Binary Metal Solutions Research Articles

Improving the Adsorption of Heavy Metals from Water Using Commercial Carbons Modified with Egg Shell Wastes

We introduce the application of hen egg shell waste to improve the adsorption capacities of heavy-metal ions using commercial carbons via the modification of their surface chemistry. Specifically, a calcium solution extracted from egg shell waste has been used as a low-cost activation agent to improve the adsorption properties of three commercial carbons. An orthogonal array of the Taguchi method has been applied to identify the optimal conditions for the adsorbent modification process using the Zn2+ batch adsorption, at 30 °C and pH 5, as the response variable. Our results show that maximum adsorption capacities of Cd2+, Ni2+, and Zn2+ ions, at 30 °C and pH 5, may increase up to 15 times, with respect to the results obtained using the commercial adsorbent without modification. The improvement of adsorbent performance may be related to the formation of calcium phosphate on the carbon surface. Finally, adsorption studies in binary metal solutions were performed to identify the competitive effects in multic...

Capacity of simultaneous removal of zinc and cadmium from contaminated media, by two microalgae isolated from a polluted site

Several aquatic environments have been contaminated with heavy metals dumped via industrial effluents. Numerous studies have been published regarding the removal of single metals from aqueous solutions by microalgal biomass. However, such studies do not reflect the actual problem associated with industrial effluents because usually more than one metal species is present. Here we studied the biosorption capacity of Zn2+ and Cd2+ as single- and binary-metal systems by two microalgae, Scenedesmus obliquus and Desmodesmus pleiomorphus, isolated from a polluted site in Northern Portugal. For each metal independently, D. pleiomorphus showed a higher metal sorption capacity than S. obliquus, at concentrations ranging from 60 to 300 mg/l (except 150 mgCd/l). Maximum amounts of Zn2+ and Cd2+ removed were 22.3 and 60.8 mg/g by S. obliquus, and 83.1 and 58.6 mg/g by D. pleiomorphus. In binary-metal solutions, S. obliquus was in general able to remove Zn2+ to higher extents than Cd2+, whereas the opposite was observed with D. pleiomorphus. The simultaneous uptake of Zn2+ and Cd2+ by both microalgae was considerably lower than that of their single-metal counterparts, at equivalent concentrations. Although microalgal uptake from binary-metal solutions was lower than from single-metal ones, the wild microalgae selected were able to efficiently take up mixtures of Zn2+ and Cd2+ up to 300 mg/l of both metals—thus materializing a promising bioremediation vector for polluted waters.

Study of mango biomass (Mangifera indica L) as a cationic biosorbent

Unfertilizable fruiting buds of mango plant Mangifera Indica L, an agrowaste, is used as a biomass in this study. The efficacy of the biosorbent was tested for the removal of lead, copper, zinc and nickel metal ions using batch experiments in single and binary metal solution under controlled experimental conditions. It is found that metal sorption increases when the equilibrium metal concentration rises. At highest experimental solution concentration used (150 mg/L), the removal of metal ions were 82.76 % for lead, 76.60 % for copper, 63.35 % for zinc and 59.35 % for nickel while at lowest experimental solution concentration (25 mg/L), the removal of metal ions were 92.00% for lead, 86.84 % for copper, 83.96 % for zinc and 82.29 % for nickel. Biosorption equilibrium isotherms were plotted for metal uptake capacity (q) against residual metal concentrations (Cf) in solution. The q versus Cf sorption isotherm relationship was mathematically expressed by Langmuir and Freundlich models. The values of separation factor were between zero and one indicating favourable sorption for four tested metals on the biosorbent. The surface coverage values were approaching unity with increasing solution concentration indicating effectiveness of biosorbent under investigation. The non-living biomass of Mangifera indica L present comparable biosorption capacity for lead, copper, zinc and nickel metal ions with other types of biosorbent materials found in literature and is effective to remove metal ions from single metal solutions as well as in the presence of other co-ions with the main metal of solution.

Competitive effect of Cu(II) and Zn(II) on the biosorption of lead(II) by Myriophyllum spicatum

Batch experiments were conducted to assess the effects of Cu(II) and Zn(II) on the biosorption of Pb(II) ions by fresh tissues of Myriophyllum spicatum. The biosorption of Pb(II) was examined for single, binary and ternary solutions at different initial concentrations and different pH values. The experimental results showed that the biosorption capacity increased with increasing pH from 2.0 to 6.0. Both Cu(II) and Zn(II) ions were found to have an adverse effect on the biosorption of Pb(II). The biosorption equilibrium data for single-metal solution were fitted to three isotherm models: Langmuir, Freundlich and Sips, and the Sips isotherm model gave the best fit for the experimental data. The maximum biosorption of Pb(II) in Pb–Cu binary system decreased with increasing concentration of copper ions, and the biosorption equilibrium data for the binary metal solution fitted the Langmuir competitive model well. Comparison between biosorption of Pb(II) and Cu(II) by M. spicatum in the binary solution could lead to the conclusion that the biosorbent ( M. spicatum) has no preference of Pb(II) over Cu(II). Fourier transform infrared (FT-IR) spectroscopy was used to characterize the interaction between M. spicatum and Pb(II) ions. The results revealed that the carboxyl, hydroxyl and carbonyl groups are the main binding sites for Pb(II).

Single and binary component sorption of the fission products Sr 2+, Cs + and Co 2+ from aqueous solutions onto sulphate reducing bacteria

This study investigates the removal of the fission products Sr 2+, Cs + and Co 2+ in single and binary metal solutions by a sulphate reducing bacteria (SRB) biomass. The effect of initial concentration and pH on the sorption kinetics of each metal was evaluated in single metal solutions. Binary component equilibrium sorption studies were performed to investigate the competitive binding behaviour of each metal in the presence of a secondary metal ion. Results obtained from single metal equilibrium sorption studies indicated that SRB have a higher binding capacity for Sr 2+ ( q max = 416.7 mg g −1), followed by Cs + ( q max = 238.1 mg g −1), and lastly Co 2+ ( q max = 204.1 mg g −1). Among the binary systems investigated, Co 2+ uptake was the most sensitive, resulting in a 76% reduction of the sorption capacity ( q max) in the presence of Cs +. These findings are significant for future development of effective biological processes for radioactive waste management under realistic conditions.

Kinetics and Thermodynamics of Arsenate and Arsenite Biosorption by Pretreated Spent Grains

Using chemically modified spent grains as a new biosorbent to treat arsenate and arsenite ions was studied. The influences of pH, contact time, initial concentration and temperature were studied in batch experiments. The equilibrium process was described well by Langmuir isotherm model with maximum biosorption capacities of 13.39 and 4.86 mg/g of arsenate and arsenite on spent grains, respectively. The initial removal was rapid, and equilibrium was established in less than 180 min. Good correlation coefficients were obtained for the pseudo-second-order kinetic model. In the binary metal solutions, the finite sites on the surface of spent grains showed a greater preference for As(V) ions. The enthalpy of biosorption was exothermic and the increase in As(III) removal was larger than that of As(V) over the same rise in temperature. In this study, spent grains proved to be suitable for removal of As(V) and As(III) from the effluent of metallurgical industry.

Selective separation of Hg(II) and Cd(II) from aqueous solutions by complexation–ultrafiltration process

Complexation–ultrafiltration process was investigated to separate selectively Hg(II) and Cd(II) from binary metal solutions by using poly (acrylic acid) sodium salt as a complexing agent. Effects of operating parameters on selective separation factors ( β Cd/Hg) of the both metals have been examined in detail. Results indicated that loading rate, pH, concentration of salt added and low-molecular competitive complexing agent affect significantly β Cd/Hg value. Further, a concentration experiment was carried out according to the previous optimum parameters. Rejection coefficient of mercury is close to 1, while that of cadmium is about 0.1. The experiment was characterized by good effectiveness, and enabled the rapid linear increase of mercury concentration and very slow increase of cadmium concentration in the retentate. Then, a diafiltration technique was applied to separate further the both metals. Cadmium concentration in the retentate declines sharply with the diafiltration volume, whereas for mercury it is the contrary.

Competitive adsorption of Cu(II) and Cd(II) ions on spray-dried chitosan loaded with Reactive Orange 16

Chitosan microspheres cross-linked with glutaraldehyde and containing the reactive dye Orange 16 (RO 16) as a chelating agent were obtained by spray drying technique. These microspheres (CHS-RO 16) were characterized by FTIR, TGA, DSC, SEM and EDX analyses, and tested for metal adsorption. The new adsorbent was used in batch experiments to evaluate the adsorption of Cu(II) and Cd(II) ions in single and binary metal solutions. In single metal solutions, the maximum adsorption capacity for Cu(II), obtained by Langmuir model, was close to 1.69 mmol Cu g − 1 ; this means the double of the adsorption capacity for Cd(II) (i.e. 0.80 mmol Cd g − 1 ). Adsorption isotherms for binary solutions showed that the presence of Cu(II) decreased Cd(II) adsorption due to a significant competition effect. On the other hand, Cu(II) adsorption hardly changed when the initial concentration of Cd(II) increased: the new adsorbent was selective to Cu(II) against Cd(II). The metal ions were efficiently desorbed from chitosan-RO 16 with aqueous solutions of H 2SO 4.

Biosorption of Hg from aqueous solutions by crab carapace

Carapace from the edible crab was assessed for the biosorption of Hg from aqueous solutions. Batch adsorption studies were used to determine the effects of contact time, pH, concentration, particle size and Cu(II) as a co-ion. The removal of Hg was fast and efficient, attaining >80.0% from 500 mg/L by 60 min. Specific uptake increased from 0.1 to 13.0 mg/g as initial concentration increased from 0.5 to 1000 mg/L while the removal efficiency decreased from 100.0% over the 0.5–10.0 mg/L range to 65.0% at 1000 mg/L. As particle size decreases from >2.5 to <0.15 mm, the Hg uptake increased from 1.4 to 8.3 mg/g. In binary metal solutions, Cu(II) reduced the Hg removal by 80.0% while the presence of Hg increased Cu(II) removal by ∼7.0%. Crab carapace is a readily available alkaline waste and easily processed into durable granular forms. Therefore, it offers potential as a low-cost alternative to commercial adsorbents or as a complimentary polishing process for the removal of Hg from acidic solutions.

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.

Mono-component versus binary isotherm models for Cu(II) and Pb(II) sorption from binary metal solution by the green alga Pithophora oedogonia

The sorption of Cu(II) and Pb(II) by Pithophora markedly decreased as the concentration of the secondary metal ion, Cu(II) or Pb(II), increased in the binary metal solution. However, the test alga showed a greater affinity to sorb Cu(II) than Pb(II) from the binary metal solution. Mono-component Freundlich, Langmuir, Redlich–Peterson and Sips isotherms successfully predicted the sorption of Cu(II) and Pb(II) from both single and binary metal solutions. None of the tested binary sorption isotherms could realistically predict Cu(II) and Pb(II) sorption capacity and affinity of the test alga for the binary metal solutions of varying composition, which mono-component isotherms could very well accomplish. Hence, mono-component isotherm modeling at different concentrations of the secondary metal ion seems to be a better option than binary isotherms for metal sorption from binary metal solution.

Removal of Cd (II) and Pb (II) from aqueous environment using Moringa Oleifera seeds as biosorbent: A low cost and ecofriendly technique for water purification

Ever-growing list of chemical contaminants released into the environment through excessive industrialization on a large scale includes numerous chemical pollutants more prominently heavy metals. The discharge of heavy metals in aqueous system and their removal have been a challenging task for environmentalists for last one decade. Keeping these views in mind, the present study highlights the efficacy of shelled Moringa oleifera seeds (SMOS) in decontaminating Cd (II) and Pb (II) ions from aqueous environment both present as single metal and as binary metal solution. The extent of adsorption capacity for Cd (II) and Pb (II) on Moringa oleifera seeds for binary metal ions [76.59% and 81.10%] was found to be low as compared to single metal ions [85.10% and 96.10%]. Morphological changes observed in Scanning Electron Micrographs of native and treated SMOS indicates the existence of biosorption phenomenon. Fourier Transform Infrared Spectrometry of the exhausted seed biomass highlights amino acids-metal interaction responsible for sorption phenomenon. The sorption capacity of regenerated biomass remained almost constant after three cycle of sorption suggesting that the lifetime cycle was sufficient for continuous application.

Calcium alginate beads from Laminaria digitata for the removal of Cu +2 and Cd +2 from dilute aqueous metal solutions

Sodium alginate extracted from the brown algae Laminaria digitata was used to prepare metal sorbing beads. Their metal binding properties were investigated with respect to copper and cadmium ions in single and binary metal solutions. Their behaviour in batch kinetic experiments and in a flow through column for the remediation of dilute aqueous metal solutions was studied. Alginate was found to be a promising material for heavy metal sequestration while sorption was found to be following a competitive mechanism in multi-metal solutions. The obtained maximum adsorption capacities for Cu +2 and Cd +2 were 1.5 mmol/g and 2.09 mmol/g respectively. The calculated diffusion coefficients — 2.8–3.0 × 10 −5 cm 2/s for copper and 4.4–4.5 × 10 −5 cm 2/s for cadmium ions — were independent of the initial concentration. Finally, the obtained diffusion coefficients were used for the simulation of the breakthrough curves on column filtration experiments. Linear adsorption driving force model was used to provide a rough estimation of the operational and design parameters in flow column adsorption processes.

Effect of Cu(II), Cd(II) and Zn(II) on Pb(II) biosorption by algae Gelidium-derived materials

Biosorption of Pb(II), Cu(II), Cd(II) and Zn(II) from binary metal solutions onto the algae Gelidium sesquipedale, an algal industrial waste and a waste-based composite material was investigated at pH 5.3, in a batch system. Binary Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II) solutions have been tested. For the same equilibrium concentrations of both metal ions (1 mmol l −1), approximately 66, 85 and 86% of the total uptake capacity of the biosorbents is taken by lead ions in the systems Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II), respectively. Two-metal results were fitted to a discrete and a continuous model, showing the inhibition of the primary metal biosorption by the co-cation. The model parameters suggest that Cd(II) and Zn(II) have the same decreasing effect on the Pb(II) uptake capacity. The uptake of Pb(II) was highly sensitive to the presence of Cu(II). From the discrete model it was possible to obtain the Langmuir affinity constant for Pb(II) biosorption. The presence of the co-cations decreases the apparent affinity of Pb(II). The experimental results were successfully fitted by the continuous model, at different pH values, for each biosorbent. The following sequence for the equilibrium affinity constants was found: Pb > Cu > Cd ≈ Zn.

Kinetics modelling of biosorption by algal biomass from binary metal solutions using batch contactors

The biosorption from four binary metal solutions, Pb 2+/Cu 2+, Pb 2+/Cd 2+, Pb 2+/Zn 2+ and Cd 2+/Zn 2+, onto algae Gelidium, algal waste and composite material, at pH 5.3 and 20 °C, were studied in batch adsorber. A mass transfer model based on a one-dimensional intraparticle diffusion rate, combined with a binary Langmuir isotherm, was applied to describe the overall biosorption rate of binary metal solutions mixture in flat seaweed biomass. A good correlation has been found between mass transfer model and experimental data for all systems. Model equations were solved numerically yielding the metal ions homogeneous diffusion coefficients. The biosorbents showed a preference for sorbing Pb over Cd, Zn and Cu even for low lead initial concentrations. Cu and Pb show a similar competition for the binding sites, although a higher uptake was found for copper ions, due to the higher initial copper concentration.

Copper(II) and lead(II) sorption from aqueous solution by non-living Spirogyra neglecta

Dried biomass of Spirogyra neglecta rapidly sorbed the test metals and the process became saturated in 10–20 min. Maximum sorption of Pb(II) [116.1 mg g −1] and Cu(II) [115.3 mg g −1] occurred at 0.1 g l −1 biomass and 100 mg l −1 metal concentration in the solution. Sorption of Cu(II) and Pb(II) occurred optimally at pH 4.5 and 5.0, respectively. Lead(II) and Cu(II) sorption were lesser from binary metal solution than from single metal solution. Lead(II) more severely inhibited Cu(II) sorption than vice versa thus reflecting greater affinity of Pb(II) for the biomass. NaOH pretreatment slightly enhanced the metal removal ability of the biomass. During repeated sorption/desorption cycles, Pb(II) and Cu(II) sorption decreased by 11% and 27%, respectively, at the end of the fifth cycle due inter alia to 10–15% loss of biomass. Nevertheless, Spirogyra appears to be a good sorbent for removing metals Cu(II) and Pb(II) from wastewaters.

Copper and zinc decontamination from single- and binary-metal solutions using hydroxyapatite

Toxic metals contamination of waters, soils and sediments can seriously affect plants, animals and human being. The bioavailability of metal ions can be reduced trapping them in minerals with low solubilities. This study investigated the sorption of aqueous Cu and Zn onto hydroxyapatite surfaces. Batch experiments were carried out using synthetic hydroxyapatite. The metals were applied as single or binary species, in a range of metal concentrations ranging from 0 to 8 mmol/L at 25 ± 2 °C. The removal capacity of hydroxyapatite was 0.016–0.764 mmol of Cu/g and 0.015–0.725 mmol of Zn/g. In the Cu–Zn binary system, competitive metal sorption occurred with reduction of the removal capacity by 13–76% and 10–63% for Cu and Zn, respectively, compared to the single-metal systems. The sorption of Cu and Zn was well characterized by the Langmuir model. Heavy metal immobilization was attributed to a two-step mechanism: first rapid surface complexation and secondly partial dissolution of hydroxyapatite and ion exchange with Ca followed by the precipitation of a heavy metal-containing hydroxyapatite.

Novel operational method of continuous foam separation of gold – Injection of metal and/or surfactant solutions into rising foam bed

A novel operational method of continuous foam separation, in which metal and/or surfactant solutions were injected into the rising foam bed, has been applied to the Au(III) recovery from binary metal solutions with Cu(II). The effects of experimental parameters, such as an air flow rate, metal concentration and solution acidity, were discussed in terms of the percent recovery and the separation factor of Au(III). A nonionic surfactant, polyoxyethylene nonyl phenyl ether, used in this study showed a strong affinity to Au(III) in HCl media and played a double role of foam-producing and metal collecting reagent. By injecting a metal solution to the foam bed, the recovery of Au(III) was improved due to the efficient contact between the metal and the foam surface counter-currently. On the other hand, injection of a surfactant solution facilitated the washing-out of the metals in the interstitial water between the adjacent foam, enhancing the separation of Au(III) from Cu(II). Furthermore, simultaneous injection of metal and surfactant solutions to the foam bed was also examined, and satisfactory results were obtained both in the yield and purity of Au(III).

Equilibrium modelling of single and binary adsorption of cadmium and nickel onto bagasse fly ash

Abstract The present study deals with the competitive adsorption of cadmium (Cd(II)) and nickel (Ni(II)) ions onto bagasse fly ash (BFA) from single component and binary systems. BFA is a waste material obtained from the flue gas of the bagasse-fired boilers of sugar mills. Equilibrium adsorption is affected by the initial pH (pH0) of the solution. The pH0 ≈ 6.0 is found to be the optimum for the individual removal of Cd(II) and Ni(II) ions by BFA. The pH of the system, however, increases during the initial sorption process for about 20 min and, thereafter, it remains constant. The equilibrium adsorption data were obtained at different initial concentrations (C0 = 10–100 mg/l), 5 h contact time, 30 °C temperature, BFA dosage of 10 mg/l at pH0 6. The single ion equilibrium adsorption data were fitted to the non-competitive Langmuir, Freundlich and Redlich–Peterson (R–P) isotherm models. The R–P and the Freundlich models represent the equilibrium data better than the Langmuir model in the studied initial metal concentration range (10–100 mg/l). The adsorption capacity of Ni(II) is higher than that for Cd(II) for the binary metal solutions and is in agreement with the single-component adsorption data. The equilibrium metal removal decreases with increasing concentrations of the other metal ion and the combined action of Cd(II) and Ni(II) ions on BFA is generally found to be antagonistic. Equilibrium isotherms for the binary adsorption of Cd(II) and Ni(II) ions onto BFA have been analyzed by using non-modified Langmuir, modified Langmuir, extended Langmuir, extended Freundlich and Sheindorf–Rebuhn–Sheintuch (SRS) models. The competitive extended Freundlich model fits the binary adsorption equilibrium data satisfactorily and adequately. Desorption with various solvents showed that the hydrochloric acid is the best solvent; the maximum elution being about 65% for Cd(II) and about 42% for Ni(II). Since BFA is a waste material obtained at almost no cost, the spent BFA can be combusted to recover its energy value and the bottom ash can be blended with cementitious mixture for making building blocks.

Removal of lead and copper ions from aqueous solutions by bacterial strain isolated from soil

Biosorption of Pb(II) and Cu(II) ions from aqueous solutions has been studied in a batch system by using a bacterial strain isolated from metal polluted soil. The bacterial strain was identified as Bacillus sp. The optimum conditions of biosorption were determined by investigating the initial pH, contact time and the initial concentrations of metal ions at constant temperature (25 ◦ C). The maximum biosorption of the metal ions was observed at pH 3.0 ± 0.1 for Pb(II) and pH 5.0 ± 0.1 for Cu(II) ions. Biosorption equilibrium times for Pb(II) and Cu(II) ions were observed in 15 and 30 min, respectively. The maximum biosorption capacities of Pb(II) and Cu(II) ions on Bacillus sp. were determined to be 92.27 ± 1.17 mg g −1 at 250 mg l −1 concentration and 16.25 ± 1.64 mg g −1 at 200 mg l −1 concentration, respectively. The experimental adsorption data were fitted to Langmuir isotherm model. Competition of metal ions during biosorption was investigated in binary metal solutions. The interactions between metal ions and functional groups on the cell wall surface of the biomass were confirmed by FTIR, SEM and EDAX analysis. The results indicated that bacterial isolate Bacillus sp. is a suitable biosorbent for the removal of Pb(II) and Cu(II) ions from aqueous solutions. © 2005 Published by Elsevier B.V.