Biosorption of phenolic compounds from aqueous solutions onto chitosan–abrus precatorius blended beads

BACKGROUND: This research focuses on understanding the biosorption process and developing a cost‐effective technology for the treatment of water contaminated with phenolic compounds (phenol, 2‐chlorophenol and 4‐chlorophenol), which are discharged into the aquatic environment from a variety of sources and are highly toxic. In order to remove phenolic compounds from water, a new biobased sorbent is developed, blending chitosan with abrus precatorius, both naturally occurring biopolymers. The resulting chitosan–abrus precatorius blended beads (CS/Ab) were characterized by Brunauer, Emmett and Teller (BET) analysis, Fourier Transform Infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques under batch equilibrium and column flow experimental conditions. The binding capacity of the biosorbent was investigated as a function of initial pH, contact time, initial concentration of adsorbate and dosage of adsorbent. RESULTS: The percentage removal of phenol, 2‐CP and 4‐CP increased with increasing adsorbent dose, while the adsorption capacity at equilibrium, q_e (mg g^?1) (amount of phenol, 2‐CP and 4‐CP loaded per unit weight of adsorbent) decreased. The equilibrium time was found to be 240 min for full equilibration of all adsorbates. Adsorption kinetic and isotherm studies showed that the pseudo‐first‐order model and the Langmuir isotherm were the best choices to describe the adsorption behaviors. The maximum monolayer adsorption capacity of phenol, 2‐CP and 4‐CP on to the (CS/Ab) beads was found to be 156 mg g^?1, 204 mg g^?1 and 278 mg g^?1, respectively. CONCLUSION: The experimental results suggested that (CS/Ab) blended beads are effective in the removal of phenolic compounds from aqueous medium. Copyright © 2009 Society of Chemical Industry     

Biosorption of heavy metals (Cd,Cu, Ni,Pb, Zn) by chemically-reinforced biomass of marine algae

Particles of two different sizes (0·105–0·295 mm and 0·84–1.00 mm diameter) of two marine algae, Sargassum fluitans and Ascophyllum nodosum, were crosslinked with formaldehyde (FA), glutaraldehyde (GA) or embedded in polyethylene imine (PEI), followed by glutaraldehyde crosslinking. They were used for equilibrium sorption uptake studies with cadmium, copper, nickel, lead and zinc. The metal uptake by larger particles (0·84–1·00 mm) was higher than that by smaller particles (0·105–0·295 mm). The order of adsorption for S. fluitans biomass particles was Pb > Cd > Cu > Ni > Zn, for A. nodosum copper and cadmium change places. Uptakes of metals range from q_max = 378 mg Pb g^?1 for S. fluitans (FA, big particles), to q_max = 89 mg Zn g^?1 for S. fluitans (FA, small particles) as the best sorption performance for each metal. Generally, S. fluitans is a better sorbent material for a given metal, size and modification, although there were several exceptions in which metal sorption by A. nodosum was higher. The metal uptake for different chemical modifications showed the order GA > FA > PEI. A comparison of different sorption models revealed that the Langmuir sorption model fitted the experimental data best.     

Biosorption of Zn(II) by orange waste in batch and packed‐bed systems

BACKGROUND: This research provides new insights into the biosorption of zinc on a waste product from the orange juice industry. Optimal operating conditions maximizing percentage zinc removal were determined in batch and fixed‐bed systems. Biomass was characterized by FTIR spectroscopy and by major cation content in order to better understand the biosorpion mechanism. Zn‐loaded orange waste was proposed to be used as an alternative fuel in cement kilns. RESULTS: Sorption capacity was strongly affected by biosorbent dose and solution pH, and was not strongly sensitive to particle size under the experimental conditions studied. Equilibrium data were successfully described by a Langmuir model and sorption kinetic data were adequately modelled with the pseudo‐second‐order and Elovich rate equation. The biomass was found to possess high sorption capacity (q_max = 0.664 mmol g^?1) and biosorption equilibrium was established in less than 3 h. Experimental breakthrough curves were adequately fitted to the Thomas model and the dose–response model, obtaining sorption capacities in continuous assays higher than those found in batch mode. Characterization of the biomass suggested the possible contribution of carboxyl and hydroxyl groups of biomass in Zn²⁺ biosorption and it also highlighted the important role of light metal ions in a possible ion‐exchange mechanism. CONCLUSIONS: Orange waste could be used as an effective and low‐cost alternative biosorbent material for zinc removal from aqueous solution. Copyright © 2010 Society of Chemical Industry     

Biosorption potential of Neurospora crassa cells for decolorization of Acid Red 57 (AR57) dye

Biosorption of Acid Red 57 (AR57) on to Neurospora crassa was studied with variation of pH, contact time, biosorbent and dye concentrations and temperature to determine equilibrium and kinetic models. The AR57 biosorption was fast and equilibrium was attained within 40 min. Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models were applied to experimental equilibrium data for AR57 biosorption at various temperatures. The equilibrium data fitted very well to all the equilibrium models in the studied concentration range of AR57. Maximum biosorption capacity (q_max) of AR57 on to N. crassa was 2.16 × 10^?4 mol g^?1 at 20 °C. The kinetics of biosorption of AR57 were analyzed and rate constants were derived. The overall biosorption process was best described by a pseudo‐second‐order kinetic model. The changes in Gibbs free energy, enthalpy and entropy of biosorption were also evaluated for the biosorption of AR57 on to N. crassa. The results indicate that the biosorption was spontaneous and exothermic in nature. Copyright © 2006 Society of Chemical Industry     

Removal of 4‐chlorophenol from contaminated water using coconut shell waste pretreated with chemical agents

BACKGROUND: At concentrations higher than 1 mg L^?1, 4‐chlorophenol (4‐CP) is very toxic to living organisms, and if ingested beyond the permitted concentration it causes health disorders such as cancer and mutation. This laboratory study investigates treatment of contaminated water laden with 4‐CP using coconut shell charcoal (CSC) waste. Batch studies were conducted to study the effects of dose, pH, and equilibrium time on 4‐CP removal. To improve 4‐CP removal, surface modification of the adsorbent with TiO₂, HNO₃, and/or NaOH was undertaken. RESULTS: At an initial 4‐CP concentration of 25 mg L^?1 under optimized conditions (dose 13.5 g L^?1, pH 2.0; agitation speed 150 rpm and 50 min equilibrium time), the NaOH‐treated CSC demonstrated a greater removal of 4‐CP (71%) than those oxidized with HNO₃ (40%) and/or coated with TiO₂ (52%). The adsorption capacity of the NaOH‐treated CSC (54.65 mg g^?1) was higher than those treated with HNO₃ (23.13 mg g^?1) or coated with TiO₂ (48.42 mg g^?1). CONCLUSION: Although treatment results using the NaOH‐treated CSC alone were promising, the treated effluents were still unable to meet the required limit of less than 1 mg L^?1. Therefore, subsequent treatments are still required to complement the removal of 4‐CP from the wastewater. Copyright © 2010 Society of Chemical Industry     

Direct synthesis of surface molecularly imprinted polymers based on vinyl–SiO2 nanospheres for recognition of bisphenol A

Molecularly imprinted polymers (MIP) with high performance in selectively recognizing bisphenol A (BPA) were prepared by using a novel and facile surface molecular‐imprinting technique. Vinyl‐functionalized, monodispersed silica spheres were synthesized by a one‐step emulsion reaction in aqueous solution. Then, BPA surface molecularly imprinted polymers (SMIP) were prepared by polymerization with 4‐vinylpyridine as the functional monomer and ethylene glycol dimethacrylate as the crosslinker. Maximal sorption capacity (Q_max) of the resulting SMIP was up to 600 μmol g^?1, while that of nonimprinted polymers was only 314.68 μmol g^?1. Kinetic binding study showed that sorption capacity reached 70% of Q_max in 20 min and sorption equilibrium at 80 min. SMIP had excellent accessibility and affinity toward BPA, for the selectivity coefficients of SMIP for BPA in respect to phenol, p‐tert‐butylphenol, and o‐phenylphenol were 3.39, 3.35, and 3.02, respectively. The reusage process verified the SMIP owning admirably stable adsorption capacity toward BPA for eight times. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Biosorption of palladium and platinum by sulfate‐reducing bacteria

The biosorption capacities of palladium and platinum were studied in three different species of Desulfovibrio: Desulfovibrio desulfuricans, Desulfovibrio fructosivorans and Desulfovibrio vulgaris. The influence of several parameters such as pH, acidic background and competitor anions on biosorption equilibria and biosorption kinetics were evaluated. Differences were observed between the three strains of Desulfovibrio with respect to the optimum biosorption parameters of both metals, suggesting differences in the metal speciation–dependent sorption mechanisms involved. The most promising Pd and Pt biosorption results were obtained using D desulfuricans with rapid achievement of equilibrium (90% of total sorption was achieved in 5–15 min) and a maximum value of 190 mg g^?1 dry biomass and 90 mg g^?1 dry biomass for Pd and Pt accumulation respectively, at pH 3. Copyright © 2003 Society of Chemical Industry     

Removal of Methylene Blue from aqueous solutions using as biosorbent Sargassum muticum: an invasive macroalga in Europe

Methylene Blue adsorption on Sargassum muticum, an invasive macroalga in Europe, has been investigated using visible absorption spectroscopy. Different pre‐treatments, protonation and chemical cross‐linking with CaCl₂ or H₂CO, have been tested in order to improve the stability as well as the adsorption capacity of the algal biomass. The equilibrium binding has been described in terms of Langmuir or Freundlich isotherms depending on the algal pre‐treatment; from the maximum adsorption capacity values, an estimation of the algal specific surface area was made. Moreover, it has been found that adsorption kinetics can be described according to the first order Lagergren model, from which the rate constant and the adsorption capacity were determined. Finally, simple empirical equations were obtained to evaluate the amount of Methylene Blue removed at any initial concentration and reaction time. The results obtained have shown that this type of material has a high adsorption capacity for Methylene Blue dye, this feature together with the short times needed to reach the equilibrium suggest that Sargassum muticum can be used as a low‐cost biosorbent in wastewater treatments. Copyright © 2004 Society of Chemical Industry     

Biosorption of heavy metals from aqueous solution using modified activated carbon: comparison of linear and nonlinear methods

BACKGROUND: Biosorption of heavy metals from aqueous solution by modified activated carbon with Phanerochaete chrysosporium immobilised in Ca‐alginate beads was investigated using a batch system and comparison of linear and nonlinear methods. RESULTS: The amount of Cu(II), Zn(II) and Pb(II) ion sorption by the beads was as follows: activated carbon with P. chrysosporium immobilised in Ca‐alginate beads (ACFCA) (193.4, 181.8, 136.6 mg g^?1) > activated carbon immobilised in Ca‐alginate beads (ACCA) (174.8, 162.0, 130.7 mg g^?1) > P. chrysosporium (F) (148.8, 125.6, 120.4 mg g^?1) > activated carbon (AC) (138.8, 112.3, 109.3 mg g^?1) > plain Ca‐alginate beads (PCA) (125.4, 105.2, 98.2 mg g^?1). The widely used Langmuir and Freundlich isotherm models were utilised to describe the biosorption equilibrium process. CONCLUSION: The results of this study suggest that the immobilisation of modified activated carbon with P. chrysosporium in Ca‐alginate beads is suitable for a batch system. The isotherm parameters were estimated using linear and nonlinear regression analyses. The surface charge density of the biosorbents varied with the pH of the medium; the maximum biosorption of heavy metal ions on the biosorbents was obtained when the pH was between 5.6 and 7.4. Copyright © 2008 Society of Chemical Industry     

Sorption capacity of a new generation granular activated carbon—Bio‐Sep® bead—and its use in a suspended growth bioreactor

BACKGROUND: A new generation granular activated carbon—Bio‐Sep® beads—consist of 25% polymer (Nomex) and 75% powdered activated carbon. The porous structure and high surface area of these beads make them suitable for sorbent in adsorption columns, and for immobilization media in bioreactors. The aim of this study was to study the sorption characteristics of Bio‐Sep® beads for methyl t‐butyl ether (MTBE) and t‐butyl alcohol (TBA), and to demonstrate the advantage of their usage in a suspended growth bioreactor. RESULTS: The maximum uptake capacity of Bio‐Sep® beads for MTBE and TBA, in the studied concentration range (10–100 mg L^?1), was observed to be 9.73 and 6.23 mg g^?1, respectively. A 52 h desorption experiment resulted in 13.6–42.2% MTBE and 33–53% TBA desorption corresponding to the initial solid phase concentrations of 1.68–9.73 mg g^?1 and 1.41–6.23 mg g^?1, respectively. The sorption of TBA on the Bio‐Sep® beads was significantly hindered by the presence of MTBE. The addition of 10 g Bio‐Sep® beads (dry weight) in a suspended growth bioreactor was able to eliminate the inhibitory effect of 150 mg L^?1 MTBE. CONCLUSIONS: At an equilibrium aqueous phase concentration (C_e) of 1 mg L^?1, the solid phase concentration (q_e) on Bio‐Sep® beads were observed as 1.44 and 0.47 mg g^?1 for MTBE and TBA, respectively. The results obtained in this study indicate that Bio‐Sep® beads have reasonable sorption and desorption characteristics, which can be successfully exploited for the removal/degradation of toxic organic pollutants in high rate bioreactors. Copyright © 2007 Society of Chemical Industry     

Adsorptive removal of technetium‐99 using macroporous poly(GMA‐co‐EGDMA) modified with diethylene triamine

The possibility of sorption of technetium‐99 in the form of pertechnetate anion (TcO₄^?) and the sorption kinetics for removing TcO₄^? from aqueous solution by chelating polymers based on glycidyl methacrylate (GMA) were investigated. Two samples of macroporous crosslinked poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (PGME), with different amount of the crosslinker (ethylene glycol dimethacrylate, EGDMA), were synthesized by suspension copolymerization and functionalized with diethylene triamine (deta). We propose that nonspecific sorption of pertechnetate anion via electrostatic interactions takes place at the protonated amino groups of macroporous crosslinked copolymer. The results of batch experiments performed at pH 1–14 showed fast sorption kinetics for removing TcO₄^? by amino‐functionalized PGME‐deta in a wide range of pH, that is, from 1.0 to 9.0. Almost complete removal of TcO₄^? (91–98%) was reached within 180 min in the stated pH range (1.0–9.0), with the sorption half‐times of under 25 min. The partitioning coefficients of linear adsorption isotherms, with 180‐min equilibrium time, reach the high values of 2130 mL g^?1 and 1698 mL g^?1 for the two samples of synthesized PGME‐deta. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Biosorption of methylene blue from aqueous solution by softstem bulrush (Scirpus tabernaemontani Gmel.)

BACKGROUND: The removal of methylene blue from aqueous solution was studied using softstem bulrush (Scirpus tabernaemontani Gmel.) as the biosorbent. The effects of various parameters including contact time, biosorbent dosage, ionic strength and solution pH on the biosorption were investigated. RESULTS: The sorption capacity increased with an increase in biosorbent dosage and a decrease in ionic strength. The equilibrium time was found to be 240 min for full equilibration. Pseudo‐first‐order, pseudo‐second‐order, Bangham equation and intraparticle diffusion models were applied to fit the kinetic data, and the results showed that the sorption process followed the pseudo‐second‐order model. Equilibrium data conformed to Langmuir and Redlich–Peterson isotherm models, with a maximum monolayer biosorption capacity of 53.8 mg g^?1 for the Langmuir isotherm at 18 °C. The value of ΔG was estimated to be ? 29.24 kJ mol^?1, indicating the spontaneous nature of the biosorption. The biosorption process was strongly pH‐dependent and favourable at alkaline pH. CONCLUSION: Softstem bulrush, which is readily available and inexpensive, could be employed as a promising biosorbent for the removal of dye. Copyright © 2008 Society of Chemical Industry     

Kinetic and Equilibrium Modelling on Copper(II) Removal by Live and Dead Cells of Trichoderma asperellum and the Impact of Pre-Treatments on Biosorption

In this study, the approach is to evaluate the use of Trichoderma asperellum biomass as a biosorbent for Cu²⁺ removal. Both live and dead cells are investigated. The feasibility of T. asperellum as biosorbent is further explored by pre-treating the cells and evaluating their subsequent Cu²⁺ removal efficacy. Results revealed that dead cells of T. asperellum attained biosorption equilibrium within the first 10 min of contact with Cu²⁺ while live cells reached equilibrium after 20 min. Dead cells also absorbed significantly higher amounts of Cu²⁺ (12.42 mg g^?1) compared to live cells (5.69 mg g¹). The biosorption mechanism for both live and dead cells of T. asperellum complied with the Langmuir isotherm and pseudo second-order kinetic, suggesting monolayer sorption. Pre-treatment of dead cells with alkali solutions (NaOH and laundry detergent) further improved sorption efficacy.     

Studies on the removal of Cobalt(II) from aqueous solutions by adsorption with Ficus benghalensis leaf powder through response surface methodology

Suitability of Ficus benghalensis leaf powder for the adsorptive removal of Cobalt(II) from aqueous solutions is exhaustively studied and is reported in this article. Experimentation based on response surface methodology is conducted to understand the interaction among the variables—metal ion concentration, adsorbent dosage, initial solution pH and temperature that are of significance in the treatment. A 20?mg?L^?1 of Cobalt(II) solution, treated with 25?g?L^?1 of adsorbent at a pH of 5.0 and a temperature of 303?K, yielded 98.73% removal of Cobalt(II). Langmuir isotherm proved to be a better model representation of the equilibrium. Adsorption kinetics is of pseudo second rate form. Maximum sorption capacity of F. benghalensis leaf powder, q_max, is found to be 5.65?mg?g^?1. Adsorption is endothermic and spontaneous in nature. Study on surface morphology is included in the study.     

Fixed-bed column performance of methylene blue biosorption by Luffa cylindrica: statistical and mathematical modeling

Abstract

This study aimed to investigate the adsorption capacity of Iranian Luffa cylindrica as a natural lignocellulosic adsorbent for biosorption of methylene blue (MB) using a fixed-bed column. The response surface methodology based on central composite design was used to evaluate the interactive effects of three major operating parameters (inlet MB concentration, Luffa dosage, and feed flow rate) on the dye removal percentage (response variable). The significance of the proposed quadratic model was validated by a high coefficient of determination (R²?=?0.995) and a low p value (<0.001). The optimum biosorption conditions were determined as inlet MB concentration 38.66?mg?L^?1, Luffa dosage 2.78?g, and feed flow rate 5?mL?min^?1, and the maximum MB removal efficiency was founded to be 51% (q_max?=?21.4?mg?g^?1) at optimum conditions. The breakthrough curves were predicted by the Adams–Bohart and Thomas models using nonlinear regression analysis, whereas the experimental data fitted well with the Thomas model (R²?≈?0.96–0.98). Further surface modification studies enabled us to achieve the maximum MB removal efficiency of 77% (q_max?=?46.58?mg?g^?1) with NaOH-modified Luffa, which is attributed to the intensification of the negatively charged surface of the base-modified adsorbent with hydroxyl groups. The nature of biosorbent–dye interactions was also evaluated by FTIR analysis. The highest desorption performance of MB from Luffa fibers was obtained with HCl solution reaching a desorbed amount of q_des?=?130.5?mg in the column studies. The ion exchange is introduced as the dominant biosorption mechanism of MB onto Luffa fibers in this study.     

Diffusion kinetic study of cadmium(II) biosorption by Aeromonas caviae

The removal of cadmium from aqueous solution by sorption on Aeromonas caviae particles was investigated in a well‐stirred batch reactor. Equilibrium and kinetic experiments were performed at various initial bulk concentrations, biomass loads and temperatures. Biosorption equilibrium was established in about 1 h and biosorption was well described by the Langmuir and Freundlich biosorption isotherms. The maximum biosorption capacity was found as 155.32 mg Cd(II) g^?1 at 20 °C. The obtained sorption capacity is appreciably high for most experimental conditions; so A caviae may be considered as a suitable biosorbent for the removal of cadmium. Moreover, the sorption rate of cadmium onto A caviae particles was particularly sensitive to initial bulk concentration and solid load. A detailed analysis was conducted, examining several diffusion (external and intraparticle) kinetic models in order to identify a suitable rate expression. The results are discussed and indicate that biosorption of cadmium is a complex process that is described more correctly by more than one model. Copyright © 2004 Society of Chemical Industry     

Gold‐cyanide biosorption with L‐cysteine

L ‐Cysteine increased gold‐cyanide biosorption by protonated Bacillus subtilis, Penicillium chrysogenum and Sargassum fluitans biomass. At pH 2, the maximum Au uptakes were 20.5 µmol g⁻¹, 14.2 µmol g⁻¹ and 4.7 µmol g⁻¹ of Au, respectively, approximately 148–250% of the biosorption performance in the absence of cysteine. Au biosorption mainly involved anionic AuCN₂⁻ species adsorbed by ionizable functional groups on cysteine‐loaded biomass carrying a positive charge when protonated [(biomass–cysteine–H⁺)–(AuCN₂⁻)]. Deposited gold could be eluted from Au‐loaded biomass at pH 3–5. The elution efficiencies were higher than 92% at pH 5.0 with the Solid‐to‐Liquid ratio, S/L, = 4. Increasing solution ionic strength (NaNO)₃ decreased Au uptake. FTIR analyses indicated that the main functional groups involved in gold biosorption in the presence of L ‐cysteine are probably N‐, S‐ and O‐containing groups. The present results confirm that certain waste microbial biomaterials are capable of effectively removing and concentrating gold from solutions containing residual cyanide if applied under appropriate conditions. © 2000 Society of Chemical Industry     

Heavy metals removal from solution by polyaniline/palygorskite composite

Batch adsorption experiments were carried out to remove heavy metal ions such as Cu (II), Ni (II), Cd (II), and Cr (VI) from single‐metal solutions using a polyaniline/palygorskite (PP) composite. Different parameters affecting the adsorption capacity such as contact time and pH of the solution have been investigated. The structural characteristics of the PP composite were studied in this work. Atomic absorption spectroscopy was used for the measurement of heavy metal contents, and the adsorption capacity (q_e) calculated were 114 mg Cu (II) g^?1, 84 mg Ni (II) g^?1, 56 mg Cd (II) g^?1, and 198 mg Cr (VI) g^?1 under optimal conditions. The removal of the metal ions from solutions was assigned to chelation, ionic exchange, and electrostatic attraction. Data from this study proved that the novel organic/inorganic composite presents great potential in the recovery and elimination of noble or heavy metal ions from industrial wastewater. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Sorption of Pyrene to Two Estonian Soils

Two typical Estonian soils, Brown pseudopodzolic and Rendzina, were used for sorption studies with pyrene. The soil samples were subjected to a variety of chemical and physical tests. The specific surface area reached 3.05 m² g^?1 for Rendzina, and 0.87 m² g^?1 for Brown pseudopodzolic soil. The Rendzina type of soil was characterized also by a high organic matter content (22.9%) compared with the Brown pseudopodzolic soil (6.64%). A batch technique was used to perform all adsorption studies. K_oc values 2.7 × 10⁴ mg g^?1 for Rendzina and 4.5 × 10⁴ mg g^?1 for Brown pseudopodzolic were obtained. The results suggets that pyrene sorption behaviour could be in some instances mainly influenced by the composition of organic compounds in the soil, not so much by the overall organic matter content. Also the mineral part of the soil can have a impact to pyrene sorption through Ca-binded humic substances.     

Determination of diffusion parameters and biosorption of cadmium in aqueous solution using algae biomass

The objective behind this study is to investigate the phenomenon and kinetics of Cd(II) ion biosorption by the algae fibers, as well as the development of mathematical model that would describe the phenomenon of ions transport through porous algae. The results obtained have shown an inter-particle rate constant of diffusion K_int = 0.188 (mg·g^?1·min^?1/2), R² = 0.999, and adsorption amount at equilibrium Q_Seq = 1.87 mg·g^?1. These results indicated that the diffusion of ions existed in the porous algae. The proposed mathematical model is used to optimize the biosorption of heavy metal ions by connecting the model parameters with the fiber performances.