol as a sorbent for MSPE method which was coupled with flow injection inductively coupled plasma optical emission spectrometry (FI-ICP-OES) was applied for the determination heavy metal in the water and fruit samples. The selectivity of synthesized sorbent for heavy metal ions is pH dependent. The heavy metal ions were selectively adsorbed on magnetic adsorbent, and then they were simply and rapidly isolated from sample solution with a strong magnet located in the bottom of the extraction vessel. After elution of heavy metal ions from surface of sorbent 250 μL of it was injected into the nebulizer of the FI-ICP-OES using the six-way two-position injection valve. The parameters influencing preconcentration factors of target ions, such as pH, extraction time, the sorbent amount, type of eluent, eluting solvent volume and desorption time were studied and optimized. Under the optimal conditions, the perconcentration factors in the range of 67–138 were obtained. The detection limits were as low as 0.2–0.9 μg L−1. The relative standard deviations (RSD) was lower than 6.6% (n = 6, C = 10.0 μg L−1). This new adsorbent was easily prepared with low-cost, utilized conveniently and was harmless to environment.

Application of Lignin and Its Derivatives in Adsorption of Heavy Metal Ions in Water: A Review

Water pollution by heavy metal ions is currently of great concern due to their high toxicity and carcinogenicity. In recent years, great efforts have been devoted to the search for new cost-effective adsorbents derived from biomass. Lignin is a natural amorphous polymer that has great potential for use as a building block in the production of biorenewable materials. Due to its unique polyphenol structure, physicochemical properties, and abundance, a wide variety of sorbents, particularly heavy metal ion sorbents, can be potentially obtained from lignin. This paper provides a comprehensive review of the literature about different feedstock lignin and versatile lignin derivatives used as heavy metal ion adsorbents. The adsorption capability improvement mechanism of the lignin derivatives and the comparison with commercial resins are also discussed. Therefore, this review aims to discuss the different modification categories that have been reported for the conversion of lignins into advanced heavy metal ion ...

The promise of a specially-designed graft copolymer of acrylic acid onto cellulose as selective sorbent for heavy metal ions

A specially-designed graft copolymer of acrylic acid onto in-situ formed cellulose-fulvate hybrid showed privileged tendency for uptake of Pb(II) during competitive removal from a mixture containing Cd(II) and Ni(II) within 5min at pH 5. This novel trend is attributed mainly to the crowded high content of coordinating centers within the designed graft copolymer along with the acquired superabsorbency. This provides an outstanding tool to separate some metal ions selectively from mixtures containing multiple ions on kinetic basis. Thus, the designed graft copolymer structure exhibited superior efficiency that reached ∼95% for sole removal of Pb(II). Kinetic modeling for Pb(II) individual removal showed excellent fitting with a pseudo second-order model. Intraparticle diffusion model on the other hand ensured governance of boundary layer effect over diffusion during the removal process due to the superabsorbency feature of the graft copolymer. The experimental findings were described with models such as Freundlich, Langmuir, and Dubinin–Radushkevich. The Langmuir and Freundlich models showed convenience with the adsorption isotherm of Pb(II) onto the developed graft copolymer.

Experimental characterisation and evaluation of perlite as a sorbent for heavy metal ions in single and quaternary solutions

Due to its unique properties such as low bulk density, high water retention capacity and high air-filled porosity, perlite has been recently employed as an important substrate additive to support vegetation in green roofs, vertical gardens and biofilters. Considering that the runoff quality of the above systems often comes under debate, it is important to explore the sorption capacity of substrate additives. Thus, the present study explores the potential of perlite to sorb important metal ions such as Cd2+, Cu2+, Ni2+ and Pb2+ in single and multi-component solutions. Characterisation of perlite indicated that the material possesses low bulk density (148kg/m3), high water holding capacity (27.5%) and high air-filled porosity (31.1%). Experimental results according to the Langmuir model revealed that perlite sorbed 0.130, 0.089, 0.057 and 0.025mmol/g of Pb2+, Cu2+, Ni2+ and Cd2+ respectively, at an optimum pH of 5. The kinetics data were well described by pseudo-first order model, followed by the pseudo-second order and Elovich models. Quaternary sorption experiments showed that the presence of multiple ions had an adverse effect on the sorption capacity of perlite towards individual ions. Application of Sheindorf–Rebhun–Sheintuch equation to experimental quaternary isotherm data confirmed that sorption of Cd2+ ions was severely affected whereas Pb2+ ions were favoured.

Advances in preconcentration/removal of environmentally relevant heavy metal ions from water and wastewater by sorbents based on polyurethane foam

Abstract An increased interest in the removal of heavy metal ions from aqueous media is encountered due to their toxicity and negative impacts on ecosystems, human health and economic activities. A variety of processes may be used for the removal of heavy metal ions from water and wastewater, such as chemical precipitation, ion exchange, adsorption, membrane processes, etc. However, the removal efficiencies of heavy metals by adsorption depend on several factors such as initial loads of heavy metals in the influent, purpose of treatment (drinking/industrial water production, wastewater treatment for disposal or recycling), costs of the overall process, and properties and conditions for regeneration of the sorbent materials. In this context, the use of polyurethane foams as heavy metal ion sorbents is of a special interest because they provide versatile applications in heavy metal effluent management. This study reviews relevant published researches that are concerned with new sorbents based on polyurethane foams applied in batch and dynamic systems for separation and/or preconcentration of heavy metal ions in environmental aqueous media. This review is divided into the following sections: synthesis of polyurethane foams; physical and chemical properties of polyurethane foams; preconcentration of pollutant metal ions from environmental aqueous media by different types of polyurethane foam (untreated, loaded, reacted and composite polyurethane foams); the applicability of sorbents based on polyurethane foams for water and wastewater treatment; comparison of sorbents based on polyurethane foam with other sorbents for heavy metal ion removal.

Carbon materials from waste short hemp fibers as a sorbent for heavy metal ions – Mathematical modeling of sorbent structure and ions transport

Carbonized hemp fibers obtained by carbonization of origin and chemically modified waste hemp fibers was used as a low-cost sorbent for heavy metals removal. The efficiency of carbonized hemp fiber samples as a sorbent was tested through the adsorption of lead ions as a heavy metal model ion. Although changes in carbon precursor structure, induced by chemical modification, affect the sorption process and sorption capacity of carbonized hemp fibers, all carbonized hemp fibers samples show good adsorption properties toward lead ions. Obtained experimental data was used for development of the mathematical model that describes both the phenomenon of metal ions transport through the porous sorbent matrices, and the structure of carbonized hemp fibers. Effective diffusion coefficient, damping coefficient and the lead ion concentration profile within the carbonized hemp fibers, obtained as results of proposed mathematical model, give the insight in the mechanism and the rate of adsorption process, while average tortuosity connected the sorbent structure and ions transport through the sorbent. A good agreement between model prediction for both structural and ion transport model parameters and the experimental data, indicates that the proposed mathematical model can be successfully used for optimization of heavy metal ions adsorption process by correlating the model parameters to the carbonized hemp fibers performances.

Chitin nanofibrils for rapid and efficient removal of metal ions from water system

Joint mechanical defibrillation was successfully used to downsize chitin micro-particles (CMP) into nanofibrils without changing its chemical or crystalline structure. The fine chitin nanofibrils (CNF) bearing width of about 50nm and length of more than 1μm were then developed as heavy metal ion sorbents. The uptake performance of CNF dependent on pH, ionic concentration, time, and temperature was investigated. Results show that fixation amount of Cd(II), Ni(II), Cu(II), Zn(II), Pb(II), Cr(III) on CNF was up to 2.94, 2.30, 2.22, 2.06, 1.46, and 0.31mmol/g, respectively, much higher than CMP due to high specific surface area and widely distributed pores of CNF. Adsorption kinetics of CMP and CNF followed pseudo-second-order model and Freundlich isotherm although CNF exhibited higher rate constant and sorption capacity than that of CMP. The defibrillated CNF is renewable, feasible, easily recyclable, and is thought as good candidate for heavy metal ion treatment due to their low sorption energy, rapid and efficient uptake capacity.