Biosorption of methylene blue from aqueous solution by rice husk in a fixed-bed column

In this study, the ability of rice husk to adsorb methylene blue (MB) from aqueous solution was investigated in a fixed-bed column. The effects of important parameters, such as the value of initial pH, existed salt, the flow rate, the influent concentration of MB and bed depth, were studied. The Thomas model was applied to adsorption of MB at different flow rate, influent concentration and bed depth to predict the breakthrough curves and to determine the characteristic parameters of the column useful for process design using non-linear regression. The bed-depth/service time analysis (BDST) model was also applied at different bed depth to predict the breakthrough curves. The two models were found suitable for describing the biosorption process of the dynamic behavior of the rice husk column. All the results suggested that rice husk as adsorbent to removal MB from solution be efficient, and the rate of biosorption process be rapid. When the flow rate was 8.2ml min(-1) and the influent concentration of MB was 50mgl(-1), the equilibrium adsorption biomass reached 4.41mgg(-1) according to Thomas model.     

Copper(II) and lead(II) removal from aqueous solution in fixed-bed columns by manganese oxide coated zeolite

The ability of manganese oxide coated zeolite (MOCZ) to adsorb copper and lead ions in single- (non-competitive) and binary- (competitive) component sorption systems was studied in fixed-bed column. The experiments were applied to quantify particle size, bed length, influent flow rate and influent metal concentration on breakthrough time during the removal of copper and lead ions from aqueous solutions using MOCZ column. Results of fixed-bed adsorption showed that the breakthrough time appeared to increase with increase of the bed length and decrease of influent metal concentration, but decreased with increase of the flow rate. The Thomas model was applied to adsorption of copper and lead ions at bed length, MOCZ particle size, different flow rate and different initial concentration to predict the breakthrough curves and to determine the characteristic parameters of the column useful for process design. The model was found suitable for describing the adsorption process of the dynamic behavior of the MOCZ column. The total adsorbed quantities, equilibrium uptakes and total removal percents of Cu(II) and Pb(II) related to the effluent volumes were determined by evaluating the breakthrough curves obtained at different conditions. The results suggested that MOCZ could be used as an adsorbent for an efficient removal of copper and lead ions from aqueous solution. The removal of metal ion was decreased when other additional heavy metal ion was added, but the total saturation capacity of MOCZ for copper and lead ions was not significantly decreased. This competitive adsorption also showed that adsorption of lead ions was decreased insignificantly when copper ions was added to the influent, whereas a dramatic decrease was observed on the adsorption of copper ions by the presence of lead ions. The removal of copper and lead ion by MOCZ columns followed the descending order: Pb(II) > Cu(II). The adsorbed copper and lead ions were easily desorbed from MOCZ with 0.5 mol l(-1) HNO3 solution.     

Biosorption of lead(II) and cadmium(II) by protonated Sargassum glaucescens biomass in a continuous packed bed column

Biosorption of lead(II) and cadmium(II) from aqueous solutions by protonated Sargassum glaucescens biomass was studied in a continuous packed bed column. The selective uptake of Pb2+ and Cd2+ was investigated in a binary system with initial concentration of 1 mM for each metal ion. The selective uptake capacities of Pb2+ and Cd2+ at complete exhaustion point were obtained 1.18 and 0.22 mmol/g, respectively; therefore, the biosorbent showed much higher relative affinity for Pb2+ than for Cd2+. The optimum range of empty bed contact time (EBCT) was identified as 5-10 min in the packed bed column. The efficiency of biosorbent regeneration by 0.1 M HCl was achieved about 60%, so that the maximum uptake capacity of Pb2+ by the regenerated biomass was determined to be 0.75 mmol/g while the same value for the original biomass was 1.24 mmol/g. The Thomas model was found in a suitable fitness with the experimental data (R2 > 0.90 and % < 50%) at all different operation stages. Monitoring of pH in the effluent of the column presented the simultaneous release of H+ with the uptake of heavy metals; hence, ion exchange was confirmed to be one of the main biosorption mechanisms.     

Biosorption of copper (II) onto immobilized cells of Pycnoporus sanguineus from aqueous solution: equilibrium and kinetic studies

The ability of white-rot fungus, Pycnoporus sanguineus to adsorb copper (II) ions from aqueous solution is investigated in a batch system. The live fungus cells were immobilized into Ca-alginate gel to study the influence of pH, initial metal ions concentration, biomass loading and temperature on the biosorption capacity. The optimum uptake of Cu (II) ions was observed at pH 5 with a value of 2.76mg/g. Biosorption equilibrium data were best described by Langmuir isotherm model followed by Redlich-Peterson and Freundlich models, respectively. The biosorption kinetics followed the pseudo-second order and intraparticle diffusion equations. The thermodynamic parameters enthalpy change (10.16kJ/mol) and entropy change (33.78J/molK) were determined from the biosorption equilibrium data. The FTIR analysis showed that OH, NH, CH, CO, COOH and CN groups were involved in the biosorption of Cu (II) ions onto immobilized cells of P. sanguineus. The immobilized cells of P. sanguineus were capable of removing Cu (II) ions from aqueous solution.     

Removal of copper(II) and lead(II) from aqueous solution by manganese oxide coated sand II. Equilibrium study and competitive adsorption

The adsorption equilibrium of MOCS and the Cu(II) and Pb(II) ions removal capacity by MOCS in single-(non-competitive) and binary-(competitive) component sorption systems from aqueous solutions were investigated. The equilibrium data were analyzed using the Langmuir, Freundlich, Temkin and Redlich-Peterson isotherms. The characteristic parameters for each isotherm were determined. The Langmuir and Redlich-Peterson isotherms provided the best correlation for both Cu(II) and Pb(II) onto MOCS. From the Langmuir isotherms, maximum adsorption capacities of MOCS towards Cu(II) and Pb(II) are determined at different temperature. The maximum adsorption capacity of Cu(II) and Pb(II) per gram MOCS in single component sorption systems were from 5.91 and 7.71 micromol to 7.56 and 9.22 micromol for the temperature range of 288-318 K, respectively. The order of affinity based on a weight uptake by MOCS was as follows: Pb(II)>Cu(II). The same behavior was observed during competitive adsorption that is in the case of adsorption from their binary solution. The thermodynamic parameters (DeltaG degrees , DeltaH degrees , and DeltaS degrees) for Cu(II) and Pb(II) sorption on MOCS were also determined from the temperature dependence. This competitive adsorption showed that the uptake of each metal was considerably reduced with an increasing concentration of the other, the adsorption of Cu(II) being more strongly influenced by Pb(II) than vice versa due to the higher affinity of MOCS for the latter.     

Removal of copper(II) from aqueous solution by Jordanian pottery materials

The aim of this work was to assess the possibility of removing some heavy metals from water by a low-cost adsorbent, like Jordanian raw pottery. Five types of raw and modified pottery materials have been investigated. The effects of initial metal concentration, agitation time, pH and temperature on the removal of Cu(II) were studied. A pseudo-first order was used to test the adsorption kinetics. In order to investigate the sorption isotherm, two equilibrium models, the Freundlich and Langmuir isotherms, were analyzed. The effect of solution pH on the adsorption onto pottery was studied in the pH range 1-5. The adsorption was exothermic at ambient temperature and the computation of the parameters, DeltaH, DeltaS and DeltaG, indicated the interactions to be thermodynamically favorable.     

Removal of copper(II) and lead(II) from aqueous solution by manganese oxide coated sand I. Characterization and kinetic study

The preparation, characterization, and sorption properties for Cu(II) and Pb(II) of manganese oxide coated sand (MOCS) were investigated. A scanning electron microscope (SEM), X-ray diffraction spectrum (XRD) and BET analyses were used to observe the surface properties of the coated layer. An energy dispersive analysis of X-ray (EDAX) and X-ray photoelectron spectroscopy (XPS) were used for characterizing metal adsorption sites on the surface of MOCS. The quantity of manganese on MOCS was determined by means of acid digestion analysis. The adsorption experiments were carried out as a function of solution pH, adsorbent dose, ionic strength, contact time and temperature. Binding of Cu(II) and Pb(II) ions with MOCS was highly pH dependent with an increase in the extent of adsorption with the pH of the media investigated. After the Cu(II) and Pb(II) adsorption by MOCS, the pH in solution was decreased. Cu(II) and Pb(II) uptake were found to increase with the temperature. Further, the removal efficiency of Cu(II) and Pb(II) increased with increasing adsorbent dose and decreased with ionic strength. The pseudo-first-order kinetic model, pseudo-second-order kinetic model, intraparticle diffusion model and Elovich equation model were used to describe the kinetic data and the data constants were evaluated. The pseudo-second-order model was the best choice among all the kinetic models to describe the adsorption behavior of Cu(II) and Pb(II) onto MOCS, suggesting that the adsorption mechanism might be a chemisorption process. The activation energy of adsorption (E(a)) was determined as Cu(II) 4.98 kJ mol(-1) and Pb(II) 2.10 kJ mol(-1), respectively. The low value of E(a) shows that Cu(II) and Pb(II) adsorption process by MOCS may involve a non-activated chemical adsorption and a physical sorption.     

Biosorption of cadmium (II) and lead (II) from aqueous solutions using mushrooms: A comparative study

Sorption capacity of oyster mushroom (Pleurotus platypus), button mushroom (Agaricus bisporus) and milky mushroom (Calocybe indica) were evaluated on biosorption of heavy metals, viz. cadmium (II) and lead (II) from aqueous solutions. The optimum sorption conditions were studied for each metal separately. The desired pH of the aqueous solution was found to be 6.0 for the removal of cadmium (II) and 5.0 for removal of lead (II) for all the mushrooms. The percent removal of both the metals was found to increase with the increase in biosorbent dosage and contact time. The fitness of the biosorption data for Langmuir and Freundlich adsorption models was investigated. It was found that biosorption of cadmium (II) and lead (II) ions onto the biomass of the three mushrooms were better suitable to Langmuir than Freundlich adsorption model. P. platypus showed the highest metal uptake potential for cadmium (q_max 34.96 mg/g) whereas A. bisporus exhibited maximum potential for lead (q_max 33.78 mg/g). Milky mushroom showed the lowest metal uptake capacity for both the metals. The present data confirms that mushrooms may be used as efficient biosorbent for the removal of cadmium (II) and lead (II) ions from aqueous solution.     

Biosorption of Pb(II) and Cd(II) from aqueous solution using green alga (Ulva lactuca) biomass

The biosorption characteristics of Pb(II) and Cd(II) ions from aqueous solution using the green alga (Ulva lactuca) biomass were investigated as a function of pH, biomass dosage, contact time, and temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherm of the metal ions by U. lactuca biomass. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The monolayer biosorption capacity of U. lactuca biomass for Pb(II) and Cd(II) ions was found to be 34.7mg/g and 29.2mg/g, respectively. From the D-R isotherm model, the mean free energy was calculated as 10.4kJ/mol for Pb(II) biosorption and 9.6kJ/mol for Cd(II) biosorption, indicating that the biosorption of both metal ions was taken place by chemisorption. The calculated thermodynamic parameters (DeltaG degrees , DeltaH degrees and DeltaS degrees ) showed that the biosorption of Pb(II) and Cd(II) ions onto U. lactuca biomass was feasible, spontaneous and exothermic under examined conditions. Experimental data were also tested in terms of biosorption kinetics using pseudo-first-order and pseudo-second-order kinetic models. The results showed that the biosorption processes of both metal ions followed well pseudo-second-order kinetics.     

Biosorption of Cu(II) from aqueous solutions by mimosa tannin gel

The biosorption of Cu(II) from aqueous solutions by mimosa tannin resin (MTR) was investigated as a function of particle size, initial pH, contact time and initial metal ion concentration. The aim of this study was to understand the mechanisms that govern copper removal and find a suitable equilibrium isotherm and kinetic model for the copper removal in a batch reactor. The experimental isotherm data were analysed using the Langmuir, Freundlich and Temkin equations. The equilibrium data fit well in the Langmiur isotherm. The experimental data were analysed using four sorption kinetic models -- the pseudo-first- and second-order equations, and the Elovich and the intraparticle diffusion equation -- to determine the best fit equation for the biosorption of copper ions onto mimosa tannin resin. Results show that the pseudo-second-order equation provides the best correlation for the biosorption process, whereas the Elovich equation also fits the experimental data well. Thermodynamic parameters such as the entropy change, enthalpy change and Gibb's free energy change were found out to be 153.0 J mol(-1)K(-1), 42.09 kJ mol(-1) and -2.47 kJ mol(-1), respectively.     

Removal of Ni(II) ions from aqueous solutions using waste of tea factory: adsorption on a fixed-bed column

The removal efficiency of waste tea from nickel containing aqueous solutions was investigated. All experiments were conducted fixed-bed columns. Experiments were carried out as a function of liquid flow rate (5-20 mL/min), initial Ni(II) concentration (50-200 mg/L), bed height (10-30 cm), pH of feed solution (2.0-5.0) and particle size (0.15-0.25 to 1.0-3.0 mm) of adsorbent. The total adsorbed quantities, equilibrium uptakes and total removal percents of Ni(II) related to the effluent volumes were determined by evaluating the breakthrough curves obtained at different flow rates, different inlet Ni(II) concentrations, different pH value, different bed height and different particle size for waste tea. The longest breakthrough time and maximum of Ni(II) adsorption is obtained at pH 4.0. Decrease in the particle size from 1.0-3.0 to 0.15-0.25 mm resulted in significant increase in the treated volume, breakthrough time and bed capacity. The results show that the column performed well at lowest flow rate. Also, column bed capacity and exhaustion time increased with increasing bed height. When the initial Ni(II) concentration is increased from 50 to 200 mg/L, the corresponding adsorption bed capacity appears to increase from 7.31 to 11.17 mg/g. The bed depth service time (BDST) model and the Thomas model were used to analyze the experimental data and the model parameters were evaluated. Good agreement of the experimental breakthrough curves with the model predictions was observed.     

Adsorption of copper (II), chromium (III), nickel (II) and lead (II) ions from aqueous solutions by meranti sawdust

The present study proposed the use of meranti sawdust in the removal of Cu(II), Cr(III), Ni(II) and Pb(II) ions from synthetic aqueous solutions. Batch adsorption studies showed that meranti sawdust was able to adsorb Cu(II), Cr(III), Ni(II) and Pb(II) ions from aqueous solutions in the concentration range 1–200 mg/L. The adsorption was favoured with maximum adsorption at pH 6, whereas the adsorption starts at pH 1 for all metal ions. The effects of contact time, initial concentration of metal ions, adsorbent dosage and temperature have been reported. The applicability of Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) isotherm was tried for the system to completely understand the adsorption isotherm processes. The adsorption kinetics tested with pseudo-first-order and pseudo-second-order models yielded high R² values from 0.850 to 0.932 and from 0.991 to 0.999, respectively. The meranti sawdust was found to be cost effective and has good efficiency to remove these toxic metal ions from aqueous solution.     

Biosorption of palladium(II) from aqueous solution by moss (Racomitrium lanuginosum) biomass: equilibrium, kinetic and thermodynamic studies

Arsenite (As(III)) and arsenate (As(V)) removal by direct contact membrane distillation (DCMD) were investigated with self-made polyvinylidene fluoride (PVDF) membranes in the present work. Permeability and ion rejection efficiency of the membrane were tested before the arsenic removal experiments. A maximum permeate flux 20.90 kg/m(2)h was obtained, and due to the hydrophobic property, the PVDF membrane had high rejection of inorganic anions and cations which was independent of the solution pH and the temperature. The experimental results indicated that DCMD process had higher removal efficiency of arsenic than pressure-driven membrane processes, especially for high-concentration arsenic and arsenite removal. The experimental results indicated that the permeate As(III) and As(V) were under the maximum contaminant limit (10 microg/L) until the feed As(III) and As(V) achieved 40 and 2000 mg/L, respectively. The 250 h simultaneous DCMD performance of 0.5mg/L As(III) and As(V) solution was carried out, respectively. The permeate arsenic was not detected during the process which showed the PVDF membrane had stable arsenic removal efficiency. Membrane morphology changed slightly after the experiments, however, the permeability and the ion rejection of the membrane did not change.     

Biosorption of cadmium(II) from aqueous solution by red algae (Ceramium virgatum): equilibrium, kinetic and thermodynamic studies

The biosorption characteristics of Cd(II) ions using the red alga (Ceramium virgatum) were investigated. Experimental parameters affecting the biosorption process such as pH, contact time, biomass dosage and temperature were studied. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherms. The biosorption capacity of C. virgatum biomass for Cd(II) ions was found to be 39.7 mg/g. From the D-R isotherm model, the mean free energy was calculated as 12.7 kJ/mol, indicating that the biosorption of Cd(II) the metal ions was taken place by chemisorption. The calculated thermodynamic parameters (DeltaG degrees , DeltaH degrees and DeltaS degrees ) showed that the biosorption of Cd(II) ions onto C. virgatum was feasible, spontaneous and exothermic at 293-323 K. Evaluation of experimental data in terms of biosorption kinetics showed that the biosorption of Cd(II) C. virgatum followed well pseudo-second-order kinetics.     

Removal of lead (II) ions from synthetic and real effluents using immobilized Pinus sylvestris sawdust: adsorption on a fixed-bed column

The purpose of this work was to evaluate the potential of Pinus sylvestris sawdust, in a continuous flow removal of lead (II) ions from synthetic and industrial aqueous effluents. The kinetic parameters obtained in a batch process were used to scale-up the process on a mini-column and to choose the breakthrough model. The column experimental data concerning the volumes treated were correlated using the bed depth service time model. These experimental data closely fitted the bed depth service time model at 10% of the breakthrough curve. The results from the bed depth service time model on the mini-column were then used to design a pilot plant adsorption unit. The performance of the pilot plant column accurately agreed with that obtained from the mini-column. The experiments carried out in a dynamic reactor allowed to bring out the influence of various parameters on the efficiency of the P. sylvestris sawdust. In addition, the process was checked for the treatment of industrial aqueous effluents on a pilot plant scale and the results were in accordance with those obtained from synthetic effluents.     

Removal of methylene blue from aqueous solution by chaff in batch mode

A new adsorbent system for removing methylene blue (MB) from aqueous solutions has been investigated. This new adsorbent is cereal chaff, an agriculture product in middle-west region in China. Variables of the system, including biosorption time, chaff dose, pH, salt concentration and initial MB concentration, were adopted to study their effects on MB removal. The results showed that as the dose of chaff increased, the percentage of MB sorption increased accordingly. There was no significant difference in the dye concentration remaining when the pH was increased from 4.0 to 11.0. The salt concentration has negative effect on MB removal. At the experimental range of MB concentration, the amount of MB adsorbed onto per unit mass of chaff (q(e)) is direct ratio to MB initial concentration (c(0)). The equilibrium data were analyzed using five equilibrium models, the Langmuir, the Freundlich, the Redlich-Peterson, the Koble-Corrigan and the Temkin isotherms. The results of non-linear regressive analysis are that the isotherms of Langmuir, Redlich-Peterson and Koble-Corrigan are better fit than the isotherms of Freundlich and Temkin at different temperatures according to the values of determined coefficients (R(2)) and Chi-square statistic (chi(2)). The maximum equilibrium capacities of chaff from Langmuir models are 20.3, 25.3 and 26.3 mg g(-1) at 298, 318 and 333K, respectively. Using the equilibrium concentration constants obtained at different temperatures, various thermodynamic parameters, such as DeltaG(0), DeltaH(0) and DeltaS(0), have been calculated. The thermodynamics parameters of MB/chaff system indicate spontaneous and endothermic process. It was concluded that an increase in temperature results in a bigger MB loading per unit weight of the chaff.     

Biosorption of uranium(VI) from aqueous solution using calcium alginate beads

In this paper, sorption potentials of uranium ions were studied using alginate polymer beads in diluted aqueous solutions. The ability of alginate beads to adsorb uranium(VI) from aqueous solution has been studied at different optimized conditions of pH, U(VI) concentration, contact time, biomass dosage and temperature. In order to determine the adsorption characteristics, Langmuir, Freundlich, and Dubinin–Radushkevich adsorption isotherms were applied to the adsorption data. The thermodynamic parameters such as variations of enthalpy ΔH, entropy ΔS and variation of Gibbs free energy ΔG were calculated from the slope and intercept of ln K_d vs. 1/T plots. The results suggested that alginate beads could be suitable as a sorbent material for adsorption and removal of uranium ions from dilute aqueous solutions.     

Pre-treatment processes of Azolla filiculoides to remove Pb(II), Cd(II), Ni(II) and Zn(II) from aqueous solution in the batch and fixed-bed reactors

Intact and treated biomass can remove heavy metals from water and wastewater. This study examined the ability of the activated, semi-intact and inactivated Azolla filiculoides (a small water fern) to remove Pb(2+), Cd(2+), Ni(2+) and Zn(2+) from the aqueous solution. The maximum uptake capacities of these metal ions using the activated Azolla filiculoides by NaOH at pH 10.5 +/- 0.2 and then CaCl(2)/MgCl(2)/NaCl with total concentration of 2 M (2:1:1 mole ratio) in the separate batch reactors were obtained about 271, 111, 71 and 60 mg/g (dry Azolla), respectively. The obtained capacities of maximum adsorption for these kinds of the pre-treated Azolla in the fixed-bed reactors (N(o)) were also very close to the values obtained for the batch reactors (Q(max)). On the other hand, it was shown that HCl, CH(3)OH, C(2)H(5)OH, FeCl(2), SrCl(2), BaCl(2) and AlCl(3) in the pre-treatment processes decreased the ability of Azolla to remove the heavy metals in comparison to the semi-intact Azolla, considerably. The kinetic studies showed that the heavy metals uptake by the activated Azolla was done more rapid than those for the semi-intact Azolla.     

Biosorption of Cr(III) from aqueous solution using algal biomass spirogyra spp

In the present investigation, a fresh water green algae spirogyra spp. was used as an inexpensive and efficient biosorbent for Cr(III) removal from aqueous solution. The algal biomass was treated with 0.1M NaOH, 0.2M CaCl(2) and 5% HCHO. The biosorption efficiency was compared with untreated biomass. The effects of various physico-chemical parameters were studied, e.g. pH 3.0-6.0, initial metal ions concentration 20-150mgL(-1), algal dose 1.0-3.0gL(-1), and contact time 15-180min, respectively. Biosorption of Cr(III) is highly pH dependent. Maximum 81.02% adsorption of Cr(III) was observed with 0.2M CaCl(2) treated biomass at pH 5.0. Removal of Cr(III) was more than 70% in 45min of contact time with different treated and untreated algal biomass at concentration 30mgL(-1). Maximum metal uptake (Q(max)) was observed as 30.21mgg(-1) with 0.2M CaCl(2) treated algal biomass indicate good biosorbents than other treated and untreated biomass. The high values of correlation coefficient (r(2)<0.90) indicate equilibrium data of treated and untreated form of algal biomass well fitted in Freundlich than Langmuir isotherms model equations.