Biosorption Of Zinc Research Articles

Zinc biosorption in EBBR using mixed culture bacteria

Zinc biosorption in EBBR using mixed culture bacteria

Mechanism of Biosorption of Heavy Metals by Mucor rouxii

AbstractFungi such as Aspergillus niger and Mucor rouxii are capable of removing heavy metals from aqueous solutions. The role various functional groups play in the cell wall of M. rouxii in metal biosorption of lead, cadmium, nickel and zinc was investigated in this paper. The biomass was chemically treated to modify the functional carboxyl, amino and phosphate groups. These modifications were examined by means of infrared spectroscopy. It was found that an esterification of the carboxyl groups and phosphate and a methylation of the amine groups significantly decreased the biosorption of the heavy metals studied. Thus, the carboxylate, amine and phosphate groups were recognized as important in the biosorption of metal ions by M. rouxii biomass. The role the lipids fraction play was not significant. The study showed that Na, K, Ca and Mg ions were released from the biomass after biosorption of Pb, Cd, Ni and Zn, indicating that ion exchange was a key mechanism in the biosorption of metal ions by M. rouxii biomass.

Optimization of a biosorption column performance.

The dynamics of copper and zinc biosorption by Sargassum fluitans was analyzed under variable column operating conditions including different column lengths (15 and 45 cm), metal-feed solution concentrations (1 and 6 meq L(-1)), metal-sorbent affinities (2.01 and 0.45), and interstitial velocities (12 and 4 cm min(-1)). The experimental breakthrough curves obtained under these varying conditions were also simulated using a mathematical model taking into account the mass transfer as well as the axial dispersion phenomena. The column performance was evaluated using two performance indicators: the service time (t(s)) and the unused portion of the column as reflected in the area under the breakthrough curve (A(c)). Sensitivity analysis results indicated that the feed stream concentration, mass transfer coefficient, column length, and interstitial velocity had the most important effect on the column performance. Applying chromatography theories, the optimization of the biosorption process for productivity and sorption performance, in terms of operating conditions (interstitial velocity) and design parameters (column length), was outlined. The corresponding optimum curve relating the interstitial velocity and the column length resulted with the pressure drop limitations recognized. As an example, a laboratory column 100 cm long will necessitate an interstitial velocity of 19 cm min(-1) to yield the best sorption results.

Biosorption of Zn and Co ions by Evernia prunastri from single and binary metal solutions

Dried biomass of lichen Evernia prunastri was studied as biosorbent for zinc and cobalt removal from single and binary ZnCl2 and CoCl2 solutions. The solution pH significantly influenced both cobalt and zinc biosorption. Maximum uptake was reached at pH 4–6 and negligible biosorption was observed at pH 2. The experimental data were fitted to the adsorption isotherms. The Langmuir, Redlich-Peterson and Langmuir-Freundlich isotherms were found to represent the measured sorption data well. The maximum sorption capacities onto lichen biomass from single metal solutions calculated by Langmuir equation were 112 μmol g−1 for Zn and 97 μmol g−1 for Co. To evaluate the Zn-Co sorption system, simple curves were replaced by three-dimensional sorption isotherm surfaces. Binary Langmuir type equations were used to fit the experimental data. Results revealed that E. prunastri exhibited preferential uptake of zinc from equimolar binary Zn 2+−Co 2+ mixtures.

Competitive biosorption of zinc(II) and cobalt(II) in single- and binary-metal systems by aerobic granules

The biosorption process for removal of cobalt(II) and zinc(II) by aerobic granules was characterized. Single component and binary equimolar systems were studied at different pH values. The equilibrium was well described by Redlich–Peterson adsorption isotherm. The maximal adsorption capacity of the granules, in single systems (55.25 mg g −1 Co; 62.50 mg g −1 Zn) compared with binary systems (54.05 mg g −1 Co; 56.50 mg g −1 Zn) showed reduction in the accumulation of these metals onto aerobic granules. The kinetic modelling of metal sorption by granules has been carried out using Lagergren equations. The regression analysis of pseudo second-order equation gave a higher R 2 value, indicating that chemisorption involving valent forces through the sharing or exchange of electrons between sorbent and sorbate may be the rate limiting step. The initial biosorption rate indicated that aerobic granules can adsorb Co(II) more rapidly than Zn(II) from aqueous solutions. Meanwhile, FTIR and XPS analyses revealed that chemical functional groups (e.g., alcoholic and carboxylate) on aerobic granules would be the active binding sites for biosorption of Co(II) and Zn(II).

Biosorption of cadmium(II), zinc(II) and lead(II) by Penicillium simplicissimum: Isotherms, kinetics and thermodynamics

The isotherms, kinetics and thermodynamics of Cd(II), Zn(II) and Pb(II) biosorption by Penicillium simplicissimum were investigated in a batch system. The effects of pH, initial metal ions concentration, biomass dose, contact time, temperature and co-ions on the biosorption were studied. Adsorption data were well described by both the Redlich–Peterson and Langmuir model. Chemical ion-exchange was found to be an important process based on free energy value from Dubini–Radushkevich isotherm for all metal ions. The results of the kinetic studies of all metal ions at different temperature showed that the rate of adsorption followed the pseudo second-order kinetics well. The thermodynamics constants Δ G°, Δ H° and Δ S° of the adsorption process showed that biosorption of Cd(II), Zn(II) and Pb(II) ions on Penicillium simplicissimum were endothermic and spontaneous.

Kinetic, isotherm and thermodynamic studies of the biosorption of zinc (II) from solution by maize wrapper

2+ from solution. The optimum pH obtained was in the range pH 5 - 7, therefore pH 6 was used for other studies. The kinetic study shows that uptake of Zn 2+ increased with time and that maximum biosorption was obtained within 60 min of the process. The result obtained showed that the pseudo- first order model correlated with the experimental data better than the pseudo-second order model examined in this study. Freundlich and Langmuir isotherm models were used to analyse the experimental data of the biosorption process. The Freundlich and Langmuir equations obtained are log � = 0.643 log Ce + 1.1177 and 1/� = 0.0411/Ce + 0.009, respectively. The correlation factors are 0.9971 and 0.9889, respectively. The free energy change for the biosorption of Zn 2+ at 27oC, initial

Biosorption of nickel, chromium and zinc by MerP-expressing recombinant Escherichia coli

Escherichia coli hosts able to over-express metal-binding proteins (MerP) originating from Gram-positive ( Bacillus cereus RC607) and Gram-negative ( Pseudomonas sp. K-62) bacterial strains were used to adsorb Ni 2+, Zn 2+ and Cr 3+ in aqueous solutions. The initial adsorption rate and adsorption capacity were determined to evaluate the performance of the biosorbents. With the expression of MerP protein, the metal adsorption capacity of the recombinant strains for Ni 2+, Zn 2+ and Cr 3+ significantly improved. The cells carrying Gram-positive merP gene (GB) adsorbed Zn 2+ and Cr 3+ at a capacity of 22.3 and 0.98 mmol/g biomass, which is 121% and 72% higher, respectively, over that of the MerP-free host cells. Adsorption capacity of the cells carrying Gram-negative merP gene (GP) also increased 144% and 126% for Zn 2+ and Cr 3+, respectively. Both recombinant strains also exhibited 24% and 5% enhancement in adsorption of Ni 2+ for GB and GP, respectively. The initial adsorption rate of the recombinant biosorbents was also higher than that of the MerP-free host, suggesting an increased metal-binding affinity with MerP expression. Severe cell damage on GB biosorbent was observed after Cr 3+ adsorption, probably due to the metal toxicity effect on the cells.

The use of Neem biomass for the biosorption of zinc from aqueous solutions

An adsorbent was developed from mature leaves and stem bark of the Neem ( Azadirachta indica) tree for removing zinc from water. Adsorption was carried out in a batch process with several different concentrations of zinc by varying pH. The uptake of metal was very fast initially, but gradually slowed down indicating penetration into the interior of the adsorbent particles. The data showed that optimum pH for efficient biosorption of zinc by Neem leaves and stem bark was 4 and 5, respectively. The maximum adsorption capacity showed that the Neem biomass had a mass capacity for zinc (147.08 mg Zn/g for Neem leaves and 137.67 mg Zn/g Neem bark). The experimental results were analyzed in terms of Langmuir and Freundlich isotherms. The adsorption followed pseudo-second-order kinetic model. The thermodynamic assessment of the metal ion-Neem tree biomass system indicated the feasibility and spontaneous nature of the process and Δ G° values were evaluated as ranging from −26.84 to −32.75 (Neem leaves) kJ/mol and −26.04 to −29.50 (Neem bark) kJ/mol for zinc biosorption. Due to its outstanding zinc uptake capacity, the Neem tree was proved to be an excellent biomaterial for accumulating zinc from aqueous solutions.

Biosorption of zinc from aqueous solution using Azadirachta indica bark: Equilibrium and kinetic studies

The removal of zinc ions from aqueous solutions on the biomass of Azadirachta indica bark has been studied by using batch adsorption technique. The biosorption studies were determined as a function of contact time, pH, initial metal ion concentration, average biosorbent size and biosorbent dosage. The equilibrium metal uptake was increased and percentage biosorption was decreased with an increase in the initial concentration and particle size of biosorbent. The maximum zinc biosorption occurred at pH 6 and percentage biosorption increases with increase in the biosorbent dosage. Experimental data obtained were tested with the adsorption models like Langmuir, Freundlich and Redlich–Peterson isotherms. Biosorption isothermal data were well interpreted by Langmuir model with maximum biosorption capacity of 33.49 mg/g of zinc ions on A. indica bark biomass and kinetic data were properly fitted with the pseudo-second-order kinetic model.

Kinetics of Zinc(II) Ion Biosorption onto Powdered Waste Sludge (PWS) at Different Operating Conditions

Batch biosorption kinetics of zinc(II) ions onto powdered waste sludge (PWS) were investigated under different experimental conditions such as variable pH (3–6), temperature (30–50°C), Zinc ion (50–350 mg L−1) and PWS (0.25–3 g L−1) concentrations and PWS particle size (53–231 μm). The rate and the extent of zinc(II) biosorption increased with pH yielding pH 5 (qm = 60 mg g−1) as the optimal value without Zn(OH)2 precipitation. Increases in temperature also resulted in increases in biosorption rate with an activation energy of 6 kcal mol−1 according to the second-order kinetics. Maximum biosorbed Zn(II) concentration was 72 mg g−1 at 50°C. Biosorbed zinc(II) concentration at the end of 6 h of incubation increased with increasing zinc(II) concentration (qm = 95 mg g−1 at 300 mg L−1 Zn), but with decreasing particle size (qm = 70 mg g−1 with Dp = 53 μm) and concentration of PWS (qm = 168 mg g−1 with PWS of 0.25 g L−1). Pseudofirst- and second-order kinetics were used for correlation of biosorption data and for determination of the rate constants. The pseudosecond-order kinetics was found to be more suitable for representation of the kinetic data for almost all cases due to similarity between the adsorption kinetics and bimolecular reactions. Kinetic constants increased with increasing pH, temperature, and PWS concentration, but decreased with increasing zinc(II) concentrations and the particle size of PWS. The highest rate constants for the pseudofirst- and second-order kinetics were 0.71 h−1 and 0.024 (mg/g)−1 h−1 , respectively, for the smallest particle size of 53 μm. The highest Zn(II) biosorption capacity of 168 mg g−1 was obtained with PWS and Zn(II) concentrations of 0.25 g L−1 and 100 mg L−1at the end of 6 h biosorption period.

Zinc Biosorption by Seaweed Illustrated by the Zincon Colorimetric Method and the Langmuir Isotherm

Heavy metals are major pollutants in marine, ground, industrial, and even treated waters. Sorption of heavy metals onto live or dead biological materials (biosorption) is a potential method of removing toxic metals. Zinc and two algae, Ulva sp. and Gymnogongrus torulosus, were evaluated in this study. A linear zinc calibration curve in the range 1–8 mg L-1 was obtained using the zincon colorimetric method. In the biosorption assays, a rapid zinc uptake was observed and kinetic curves stabilized after 60 minutes. Experiments using initial zinc concentrations of 50 mg L-1 showed that 20% and 60% of zinc ions were removed from solution by Ulva sp. and Gymnogongrus torulosus, respectively. Results obtained from varying initial zinc concentrations allowed data fitting to Langmuir model with a good correlation. The maximum zinc uptake capacity and affinity constant obtained for Gymnogongrus torulosus were higher than those for Ulva sp. Maximum zinc uptake capacities were 42.8 x10-3 and 26.8 x10-3 for Gymnogon...

Determination of model parameters for zinc (II) ion biosorption onto powdered waste sludge (PWS) in a fed–batch system

Biosorption of zinc (II) ions onto pre-treated powdered waste sludge (PWS) was investigated using a completely mixed tank operating in fed–batch mode instead of an adsorption column. Experiments with variable feed flow rate (0.05–0.5 L h −1), feed Zn(II) ion concentrations (37.5–275 mg L −1) and amount of adsorbent (1–6 g PWS) were performed using fed–batch operation at pH 5 and room temperature (20–25 °C). Break-through curves describing variations of aqueous (effluent) zinc ion concentrations with time were determined for different operating conditions. Percent zinc removal from the aqueous phase decreased, but the biosorbed (solid phase) zinc ion concentration increased with increasing feed flow rate and zinc concentration. A modified Bohart–Adams equation was used to determine the biosorption capacity of PWS ( q′ s) and the rate constant ( K) for zinc ion biosorption. Biosorption capacity ( q′ s=57.7 g Zn kg −1 PWS) of PWS in fed–batch operation was found to be comparable with powdered activated carbon (PAC) in column operations. However, the adsorption rate constant ( K=9.17 m 3 kg −1 h −1) in fed–batch operation was an order of magnitude larger than those obtained in adsorption columns because of elimination of mass transfer limitations encountered in the column operations. Therefore, a completely mixed tank operated in fed–batch mode was proven to be more advantageous as compared to adsorption columns due to better contact between the phases yielding faster adsorption rates.

Biosorption of Zinc on Palm Tree Leaves: Equilibrium, Kinetics, and Thermodynamics Studies

The efficiency of using palm tree leaves to remove zinc ions from aqueous solution was studied. Adsorption isotherms, kinetics, and thermodynamics studies were conducted. The influence of different experimental parameters, such as equilibrium pH, shaking rate, temperature, and the presence of other pollutants such as chelating agents on the biosorption of zinc on palm tree leaves was investigated. Batch biosorption experiments showed that palm tree leaves used in this study proved to be suitable for the removal of zinc from dilute solutions where a maximum uptake capacity of 14.7 mg/g was obtained at 25°C. Zinc biosorption on palm tree leaves was found to be highly pH dependent. The biosorption process was found to be rapid with 90% of the adsorption completed in about 10 min. Dynamics studies of the biosorption of zinc on palm tree leaves showed that the biosorption process followed the pseudo second‐order kinetics with little intraparticle diffusion mechanism contribution. The equilibrium results indicated that zinc biosorption on palm tree leaves could be described by the Langmuir, Freundlich, Gin et al., and Sips models. Using the Langmuir equilibrium constants obtained at different temperatures, the thermodynamics properties of the biosorption (ΔG0, ΔH0, and ΔS0) were also determined. The values of these parameters indicated the spontaneous and endothermic nature of zinc biosorption on palm tree leaves.

Zinc biosorption on Tectona grandis L.f. leaves biomass: Equilibrium and kinetic studies

The biosorption of zinc ions from aqueous solution by Tectona grandis L.f. was studied in a batch adsorption system as a function of pH, contact time, zinc ion concentration, adsorbent concentration and adsorbent size. The biosorption capacities and rates of zinc ions onto T. grandis L.f. were evaluated. The Langmuir, Freundlich, Redlich–Peterson and Temkin adsorption models were applied to describe the isotherms and isotherm constants. Biosorption isothermal data could be well interpreted by the Langmuir model followed by Temkin model with maximum adsorption capacity of 16.42 mg g−1 of zinc ion on T. grandis L.f. leaves biomass. The kinetic experimental data was properly correlated with the second-order kinetic model. Various thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were calculated indicating that this system was a spontaneous and exothermic process.

Biosorption of Zinc from Aqueous Solutions by Rice Bran: Kinetics and Equilibrium Studies

Rice bran, an agricultural by‐product, was used for the removal of zinc ions from aqueous solution. The work considered the determination of zinc‐biomass equilibrium data in batch system. These studies were carried out in order to determine some operational parameters of zinc sorption such as the time required for the Zinc‐biosorbent equilibrium, the effects of biomass particle size, pH, and temperature. The results showed that pH has an importance effect on zinc biosorption capacity. The biosorbent size also affects the zinc biosorption capacity. The sorption process follows pseudo‐second‐order kinetics. The intraparticle diffusion may be the rate‐controlling step involved in the adsorption zinc ions onto the rice bran up to 30 min. The equilibrium data could be best fitted by the Langmuir sorption isotherm equation over the entire concentration range (40–160 mg/dm3). Thermodynamic parameters, such as ΔG°, ΔH°, ΔS°, have been calculated. The thermodynamics of zinc ion/rice bran system indicate spontaneous and endothermic nature of the process.

Tolerance and biosorption of copper and zinc byPseudomonas putidaCZ1 isolated from metal-polluted soil

A strain of Pseudomonas sp. CZ1, which was isolated from the rhizosphere of Elsholtzia splendens obtained from the heavy-metal-contaminated soil in the north-central region of the Zhejiang province of China, has been studied for tolerance to copper (Cu) and zinc (Zn) and its capacities for biosorption of these metals. Based on 16S ribosomal DNA sequencing, the microorganism was closely related to Pseudomonas putida. It exhibited high minimal inhibitory concentration values (about 3 mmol Cu.L-1 and 5 mmol Zn.L-1) for metals and antibiotic resistance to ampicillin but not to kanamycin. Based on the results of heavy metal toxicity screening, inhibitory concentrations in solid media were lower than those in liquid media. Moreover, it was found that the toxicity of Cu was higher than that of Zn. Pseudomonas putida CZ1 was capable of removing about 87.2% of Cu and 99.8% of Zn during the active growth cycle, with specific biosorption capacities of 24.2 and 26.0 mg x L-1, respectively. Although at low concentrations, Cu and Zn slightly damage the surface of some cells, P. putida demonstrated high capacities for biosorption of Cu and Zn. Since P. putida CZ1 could grow in the presence of significant concentrations of metals and because of its high metal uptake capacity in aerobic conditions, this bacterium may be potentially applicable in bioreactors or in situ bioremediation of heavy-metal-contaminated aqueous or soil systems.

Biosorption and Recovery of Copper and Zinc from Aqueous Solutions by Nonliving Biomass of Marine Brown Algae of Sargassum sp.

Biosorption and Recovery of Copper and Zinc from Aqueous Solutions by Nonliving Biomass of Marine Brown Algae of Sargassum sp.

Biosorption of heavy metals on Aspergillus fumigatus immobilized Diaion HP-2MG resin for their atomic absorption spectrometric determinations

A solid phase extraction procedure based on biosorption of copper(II), lead(II), zinc(II), iron(III), nickel(II) and cobalt(II) ions on Aspergillus fumigatus immobilized Diaion HP-2MG has been investigated. The analytical conditions including amounts of A. fumigatus, eluent type, flow rates of sample and eluent solutions were examined. Good recoveries were obtained to the spiked natural waters. The influences of the concomitant ions on the retentions of the analytes were also examined. The detection limits (3sigma, N = 11) were 0.30 μg l −1 for copper, 0.32 μg l −1 for iron, 0.41 μg l −1 for zinc, 0.52 μg l −1 for lead, 0.59 μg l −1 for nickel and 0.72 μg l −1 for cobalt. The relative standard deviations of the procedure were below 7%. The validation of the presented procedure is performed by the analysis of three standard reference materials (NRCC-SLRS 4 Riverine Water, SRM 1515 Apple leaves and GBW 07605 Tea). The procedure was successfully applied for the determination of analyte ions in natural waters microwave digested samples including street dust, tomato paste, black tea, etc.

Seaweeds for the remediation of wastewaters contaminated with zinc(II) ions

Eleven different species of marine macroalgae were screened at different pH conditions on the basis of zinc(II) biosorption potential. Among the seaweeds, a green alga, Ulva reticulata, exhibited a highest uptake of 36.1 mg/g at pH 5.5 and 100 mg/l initial zinc(II) concentration. Further experiments were conducted to evaluate the zinc(II) biosorption potential of U. reticulata. Sorption isotherm data obtained at different pH (5–6) and temperature (25–35 °C) conditions were fitted well with Sips model followed by Freundlich, Redlich–Peterson and Langmuir models. A maximum zinc(II) biosorption capacity of 135.5 mg/g was observed at optimum conditions of 5.5 (pH) and 30 °C (temperature), according to the Langmuir model. It was observed from the kinetic data that the zinc(II) biosorption process using U. reticulata follows pseudo-second-order kinetics. Various thermodynamic parameters, such as Δ G°, Δ H° and Δ S° were calculated and they indicated that the present system was a spontaneous and an endothermic process. The influence of the co-ions (Na +, K +, Ca 2+ and Mg 2+) along with zinc(II) present in the wastewater was also studied. Desorption of zinc(II) ions from the zinc(II)-loaded biomass were examined using 0.1 M CaCl 2 at different pH conditions in three sorption–desorption cycles. A fixed-bed column (2 cm i.d. and 35 cm height) was employed to evaluate the continuous biosorption performance of U. reticulata. The column experiments at different bed heights and flow rates revealed that the maximum zinc(II) uptake was obtained at the highest bed height (25 cm) and the lowest flow rate (5 ml/min). Column data were fitted well with Thomas, Yoon–Nelson and modified dose–response models. The column regeneration studies were carried out for three sorption–desorption cycles. A loss of sorption performance was observed during regeneration cycles indicated by a shortened breakthrough time and a decreased zinc(II) uptake.