Adsorption characterization of lead(II) and cadmium(II) on crosslinked carboxymethyl starch

The adsorption of Pb(II) and Cd(II) ions with crosslinked carboxymethyl starch (CCS) was investigated as function of the solution pH, contact time, initial metal‐ion concentration, and temperature. Isotherm studies revealed that the adsorption of metal ions onto CCS better followed the Langmuir isotherm and the Dubinin–Radushkevich isotherm with adsorption maximum capacities of about 80.0 and 47.0 mg/g for Pb(II) and Cd(II) ions, respectively. The mean free energies of adsorption were found to be between 8 and 16 kJ/mol for Pb(II) and Cd(II) ions; this suggested that the adsorption of Pb(II) and Cd(II) ions onto CCS occurred with an ion‐exchange process. For two‐target heavy‐metal ion adsorption, a pseudo‐second‐order model and intraparticle diffusion seem significant in the rate‐controlling step, but the pseudo‐second‐order chemical reaction kinetics provide the best correlation for the experimental data. The enthalpy change for the process was found to be exothermic, and the ΔS^θ values were calculated to be negative for the adsorption of Pb(II) and Cd(II) ions onto CCS. Negative free enthalpy change values indicated that the adsorption process was feasible. The studies of the kinetics, isotherm, and thermodynamics indicated that the adsorption of CCS was more effective for Pb(II) ions than for Cd(II) ions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Investigation of adsorption of lead,mercury and nickel from aqueous solutions onto carbon aerogel

Recently a new form of activated carbon has appeared: carbon aerogel (CA). Its use for the removal of inorganic (and especially metal ions) has not been studied. In the present study, the adsorption of three metal ions, Hg(II), Pb(II) and Ni(II), onto carbon aerogel has been investigated. Batch experiments were carried out to assess adsorption equilibria and kinetic behaviour of heavy metal ions by varying parameters such as agitation time, metal ions' concentration, adsorbent dose and pH. They facilitated the computation of kinetic parameters and maximum metal ion adsorption capacities. Increasing the initial solution pH (2–10) and carbon concentration (50–500 mg per 50 cm³) increases the removal of all three metal ions. A decrease of equilibrium pH with an increase of metal ion concentration led us to propose an adsorption mechanism by ion exchange between metal cations and H⁺ at the carbon aerogel surface. Carboxylic groups are especially involved in this adsorption mechanism. Langmuir and Freundlich isotherm models were used to analyse the experimental data of carbon aerogel. The thermodynamics of the metal adsorption was also investigated for the practical implementation of the adsorbent. The sorption showed significant increase with increase of temperature. Kinetics models describing the adsorption of Hg(II), Pb(II) and Ni(II) ions onto carbon aerogel have been compared. Kinetics models evaluated include the pseudo‐first order and second order model. The parameters of the adsorption rate constants have been determined and the effectiveness of each model assessed. The result obtained showed that the pseudo‐second order kinetic model correlated well with the experimental data and better than the pseudo‐first order model examined in the study. Mass transfer coefficients obtained can be useful in designing wastewater treatment systems or in the development of environmental technologies. Copyright © 2005 Society of Chemical Industry     

Metal‐chelating properties of poly(2‐hydroxyethyl methacrylate–methacryloylamidohistidine) membranes

Metal‐chelating membranes have advantages as adsorbents in comparison with conventional beads because they are not compressible and they eliminate internal diffusion limitations. The aim of this study was to explore in detail the performance of poly(2‐hydroxyethyl methacrylate–methacryloylamidohistidine) [poly(HEMA–MAH)] membranes for the removal of three toxic heavy‐metal ions—Cd(II), Pb(II), and Hg(II)—from aquatic systems. The poly(HEMA–MAH) membranes were characterized with scanning electron microscopy and ¹H‐NMR spectroscopy. The adsorption capacity of the poly(HEMA–MAH) membranes for the selected heavy‐metal ions from aqueous media containing different amounts of these ions (30–500 mg/L) and at different pH values (3.0–7.0) was investigated. The adsorption capacity of the membranes increased with time during the first 60 min and then leveled off toward the equilibrium adsorption. The maximum amounts of the heavy‐metal ions adsorbed were 8.2, 31.5, and 23.2 mg/g for Cd(II), Pb(II), and Hg(II), respectively. The competitive adsorption of the metal ions was also studied. When the metal ions competed, the adsorbed amounts were 2.9 mg of Cd(II)/g, 14.8 mg of Pb(II)/g, and 9.4 mg of Hg(II)/g. The poly(HEMA–MAH) membranes could be regenerated via washing with a solution of nitric acid (0.01M). The desorption ratio was as high as 97%. These membranes were suitable for repeated use for more than three adsorption/desorption cycles with negligible loss in the adsorption capacity. The stability constants for the metal‐ion/2‐methacryloylamidohistidine complexes were calculated to be 3.47 × 10⁶, 7.75 × 10⁷, and 2.01 × 10⁷ L/mol for Cd(II), Pb(II), and Hg(II) ions, respectively, with the Ruzic method. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1213–1219, 2005     

Selective separation and concentration of Pd(II) from Fe(III), Co(II), Ni(II), and Cu(II) ions using thiourea‐formaldehyde resin

Thiourea‐formaldehyde (TUF), a well‐known chelating resin, has been synthesized and it was used in the adsorption, selective separation, and concentration of Pd(II) ions from Fe(III), Co(II) Ni(II), and Cu(II) base metal ions. The composition of the synthesized resin was determined by elemental analysis. The effect of initial acidity/pH and the adsorption capacity for Pd(II) ions were studied by batch technique. The adsorption and separation of Pd(II) were then examined by column technique. FTIR spectra and SEM/EDS analysis were also recorded before and after the adsorption of Pd(II). The optimum pH was found to be 4 for the adsorption. The adsorption data fitted well to the Langmuir isotherm. The maximum adsorption capacity of the TUF resin for Pd(II) ions was found to be 31.85 mg g⁻¹ (0.300 mmol g⁻¹). Chelating mechanism was effective in the adsorption. Pd(II) ions could be separated efficiently from Fe(III), Cu(II), Ni(II), and Co(II) ions using TUF resin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Investigation of Pb(II) adsorption onto natural and synthetic polymers

Adsorption of toxic metal ion Pb(II) onto two different insoluble humic acids (IHAs) obtained from Beysehir (BIHA) and Ermenek (EIHA) low grade lignites and two synthesized terpolymers: styrene-divinylbenzene-methacrylic acid (SDBM) and styrene-divinylbenzene allylmethacrylate (SDBAM) were investigated and compared with commercial activated carbon (AC). The synthesized polymers were characterized by FTIR. Effects of pH (in neutral and acidic range), time, and initial metal concentration on the effectiveness of IHAs and terpolymers were determined. All synthesized adsorbents could adsorb Pb(II) with much higher capacity at half of the retention of AC in acidic medium. The adsorption capacities varied in the range of 51–76 mg g⁻¹. The affinity order of polymers in acidic medium for Pb(II) ions was observed as: SDBAM>SDBM>BIHA≈EIHA>AC. IHAs fit Freundlich model while SDB polymers were fitting Langmuir isotherm. The maximum adsorption capacities in neutral medium were 48 mg g⁻¹ for SDBM and 15 mg g⁻¹ for BIHA. Desorption studies for the polymer of highest performance indicated that about 90% desorption was achieved at 5 h by using EDTA regenerant solution. The polymer can be used repeatedly in Pb(II) adsorption with close capacities to initial use. The higher selectivity of SDBAM to Pb(II) ions in multimetal solution was also indicated in the study. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Enhanced adsorption and recovery of Pb(II) from aqueous solution by alkali‐treated persimmon fallen leaves

Persimmon fallen leaves were employed to prepare a renewable and low‐cost biosorbent named as NPFL. Effects of initial pH, contact time, initial Pb(II) concentration, coexisting metal ions, and ionic strength on adsorption of Pb(II) from aqueous solution by NPFL were studied in detail. Enhanced removal capacity of NPFL toward Pb(II) was observed, and the maximum adsorption capacity was evaluated as 256 mg g^?1 by Langmuir modeling calculation. The fast adsorption process and the well‐fitted kinetics data with pseudo‐second‐order model indicated that chemisorption is the main rate‐limiting step for the adsorption process. NPFL had superior adsorption selectivity for Pb(II) from aqueous solution with coexisting metal ions. Characterization of NPFL and adsorption mechanism (electrostatic attraction, ion exchange, and chelation) were performed using XRD, SEM‐EDS, FT‐IR, XPS, and TGA. The results suggested that NPFL could be utilized as a potential candidate for the preconcentration of Pb(II) recovery and its removal in practice. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43656.     

Metal‐chelated polyamide hollow fibers for human serum albumin separation

We modified microporous polyamide hollow fibers by acid hydrolysis to amplify the reactive groups and subsequent binding of Cibacron Blue F3GA. Then, we loaded the Cibacron Blue F3GA‐attached hollow fibers with different metal ions (Cu²⁺, Ni²⁺, and Co²⁺) to form the metal chelates. We characterized the hollow fibers by scanning electron microscopy. The effect of pH and initial concentration of human serum albumin (HSA) on the adsorption of HSA to the metal‐chelated hollow fibers were examined in a batch system. Dye‐ and metal‐chelated hollow fibers had a higher HSA adsorption capacity and showed less nonspecific protein adsorption. The nonspecific adsorption of HSA onto the polyamide hollow fibers was 6.0 mg/g. Cibacron Blue F3GA immobilization onto the hollow fibers increased HSA adsorption up to 147 mg/g. Metal‐chelated hollow fibers showed further increases in the adsorption capacity. The maximum adsorption capacities of Co²⁺‐, Cu²⁺‐, and Ni²⁺‐chelated hollow fibers were 195, 226, and 289 mg/g, respectively. The recognition range of metal ions for HSA from human serum followed the order: Ni(II) > Cu(II) > Co(II). A higher HSA adsorption was observed from human serum (324 mg/g). A significant amount of the adsorbed HSA (up to 99%) was eluted for 1 h in the elution medium containing 1.0M sodium thiocyanide (NaSCN) at pH 8.0 and 25 mM ethylenediaminetetraacetic acid at pH 4.9. Repeated adsorption–desorption processes showed that these metal‐chelated polyamide hollow fibers were suitable for HSA adsorption. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3346–3354, 2002     

Pyromellitic dianhydride‐modified β‐cyclodextrin microspheres for Pb(II) and Cd(II) adsorption

In this work, the pyromellitic dianhydride (PMDA)‐grafted β‐cyclodextrin (β‐CD) microspheres have been prepared for the removal of lead and cadmium metal ions in aqueous solution by a batch‐equilibration technique. The effects of the pH of the solution, contact time, and initial metal concentration were studied. The adsorption capacities for the two metal ions increase significantly as a large number of carboxyl groups are present on the microspheres surface. The equilibrium process is better described by the Langmuir isotherm than the Freundlich isotherm. The maximum adsorption capacities are 135.69 and 92.85 mg g^?1 for Pb(II) and Cd(II), respectively. Kinetic studies show good correlation coefficients for a pseudosecond‐order kinetic model, confirming that the sorption rate is controlled by chemical adsorption. The regeneration of the adsorbent can be carried out by treating the loaded microspheres with 0.2 (mol L^?1) HCl obtaining high desorption rate for the two metal ions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Comparison of Biosorption of Nickel (II) and Copper (II) Ions from Aqueous Solution by Sphaeroplea Algae and Acid Treated Sphaeroplea Algae

Abstract

Biosorption of nickel (II) and copper (II) ions from aqueous solution by dead sphaeroplea algae in natural and acid treated forms were studied as a function of concentration, pH, and adsorbent dose. The optimum pH for nickel (II) and copper (II) biosorption was found to be 6.0 and 4.0 respectively. The metal ion uptake increased with initial metal ion concentration studied up to 500 mg/L. Both the Freundlich and Langmuir adsorption models could fit the equilibrium data. The adsorption reasonably fitted the Lagergren kinetic model. Further the biomass was characterized by FTIR spectra. Surface area values are measured to be 0.9 and 2.1 m²/g for natural and acid treated forms respectively. The maximum adsorption capacity was found to be 3.40, 4.15 mmol/g for nickel (II) and 2.21, 3.41 mmol/g for copper (II) in natural and acid treated forms respectively.     

Modelling Individual and Competitive Adsorption of Cadmium(II) and Zinc(II) Metal Ions from Aqueous Solution onto Bagasse Fly Ash

Abstract

The present study deals with the competitive adsorption of cadmium (Cd(II)) and zinc (Zn(II)) ions onto bagasse fly ash (BFA) from binary systems. BFA is a waste obtained from the bagasse‐fired boilers of sugar mills. The initial pH≈6.0 is found to be the optimum for the individual removal of Cd(II) and Zn(II) ions by BFA. The equilibrium adsorption data were obtained at different initial concentrations (C ₀ = 10–100 mg/l), 5 h contact time, 30°C temperature, BFA dosage of 10 mg/l at pH ₀ = 6. The Redlich–Peterson (R–P) and the Freundlich models represent the single ion equilibrium adsorption data better than the Langmuir model. The adsorption capacities in the binary‐metal mixtures are in the order Zn(II)>Cd(II) 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 Zn(II) ions on BFA is found to be antagonistic. Equilibrium isotherms for the binary adsorption of Cd(II) and Zn(II) ions on BFA have been analyzed by non‐modified Langmuir, modified Langmuir, extended‐Langmuir, Sheindorf–Rebuhn–Sheintuch (SRS), non‐modified R–P and modified R–P adsorption models. The isotherm model fitting has been done by minimizing the Marquardt's percent standard deviation (MPSD) error function using MS Excel. The SRS model satisfactory fits for most of the adsorption equilibrium data of Cd(II) and Zn(II) ions onto BFA.     

Adsorption of Cd(II), Pb(II), and Ag(I) in aqueous solution on hollow chitosan microspheres

Cross‐linked chitosans synthesized by the inverse emulsion cross‐link method were used to investigate adsorption of three metal ions [Cd(II), Pb(II), and Ag(I)] in an aqueous solution. The chitosan microsphere, was characterized by FTIR and SEM, and adsorption of Cd(II), Pb(II), and Ag(I) ions onto a cross‐linked chitosan was examined through analysis of pH, agitation time, temperature, and initial concentration of the metal. The order of adsorption capacity for the three metal ions was Cd²⁺ > Pb²⁺ > Ag⁺. This method showed that adsorption of the three metal ions in an aqueous solution followed the monolayer coverage of the adsorbents through physical adsorption phenomena and coordination because the amino (? NH₂) and/or hydroxy (? OH) groups on chitosan chains serve as coordination sites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Investigation of zinc(II) adsorption on Cladophora crispata in a two‐staged reactor

In this study, the adsorption of zinc(II) ions on Cladophora crispata, a green alga, was studied with respect to initial pH, temperature, initial metal ion and biomass concentration in order to determine the optimum adsorption conditions. Optimum initial pH values for zinc(II) ions were found to be 5.0 at optimum temperature, 25 °C. The initial adsorption rates increased with increasing initial zinc(II) ion concentration up to 100 mgdm⁻³. The Freundlich and Langmuir adsorption isotherms were developed at various initial pH and temperature values. Then, the adsorption of zinc(II) ions to C crispata was investigated in a two‐staged mixed batch reactor. The residual metal ion concentrations (C_eq) at equilibrium at each stage for a given quantity of dried algae (X_o)/volume of solution containing heavy metal ion (V_o) ratio were calculated by using Freundlich and Langmuir isotherm constants. It was observed that the experimental biosorption equilibrium data for zinc(II) ions are in good agreement with those calculated using both Freundlich and Langmuir models. The adsorbed zinc(II) ion concentration increased with increasing X_o/V_o ratios while the adsorbed metal quantities per unit mass of dried algae decreased. © 2000 Society of Chemical Industry     

Adsorption of lanthanum by magnetic alginate‐chitosan gel beads

BACKGROUND: The risk of environmental pollution is aggravated by the increasing application of considerable amounts of rare earth elements in advanced materials. This paper reports the preparation of novel magnetic alginate–chitosan gel beads and their application for adsorption of lanthanum ions from aqueous solution. RESULTS: Stable magnetic alginate–chitosan gel beads with average diameter 0.85 ± 0.05 mm were prepared by loading iron oxide nanoparticles onto a combined alginate and chitosan absorbent. The performance of the prepared beads for the adsorption of lanthanum ions from aqueous solution was tested. It was found that various parameters, such as aqueous pH, contact time, metal ion concentration, ion strength and temperature, have an effect on the adsorption. Adsorption equilibrium was reached in 10 h and the maximum uptake capacity was 97.1 mg g^?1. From the analysis of pH, FTIR and XPS data, it is proposed that lanthanum adsorption proceeds through mechanisms of cation exchange, electrostatic interaction and surface complexation, with the oxygen atoms the main binding sites. In addition, lanthanum ions could be selectively separated from coexisting base metal ions such as Pb (II), Cd (II), Co (II), Ni (II) and Cu (II) in the aqueous solution. CONCLUSION: The prepared magnetic alginate–chitosan gel beads exhibit high uptake capacity and selectivity for lanthanum sorption, and thus can be used for adsorptive recovery of lanthanum from aqueous solutions. Copyright © 2010 Society of Chemical Industry     

Biosorption of Pb(II) and Ni(II) ions by chemically modified Eclipta alba stem powder: Kinetics and equilibrium studies

Biosorption of Pb(II) and Ni(II) ions onto the Eclipta alba stem powder (EAS) was investigated in a batch system. The biosorbent was characterized by fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM) and elemental analysis. Adsorption influencing factors like pH, adsorbent dose, initial metal ion concentration and contact time were investigated. The adsorption mechanism of Pb(II) and Ni(II) followed the pseudo-second-order kinetic model (R² > 0.998). The Langmuir isotherm model fitted well and the maximum monolayer adsorption capacity of the sorbent for Pb(II) and Ni(II) was found to be 66.2 ± 1.9 mg g^?1and 62.5 ± 1.8 mg g^?1, respectively. Desorption and recovery were carried out using dilute HCl solution.     

Removal of Cu2+ and Pb2+ ions from aqueous solutions by starch-graft-acrylic acid/montmorillonite superabsorbent nanocomposite hydrogels

In this study, the removal of copper(II) and lead(II) ions from aqueous solutions by Starch-graft-acrylic acid/montmorillonite (S-g-AA/MMT) nanocomposite hydrogels was investigated. For this purpose, various factors affecting the removal of heavy metal ions, such as treatment time with the solution, initial pH of the solution, initial metal ion concentration, and MMT content were investigated. The metal ion removal capacities of copolymers increased with increasing pH, and pH 4 was found to be the optimal pH value for maximum metal removal capacity. Adsorption data of the nanocomposite hydrogels were modeled by the pseudo-second-order kinetic equation in order to investigate heavy metal ions adsorption mechanism. The observed affinity order in competitive removal of heavy metals was found Cu²⁺ > Pb²⁺. The Freundlich equations were used to fit the equilibrium isotherms. The Freundlich adsorption law was applicable to be adsorption of metal ions onto nanocomposite hydrogel.     

Continuous preparation of Fe3O4 nanoparticles combined with surface modification by L-cysteine and their application in heavy metal adsorption

L-cysteine functionalized Fe₃O₄ magnetic nanoparticles (Cys–Fe₃O₄ MNPs) were continuously fabricated by a simple high-gravity reactive precipitation method combined with surface modification through a novel impinging stream-rotating packed bed with the assistance of sonication. The obtained Cys–Fe₃O₄ MNPs was characterized by XRD, TEM, FTIR, TGA and VSM, and further used for the removal of heavy metal ions from aqueous solution. The influence of pH values, contact time and initial metal concentration on the adsorption efficiency were investigated. The results revealed that the adsorption of Pb(II) and Cd(II) were pH dependent process, and the pH 6.0 was found to be optimum condition. Moreover, the adsorption kinetic for Cys–Fe₃O₄ MNPs followed the mechanism of the pseudo-second order kinetic model, and their equilibrium data were fitted with the Langmuir isothermal model well. The maximum adsorption capacities calculated from Langmuir equation were 183.5 and 64.35 mg g⁻¹ for Pb(II) and Cd(II) at pH 6.0, respectively. Furthermore, the adsorption and regeneration experiment showed there was about 10% loss in the adsorption capacity of the as-prepared Cys–Fe₃O₄ MNPs for heavy metal ions after 5 times reuse. All the above results provided a potential method for continuously preparing recyclable adsorbent applied in removing toxic metal ions from wastewater through the technology of process intensification.     

EQUILIBRIUM AND KINETIC STUDIES FOR THE ADSORPTION OF MN(II) AND CO(II) FROM AQUEOUS MEDIUM USING AGAR–AGAR AS SORBENT

An extensive increase in industrial activities and environmental accidents in recent years have greatly contributed to increasing metal pollution in water resources, thereby causing threats to terrestrial as well as aquatic life. The toxicity of metal pollution is slow and long lasting, as these metal ions are nonbiodegradable. The most appropriate solution for controlling the biogeochemistry of metal contaminants to produce high-quality treated effluents from polluted wastewaters is sorption technique. Agar–agar, a readily available seaweed, was used as sorbent for the removal of Mn(II) and Co(II) from aqueous media. Batch experiments were performed to study adsorption as a function of process parameters: sorption time, initial pH, concentration of sorbate and sorbent. The Freundlich model fitted best with the experimental equilibrium data between the two adsorption isotherm models tested. The kinetic data correlated well with the Lagergren pseudo-second-order kinetic model for the sorption of both Mn(II) and Co(II) using agar–agar. Adsorbed metal ions were quantitatively recovered from the spent adsorbent using 5.0 mol L^?1 HCl. The efficiency of agar–agar for decontaminating Mn(II) and Co(II) from electroplating effluent has also been evaluated. The results proved agar–agar to be a favorable adsorbent to remove and recover Mn(II) and Co(II) from waste effluent for further use in diversified industrial applications.     

Optimization of parameters for competitive adsorption of heavy metal ions (Pb+2, Ni+2, Cd+2) onto activated carbon

This study investigates optimization of various competitive adsorption parameters for removal of Cd(II), Ni(II) and Pb(II) from aqueous solutions by commercial activated carbon (AC) using the Taguchi method. Adsorption parameters such as initial metal concentration of each metal ion (C_0,i ), initial pH (pH₀), adsorbent dosage (m) and contact time (t) in batch technique were studied to observe their effects on the total adsorption capacity of metals onto activated carbon (q _tot ). The adsorbent dosage has been found to be the most significant parameter. Interactions between C_0,Cd ×C_0,Ni , C_0,Cd ×C_0,Pb and C_0,Ni ×C_0,Pb have been considered for simultaneous metal ions adsorption. The optimum condition for adsorption of metal ions were obtained with C_0,i =100 mg L^?1, pH₀=7, m=2 g L^?1 and t=80 min. Finally, experimental results showed that a multi-staged adsorptive treatment would be necessary to reach the minimal discharge standards of metal ions in the effluent.     

Investigation on selective adsorption of Hg(II) ions using 4‐vinyl pyridine grafted poly(ethylene terephthalate) fiber

In the work, poly(ethylene terephthalate) (PET) fibers were grafted with 4‐vinyl pyridine (4‐VP) monomer using benzoyl peroxide (Bz₂O₂) as initiator in aqueous media. The removal of Hg(II) ions from aqueous solution by the reactive fiber was examined by batch equilibration technique. Effects of various parameters such as pH, graft yield, adsorption time, initial ion concentration, and adsorption temperature on the adsorption amount of metal ions onto reactive fibers were investigated. The optimum pH of Hg(II) was found 3. The maximum adsorption capacity was found as 137.18 mg g^?1. Moreover such parameters as the adsorption kinetics, the adsorption isotherm, desorption time and the selectivity of the reactive fiber were studied. The adsorption kinetics is in better agreement with pseudo‐first order kinetics, and the adsorption data are good fit with Freundlich isotherms. The grafted fiber is more selective for Hg(II) ions in the mixed solution of Hg(II)‐Ni(II), Hg(II)‐Zn(II), and Hg(II)‐Ni(II)‐Zn(II) at pH 3. Adsorbed Hg(II) ions were easily desorbed by treating with 1M HNO₃ at room temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of cibacron blue F3GA‐attached polyamide hollow fibers for heavy metal removal

Dye‐affinity adsorption has been used increasingly for heavy metal removal. Synthetic hollow fibers have advantages as support matrices in comparison to conventional bead supports because they are not compressible and they eliminate internal diffusion limitations. The goal of this study was to investigate in detail the performance of hollow fibers composed of modified polyamide to which Cibacron Blue F3GA was attached for the removal of heavy metal ions. The Cibacron Blue F3GA loading was 1.2 mmol/g. The internal matrix was characterized by scanning electron microscopy. No significant changes in the hollow fiber cross‐section or outer layer morphology were observed after dye modification. The effect of the initial concentration of heavy metal ions and medium pH on the adsorption efficiency were studied in a batch reactor. The adsorption capacity of the hollow fibers for the selected metal ions [i.e., Cu(II), Zn(II) and Ni(II)] were investigated in aqueous media with different amounts of these ions (10–400 ppm) and at different pH values (3.0–7.0). The maximum adsorptions of metal ions onto the Cibacron Blue F3GA‐attached hollow fibers were 246.2 mg/g for Cu(II), 133.6 mg/g for Zn(II), and 332.7 mg/g for Ni(II). Furthermore, a Langmuir expression was calculated to extend the adsorption equilibrium. Nitric acid (0.1M) was chosen as the desorption solution. High desorption ratios (up to 97%) were observed in all cases. Consecutive adsorption/desorption operations showed the feasibility of repeated use of this novel sorbent system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3089–3098, 2002; DOI 10.1002/app.2338