Simultaneous Adsorption Of Cu Research Articles

Hydroxyapatite incorporated metakaolin/sludge based geopolymer adsorbent for copper ions and ciprofloxacin removal: Synthesis, characterization and mechanisms

The efficacy of copper Cu(II) adsorption is significantly affected by the presence of antibiotics, such as ciprofloxacin (CIP). Therefore, researchers are highly interested in conducting extensive investigations on the simultaneous adsorption of Cu(II) and CIP. However, most of the adsorbents exhibited low adsorption capacity of CIP with increasing Cu(II) concentration due to the competition for adsorption sites. Hence, the integration of various adsorbents into a single composite could be an effective way to increase the adsorption sites. Thus, this study aims to incorporate hydroxyapatite (Hap) into metakaolin/sludge based geopolymer adsorbent for simultaneous adsorption of Cu(II) and CIP. The effect of different filler loading of Hap (1–3 %) on the metakaolin/sludge geopolymerization and also on the removal efficiency of Cu(II) and CIP were studied in a single and binary system. Moreover, the effects of varied concentrations of Cu(II) (0–100 mg/L) on the removal efficiency of CIP were investigated. Characterization techniques such as x-ray diffraction (XRD), fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), brunauer-emmett-teller (BET) and neutron tomography imaging were employed to characterize the physicochemical properties of the synthesized geopolymer. It was found that the Hap content has a significant impact on the removal efficiency of CIP and Cu(II). The addition of 2 % Hap providing more nucleation site for the increasing geopolymerization (C-A-S-H) and silicoalumino phosphate gel (SAP) leading to the formation of highly cross-linked geopolymer network and abundant active sites which would favour the adsorption. Moreover, the removal efficiency of CIP by 2 % Hap-geopolymer increased (25.6 % to 61.51 %) with increasing Cu(II) concentration by the complexation and bridging effect between Cu(II) and CIP resulting in the formation of GMK25S1-2Hap-Cu(II)-CIP complexes. Therefore, the hybrid method of geopolymer and Hap is an exceptionally efficient approach for the treatment of wastewater that comprises Cu(II) and CIP.

Simultaneous adsorption of Cu(II), Zn(II), Cd(II) and Pb(II) from synthetic wastewater using NaP and LTA zeolites prepared from biomass fly ash

Herein, NaP and LTA zeolites were successfully synthesised from woody biomass ash with alkali fusion-assisted hydrothermal method by altering the NaOH/ash ratio, crystallisation time and crystallisation temperature. In order to reduce the synthesis costs, NaP zeolite was synthesised with no additional source of aluminium and silicon. The synthesised zeolites were utilized for the monocomponent and simultaneous adsorption of Cu(II), Cd(II), Pb(II) and Zn(II) ions. The maximum adsorbed amount of metals had the trend Pb(II) > Cu(II) > Cd(II) > Zn(II) for both NaP and LTA zeolite. The kinetic data fit well to the pseudo-second order model indicating that chemisorption is the rate-limiting step. The isotherm data were well described with Sips and Redlich-Peterson models indicating a non-ideal heterogeneous adsorption process. Maximum adsorption capacity of NaP zeolite was 42.9 mg/g for Cu(II) and 117.3 mg/g for Cd(II), while LTA had 140.1 mg/g and 223.5 mg/g for Cu(II) and Cd(II) ions, respectively.

Simultaneous Adsorption of Cu2+ and Cd2+ by a Simple Synthesis of Environmentally Friendly Bamboo Pulp Aerogels: Adsorption Properties and Mechanisms.

The highly efficient, pollution-free and degradable biomass-based adsorbents used for the purification of wastewater are currently being highlighted in the research. Bamboo is an excellent raw material for pulp production due to its characteristics of fast growth, wide distribution and high cellulose content. In this study, a tannin/chitosan/bamboo pulp aerogel (TCPA), an environmentally friendly, renewable and low-density adsorbent, was synthesized using a simple freeze-drying method and analyzed by FTIR, XPS, SEM, TEM, TGA and surface area and porosity methods. TCPA has a large specific surface area (137.33 m2/g) and 3D porous structure, and its surface has multiple functional groups including amino, carboxyl and hydroxyl groups, which lead to a simultaneous absorption effect with Me2+ (Cu2+ and Cd2+). The maximum adsorption capacity for Cu2+ and Cd2+ of the TCPA was 72.73 mg/g and 52.52 mg/g, respectively. The adsorption processes of Me2+ by TCPA follow the pseudo-second-order model and Langmuir isotherm mode, and the adsorption processes are spontaneous and endothermic. The study provides a promising candidate for the treatment of wastewater containing heavy metal mixtures.

Synthesis of novel magnetic rhamnolipid-activated layered double hydroxides nanocomposite for simultaneous adsorption of Cu(II) and m-cresol from aqueous solution

A novel magnetic rhamnolipid (RL)-activated layered double hydroxides (LDH) nanocomposite (Fe3O4/RL-LDH) was prepared by coprecipitation and ion exchange method for the simultaneous adsorption of Cu(II) and m-cresol from aqueous solution. The physical and chemical properties of Fe3O4/RL-LDH were characterized using various techniques, and it was found that Fe3O4/RL-LDH exhibited platelet-like morphology, i.e., tiny Fe3O4 particles with diameter of approximately 40 nm were dispersed over the RL-LDH lamella. Adsorption experiments were carried out to remove Cu(II) and m-cresol by changing the adsorption conditions such as adsorbent dosage (0.2–2 g·L−1), pH (5–10), initial Cu(II) and m-cresol concentrations (10–200 mg·L−1 and 5–100 mg·L−1), adsorption time (0–180 min), temperature (25–45 °C) and coexisting anions (SO42− and NO3−). The optimum adsorbent dosage, pH and contact time to reach equilibrium were 0.8 g·L−1, 5.5 and 120 min, respectively. The experimental results showed that the adsorption kinetics of Fe3O4/RL-LDH for Cu(II) and m-cresol agreed well with the pseudo-second-order kinetic equation, and the adsorption isotherms were well depicted by the Freundlich equation. According to the results obtained from adsorption kinetics and thermodynamic studies, powder X-ray diffractometer (PXRD) and X-ray photoelectron spectroscopy (XPS) analysis of Fe3O4/RL-LDH before and after adsorption, it could be inferred that the adsorption mechanism of Cu(II) mainly involved the complexation between RL anions (intercalated in the interlayers of LDH) with Cu(II) ions and that of m-cresol involved the hydrophobic interaction between RL anions and m-cresol. Both Cu(II) and m-cresol adsorptions were spontaneous and exothermic. The magnetic property of Fe3O4/RL-LDH enabled the separation and recovery of Cu(II) and m-cresol from aqueous solution using an external magnet. Thus, the novel magnetic adsorbent Fe3O4/RL-LDH has a potential for simultaneous remediation of organic and heavy metal pollutants.

Application of pyridine-modified chitosan derivative for simultaneous adsorption of Cu(II) and oxyanions of Cr(VI) from aqueous solution

The bioadsorbent C1, which is a chitosan derivative prepared in a one-step synthesis, was successfully used to adsorb Cr(VI) and Cu(II) simultaneously. Here, for the first time the simultaneous adsorption of a cation and an anion was modeled using the Corsel model for kinetics and the Real Adsorbed Solution Theory model for equilibrium data. Batch studies of the adsorption of Cu(II) and Cr(VI) in single and binary aqueous solutions were performed as a function of initial solute concentration, contact time, and solution pH. The maximum adsorption capacities of C1 in single and binary aqueous solutions were 1.84 and 1.13 mmol g−1 for Cu(II) and 3.86 and 0.98 mmol g−1 for Cr(VI), respectively. The reuse of C1 was investigated, with Cu(II) ions being almost completely desorbed and fully re-adsorbed. For Cr(VI), the desorption was incomplete resulting in a lower re-adsorption. Energy-dispersive X-ray spectroscopy was used for mapping the distributions of Cr(VI) and Cu(II) adsorbed on the C1 surface in single and binary adsorption systems. Isothermal titration calorimetry experiments were performed for Cr(VI) and Cu(II) adsorption in single solutions. The thermodynamic parameters of adsorption showed that the adsorption of both metal ions was enthalpically driven, but entropically unfavorable.

Simultaneous adsorption of Cu(II) ions and poly(acrylic acid) on the hybrid carbon-mineral nanocomposites with metallic elements

In order to propose a novel, effective adsorbent of Cu(II) ions, hybrid carbon-mineral nanocomposites with metallic elements (Mn/Fe in the case of B-6, Mn – B-8) were examined. A combination of mechanochemical and pyrolytic methods was used to obtain these bimodal micro-mesopore systems. First, mechanochemical mixing of phenol-formaldehyde resin and inorganic compounds in a ball mill was carried out. Then, the pyrolysis of the mixture under inert atmosphere at 800 °C was performed. The obtained composites were characterized using nitrogen adsorption/desorption, Fourier transform infrared spectroscopy, electron microscopes as well as X-ray diffraction, X-ray fluorescence and X-ray photoelectron spectroscopy. Adsorption, electrokinetic and aggregation studies were also performed, in the absence and presence of poly(acrylic acid) (PAA) – a macromolecular compound commonly used in industry and agriculture, which may be present in wastewater together with copper(II) ions. Under examined conditions (at pH 5 and 6), Cu(II) adsorbed amount was higher on the B-8 surface than on the B-6 one. At pH 6 for the initial Cu(II) concentration 100 ppm, 51.74% of the ions was adsorbed on B-8% and 46.68% – on B-6. Heavy metal adsorption contributes to stronger aggregation of nanocomposite particles. Thus, the presented bimodal solids, especially that containing Mn (called B-8), can be considered as adsorbents in heavy metal removal from aqueous solutions.

Simultaneous adsorption of Cu2+ and Cr (VI) using HDTMA-modified zeolite: isotherm, kinetic, mechanism, and thermodynamic studies.

Clinoptilolite modified by hexadecyltrimethylammonium bromide (HDTMA-Br) was used to simultaneously remove copper and hexavalent chromium from aqueous solutions. The surface properties of HDTMA-modified natural zeolite (HMNZ) were characterized using scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), zeta potential and Fourier transform infrared spectroscopy (FTIR) techniques. SEM images showed that surfactant is adsorbed on the surface of the zeolite, which is confirmed by the FTIR result. The results from BET demonstrated a reduction in the specific surface area and pore volume due to the presence of surfactant molecules on the external surface of zeolite. The effects of important parameters on adsorption efficiency of Cu2+ and Cr (VI) were evaluated by Box-Behnken design. The Langmuir isotherm provided the best fit to the equilibrium data of Cu2+ and Cr (VI), with the maximum adsorption capacity of 0.068 and 0.0093(mmolg-1), respectively. The film diffusion mechanism was found to control the mass transfer, and the adsorption reactions were computed as endothermic for Cu2+ (ΔHads ° = 17.58 kJmol-1) and exothermic for Cr (VI) (ΔHads ° -26.18 kJmol-1). The results indicated that surfactant modification changes the surface charge of zeolite from negative to positive, which makes zeolites economic adsorbents with the possibility of simultaneous removal of cations and oxyanions. The results also showed that the removal efficiency of Cr (VI) increases in the presence of copper cations due to there being more positive sites on the adsorbent surface.

Improved simultaneous adsorption of Cu(II) and Cr(VI) of organic modified metakaolin-based geopolymer

In this paper, a metakaolin-based mesoporous geopolymer (GP-CTAB) was used as adsorbent for Cu(II) and Cr(VI) through a novel and simple synthetic route using cetyltrimethylammonium bromide (CTAB) as an organic modifier. The application of GP-CTAB for the simultaneous removal of metal anions and cations in aqueous solution was studied for the first time. The results of X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Brunauer, Emmett and Teller (BET), and Barrett, Joyner, and Halenda (BJH) methods indicate that GP-CTAB is still geopolymer even in the presence of quaternary ammonium salt cations. The material was tested to simultaneously adsorb Cu(II) and Cr(VI) from an aqueous solution. The results show that GP-CTAB can adsorb anions simultaneously without sacrificing the adsorption properties of heavy metal cations, which is superior to conventional geopolymers. The maximum theoretical adsorption capacity of GP-CTAB for Cu(II) and Cr(VI) was 108.2 mg/g and 95.3 mg/g in the binary system, respectively. It was also found that the presence of Cu(II) in the solution promoted the adsorption of Cr(VI). Given this characteristic of GP-CTAB, it has shown great application prospects in the prevention and control of heavy metal pollution.

Simultaneous adsorption of Cu2+ and Acid fuchsin (AF) from aqueous solutions by CMC/bentonite composite

Carboxymethyl-chitosan (CMC)/bentonite composite was prepared by the method of membrane-forming, and characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. The simultaneous adsorption of Cu2+ and Acid fuchsin (AF) applying CMC/bentonite composite as an adsorbent in single or binary systems was investigated. The adsorption study was conducted systematically by varying the ratio of CMC to bentonite, adsorbent dosage, initial pH value, initial Cu2+ (or AF) concentration, contact time and the interaction of two components in binary solutions. The results showed that the presence of Cu2+ hindered the adsorption of AF, while the presence of AF almost had no influence on the adsorption of Cu2+ in binary systems. The adsorption data of Cu2+ and AF were both suitable for Langmuir isotherm model, and the maximum adsorption capacities of CMC/bentonite composite, according to the Langmuir isotherm model were 81.4 mg/g for Cu2+ and 253.2 mg/g for AF at 298 K. The pseudo-second-order model could better describe the adsorption process of Cu2+ and AF. Thermodynamic constant values illustrated that the adsorption of Cu2+ was endothermic, while the adsorption process of AF was exothermic.

A bifunctional adsorbent of silica gel-immobilized Schiff base derivative for simultaneous and selective adsorption of Cu(II) and SO42−

Abstract A ditopic zwitterionic Schiff base modified silica gel adsorbent SG-H 2 L 2 was prepared and it was characterized by Fourier transform infrared spectroscopy, elemental analysis, solid state NMR, thermogravimetry and porous structure analysis. SG-H 2 L 2 could simultaneously adsorb metal ions and attendant anions from the aqueous solution of metal salts . SG-H 2 L 2 exhibited a cooperative effect between the adsorption of metal cations and the attendant anions, and the adsorption efficiency decreased in the order MSO 4 > M(NO 3 ) 2 > MCl 2 (M = Cu, Co, Ni, Mn, Cd). SG-H 2 L 2 displayed good adsorption selectivity for Cu(II) and SO 4 2− from the aqueous solutions containing mixed metal ions of Cu(II), Co(II), Ni(II), Mn(II) and Cd(II) or mixed anions of SO 4 2− , NO 3 − , and Cl − . The preliminary mechanism for simultaneous and selective adsorption of the metal ions and attendant anions were discussed. The effect of different parameters including pH, contact time and initial concentrations of Cu(II) and SO 4 2− on the simultaneous adsorption of Cu(II) and SO 4 2− ions were investigated. The efficient adsorption of Cu(II) and SO 4 2− could be achieved in neutral pH region and the maximum adsorption capacities for Cu(II) and SO 4 2− , respectively, were the same of 0.42 mmol g −1 at 25 °C. The adsorption isotherms for Cu(II) and SO 4 2− fitted well with Langmuir model, while their adsorption kinetics followed the pseudo-second order model. Regeneration of SG-H 2 L 2 was realized by adjusting the solution pH with diluted H 2 SO 4 and ammonia solution, respectively. SG-H 2 L 2 exhibited good recyclability and reusability for four cycles use without deterioration in its functionality. SG-H 2 L 2 was also applied in different water samples and good recoveries and the selective adsorption of Cu(II) and SO 4 2− were achieved. This study provides a new bifunctional adsorbent which may be used for the effective removal of Cu(II) and SO 4 2− from water effluents containing mixed metal ions and anions.

Selective adsorption of CuSO4 from mixed sulfate solutions by Cu(II) ion-imprinted polymers containing salicylaldoximes, ammonium cations, and tertiary amino groups

A polymerizable complex of copper(II) ion with unsaturated quaternary ammonium cation-modified salicylaldoxime ligand was prepared and used to synthesize a novel copper(II) ion imprinted polymers (Cu(II)-IIPs). Elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), and NMR spectroscopy confirmed the structures of the polymerizable complex and Cu(II)-IIPs. Thermogravimetric analysis (TGA), Brunauer–Emmett–Teller surface area analysis (BET), and scanning electron microscopy (SEM) characterized physical properties and morphologies of synthesized metal complex and corresponding polymers. The effect of pH, contact time, and initial Cu2+ and SO42− concentration on the simultaneous adsorption of Cu2+ and SO42− ions of Cu(II)-IIPs were investigated. Cu(II)-IIPs showed high hydrophilicity and simultaneously rapid adsorption of Cu2+ and SO42− from solution. Moreover, Cu(II)-IIPs displayed highest adsorption capacity in the pH range of 5.0–6.5, the separation factor (β) between Cu2+ with respect to Fe3+ was 1866, the equilibrium adsorption capacities for Cu2+ and SO42− were almost the same and close to 0.13mmolg−1 at 25°C. Stripping experiments revealed that 1.5molL−1 H2SO4 was an effective eluent for desorbing copper (II) ions from Cu(II)-IIPs. In additional, Cu(II)-IIPs exhibited good recyclability and reusability for 5cycles without deterioration of its selective ion-absorbing capacity.

Simultaneous adsorption of Cu(II) and SO42− ions by a novel silica gel functionalized with a ditopic zwitterionic Schiff base ligand

Abstract A novel silica gel based absorbent SG-H2L1, capable of simultaneous adsorption of cations and anions from aqueous solution, was prepared by immobilization of a ditopic zwitterionic Schiff base ligand H2L1 onto a modified silica gel. The functionalized silica gels were characterized by Fourier transform infrared spectroscopy, elemental analysis, thermogravimetric analysis and porous structure analysis. The results showed a degree of functionalization of 0.32 mmol H2L1 per gram of SG-H2L1. The effect of pH, contact time and initial Cu(II) and SO42− concentration parameters on the simultaneous adsorption of Cu(II) and SO42− ions were investigated. The adsorption was fast and the effective pH range for simultaneous adsorption of Cu(II) and SO42− was neutral region. The adsorption study showed that SG-H2L1 had good adsorption efficiency for Cu(II) and SO42−, and the maximum adsorption capacity for Cu(II) and SO42−, respectively, was the same of 0.65 mmol g−1 at 25 °C. Langmuir and Freundlich isotherm models were employed to analyze the experimental data, and the Langmuir model fitted better for both Cu(II) and SO42−. Due to the zwitterionic feature, desorption and regeneration of the absorbent was readily realized by adjusting the pH of the regenerating media with diluted H2SO4 (0.5 mol L−1) and ammonia solution (pH = 10), respectively. The new type absorbent SG-H2L1 exhibited good recyclability and reusability for 5 cycles use without deterioration in its functionality. Therefore, the adsorbent can be used effectively for efficient and simultaneous adsorption of Cu(II) and SO42− from waste water. The mechanism for simultaneous adsorption of cation and anions on SG-H2L1 was also discussed. This study provides a strategy for the development of new absorbents for simultaneous adsorption of hazardous metal ions and anions from waste water effluents.

Simultaneous Adsorption of Cu (II), Zn (II) and Ni (II) on Clays from Solimões Formation

Simultaneous Adsorption of Cu (II), Zn (II) and Ni (II) on Clays from Solimões Formation

Characterization of activated carbons from different sources and the simultaneous adsorption of Cu, Cr, and Zn from metallurgic effluent

Activated carbon is often used in metal ion adsorption processes due to the large surface area it provides. In addition, activated carbon is an inexpensive and environmentally friendly material that provides good cost-benefit for the industries that use it. In this study, activated carbons from different sources were characterized physically and chemically. For example, surface area, thermogravimetric analysis, scanning electronic microscopy, energy dispersive X-ray fluorescence, zeta potential, surface basic and acid groups, iodine number, and ash content were determined. Principal components analysis (PCA) was also used to evaluate the relationship between these characteristics and the origin of the activated carbons examined. The capacity for these adsorbents to simultaneously remove Cu(II), Cr(VI), and Zn(II) from a metallurgic effluent were also evaluated, with some of the adsorbents being able to remove these ions very efficiently.

Simultaneous adsorption and degradation of Zn2+ and Cu2+ from wastewaters using nanoscale zero-valent iron impregnated with clays

Clays such as kaolin, bentonite and zeolite were evaluated as support material for nanoscale zero-valent iron (nZVI) to simultaneously remove Cu(2+) and Zn(2+) from aqueous solution. Of the three supported nZVIs, bentonite-supported nZVI (B-nZVI) was most effective in the simultaneous removal of Cu(2+) and Zn(2+) from a aqueous solution containing a 100 mg/l of Cu(2+) and Zn(2+), where 92.9 % Cu(2+) and 58.3 % Zn(2+) were removed. Scanning electronic microscope (SEM) revealed that the aggregation of nZVI decreased as the proportion of bentonite increased due to the good dispersion of nZVI, while energy dispersive spectroscopy (EDS) demonstrated the deposition of copper and zinc on B-nZVI after B-nZVI reacted with Cu(2+) and Zn(2+). A kinetics study indicated that removing Cu(2+) and Zn(2+) with B-nZVI accorded with the pseudo first-order model. These suggest that simultaneous adsorption of Cu(2+)and Zn(2+) on bentonite and the degradation of Cu(2+)and Zn(2+) by nZVI on the bentonite. However, Cu(2+) removal by B-nZVI was reduced rather than adsorption, while Zn(2+) removal was main adsorption. Finally, Cu(2+), Zn(2+), Ni(2+), Pb(2+) and total Cr from various wastewaters were removed by B-nZVI, and reusability of B-nZVI with different treatment was tested, which demonstrates that B-nZVI is a potential material for the removal of heavy metals from wastewaters.

Self‐assembled and crystallized composites made from poly(ether amine) and montmorillonite in the presence of copper(II) ions

AbstractSelf‐assembled and crystallized composites made from montmorillonite (MMT) by intercalation with poly(ether amine) salts and copper(II) [Cu(II)] ions simultaneously were studied. The manipulation of the silicate unit structure of the secondary (001) lattice by physically imposed osmotic pressure on the platelet interlayer was used. Divalent copper salt assisted a strong depletion effect with balancing the counterions in the clay interlayer and resulted in the extension of the dimensions of the (001) plane by increasing the spacing expansion by more than two orders of magnitude. The simultaneous adsorption of Cu(II) and intercalation of poly(oxypropylene)amine (POP) salts onto the MMT units ultimately minimized their amorphous aggregation through electrostatic attraction between the negative surface and positive edge among the silicate units. Alternatively, the attraction force through face‐to‐face stacking on the silicate surface is proposed, and the conformation of the POP/Cu(II) complex aligned with the approaching platelets to form orderly structures. X‐ray diffraction of the MMT units exhibited a high order of reflection (i.e., (006)) in Bragg's pattern; this implied a repetitive regularity between the plate–plate distances. The high regularity disappeared when the Cu(II) adsorption exceeded the critical clay cation‐exchange capacity of 1.4. The conformation of the flexible polyether backbone was altered and could no longer sustain the plate distance and the symmetric packing was destroyed when the basal spacing was decreased from 82.6 to 18.0 Å. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Modeling competitive adsorption of copper(II), lead(II), and cadmium(II) by kaolinite‐based clay mineral/humic acid system

AbstractThe aim of this work is to investigate and model the simultaneous adsorption of Cu(II), Cd(II), and Pb(II) in the presence and absence of humic acid on kaolinite‐based clays. The preliminary capacity estimation of clays for metal was made with the use of a modified Langmuir approach, and adsorption data collected at various pH were processed using the FITEQL 3.2 computer program to establish the model. The three types of surface sites responsible for adsorption were considered to be the permanent charge sites X, and variable charge sites comprised of S1OH silanol groups and S2OH aluminol groups of kaolinite‐based clays. Heavy metal cations were assumed to bind to the surface in the form of outer sphere and inner sphere monodentate complexes. When humic acid was added, divalent metal ion adsorption was modeled using a multisite binding model by the aid of FITEQL 3.2. Since the stability of the ternary surface complexes in the presence of humic acid was higher than that of the corresponding binary heavy metal cation complexes, the adsorption versus pH curves were steeper (and distinctly S‐shaped) compared with the tailed curves observed in binary clay‐metal ion systems, probably due to the fact that humic acid‐coated kaolinite essentially constituted the active surface for metal sorption. Although competitive metal adsorption from (metal ions mixture+humate) solutions was generally lower than those from individual metal ion solutions, Cd2+, being the metal ion with the highest affinity toward permanent charge sites, was the least affected ion at relatively low pH from competitive adsorption. © 2008 American Institute of Chemical Engineers Environ Prog, 2009

Effect of phosphate on the adsorption of Cu and Cd on natural hematite

Interactions between anions and cations are important to understand the chemical processes of pollutants in environment. In this study, batch experiments were carried out to investigate the simultaneous adsorption of Cu and Cd on hematite as affected by phosphate. Phosphate pretreatment suppressed the maximum adsorption of Cu and Cd on hematite and moved the adsorption pH edges to a higher pH range. Phosphate application time had a marked impact on Cu and Cd adsorption and longer contact time resulted in more reduction of Cu and Cd adsorption. Results of back-titration, Fourier transform infrared (FTIR) spectroscopy study and ionic strength effect on the adsorption revealed that Cu and Cd were adsorbed on hematite mainly through the inner-sphere complex formation mechanism and phosphate treatment reduced the inner-sphere adsorption sites, thus decreasing Cu and Cd adsorption on hematite.

Prediction of simultaneous adsorption of Cu(II) and Pb(II) onto activated carbon by conventional Langmuir type equations

Removal of Cu(II) and Pb(II) by adsorption onto activated carbon was examined in single- and binary-component aqueous solutions representative of contaminated solutions containing heavy metals. Reversibility of adsorption of the heavy metals on the activated carbon was evaluated by desorption experiments. The number of the maximum adsorption sites and adsorption equilibrium constants of Cu(II) and Pb(II) were estimated by the results of single-component systems assuming the Langmuir adsorption model. The adsorption sites per gram of activated carbon resulted in similar values for Cu(II) and Pb(II) from the isotherms. The adsorption constant for Pb(II) was nearly 1.8 times greater than that of Cu(II). Rate constants of adsorption and desorption were also estimated from the kinetic analysis. Using the single set of common parameters obtained from the single-component systems, the experimental results for a binary-component system were quantitatively predicted. Competitive adsorption of Cu(II) and Pb(II) on the same adsorption sites was confirmed by both experimental and predicted results of adsorption in the binary mixture.

Adsorption of metal ion and aromatic compounds by anionic surfactant-coated particles of titanium dioxide

Adsorption of Cu 2+ and 2-naphthol from aqueous solutions was examined by anionic surfactant (sodium dodecyl sulfate, SDS) adsorbed on titanium dioxide. Two types of titanium dioxide were used; one was untreated and the other was hydrophobic with dodecyl chain groups. At pH 3, 4 and 5, the adsorption of Cu 2+ increased with increasing SDS concentration and then decreased slightly on untreated titanium dioxide; the adsorption of Cu 2+ decreased in a following order, pH 5>pH 4>pH 3. The adsorption behavior of Cu 2+ by the SDS adsorbed on hydrophobic titanium dioxide was similar to that on untreated titanium dioxide, although the amount of SDS adsorbed on the former was half as that on the latter. This difference derives from different adsorption states of SDS. In addition, simultaneous adsorption of Cu 2+ and 2-naphthol on both untreated and hydrophobic titanium dioxides by addition of SDS was performed at pH 5; the amount of Cu 2+ adsorbed was almost the same as those without 2-naphthol for both titanium dioxides and the amount of SDS adsorbed was enhanced in the presence of 2-naphthol where 2-naphthol was adsolubilized more efficiently in the SDS adsorbed layer on hydrophobic titanium dioxide than on untreated titanium dioxide. This anionic surfactant-adsorbed layer can remove both metal ions and the nonionic aromatic compound simultaneously.