Removal of Lead(II) from Aqueous Solutions using Pre-boiled and Formaldehyde-Treated Onion Skins as a New Adsorbent

The adsorption characteristics of Pb²⁺ on pre-boiled treated onion skins (PTOS) and formaldehyde-treated onion skins (FTOS) were evaluated. The effects of Pb²⁺ initial concentration, agitation rate, solution pH, and temperature on Pb²⁺ adsorption were investigated in batch systems. Pb²⁺ adsorption was found to increase with increase in initial concentration. The point of zero net charge (PZC) was 6.53. The optimum pH for the maximum removal of Pb²⁺ was 6.0. The adsorption equilibrium data was best represented by the Langmuir isotherm model for FTOS and the Freundlich isotherm model for PTOS. The maximum amounts of Pb²⁺ adsorbed (qm), as evaluated by the Langmuir isotherm, was 200 mgg^?1 for FTOS. The efficiencies of PTOS and FTOS for Pb²⁺ removal were 84,8.0% and 93.5% at 0.15 g/200 mL^?1 adsorbent dose, respectively. (C ₀ = 50 mg L^?1). Study concluded that onion skins, a waste material, have good potential as an adsorbent to remove toxic metals like Pb²⁺ from water. Boehm titration analysis was conducted to determine the surface groups. It was found that the adsorption kinetics of Pb²⁺ obeyed pseudo-first-order kinetic model as based on Δq (%) values. FTIR and SEM images before and after adsorption was recorded to explore changes in adsorbent-surface morphology. Activation energy (Ea) was obtained as 25.596 kJ/mol.     

Novel design of microsphere adsorbent for efficient heavy metals adsorption

The fabrication of high-efficiency and low-cost adsorbent for the wastewater treatment is a challenging task. In this study, a hollow sphere adsorbent was synthesized from solid waste coal gangue through a facile spray drying method and subsequent calcination. The structure of the synthesized coal gangue microsphere (CM) have been characterized by multimethods including X-ray diffraction, scanning electron microscope, Fourier transform infrared, and others. The factors influencing the adsorption for Cu²⁺ and Pb²⁺ by CM were also investigated systemically; pH between 6 and 8 was found to be optimal for Cu²⁺ and Pb²⁺ adsorption. The isotherm and kinetic analysis reveal that the adsorption process could be well represented by Langmuir and pseudo–second-order model with a higher R² and low χ² value. According to Langmuir model, the maximum adsorption capacity was calculated to be 6.570 and 18.904 mg/g for Cu²⁺ and Pb²⁺ at 25°C, respectively. The adsorption mechanism was proposed to contain not only the surface reaction process, but also the diffusion process. Consequently, the economic and environmental benefits make CM a promising adsorbent in wastewater treatment.     

One-step hydrothermal synthesis of a green NiCo-LDHs-rGO composite for the treatment of lead ion in aqueous solutions

Herein, we have synthesized a microspherical nickel-cobalt-layered double hydroxides-reduced graphene oxide composite (NiCo-LDHs-rGO) through a one-step hydrothermal method and then used it as an adsorbent for the removal of Pb²⁺ from aqueous solutions. Fourier transform infrared spectrophotometry (FT-IR), field emission scanning electron microscopy (FESEM), mapping elemental analysis, electron dispersive x-ray spectroscopy (EDX), x-ray diffraction analysis (XRD), and the Brunauer–Emmett–Teller (BET) method were used for the characterization of the adsorbent. Factors affecting the adsorption of Pb²⁺ ion such as solution pH, adsorbent dosage, contact time, competing ion, and regeneration were investigated in batch mode by the NiCo-LDHs-rGO. Under optimized conditions based on the Taguchi method (pH = 5.0, adsorbent dosage = 20 mg, and contact time = 30 min), the highest removal percentage was found to be 99.7% for 100 mg L⁻¹ of Pb²⁺. According to the results, NiCo-LDHs-rGO exhibited a high preference for Pb²⁺ over Cu²⁺, Zn²⁺, and Cd²⁺. This adsorbent was regenerated for several cycles (using 0.01 M HCl) with no significant deterioration in performance. Analyses of the adsorption isotherm models revealed that the adsorption of Pb²⁺ follows Freundlich isotherm with a maximum adsorption capacity of 200 mg g⁻¹. Also, the kinetic data confirmed that pseudo second order kinetic equation is the best model for predicting the kinetics. Furthermore, the Simulink modelling illustrated that the adsorption kinetics of Pb²⁺ onto NiCo-LDHs-rGO is done with high accuracy in a continuous stirred-tank reactor. Finally, dual interactions of the effective parameters can be modelled by polynomial equations in MATLAB, and according to the Taguchi model, pH is clearly the most important feature among all effective parameters.     

Highly ordered macroporous γ-alumina prepared by a modified sol-gel method with a PMMA microsphere template for enhanced Pb2+, Ni2+ and Cd2+ removal

The adsorption performance of three-dimensionally ordered macroporous (3DOM) γ-alumina was investigated for enhanced Pb²⁺, Ni²⁺ and Cd²⁺ removal. The synthesis was based on a modified sol-gel method using a colloidal crystal template (CCT) method based on PMMA microspheres. The structure was characterized by means of FTIR spectroscopy and XRD analysis. The three-dimensional structure was examined by scanning electron microscopy, which enabled image analysis that showed significantly low shrinkage (8.77%) after calcination at 800 °C. The influential parameters, including contact time and adsorbent dosage, were investigated in a batch adsorption study. The adsorption equilibrium and kinetic data were found to be in agreement with the Freundlich isotherm for Pb²⁺ removal and the Dubinin-Radushkevich isotherm for Ni²⁺ and Cd²⁺ removal. The time-dependent adsorption was best described by a pseudo-second-order kinetic model and the Weber-Morris model. High adsorption capacities: 95.39, 23.32 and 25.39 mg/g were obtained for Pb²⁺, Cd²⁺ and Ni²⁺ removal at 45 °C, respectively. The existence of interconnected macroporous and mesoporous structures of highly ordered γ-alumina enabled a higher adsorption capacity in comparison with literature data for others alumina-based adsorbents.     

Preparation of thiourea functionalized polyvinyl alcohol‐coated magnetic nanoparticles and their application in Pb2+ ions adsorption

We have prepared a novel kind of magnetic nanoparticle with high adsorption capacity and good selectivity for Pb²⁺ ions by modifying the magnetic nanoparticles with polyvinyl alcohol (PVA) and thiourea. The resultant magnetic nanoparticles were used to adsorb Pb²⁺ ions from aqueous solution. The influence of the solution pH, the adsorption time, the adsorption temperature, coexisting ions, and the initial concentration of Pb²⁺ ions on the adsorption of Pb²⁺ ions were investigated. The results indicated that Pb²⁺ ions adsorption was an endothermic reaction, and adsorption equilibrium was achieved within 30 min. The optimal pH for the adsorption of Pb²⁺ ions was pH 5.5, and the maximum adsorption capacity of Pb²⁺ ions was found to be 220 mg/g. Moreover, the coexisting cations such as Ca²⁺, Co²⁺, and Ni²⁺ had little effect on adsorption of Pb²⁺ ions. The regeneration studies showed that thiourea functionalized PVA‐coated magnetic nanoparticles could be reused for the adsorption of Pb²⁺ ions from aqueous solutions over five cycles without remarkable change in the adsorption capacity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40777.     

Competitive adsorption of Pb, Cu and Cd ions from aqueous solutions by multiwalled carbon nanotubes

The individual and competitive adsorption capacities of Pb²⁺, Cu²⁺ and Cd²⁺ by nitric acid treated multiwalled carbon nanotubes (CNTs) were studied. The maximum sorption capacities calculated by applying the Langmuir equation to single ion adsorption isotherms were 97.08 mg/g for Pb²⁺, 24.49 mg/g for Cu²⁺ and 10.86 mg/g for Cd²⁺ at an equilibrium concentration of 10 mg/l. The competitive adsorption studies showed that the affinity order of three metal ions adsorbed by CNTs is Pb²⁺>Cu²⁺>Cd²⁺. The Langmuir adsorption model can represent experimental data of Pb²⁺ and Cu²⁺ well, but does not provide a good fit for Cd²⁺ adsorption data. The effects of solution pH, ionic strength and CNT dosage on the competitive adsorption of Pb²⁺, Cu²⁺ and Cd²⁺ ions were investigated. The comparison of CNTs with other adsorbents suggests that CNTs have great potential applications in environmental protection regardless of their higher cost at present.     

Poly (acrylic acid-co-acryloyl tetrasodium thiacalix[4]arene tetrasulfonate) grafted dextrin: new supper metal ion adsorbing hydrogels

Dextrin as a biodegradable natural polymer has hydrophilic nature that capable to increase the swelling properties and biodegradability of the synthetic hydrogels. This study describes the synthesis of a poly (acrylic acid-co-acryloyl tetrasodium thiacalix[4]arene tetrasulfonate) grafted dextrin superabsorbent hydrogels (ADA) via solution polymerization. The effects of acryloyl tetrasodium thiacalix[4]arene tetrasulfonate (ACSTCA) dose (20–60) on swelling properties of the hydrogels were studied. The synthesized hydrogels were characterized by FTIR, TGA, DMTA and rheometry. The metal ion removal capacity of the gels was investigated by atomic absorption for Cd²⁺, Pb²⁺, and Hg²⁺. The tendency of metal ions adsorption decreased in the order of Pb²⁺>Cd²⁺>Hg²⁺. The effect of key operating parameters including ACSTCA content, contact time, adsorbent dosage, solution pH, and crosslinker density was experimentally studied on Pb²⁺ adsorption from aqueous solution. The equilibrium data was analyzed using Langmuir and Freundlich adsorption isotherms. Our experimental data are in best agreement with Freundlich isotherms, and adsorption of metal cation onto hydrogel followed a pseudo second-order kinetic model. According to the thermodynamic parameters, the adsorption of Pb²⁺ occurred spontaneously. The hydrogels could be regenerated after releasing heavy metal ions, and reused 5 times with less than 7 % loss of adsorption capacity.     

Preparation of nano‐structured pig bone hydroxyapatite for high‐efficiency adsorption of Pb2+ from aqueous solution

The nano‐structured hydroxyapatite was prepared from pig bone materials by mineralization. The obtained nano‐structured bone was much better compared to the bone without nanostructure for removing Pb²⁺. The process was investigated under different conditions including contact time, initial Pb²⁺ concentration, and pH. The pseudo‐second‐order kinetic model and Langmuir isotherm model were suitable for describing adsorption process. Moreover, the maximum adsorption capacities of nano‐structured bone and bone without nanostructure were 312.5 and 96.1 mg/g, respectively. Overall, the advantages of excellent adsorption capacity and simple mineralization together with low cost make nano‐structured bone an attractive material for removal of Pb²⁺ from aqueous solution.     

Kinetic and thermodynamic studies of adsorption of Cu2+ and Pb2+ onto amidoximated bacterial cellulose

Removal of Cu²⁺ and Pb²⁺ from aqueous solutions by adsorption onto amidoximated bacterial cellulose (Am-BC) was investigated. The effects of pH, initial concentration, contact time and temperature were studied in batch experiments. The pseudo-first and pseudo-second orders and intraparticle diffusion equation were used to evaluate the kinetic data and the constants were determined. The experimental data fits well to the pseudo-second order kinetic model, which indicates that the chemical adsorption is the rate-determining step, instead of mass transfer. The equilibrium adsorption data were described by the Langmuir, Freundlich, and Temkin isotherms. The Am-BC showed a better fit to the Langmuir isotherm. The separation factor (R _L ) revealed the favorable nature of the isotherm. The thermodynamic parameters (ΔH _ads⁰, ΔS _ads⁰, ΔG _ads⁰) for Cu²⁺ and Pb²⁺ adsorption onto Am-BC were also determined from the temperature dependence. The values of enthalpy and entropy indicated that this process was spontaneous and exothermic. The experimental studies indicate that Am-BC would be a potential effective adsorbent to remove the metal ions from wastewater.     

Functionalized nanostructured silica by tetradentate-amine chelating ligand as efficient heavy metals adsorbent : Applications to industrial effluent treatment

Organofunctionalized nanostructured silica SBA-15 with tri(2-aminoethyl)amine tetradentate-amine ligand was synthesized and applied as adsorbent for the removal of Cu²⁺, Pb²⁺, and Cd²⁺ from both synthetic wastewater and real paper mill and electroplating industrial effluents. The prepared materials were characterized by XRD, N₂ adsorption-desorption, TGA, and FT-IR analysis. The Tren-SBA-15 was found to be a fast adsorbent for heavy metal ions from single solution with affinity for Cu²⁺, Pb²⁺, than for Cd²⁺ due to the complicated impacts of metal ion electronegativity. The kinetic rate constant decreased with increasing metal ion concentration due to increasing of ion repulsion force. The equilibrium batch experimental data is well described by the Langmuir isotherm. The maximum adsorption capacity was 1.85 mmol g^?1 for Cu²⁺, 1.34 mmol g^?1 for Pb²⁺, and 1.08 mmol g^?1 for Cd²⁺ at the optimized adsorption conditions (pH=4, T=323 K, t=2 h, C₀=3 mmol L^?1, and adsorbent dose=1 g L^?1). All Gibbs energy was negative as expected for spontaneous interactions, and the positive entropic values from 103.7 to 138.7 J mol^?1 K^?1 also reinforced this favorable adsorption process in heterogeneous system. Experiment with real wastewaters showed that approximately a half fraction of the total amount of studied metal ions was removed within the first cycle of adsorption. Hence, desorption experiments were performed by 0.3M HCl eluent, and Tren-SBA-15 successfully reused for four adsorption/desorption cycles to complete removal of metal ions from real effluents. The regenerated Tren-SBA-15 displayed almost similar adsorption capacity of Cu²⁺, Pb²⁺, and Cd²⁺ even after four recycles. The results suggest that Tren-SBA-15 is a good candidate as an adsorbent in the removal of Cu²⁺, Pb²⁺, and Cd²⁺ from aqueous solutions.     

Preparation and adsorption mechanism of polyvinyl alcohol/graphene oxide-sodium alginate nanocomposite hydrogel with high Pb(II) adsorption capacity

A series of polyvinyl alcohol (PVA)/graphene oxide (GO)-sodium alginate (SA) nanocomposite hydrogel beads were prepared through in situ crosslinking for Pb²⁺ removal. It was found that PVA and SA molecules were intercalated into GO layers through hydrogen bonding interactions, leading to the destruction of orderly structure of GO, while GO uniformly distributed in PVA matrix. With increasing PVA solution concentration, the hydrogel beads became more regular, a large number of polygonal pores with thin walls and open pores formed, the average pore size decreased, and the dense network structure formed. Meanwhile, the permeability of the composite hydrogel decreased, leading to the decline of Pb²⁺ adsorption capacity of the composite hydrogel. With increasing GO content, the ballability of the hydrogel beads was weakened, the pore size increased, and relatively loose network structure formed, resulting in an increase in permeability and Pb²⁺ adsorption capacity of the hydrogel, reaching up to 279.43 mg g⁻¹. Moreover, the composite hydrogel presented relatively good reusability for Pb²⁺ removal. The adsorption mechanism was explored and showed that the adsorption system of the composite hydrogel belonged to the second-order kinetic model and fitted Langmuir adsorption isotherm model for Pb²⁺ removal, which might be mono-layer chemical adsorption. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47318.     

Ion-imprinted polyvinylimidazole-silica hybrid copolymer for selective extraction of Pb(II): Characterization and metal adsorption kinetic and thermodynamic studies

The current paper presents a synthesis of a novel ion-imprinted hybrid copolymer (IIHC) [poly(1-vinylimidazole)-co-(3-(trimethoxysilyl)propyl methacrylate) and its application to selective adsorption of Pb²⁺ ions. The hybrid copolymer was prepared by coupling free radical addition and sol-gel processing, using tetraethoxysilane (TEOS) as cross-linker. Thermogravimetry (TG), FT-IR, X-ray diffraction, specific surface area (BET) and scanning electron microscopy (SEM) were used to characterize the copolymers. The equilibrium data obtained were fitted very well to the non-linear Langmuir-Freundlich isotherm model, as compared to other models, and the maximum adsorption uptake was found to be 7.6 mg g⁻¹. The thermodynamic parameters, including Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) of the adsorption process, were found to be −16.23 kJ mol⁻¹, −10.37 kmol⁻¹ and −19.42 J K⁻¹ mol⁻¹, respectively. These results demonstrate that the adsorption of Pb²⁺ onto the hybrid copolymer takes place by a spontaneous and exothermic process with further decrease in the degree of freedom without disordering at the solid-solution interface due to the negative ΔS° value. Furthermore, the pseudo-first-order and pseudo-second-order models were used to describe the kinetic data. The experimental data were fitted well to the pseudo-first-order kinetics. Under competitive adsorption conditions, the ion-imprinted hybrid copolymer was 8.8, 64.9 and 16 times more selective when compared to the blank copolymer (NIC - non-imprinted copolymer) for Pb²⁺/Cu²⁺, Pb²⁺/Cd²⁺, and Pb²⁺/Zn²⁺ systems.     

Morphological,transport, and adsorption properties of ethylene vinyl acetate/polyurethane/bentonite clay composites

The effect of polyurethane (PU) foam on the morphological and transport properties of ethylene vinyl acetate (EVA) with 9% vinyl acetate and the potential application of 3%bentonite/28.5% PU/68.5% EVA composites fabricated via the melt‐blending method in heavy‐metal extraction from water systems were investigated. EVA did not swell in water, whereas the PU/EVA blend attained a maximum percentage of deionized water uptake of 2.158 mol %. A 3% bentonite/28.5% PU/68.5% EVA composite blend successfully removed 90% of Pb²⁺ from an aqueous solution with an initial concentration of 30 mg/L, whereas 3% bentonite/97% EVA could only extract 7.323% of Pb²⁺ ions. Pb²⁺ adsorption was found to obey the Langmuir adsorption isotherm and pseudo‐second‐order kinetic model. Thermodynamic studies demonstrated that the adsorption was favorable at room temperature and the uptake of Pb²⁺ was mostly by physical adsorption, as also indicated by the value n = 2.449 (where n is an empirical parameter indicating transport mode) from the Freundlich adsorption isotherm. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Reusability and selective adsorption of Pb<Superscript>2+</Superscript> on chitosan/P(2-acrylamido-2-methyl-1-propanesulfonic acid-<Emphasis Type="Italic">co</Emphasis>-acrylic acid) hydrogel

Reusability and selective adsorption toward Pb²⁺ with the coexistence of Cd²⁺, Co²⁺, Cu²⁺ and Ni²⁺ ions on chitosan/P(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylic acid) [CS/P(AMPS-co-AA)] hydrogel, a multi-functionalized adsorbent containing –NH₂, –OH, –COOH and –SO₃H groups was studied. The CS/P(AMPS-co-AA) was prepared in aqueous solution by a simple one-step procedure using glow discharge electrolysis plasma technique. The reusability of adsorbent in HNO₃, EDTA-2Na and EDTA-4Na was investigated in detail. The competitive adsorption of the metal ions at the initial stage was compared between their equal mass concentration and equal molar concentration. In addition, the adsorption mechanism of the adsorbent for adsorption of Pb²⁺ was also analyzed by XPS. The results showed that the optimum pH of adsorption was 4.8, and time of adsorption equilibrium was about 180 min. Adsorption kinetics fitted well in the pseudo second-order model. The equilibrium adsorption capacities of Pb²⁺, Cd²⁺, Co²⁺, Cu²⁺, and Ni²⁺ at pH 4.8 were obtained as 673.3, 358.3, 176.7, 235.0 and 171.7 mg g^?1, in their given order. The adsorbent displayed an excellent reusability using 0.015 mol L^?1 EDTA-4Na solution as the eluent, and the desorption ratio could not correctly reflect the true characteristics of adsorption/desorption process. Moreover, the adsorbent showed good adsorption selectivity for Pb²⁺. The molar adsorption capacity at the initial stage with equal molar concentration was more reliable than the mass adsorption capacity during the study of selective adsorption. According to the XPS results, the adsorption of Pb²⁺ ions by the CS/P(AMPS-co-AA) absorbent could be attributed to the coordination between N atom and Pb²⁺ and ion-exchange between Na⁺ and Pb²⁺.     

L-cystein modified bentonite-cellulose nanocomposite (cellu/cys-bent) for adsorption of Cu2+, Pb2+, and Cd2+ ions from aqueous solution

In this study, L-cystein modified bentonite-cellulose (cellu/cys-bent) nanocomposite was synthesized and characterized by XRD, FTIR, SEM with EDS, TGA, and TEM techniques. In order to optimize the process the effect of various operational parameters such as pH, adsorbent dosage, contact time, and temperature were also investigated. The adsorption experiments were carried out in initial concentrations range of 20-100 mg L^?1and the adsorbent affinity for metal ions was found to be in order of Cu²⁺ > Pb²⁺ > Cd²⁺. The optimum pH for adsorption of Cu²⁺ and Cd²⁺ was observed at 5 while for Pb²⁺ it was pH 6. Based on the Langmuir model, the maximum adsorption capacity of Cu²⁺, Pb²⁺, and Cd²⁺ at 50^?C was found to be 32.36, 18.52, and 16.12 mg g^?1, respectively. The Langmuir isotherm and pseudo-second order model were found to be better fitted than the other isotherms and kinetic models. The results of thermodynamic parameters confirmed the process to be endothermic and spontaneous in nature.     

Preparation of graphene oxide/carboxymethyl chitosan/polyvinyl alcohol composite nanofiber membranes by electrospinning for heavy metal adsorption

In this paper, a graphene-oxide/carboxymethyl-chitosan/polyvinyl-alcohol (GO/CMC/PVA) composite nanofiber membrane was prepared by electrospinning and cross-linking with glutaraldehyde (GA) to improve the water resistance. The composite nanofiber membrane can be used in the field of heavy metal adsorption. The membrane was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The effects of GO concentration, adsorption time, and initial concentration of heavy-metal ion (Ni²⁺, Cu²⁺, Ag⁺, and Pb²⁺) solution on the adsorption performance of the fiber membranes were investigated. The results showed that the addition of GO can reduce the diameter of nanofibers. GO, CMC, and PVA exhibited good compatibility, and the intermolecular hydrogen bonding improved. The addition of GO also improved the crystalline properties of the composite fiber membrane. In the optimal cross-linking condition, GA was saturated by steam cross-linking for 6 h. The introduction of GO improved the adsorption capacity of the membrane for heavy metals in water. The utmost adsorption capacities for Ni²⁺, Cu²⁺, Ag⁺, and Pb²⁺ were 262.1, 237.9, 319.3, and 413.6 mg/g when using the cross-linked composite fiber membranes, respectively. The results of adsorption kinetics and thermodynamics showed that the adsorption process accorded with the pseudo-second-order kinetic model and Langmuir–Freundlich isotherm model.     

Removal of Lead Ions from Aqueous Solutions by Different Types of Industrial Waste Materials: Equilibrium and Kinetic Studies

Abstract

A comparative study of the adsorbents prepared from several industrial wastes for the removal of Pb²⁺ has been carried out. Fertilizer industry waste viz. carbon slurry and steel plant wastes viz. blast furnace (B.F.) slag, dust, and sludge were investigated as low‐cost adsorbents after proper treatment in the present study. The adsorption of Pb²⁺ on different adsorbents has been found in the order: B.F. sludge>B.F. dust>B.F. slag>carbonaceous adsorbent. The least adsorption of Pb²⁺ on carbonaceous adsorbent even having high porosity and consequently greater surface area as compared to other three adsorbents, indicates that surface area and porosity are not important factors for Pb²⁺ removal from aqueous solutions. The adsorption of Pb²⁺ has been studied as a function of contact time, concentration, and temperature. The adsorption has been found to be exothermic, and the data conform to the Langmuir equation. The kinetic results reveal that the present adsorption system follows Lagergren's first order rate equation. Since all three waste products from the steel industry show higher potential to remove lead from water, therefore, it is suggested that these metallurgical wastes can be fruitfully employed as low‐cost adsorbents for effluent treatment containing toxic metal ions.     

测试——聚乙烯亚胺改性磁性膨润土对Pb2+和Cu2+的吸附性能(测试稿件)

在磁性膨润土(MBent)表面接枝聚乙烯亚胺(PEI)制备了聚乙烯亚胺改性磁性膨润土(PEI/KH560/MBent),采用FTIR、VSM、XRD、TGA、EA、SEM和EDS对其进行了表征,考察了其对水溶液中Pb_²⁺和Cu_²⁺的吸附性能。结果表明,聚乙烯亚胺已成功接枝于磁性膨润土表面,并有效提高其对Pb_²⁺和Cu_²⁺吸附量；溶液初始pH对吸附量影响较大,随着pH的增大,吸附量增加。在pH=5,溶液初始质量浓度为300 mg/L,PEI/KH560/MBent对Pb_²⁺和Cu_²⁺吸附量分别为96.21和61.08 mg/g；吸附过程符合准二级动力学模型,吸附行为符合Langmuir吸附等温模型。热力学研究表明,吸附为自发吸热过程。经过5次循环利用后,其吸附容量仍保持初始的60%以上,表明PEI/KH560/MBent具有一定的重复利用性。     

Crosslinking induced by irradiation raises selectivity of polymeric adsorbent

Amine‐type adsorbents were prepared by radiation‐induced graft polymerization. The sorption behaviors for an individual metal ion of Cu²⁺ and Pb²⁺ separately, as well as with mixed Cu²⁺/Pb^2+, were studied in both column and batch mode. Ethylenediamine‐type adsorbent exhibited a high capacity for Cu²⁺ and Pb²⁺ at a high flow rate of 1000 h^?1, but low selectivity in the mixed Cu²⁺/Pb²⁺ solutions. Radiation‐induced crosslinking of the amine‐type adsorbent was performed in water to improve selectivity. Crosslinking of the material was demonstrated by gel fraction, water content, and scanning electron microscopy image. Compared with the results from the noncrosslinked adsorbents, the breakthrough curve of Cu²⁺ right shifted, whereas the breakthrough curve of Pb²⁺ left shifted, indicating the higher adsorption capacity of Cu²⁺ and the lower adsorption capacity of Pb²⁺ from the crosslinked adsorbent. After 300 kGy irradiation, the crosslinked adsorbent was found to selectively adsorb Cu²⁺ from the mixed Cu²⁺/Pb²⁺ solution. The results revealed that crosslinking raised the selectivity of the adsorbents. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Investigation of adsorption behaviors of Cu(II), Pb(II), and Cd(II) from water onto the high molecular weight poly (arylene ether sulfone) with pendant carboxyl groups

Three types of high molecular weight polyarylether adsorbents with different molar ratios of carboxyl and phenylene were designed and synthesized through direct polycondensation in mixture solvents. The as‐prepared polymers were characterized by FTIR, ¹H‐NMR, TGA, DSC, SEM, EDS, and GPC in order to study the regularity of polymeric adsorption/thermostability performances. Because of the highest molar ratio of carboxyl and phenylene, PAES‐C‐Na presented the highest adsorption capacity of Cu²⁺ compared to PAESK‐C‐Na and PAES; therefore, PAES‐C‐Na was opted to study the impacts of adsorbent dosage, pH, contact time, and initial concentration on the adsorption of Pb²⁺ and Cd²⁺. Moreover, a kinetic analysis revealed that the adsorption process followed pseudo‐second‐order model, while the thermodynamic experimental data properly fitted with the Freundlich model. The multi‐component competitive adsorption capacity followed the order Pb²⁺ > Cu²⁺ > Cd²⁺. Additionally, the regeneration tests indicated that PAES‐C‐Na still possessed the excellent adsorption capacity after several recycles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41984.