PSSMA修饰磁性氧化石墨烯对Pb2+、Cu2+ 的吸附性能

以氧化石墨烯(GO)、FeCl_3·6H_2O及聚(4-苯乙烯磺酸-共聚-马来酸)钠盐(PSSMA)为主要原料,通过简便一步溶剂热法制备了阴离子聚电解质修饰磁性氧化石墨烯(MGO@PSSMA),并将其用于水溶液中重金属Pb~(2+)、Cu~(2+)的吸附去除。采用FTIR、SEM、TEM、VSM和DLS对制备的MGO@PSSMA进行了表征。考察了溶液pH、吸附时间、溶液初始质量浓度对Pb~(2+)、Cu~(2+)在MGO@PSSMA及未经PSSMA修饰磁性氧化石墨烯(MGO)上吸附的影响。探讨了吸附等温过程、吸附动力学及吸附作用机理。结果表明:MGO表面引入PSSMA可有效增加其对Pb~(2+)、Cu~(2+)的吸附量。在pH=5,溶液初始质量浓度为300 mg/L时,MGO@PSSMA对Pb~(2+)和Cu~(2+)的实际吸附量达141.1和104.8 mg/g。当溶液初始质量浓度为150 mg/L时,MGO@PSSMA对Pb~(2+)和Cu~(2+)的吸附平衡时间分别为2和1.5 min。MGO@PSSMA对Pb~(2+)、Cu~(2+)的吸附动力学及吸附等温数据分别符合准二级吸附动力学模型和Langmuir吸附等温模型。使用乙二胺四乙酸(EDTA)和HCl可实现MGO@PSSMA的有效再生;通过外加磁场作用可实现MGO@PSSMA的回收再利用。     

Removal of Cu(II), Fe(III), and Cr(III) from Aqueous Solution by Aniline Grafted Silica Gel

Abstract

The aniline moiety was covalently grafted onto silica gel surface. The modified silica gel with aniline groups (SiAn) was used for removal of Cu(II), Fe(III), and Cr(III) ions from aqueous solution and industrial effluents using a batch adsorption procedure. The maximum adsorption of the transition metal ions took place at pH 4.5. The adsorption kinetics for all the adsorbates fitted better the pseudo second‐order kinetic model, obtaining the following adsorption rate constants (k₂): 1.233 · 10^?2, 1.902 · 10^?2, and 8.320 · 10^?3 g · mg^?1 min^?1 for Cr(III), Cu(II), and Fe(III), respectively. The adsorption of these transition metal ions were fitted to Langmuir, Freundlich, Sips, and Redlich‐Peterson isotherm models; however, the best isotherm model fitting which presented a lower difference of the q (amount adsorbed per gram of adsorbent) calculated by the model from the experimentally measured, was achieved by using the Sips model for all adsorbates chosen. The SiAn adsorbent was also employed for the removal of the transition metal ions Cr(III) (95%), Cu(II) (95%), and Fe(III) (94%) from industrial effluents, using the batch adsorption procedure.     

Adsorption of Cu(II) and Ni(II) using a Novel Xanthated Carboxymethyl Chitosan

Removal of Cu(II) and Ni(II) from aqueous solutions by a novel xanthated carboxymethyl chitosan (XCC) was investigated. XCC obtained was characterized by FTIR, SEM, EDX, and XRD. The adsorption ability of chitosan and XCC toward Cu(II) and Ni(II) was compared. The effect of pH (2.0–7.0), contact time (5–60 min), and adsorption isotherms on adsorption were also investigated. It was observed that the modified chitosan XCC showed a remarkable increase in Cu(II) and Ni(II) adsorption as compared to chitosan and displayed a quick adsorption performance. Further, The Langmuir isotherm was found to provide the best correlation of the experimental data and the adsorption capacity obtained from the Langmuir model was 174.2 mg/g and 128.4 mg/g for Cu(II) and Ni(II), respectively. FTIR and UV spectra suggested that the amino groups, carboxyl groups, and xanthate groups of XCC participated in the adsorption.     

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.     

Removal of Cu(II) from aqueous solutions by recycled tire rubber

A batch adsorption system was applied to study the adsorption of Cu(II) ions from aqueous solutions by crumb rubber. The effects of pH ranging from 1.5 to 7.0, contact time ranging from 6 to 96 h and initial metal concentration ranging from 1 mg L^− 1 to 50 mg L^− 1 on the removal of Cu(II) were studied. Results show that adsorption of Cu(II) is pH-dependent and the best results are obtained at pH = 6.0. Results also show that copper uptake is accompanied by displacement of zinc and therefore probably involves an ion exchange type mechanism. Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. Equilibrium data agreed very well with the Langmuir model. Results clearly show that crumb rubber is an effective adsorbent for the removal of Cu(II) from aqueous solutions.     

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.     

Removal of Mercury (II) from Aqueous Solution using Chitosan-graft-Polyacrylamide Semi-IPN Hydrogels

Chitosan-graft-polyacrylamide semi-interpenetrating polymer network (IPN) superabsorbent hydrogel was prepared via UV irradiation and N, N′-methylene-bis-acrylamide was used as crosslinker. The product was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and scanning electron microscopy (SEM). The hydrogels were observed to exhibit as much as 2580.2% swelling under optimum reaction conditions. The hydrogel is an efficient selective sorbent for the removal of mercuric ions (Hg(II)) from aqueous solutions. The mercury sorption capacity under non-buffered conditions is achieved around 9.98 mmol · g^?1 (or 2001.8 mg (mercury)/g (hydrogel)) via the colorimetric method. The kinetic data were fitted to the pseudo second order model. Furthermore, the influence of pH, hydrogel dose, and initial mercury concentration on adsorption capacity of the semi-IPN hydrogel was evaluated. Also, the isothermal adsorption equilibrium data was described using the Langmuir model. Finally, the mercury loaded hydrogel was regenerated without losing its original activity and stability.     

Adsorption of cadmium (II) and copper (II) ions from aqueous solution using chitosan composite

The binary chitosan/silk fibroin composite synthesized by reinforcement of silk fibroin fiber into the homogenous solution of chitosan in formic acid was used to investigate the adsorption of two metals of Cu(II) and Cd(II) ions in an aqueous solution. The binary composite was characterized by Fourier transform infrared and scanning electron microscopy. The optimum conditions for adsorption by using a batch method were evaluated by changing various parameters such as contact time, adsorbent dose, and pH of the solution. The experimental isotherm data were analyzed using the Freundlich and Langmuir equations, indicated to be well fitted to the Langmuir isotherm equation under the concentration range studied, by comparing the correlation co‐efficient. Adsorption kinetics data were tested using pseudo‐first‐order and pseudo‐second‐order models. Kinetics studies showed that the adsorption followed a pseudo‐second‐order reaction. Due to good performance and low cost, this binary chitosan/silk fibroin composite can be used as an adsorbent for removal of Cu(II) and Cd(II) from aqueous solutions. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Walnut shell supported nanoscale Fe0 for the removal of Cu(II) and Ni(II) ions from water

The walnut shell supported nanoscale zero‐valent iron (walnut‐nZVI) was prepared from sodium borohydride, iron(II) chloride tetrahydrate, and walnut shell by liquid phase chemical reduction and characterized by FTIR, TEM, and XRD. The composites were tested as adsorbent for the removal of Cu(II) or Ni(II) ions. The equilibrium data were analyzed by the Langmuir, Freundlich, Dubinin–Radushkevich, which revealed that Langmuir isotherm was more suitable for describing Cu(II) and Ni(II) ions adsorption than the other two isotherm models. The results indicated that the maximum adsorption capacity was higher than some other modified biomass waste adsorbents under the proposed conditions, were 458.7, 327.9 mg g^?1 for Cu(II) or Ni(II). The adsorption kinetics data indicated that the adsorption fitted well with the pseudo‐second‐order kinetic model. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43304.     

Removal of Copper(II) and Zinc(II) from Aqueous Solutions Using a Lignocellulosic-Based Polymeric Adsorbent Containing Amidoxime Chelating Functional Groups

In this study, the adsorption of Cu(II) and Zn(II) ions from aqueous solutions onto amidoximated polymerized banana stem (APBS) has been investigated. Infrared spectroscopy was used to confirm graft copolymer formation and amidoxime functionalization. The different variables affecting the sorption capacity such as pH of the solution, adsorption time, initial metal ion concentration, and temperature have been investigated. The optimum pH for maximum adsorption was 10.5 (99.99%) for Zn²⁺ and 6.0 (99.0%) for Cu²⁺ at an initial concentration of 10 mg L^?1. Equilibrium was achieved approximately within 3 h. The experimental kinetic data were analyzed using pseudo-first-order and pseudo-second-order kinetic models and are well fitted with pseudo- second-order kinetics. The thermodynamic activation parameters such as ΔG^o, ΔH^o, and ΔS^o were determined to predict the nature of adsorption. The temperature dependence indicates an exothermic process. The experimental isotherm data were well fitted to the Langmuir model with maximum adsorption capacities of 42.32 and 85.89 mg g^?1 for Cu(II) and Zn(II), respectively, at 20°C. The adsorption efficiency was tested using industrial effluents. Repeated adsorption/regeneration cycles show the feasibility of the APBS for the removal of Cu(II) and Zn(II) ions from water and industrial effluents.     

Adsorption of Cr(VI) on Cross‐Linked Chitosan Beads

Abstract

A possibility of Cr(VI) removal by the adsorption method is discussed in the paper. An adsorbent were hydrogel chitosan beads are produced by the phase inversion method (by changing pH). The possibility of removing Cr(VI) ions by both pure chitosan hydrogel and its chelate compounds (chitosan cross‐linked with Cu(II) and Ag(I) ions) was investigated. The adsorption proceeded from the solutions of potassium dichromate and ammonium dichromate (NH₄)₂Cr₂O₇ and K₂Cr₂O₇. The process rates and adsorption isotherms were determined and described by relevant equations. The process rate was described by the pseudo‐ and second‐order equations, and adsorption equilibria by the Langmuir equations. A slight advantageous change in adsorption properties of chitosan beads was revealed after cross‐linking (for chromium concentration up to 10 g/dm³). A maximum adsorption was 1.1 g_Cr/g chitosan. Results of the studies show that chitosan hydrogel proves useful in the removal of Cr(VI) ions, additionally, cross‐linking with Cu(II) and Ag(I) ions has an advantageous effect in the case of low‐concentrated solutions.     

Co-Adsorption/Filtration of Heavy Metal Ions from Water using Regenerated Cellulose UF Membranes Modified with DETA Ligand

The current study investigates the coupled filtration/adsorption performance of regenerated cellulose (RC) ultrafiltration membranes functionalized with diethylenetriamine (DETA) as a metal-chelating ligand. Lead and copper ions with various concentrations (10–50 ppm) were selected as model adsorbing metals. To investigate the dynamic adsorption performance of the ions, different parameters including initial metal concentration, time of oxidization reaction, ligand concentration, and solution pH were studied. The maximum removal of Pb(II) and Cu(II) proposed by the modified membranes from their single salt solutions were 87% and 83%. Besides, the removal percentages of 56 and 50 were obtained for the competitive adsorption of Pb(II) and Cu(II) ions from their mixed solution, respectively. The selectivity factor was calculated as 1.25 indicating the potential of the process for selective adsorption of the ions. Langmuir and Freundlich isotherms were employed to describe the adsorption equilibria with the first model providing the best fit. Reusability tests showed that the modified membranes can be effectively regenerated by 0.1 M HCl eluting solution and successively reused in dynamic adsorption process.     

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.     

Microwave preparation and copper ions adsorption properties of crosslinked chitosan/ZSM molecular sieve composites

A novel chitosan‐based composite (CTS/ZSM) made of chitosan and ZSM molecular sieve was prepared under microwave irradiation and was used for the removal of Cu (II) ions from aqueous solution. The composites were characterized by FTIR spectra, XRD spectra, and thermogravimetric analysis. The effects of the ZSM content, amount of glutaraldehyde and pH value on adsorption properties of Cu (II) ions by CTS/ZSM were discussed in detail. Contrast with crosslinked chitosan (CCTS), the CTS/ZSM had higher adsorption capacity for Cu (II). Kinetic studies showed that the adsorption of Cu (II) onto CTS/ZSM composite had low correlation coefficients for the pseudo‐first and ‐second order model and intraparticle diffusion model. The equilibrium process was better described by the Langmuir than Freundlich isotherm model. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Removal of Zinc (II) Ions from Aqueous Solutions Using Surfactant Modified Bamboo Sawdust

The present study explores the ability of surfactant modified bamboo sawdust in removing zinc (II) ions from aqueous solutions. The modified bamboo sawdust is characterized by surface area analysis, Scanning Electron Microscope, and Fourier Transform Infrared and X-ray fluorescence analysis. Adsorption isotherm and kinetic models were used to study the adsorption characteristics of zinc (II) ions onto modified bamboo sawdust. The equilibrium adsorption isotherm data were fitted into the Langmuir and Freundlich adsorption isotherms. It was found that modified bamboo sawdust yielded maximum adsorption capacity of 111.12 mg/g at 50°C for zinc (II) ions. The kinetic data obtained at different initial concentrations were analyzed using first-order-reversible reaction, pseudo-first-order, and pseudo-second-order models. The results provide strong evidence to support the hypothesis of adsorption mechanism.     

Preparation and characterization of porous chitosan–tripolyphosphate beads for copper(II) ion adsorption

Porous chitosan–tripolyphosphate beads, prepared by the ionotropic crosslinking and freeze‐drying, were used for the adsorption of Cu(II) ion from aqueous solution. Batch studies, investigating bead adsorption capacity and adsorption isotherm for the Cu(II) ion, indicated that the Cu(II) ion adsorption equilibrium correlated well with Langmuir isotherm model. The maximum capacity for the adsorption of Cu(II) ion onto porous chitosan–tripolyphosphate beads, deduced from the use of the Langmuir isotherm equation, was 208.3 mg/g. The kinetics data were analyzed by pseudo‐first, pseudo‐second order kinetic, and intraparticle diffusion models. The experimental data fitted the pseudo‐second order kinetic model well, indicating that chemical sorption is the rate‐limiting step. The negative Gibbs free energy of adsorption indicated a spontaneous adsorption, while the positive enthalpy change indicated an endothermic adsorption process. This study explored the adsorption of Cu(II) ion onto porous chitosan–tripolyphosphate beads, and used SEM/EDS, TGA, and XRD to examine the properties of adsorbent. The use of porous chitosan–tripolyphosphate beads to adsorb Cu(II) ion produced better and faster results than were obtained for nonporous chitosan–tripolyphosphate beads. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effective and Selective Recovery of Precious Metals by Thiourea Modified Magnetic Nanoparticles

Adsorption of precious metals in acidic aqueous solutions using thiourea modified magnetic magnetite nanoparticle (MNP-Tu) was examined. The MNP-Tu was synthesized, characterized and examined as a reusable adsorbent for the recovery of precious metals. The adsorption kinetics were well fitted with pseudo second-order equation while the adsorption isotherms were fitted with both Langmuir and Freundlich equations. The maximum adsorption capacity of precious metals for MNP-Tu determined by Langmuir model was 43.34, 118.46 and 111.58 mg/g for Pt(IV), Au(III) and Pd(II), respectively at pH 2 and 25 °C. MNP-Tu has high adsorption selectivity towards precious metals even in the presence of competing ions (Cu(II)) at high concentrations. In addition, the MNP-Tu can be regenerated using an aqueous solution containing 0.7 M thiourea and 2% HCl where precious metals can be recovered in a concentrated form. It was found that the MNP-Tu undergoing seven consecutive adsorption-desorption cycles still retained the original adsorption capacity of precious metals. A reductive adsorption resulting in the formation of elemental gold and palladium at the surface of MNP-Tu was observed.     

Lead(II)‐ion removal by ethylenediaminetetraacetic acid ligand functionalized magnetic chitosan–aluminum oxide–iron oxide nanoadsorbents and microadsorbents: Equilibrium,kinetics, and thermodynamics

Novel nanosized and microsized chitosan–Al₂O₃–Fe₃O₄ (CANF and CAMF, respectively) adsorbents were functionalized with ethylenediaminetetraacetic acid (EDTA) ligands and applied to the removal of Pb(II) ions. The prepared adsorbents were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller analysis, and their adsorption potentials were investigated with Pb(II) as a target metal under various experimental conditions. Our results show that the EDTA functionalization of CANF and CAMF increased their adsorption capacities about 31.5 and 38 times, respectively. The optimum dosage obtained was 1.0 g/L for both EDTA‐functionalized adsorbents, and the maximum adsorption took place at pH = 5.3. The kinetic results revealed that the adsorption obeyed the pseudo‐second‐order model and that the pore diffusion process played a key role in the adsorption kinetics. Also, the results of equilibrium isotherms indicate the good fit of the experimental data by the Langmuir isotherm model under the studied concentration and temperature ranges, and the adsorptions of Pb(II) ions from aqueous solution followed the monolayer coverage of the adsorbents. The maximum Pb(II)‐ion adsorption capacities of EDTA–CANF and EDTA–CAMF were 160 and 157 mg/g, respectively. These metal‐loaded adsorbents could be readily recovered from aqueous solution by magnetic separation and reused. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44360.     

Biosorption Equilibrium and Kinetics of Au（Ⅲ） and Cu（Ⅱ） on Magnetotactic Bacteria

Magnetotactic bacteria （MTB） as biosorbents for the adsorption of Au（Ⅲ） and Cu（Ⅱ） ions from aqueous solution have been investigated. The optimum adsorption conditions for both metal ions were the initial pH scope of 1-5.5 for Au（Ⅲ） and 2.0-4.5 for Cu（Ⅱ）, room temperature, biomass concentration of 10.0g.L^-1 and sorotion du-ration more than 10 min. When the initial metal concentration were within 500mg.L^-1, the maximum biosorption capacity of 1.0g of MTB （dry mass basis） for Au（Ⅲ） and Cu（Ⅱ） were calculated as 505.2mg of Au（Ⅲ） and 493.1mg of.Cu（Ⅱ） by Langmuir model in single system, respectively. The isotherm equilibrium of Au（Ⅲ） and Cu（Ⅱ） ions in the Au-Cu binary system reflected a unique phenomenon that the adsorption of Au（Ⅲ） was rein-forced and that of Cu（Ⅱ） prohibited, compared respectively-with their performances in the single metal system.When the,concentration of-Au（Ⅲ） and Cu（Ⅱ）. were below 80mg.L^-1, the waste waterafter MTB treating, wasbelow 1.0mg.L^-1, which is in conformity with Environmental Performance Standards （EPS） of Canada. Besides, all the kinetic data were fitted well to the pseudo second-order kinetic model with a high correlation coefficient （R^2〉0.999）.     

Nickel and copper removal from aqueous solution by an immature coal (leonardite): effect of pH,contact time and water hardness

The removal of Ni(II) and Cu(II) from aqueous solutions by a low cost sorbent (leonardite) was studied. The metal uptake was pH‐dependent and the maximum sorption for two metals was obtained at around pH 5–6. Batch kinetic studies showed that equilibrium time was reached after 2 h of contact time. Equilibrium isotherms were obtained for the adsorption data of the two metals in single and binary systems. Equilibrium data were fitted to Langmuir and Freundlich models and the maximum adsorption capacities were found to be 0.33 mmol of copper and 0.26 mmol of nickel per gram of leonardite. In binary solutions containing the two metals an important reduction of nickel uptake was observed while the sorption of copper was less affected. The presence of Ca²⁺ affected the removal of both copper and nickel ions, although the adsorption of nickel was reduced more than that of copper. Copyright © 2005 Society of Chemical Industry