Removal of heavy metals from aqueous solution by poly(acrylamide-co-acrylic acid) modified with porous materials

In this study, a series of poly acrylamide-co-acrylic acid/NaY zeolite, poly acrylamide-co-acrylic acid/MCM-41, and poly acrylamide-co-acrylic acid/clinoptilolite nanocomposites were synthesized. These materials were characterized by using FT-IR spectroscopy, XRD, TGA, and SEM. Removal capacity of Pb(II) and Cd(II) ions in aqueous solutions by using these nanocomposites was investigated with controlled time, initial metal ions concentration, pH values, adsorbent content, and temperature by using atomic absorption spectrometry. Results show that these nanocomposites have further adsorption related to NaY, MCM-41, and clinoptilolite. Poly(AAm-co-AAc)/NaY, poly(AAm-co-AAc)/MCM-41, and poly(AAm-co-AAc)/clinoptilolite exhibit superior Pb(II) (about 90–99%) and Cd(II) (about 88–98%) adsorption behavior at room temperature and the poly(AAm-co-AAc)/NaY nanocomposite had the best adsorption behavior. Finally, the equilibrium removal performance of the composites is analyzed according to the Langmuir and Freundlich adsorption isotherm model that shows result fitted to Langmuir model and have monolayer adsorption.     

Removal of Ni(II), Cd(II), and Pb(II) from a ternary aqueous solution by amino functionalized mesoporous and nano mesoporous silica

In the present study, the application for the removal of Ni(II), Cd(II) and Pb(II) ions from aqueous solution by using mesoporous silica materials, namely, MCM-41, nanoparticle of MCM-41, NH₂-MCM-41 (amino functionalized MCM-41) and nano NH₂-MCM-41 was investigated. Suitable adsorbents preparation techniques were developed in the laboratory. The effects of the solution pH, metal ion concentrations, adsorbent dosages, and contact time were studied. It was found that NH₂-MCM-41 showed the highest uptake for metal ions in aqueous solution. The results indicated that the adsorption of Ni(II), Cd(II) and Pb(II) ions on the surface of the adsorbent was increased with increasing solution pH. The experimental data were analyzed using the Langmuir and Freundlich equations. Correlation coefficients were determined by analyzing each isotherm. It was found that the Langmuir equation showed better correlation with the experimental data than the Freundlich. According to the parameters of the Langmuir isotherm, the maximum adsorption capacity of NH₂-MCM-41 for Ni(II), Cd(II) and Pb(II) was found to be 12.36, 18.25 and 57.74 mg/g, respectively. The kinetic data of adsorption reactions and the evaluation of adsorption equilibrium parameters were described by pseudo-first-order and pseudo-second-order equations. The synthesized solid sorbents were characterized by Fourier transform infrared (FT-IR) spectrometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen sorption measurements.     

Removal Characteristics of Cd(II), Cu(II), Pb(II), and Zn(II) by Natural Mongolian Zeolite through Batch and Column Experiments

The removal characteristics of Cd(II), Cu(II), Pb(II), and Zn(II) from model aqueous solutions by 5 natural Mongolian zeolites were investigated. The adsorption of metals on zeolites reached a plateau value within 6 h. The adsorption kinetic data were fitted with adsorption kinetic models. The equilibrium adsorption capacity of the zeolites was measured and fitted using Langmuir and Freundlich isotherm models. The order of adsorption capacity of zeolite was Pb(II) > Zn(II) > Cu(II) > Cd(II). The maximum adsorption capacity of natural zeolite depends on its cation exchange capacity and pH. The leaching properties of metals were simulated using four leaching solutions. The results show that natural zeolite can be used as an adsorbent for metal ions from aqueous solutions or as a stabilizer for metal-contaminated soils.     

Effect of pH and temperature on the ion‐exchange isotherm of Cd(II) and Pb(II) on clinoptilolite

The ion‐exchange equilibrium of Pb(II) and Cd(II) on clinoptilolite from different deposits was studied in this work. The Langmuir isotherm fitted the ion‐exchange equilibrium data of both ions better than the Freundlich isotherm. The capacity of the natural zeolite to exchange Cd(II) and Pb(II) increased, augmenting the solution pH. This behaviour was attributed to the interactions between the ions in solution and the surface charge of the zeolite. Moreover, the capacity of the natural zeolite to exchange Cd(II) and Pb(II) was increased when the temperature was raised from 15 to 35 °C. This tendency was explained by assuming that the ion exchange was an endothermic reaction. The selectivity of the zeolite for the metal cations decreased in the following order: Pb(II) > Cd(II). This order was not modified while reducing the solution pH, but the zeolite selectivity was increased. At pH 2 the selectivity of the zeolite for Pb(II) was nearly three times larger than at pH 4. Copyright © 2006 Society of Chemical Industry     

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     

Adsorption of Cr(III), Ni(II), Zn(II), Co(II) ions onto phenolated wood resin

In this study, phenolated wood resin was used an adsorbent for the removal of Cr(III), Ni(II), Zn(II), Co(II) ions by adsorption from aqueous solution. The adsorption of metal ions from solution was carried at different contact times, concentrations and pHs at room temperature (25°C). For individual metal ion, the amount of metal ions adsorbed per unit weight of phenolated wood resin at equilibrium time increased with increasing concentration and pH. Also, when the amounts of metal ions adsorbed are compared to each other, it was seen that this increase was order of Cr(III) > Ni(II) > Zn(II) > Co(II). This increase was order of Cr(III) > Ni(II) > Co(II) > Zn(II) for commercial phenol–formaldehyde resin. Kinetic studies showed that the adsorption process obeyed the intraparticle diffusion model. It was also determined that adsorption isotherm followed Langmuir and Freundlich models. Adsorption isotherm obtained for commercial phenol–formaldehyde resin was consistent with Freundlich model well. Adsorption capacities from Langmuir isotherm for commercial phenol–formaldehyde resin were higher than those of phenolated wood resin, in the case of individual metal ions. Original adsorption isotherm demonstrated the monolayer coverage of the surface of phenolated wood resin. Adsorption kinetic followed the intraparticle diffusion model. The positive values of ΔG° determined using the equilibrium constants showed that the adsorption was not of spontaneous nature. It was seen that values of distribution coefficient (K_D) decreasing with metal ion concentration in solution at equilibrium (C_e) indicated that the occupation of active surface sites of adsorbent increased with metal ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2838–2846, 2006     

Kinetic and equilibrium studies of Pb(II) and Cd(II) removal from aqueous solution onto colemanite ore waste

The adsorption characteristics of Pb(II) and Cd(II) onto colemanite ore waste (CW) from aqueous solution were investigated as a function of pH, adsorbent dosage, contact time, and temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the adsorption isotherms. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The adsorption capacity of CW was found to be 33.6 mg/g and 29.7 mg/g for Pb(II) and Cd(II) ions, respectively. Analyte ions were desorbed from CW using both 1 M HCl and 1 M HNO₃. The recovery for both metal ions was found to be higher than 95%. The mean adsorption energies evaluated using the D-R model indicated that the adsorption of Pb(II) and Cd(II) onto CW were taken place by chemisorption. The thermodynamic parameters (ΔG^o, ΔH^o and ΔS^o) showed that the adsorption of both metal ions was feasible, spontaneous and exothermic at 20-50 °C. Adsorption mechanisms were also investigated using the pseudo-first-order and pseudo-second-order kinetic models. The kinetic results showed that the adsorption of Pb(II) and Cd(II) onto CW followed well pseudo-second order kinetics.     

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     

Kinetics and Thermodynamics of Lead (II) Adsorption on Vermiculite

Abstract

The kinetics and thermodynamics of Pb(II) adsorption on vermiculite have been studied by the sets of experiments at various conditions (temperature, initial lead concentration and adsorption time). The structures of the vermiculite before and after Pb(II) adsorption were measured using X‐ray diffraction (XRD), thermogravimetric analysis (TA), and X‐ray photoelectron spectroscopy (XPS). Adsorption of Pb(II) was strongly affected by pH. First order kinetics model best described the reaction rate, and the adsorption capacity calculated by the model was consistent with that actual measurement. Isotherms for the adsorption of Pb(II) on vermiculite were developed and the equilibrium data fitted well to the Langmuir and Freundlich models. Thermodynamic parameters such as enthalpy, entropy, and free energy were calculated using the Van't Hoff equations. The thermodynamics of Pb(II) on vermiculite indicates the spontaneous and endothermic nature of adsorption. Quantitative desorption of Pb(II) from vermiculite was found to be more than 40% which facilitates the sorption of metal by ion exchange     

羊骨炭对Pb(Ⅱ)、Cr(Ⅵ)、Cd(Ⅱ)吸附性能研究

以CO2为活化剂制备羊骨炭,在不同溶液pH、初始浓度、活性炭投加量等条件下,通过动态吸附试验考察羊骨炭对Pb(Ⅱ)、Cr(Ⅵ)和Cd(Ⅱ)的吸附规律,并用Langmuir和Freundlich吸附等温模型对其吸附性能进行了分析。结果表明,当羊骨炭对Pb(Ⅱ)、Cr(Ⅵ)和Cd(Ⅱ)的最佳吸附量分别为:4.2 mg/g、0.07 mg/g和2.7 mg/g时,吸附液的pH值Pb(Ⅱ)、Cd(Ⅱ)为7～8、Cr(Ⅵ)为酸性pH<6;羊骨炭的投加量分别为:0.2、0.7、0.03 g;最佳初始浓度分别为:60 mg/L、15 mg/L、30 mg/L。羊骨炭对3种离子的吸附行为基本符合Langmuir吸附等温模型和Freundlich吸附等温模型,计算得四种离子的最大吸附量分别为:4.854、1.247、0.402 mg/g。     

Characterization of Ag(I), Co(II) and Cu(II) removal process from aqueous solutions using dolomite powder

Dolomite, a natural adsorbent, was used for removal of Ag(I), Cu(II) and Co(II) from aqueous solutions. Adsorption parameters including pH, temperature and contact time have been investigated to obtain adsorption mechanism. The results of experiments showed that adsorption of the metal ions increased by increasing pH values up to 5.5. The adsorption process was initially fast. Equilibrium isotherm data were analyzed using Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. Maximum adsorption capacity of Ag(I), Cu(II) and Co(II) was 1.34, 1.63 and 2.84 mg/g at 20 oC, respectively. Kinetic models including Lagergren first-order and pseudo-second-order were used to test kinetic data. The results showed that pseudo-second-order has good agreement with experimental data. Thermodynamic parameters of the process were also investigated at different temperatures. The negative values of Gibbs free energy and enthalpy changes for Ag(I), Cu(II) and Co(II) indicated the spontaneous and exothermic nature of the adsorption process.     

Sorption of Pb(II), Cd(II) and Zn(II) by iminodiacetate chelating resins in non-competitive and competitive conditions

Two chelating resins (CRs) bearing iminodiacetate (IDA) groups derived from acrylonitrile - divinylbenzene (AN-DVB) copolymers having 10 and 15 wt.% nominal cross-linking degrees and a high mobility of the functional groups caused by the presence of a longer spacer between the matrix and the IDA groups were synthesized and tested as sorbents for heavy metal ions like: Pb(II), Cd(II) and Zn(II) from aqueous solutions by batch and column techniques. Experimental data obtained from batch equilibrium tests have been analyzed by two isotherm models: Freundlich and Langmuir. The overall adsorption tendency of CRs toward Pb(II), Cd(II) and Zn(II), under non-competitive conditions, followed the order: Cd(II) > Pb(II) > Zn(II). Selectivity studies were performed in ternary mixture of Pb(II), Cd(II) and Zn(II) to check if the synthesized CRs can be useful for selective separation of heavy metal cations. The results revealed that the CRs with IDA groups exhibited high selectivity toward Pb(II), both in batch and column techniques. Regeneration of the resins was achieved using 0.1 M HCl solution.     

Factors Affecting on the Sorption/Desorption of Eu (III) using Activated Carbon

Abstract

The sorption and desorption of Eu (III) on H‐APC activated carbon using a batch technique has been studied as a function of carbon type, shaking time, initial pH solution, temperature, particle size of carbon, and concentration of the adsorbent and the adsorbate. The influence of different anions and cations on adsorption has been examined. The experimental data have been analyzed by Langmuir, Freundlich, and Temkin sorption isotherm models and the adsorption data for Eu (III) onto activated carbon were better correlated to the Temkin isotherm and the maximum absorption capacities obtained was 46.5 mg g^?1. Anions of phosphate, carbonate, oxalate, and acetate were found to increase the adsorption of Eu (III), whereas nitrate, chloride and all studied cations, potassium, sodium, calcium, magnesium, and aluminum have a negative effect on the adsorption capacity. More than 99% europium adsorbed on H‐APC eluted with 0.5 M HCl solution. The activated carbon prepared from apricot stone using 70% H₃PO₄ could be considered as an adsorbent that has a commercial potential for Eu (III) treatment.     

Removal of Pb(II) from Aqueous Solutions by using Chitosan Coated Zero Valent Iron Nanoparticles

This study reports the synthesis, characterization, and application of chitosan coated zero valent iron nanoparticles (CTS-Fe⁰) in the removal of Pb(II) from aqueous medium. This nano adsorbent showed a high adsorption capacity and efficient adsorption towards Pb(II) in aqueous medium. Adsorption of Pb(II) on CTS-Fe⁰ obeyed pseudo-second order kinetics and was controlled by a film diffusion process. Among the various isotherm models the experimental data followed the Langmuir isotherm and the maximum adsorption capacity was found to be 666.6 mg/g at pH 5.0 and 318 K. The sorption mean free energy from D-R isotherm was found to be 72, 131, and 177 J/mol at 298, 308, and 318 K, respectively, indicating a physical sorption. The percentage of Pb(II) removal by CTS-Fe⁰ particles is more than 90% at 318 K. The calculated thermodynamic parameters showed that the adsorption of Pb(II) is feasible, spontaneous, and endothermic in nature. Experimental results indicated that the CTS-Fe⁰ appears to be a promising adsorbent for the removal of Pb(II) from aqueous media.     

Equilibrium Studies in Adsorption of Hg(II) from Aqueous Solutions using Biocompatible Polymeric Polypyrrole-Chitosan Nanocomposite

This article deals with the adsorption of Hg(II) ions from aqueous solution on biocompatible polymeric polypyrrole-chitosan (PPy/CTN) nanocomposite. The Hg(II) uptake of PPy/CTN was quantitatively evaluated using sorption isotherms. In order to describe the isotherm mathematically, the experimental data of the removal equilibrium were correlated by either the Langmuir, Freundlich and Temkin equations. Results indicated that the Langmuir model gave a better fit to the experimental data than the other two equations. The adsorption capacity (q_max) of PPy/CTN for Hg(II) ions in terms of monolayer adsorption was 40 mg/g.     

Batch and fixed‐bed column adsorption of Cu(II), Pb(II) and Cd(II) from aqueous solution onto functionalised SBA‐15 mesoporous silica

Functionalised SBA‐15 mesoporous silica with polyamidoamine groups (PAMAM‐SBA‐15) was successfully prepared with the structure characterised by X‐ray diffraction, nitrogen adsorption–desorption, Fourier transform infrared spectra and thermogravimetric analysis. PAMAM‐SBA‐15 was applied as adsorbent for Cu(II), Pb(II) and Cd(II) ions removal from aqueous solution. The effects of the solution pH, adsorbent dosage and metal ion concentration were studied under the batch mode. The Langmuir model was fitted favourably to the experimental data. The maximum sorptive capacities were determined to be 1.74 mmol g^?1 for Cu(II), 1.16 mmol g^?1 for Pb(II) and 0.97 mmol g^?1 for Cd(II). The overall sorption process was fast and its kinetics was fitted well to a pseudo‐first‐order kinetic model. The mean free energy of sorption, calculated from the Dubinin–Radushkevich isotherm, indicated that the sorption of lead and copper, with E > 16 kJ mol^?1, followed the sorption mechanism by particle diffusion. The adsorbent could be regenerated three times without significant varying its sorption capacity. A series of column tests were performed to determine the breakthrough curves with varying bed heights and flow rates. The breakthrough data gave a good fit to the Thomas model. Maximum sorption capacity of 1.6, 1.3 and 1.0 mmol g^?1 were found for Cu(II), Pb(II) and Cd(II), respectively, at flow rate of 0.4 mL min^?1 and bed height of 8 cm, which corresponds to 83%, 75% and 73% of metallic ion removal, respectively, which very close to the value determined in the batch process. Bed depth service time model could describe the breakthrough data from the column experiments properly. © 2012 Canadian Society for Chemical Engineering     

Adsorption of As(III), As(V), Cd(II), Cu(II), and Pb(II) from Aqueous Solutions by Natural Muscovite

Various parameters were tested for the application of natural muscovite (NM) in the removal of metals from aqueous solutions: contact time, pH, ionic strength, and initial metal concentrations. Kinetic studies showed that the pseudo-second-order model explains well the sorption process. The adsorption of metals was greatly influenced by solution pH but not by ionic strength. The results from isotherm studies agreed more with the Freundlich isotherm model than with the Langmuir isotherm model. The adsorbed quantity of metals by NM was lower than that by the purified mica. These results suggested that the composition and surface characteristics of natural minerals may seriously influence applications for water purification.     

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     

Removal of Pb(II) from aqueous solution by adsorption using activated tea waste

A basic investigation on the removal of Pb(II) ions from aqueous solutions by using activated tea waste was conducted in batch conditions. An inexpensive and effective adsorbent was developed from waste tea leaves for the uptake of Pb(II) from aqueous solution. The influence of different experimental parameters—shaking time, particle size, adsorbent dose, initial pH, temperature, etc.—on lead uptake was evaluated. Lead is adsorbed by the developed adsorbent up to maximum of 99.7%. The initial Pb(II) concentrations were 5, 10, 15 and 20 mg/l in the experiment. The adsorption was found to be exothermic in nature. The Langmuir, Freundlich and Tempkin isotherm models were tried to represent the equilibrium data of Pb(II) adsorption. The adsorption data was fitted very well to the Langmuir isotherm model in the studied concentration range of Pb(II) adsorption. Isotherms have been used to determine thermodynamic parameters of the process: free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°). Column experiments were performed to study the practical applicability of the system. The kinetics and the factors controlling the adsorption process were also discussed. Activated tea waste is a better adsorbent compared to other adsorbents available in literature.     

Biosorption of Pb(II) and Cd(II) ions from aqueous solution using polyaniline/chitin composite

In this study, chitin (Ch) was made composite with polyaniline (PANI) and used for the removal of Pb(II) and Cd(II) ions from aqueous solution. Characterization techniques such as Fourier transform infrared spectroscopy, scanning electron microscope, energy-dispersive X-ray analyser and X-ray diffraction were employed to characterize the prepared PANI/Ch composite. Influence of various equilibrium parameters on the adsorption of Pb(II) and Cd(II) ions onto PANI/Ch composite was investigated. The adsorption process followed the Freundlich isotherm model, and the calculated maximum monolayer sorption capacity of PANI/Ch composite for Pb(II) and Cd(II) ions is 7.03 and 6.05 mg g^?1 at 303 K. The kinetic data were well described by the pseudo-second-order model.