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。     

Adsorption of Cu2+ Cations from Aqueous Solution by S-doped TiO2

S-doped TiO₂ as a novel adsorbent for Cu²⁺ cations removal from aqueous solutions was synthesized by simple sol-gel process. Removal of Cu²⁺ cations from aqueous solutions was investigated with particular reference to the effects of initial Cu²⁺ cations concentration, pH-value, adsorbent dosage, and temperature on adsorption. It was found that the maximum adsorption capacity was 96.35 mg g^?1 at 328 K. The adsorption equilibrium isotherms and the kinetic data were well described by the Langmuir and pseudo-second-order kinetic models, respectively. The high uptake capability of S-doped TiO₂ makes it a potentially attractive adsorbent for the removal of heavy metal pollutants from aqueous solution.     

Modification and magnetization of MOF (HKUST-1) for the removal of Sr2+ from aqueous solutions. Equilibrium,kinetic and thermodynamic modeling studies

In this research, metal-organic framework MOF(HKUST-1) was synthesized, magnetized and modified by hexacyanoferrate in order to prepare an efficient adsorbent for the removal of Sr²⁺ from aqueous solutions. The synthesized adsorbent was characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, thermal methods (TG-DTG[Themogravimetry- Derivative Theromogravimetry]), Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) surface area and scanning electron microscopy (SEM). The non-magnetized (MOF/KNiFC[potassium nickel hexacyanoferrate]) and magnetized (MOF/Fe₃O₄/KNiFC) adsorbents were then employed for the removal of Sr²⁺ from aqueous solutions. The adsorption capacity of 110 and 90 mg.g^?1 was obtained, respectively, for MOF/KNiFC and MOF/Fe₃O₄/KNiFC. The adsorption process was kinetically fast and the equilibration was established within 45 min. The magnetic capability of the adsorbent examined by the vibrating sample magnetometer (VSM) technique indicated that the used adsorbent was capable of separating from the solution by applying an external magnetic field. The adsorbent showed good selectivity toward Sr²⁺ in the presence of Cs⁺, Na⁺, Mg²⁺, Ca²⁺ and Ba²⁺. The regenerated adsorbent retained more than 90% of its initial capacity. Different isotherm models including Langmuir, Freundlich, Tempkin, Sips and Redlich–Peterson were employed to examine the applicability of the isotherms to the experimental data. It was concluded that the data was best fitted to the Langmuir isotherm model. The thermodynamic parameters showed that the process was endothermic.     

Nano-Mg(OH)2 platelets coated flexible polyurethane foam for fast and environment-friendly removal of Cu2+ from aqueous solution

In this study, flexible polyurethane foam (FPUF) was successfully coated with nano-Mg(OH)₂ platelets. Due to the strong interaction between chitosan and nano-Mg(OH)₂, it was possible to yield modified foam with a weight-gain of up to 15 wt% by depositing one chitosan layer and one nano-Mg(OH)₂ layer. Meanwhile, the adsorption isotherms of Cu²⁺ on FPUF covered with 10 wt% coating (FPUF-10) shows the Langmuir behavior. It was found that for the FPUF-10, the removal % for Cu²⁺ after 30 min and 50 min treatment were 86% and 90%, respectively. Moreover, the maximum removal % could reach up to 95%.     

Simultaneous adsorptive removal of methylene blue and copper ions from aqueous solution by ferrocene‐modified cation exchange resin

Resin was modified with ferrocene (Fc) to enhance removal of Methylene Blue (MB) and Cu²⁺ from simulated wastewater. The FTIR, N₂‐BET, and X‐ray fluorescence analysis confirmed that Fc was successfully grafted onto the surface of resin. The adsorption capacity of Fc modified cation exchange resin (FMCER) was calculated to be 392.16 mg/g Cu²⁺ and 10.01 mg/g MB. Both processes were spontaneous and exothermic, best described by Langmuir equation. Pseudo‐first‐order kinetic model satisfied the adsorption of MB, while the intraparticle‐diffusion model fitted the kinetics of Cu²⁺ adsorption best. The result revealed a multilayer adsorption of Cu²⁺ on FMCER, and the kinetics maybe controlled by intraparticle diffusion, film diffusion, and competition force. The adsorption of MB and Cu²⁺ on FMCER were physicosorptive, with activation energies of 2.09 and 1.27 kJ/mol. pH 2–7 and 4–5 are optimum for the removal of MB and Cu²⁺, and pH 4 is optimal for the simultaneous removal of MB and Cu²⁺. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41029.     

A novel carbon aerogel prepared for adsorption of copper(II) ion in water

A novel carbon aerogel with network pore and surface group of hydroxyl was prepared from cellulose colloid, through sol-gel reaction, freeze-drying and carbonization. Surfactant like isooctyl alcohol ether phosphate was taken as structure inducer in sol-gel reaction, for construction of porous network in the prepared samples. Characteristic of a specific area about 725.12 m²/g and total pore volume about 0.64 cm³/g, the prepared cellulose-based carbon aerogel of CCA₂, has a maximum capacity about 55.25 mg/g for Cu²⁺ in neutral aqueous solution. Its adsorption equilibrium can be reached within 10 min in an aqueous solution of pH7.0 at 25?°C, while desorption of Cu²⁺ need about 1 h eluted by HCl or HNO₃ solution of 0.01 M. And regeneration of the carbon aerogel in adsorption of Cu²⁺ can be repeated for five times, remaining 96% adsorption capacity. It is also found in adsorption process the kinetics nicely follows pseudo-second-order rate expression, and the isotherm fits Langmuir model.     

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.     

An investigation of heavy metal adsorption by hexa-dentate ligand-modified magnetic nanocomposites

Advancement of an efficient and cost-effective method for heavy metal removal from contaminated water utilising Fe₃O₄–APTES–EDTA (FAE) nanocomposite, a productive reusable adsorbent, is explained in this study. The novel FAE nanocomposite was prepared and characterised using different techniques such as FTIR, XRD, TEM, EDS, BET, TGA, EDX and Zeta potential techniques. FAE is found to be a good adsorbent for Pb²⁺, Cd²⁺, Ni²⁺, Co²⁺ and Cu²⁺ removal with a higher adsorption capacity. The maximum adsorption capacity of Pb²⁺, Cd²⁺, Ni²⁺, Co²⁺ and Cu²⁺ are found to be 11.31, 13.88, 7.64, 4.86 and 78.67 mg/g, respectively. The adsorption and desorption cycle was studied for five cycles with minimal loss of efficiency.     

Removal of metal ions using lignite in aqueous solution—Low cost biosorbents

Turkish lignite can be used as a new adsorption material for removing some toxic metals from aqueous solution. The adsorption of lignite (brown young coals) to remove copper (Cu²⁺), lead (Pb²⁺), and nickel (Ni²⁺) from aqueous solutions was studied as a function of pH, contact time, metal concentration and temperature. Adsorption equilibrium was achieved between 40 and 70 min for all studied cations except Pb²⁺, which is between 10 and 30 min. The adsorption capacities are 17.8 mg/g for Cu²⁺, 56.7 mg/g for Pb²⁺, 13.0 mg/g for Ni²⁺ for BC₁ (Ilg?n lignite) and 18.9 mg/g for Cu²⁺, 68.5 mg/g for Pb²⁺, 12.0 mg/g for Ni²⁺ for BC₂ (Beysehir lignite) and 7.2 mg/g for Cu²⁺, 62.3 mg/g for Pb²⁺, 5.4 mg/g for Ni²⁺ for AC (activated carbon). More than 67% of studied cations were removed by BC₁ and 60% BC₂, respectively from aqueous solution in single step. Whereas about 30% of studied cations except Pb²⁺, which is 90%, were removed by activated carbon. Effective removal of metal ions was demonstrated at pH values of 3.8–5.5. The adsorption isotherms were measured at 20 °C, using adsorptive solutions at the optimum pH value to determine the adsorption capacity. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. The rise in temperature caused a slight decrease in the value of the equilibrium constant (K_c) for the sorption of metal ions. The mechanism for cations removal by the lignite includes ion exchange, complexation and sorption. The process is very efficient especially in the case of low concentrations of pollutants in aqueous solution, where common methods are either economically unfavorable or technically complicated.     

A Green Method to Fabricate Polyethyleneimine-Alginate Multilayer Coatings Modified Polyurethane Foam for Cu2+ Adsorption from Aqueous Solution

In this study, flexible polyurethane foam (FPUF) was modified with bio-based coatings composed of polyethylenimine (PEI) and alginate (ALG), fabricated by layer-by-layer (LbL) self-assembly. LbL self-assembled coatings modified FPUFs were studied for their potentials for removing Cu²⁺ ions from aqueous solutions by using batch adsorption technique, as a function of assembled bilayers number, pH value, carrier amount and adsorption time. The maximum adsorption capacity of the modified FPUF was shown to be 54 mg/g for Cu²⁺. Results suggested that the LbL self-assembly could potentially be a promising cost-effective technique for fabricating advanced adsorbent materials for removing pollutants from wastewater.     

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.     

Removal of Sr(II) from Aqueous Solutions by Aminosilane Functionalized MCM-48

In this research, NH₂-MCM-48 adsorbent was synthesized by grafting of aminopropyl on the surface of MCM-48 mesoporous silica material. The synthesized adsorbent was characterized by FT-IR, XRD, thermogravimetric, and surface area techniques. The removal of Sr (II) by the synthesized adsorbent was studied and the effect of initial pH, contact time, cation concentration, and temperature on the Sr²⁺ adsorption was studied and optimized. Under optimized conditions, the removal capacity of 5.95 meq/g was obtained. The experimental data were analyzed using the Langmuir and Freundlich equations. Adsorption data was fitted with the Langmuir isotherm, indicating that the process was monolayer and chemical in nature. The calculated thermodynamic parameters, ΔH°, ΔS°, and ΔG° confirmed that the adsorption process was endothermic and spontaneous. The regeneration of the adsorbent was examined and it was found that 92% of the initial capacity was conserved after five successive regeneration cycles.     

Adsorption of chromium (VI) on functionalized and non-functionalized carbon nanotubes

We did a comparative study on the adsorption capacity of Cr (VI) between functionalized carbon nanotubes (CNTs) and non-functionalized CNTs. The statistical analysis reveals that the optimum conditions for the highest removal of Cr (VI) are at pH 9, with dosage 0.1 gram, agitation speed and time of 120 rpm and 120 minutes, respectively. For the initial concentration of 1.0 mg/l, the removal efficiency of Cr (VI) using functionalized CNTs was 87.6% and 83% of non-functionalized CNTs. The maximum adsorption capacities of functionalized and non-functionalized CNTs were 2.517 and 2.49 mg/g, respectively. Langmuir and Freundlich models were adopted to study the adsorption isotherm, which provided a K _L and K _F value of 1.217 L/mg and 18.14 mg^1?n L ⁿ /g functionalized CNT, while 2.365 L/mg and 2.307 mg^1?n L ⁿ /g for non-functionalized CNTs. This result proves that functionalized CNTs are a better adsorbent with a higher adsorption capacity compared with the non-functionalized CNTs.     

Acid Black 172 dye adsorption from aqueous solution by hydroxyapatite as low-cost adsorbent

The Acid Black 172 dye adsorption on the uncalcined hydroxyapatite nanopowder was investigated. The hydroxyapatite prepared by wet coprecipitation method has high specific surface area of 325 m²/g and crystal sizes smaller than 70 nm. The batch adsorption experiments revealed that under the optimum adsorption conditions (pH 3, hydroxyapatite dosage 2 g/L, initial dye concentration 400 mg/L and temperature 20 °C) the dye removal efficiency was 95.78% after 1 h of adsorption. The adsorption kinetics was best described by the pseudo-second order kinetic model. The intraparticle diffusion model shows that intraparticle diffusion is not the sole rate-limiting step; the mass transfer also influences the adsorption process in its initial period. The Langmuir isotherm model best represented the equilibrium experimental data, and the maximum adsorption capacity (q _m ) was 312.5 mg/g.     

Ion-Exchange Characteristics of a Layered Metal Sulfide for Removal of Sr2+ from Aqueous Solutions

Strontium-90 (⁹⁰Sr) is the most abundant radionuclide in radioactive wastes, and is typically isolated by treatment with an inorganic ion-exchange material. Most inorganic ion-exchange materials contain oxygen. The ion-exchange chemistry of layered metal sulfides is relatively poorly explored compared with that of oxide ion-exchange materials. Here, a layered metal sulfide (UCR-28), constructed from [ZnGe₃S₉(H₂O)]^4? supertetrahedral clusters, was prepared under hydrothermal conditions and used for the removal of Sr²⁺ ions from aqueous solution. Batch experiments showed that UCR-28 had affinity for Sr²⁺ ions at pH values ranging from 1 to 10 and the maximum ion-exchange capacity of UCR-28 (50.1 mg/g) was achieved at pH 7. Thermodynamic parameters for the ion-exchange process were evaluated, and the enthalpy and Gibbs free energy results suggested the Sr²⁺ ion-exchange process was endothermic and spontaneous. The ion-exchange data were a good fit to the Langmuir model. In addition, the metal sulfide reported here had a relatively high thermal stability. The results of this study provide insight into the largely unknown ion-exchange chemistry of metal sulfides, and could be used for design of new chalcogenide frameworks with improved ion-exchange properties.     

Adsorption studies of Cu2+ onto poly (vinyl alcohol)/poly (acrylamide-co-N-isopropylacrylamide) core–shell nanogels synthesized through surfactant-free emulsion polymerization

Poly (vinyl alcohol) (PVA) nanoparticle core and poly (acrylamide-co-N-isopropylacrylamide) P(AAm-co-NIPAm) hydrogel shell were fabricated to produce well-defined PVA/P(AAm-co-NIPAm) core–shell nanogels using Surfactant Free Emulsion Polymerization (SFEP). The nanogel was characterized by the FTIR, TEM TGA thermogram and SEM techniques. The adsorbent was utilized for Cu²⁺ removal from aqueous solution. Batch adsorption process indicated that 0.9 mol% PAAm nanogel exhibited higher adsorption affinity toward Cu²⁺. The kinetics parameters were investigated according to the pseudo-first-order, pseudo-second-order and intraparticle diffusion rate models. The adsorption equilibrium match with Langmuir adsorption isotherm rather than Freundlich isotherm. The Cu²⁺ loaded nanogels were effectively desorbed using 0.1 mol/l from HCl as stripping agent.     

Study on preparation and solution properties of hydrophobically associating polyacrylamide by emulsifier-free ultrasonic assisted radical polymerization

Removal of heavy metals from aqueous solutions has attracted much attention worldwide. Many processes and technologies have been developed to remove heavy metals ions. In our previous study, a silica-poly acrylic amphoteric hybrid hydrogel was successfully prepared with double-network (DN) structure using ??-aminoporpyltriethoxysilane as precursor through a two-step sequential network formation technique. In the present research, the absorption behavior of this hydrogel was investigated carefully using Cu²⁺ ions and Cr₂O ₇ ^2? ions as representatives of negative and positive ions respectively. Under different adsorption conditions, the adsorption behaviors of the hydrogel were studied in detail, including initial concentration of the adsorbed ions, adsorption time, pH and ionic strength. The results showed the absorption capacity to Cu²⁺ can reach 700?mg/g with an initial Cu²⁺ concentration of 1,200?mg/L within 2?h. The experimental results show that the Freundlich adsorption law is applicable to the adsorption of Cu²⁺ and Cr₂O ₇ ^2? on the hydrogel.     

Synthesis of High Surface Area MgAl2O4 Nanopowder as Adsorbent for Leather Dye Removal

Abstract

MgAl₂O₄ nanopowder has been prepared by alkoxides hydrolysis with further calcination at temperature of 700°C. The adsorption of a leather dye, Direct Black 38, onto this material was investigated. The sample was characterized by X-ray-diffraction (XRD), N₂ adsorption–desorption isotherm and Fourier transform infrared spectroscopy. The results showed that sample present a pure phase, and the average nanocrystal size of 8 nm, the BET surface area is about 206.5 m² · g^?1 and total pore volume is about 1.44 cm³ · g^?1. Adsorption kinetics data were modeled by film and pore diffusion model. The experimental isotherm was described by the Langmuir model. MgAl₂O₄ nanopowder presented a great removal efficiency of leather dye by adsorption process, with a maximum adsorption capacity of 833 mg of dye per gram of adsorbent.     

Development of fly ash and iron ore tailing based porous geopolymer for removal of Cu(II) from wastewater

This work aims to verify the feasibility of utilizing iron ore tailing (IOT) in porous geopolymer and intends to broaden the application of porous geopolymer in heavy metal removal aspect. Porous geopolymer was prepared using fly ash as resource material, which was partially replaced by IOT at level of 30%, by weight, with H₂O₂ as foaming agent and removal efficiency, adsorption affecting factors, adsorption isotherms and thermodynamics of Cu²⁺ by the developed porous geopolymer were investigated.The experimental results uncover that the porous amorphous geopolymer was successful synthesized with total porosity of 74.6%. The transformation of fly ash and IOT into foaming geopolymer leads to the formation of porous structure encouraging Cu²⁺ sorption. Batch sorption tests were carried out and geopolymer dosage, Cu²⁺ initial concentration, pH, contact time and temperature were the main concern. Both Langmuir and Freundlich models could explain the adsorption of Cu²⁺ on the porous geopolymer due to the high fitting coefficients. The uptake capacity reaches the highest value of 113.41 mg/g at 40 °C with pH value of 6.0. The thermodynamic parameters ΔHº, ΔSº and ΔGº suggests the spontaneous nature of Cu²⁺ adsorption on porous geopolymer and the endothermic behavior of sorption process.     

Influence of Fe3O4 nanoparticles decoration on dye adsorption and magnetic separation properties of Fe3O4/rGO nanocomposites

Magnetite (Fe₃O₄) nanoparticles were prepared by solvothermal method and its composites with reduced graphene oxide namely FG1, FG2, and FG3 (changing magnetite precursor loading 0.1, 0.5, and 1 respectively) were used as adsorbents for the removal of methyl violet (MV) dye. The structural and morphological results confirm that rGO sheets were decorated with Fe₃O₄ and it ensures the variation of active sites toward dye removal property. The maximum adsorption capacity obtained for FG2 was 196 mg/g. The adsorption isotherms and kinetics better fit Langmuir and pseudo-second-order kinetic model for FG1 and FG2. Increasing of Fe₃O₄ loading on rGO reduces the dye adsorption sites and too low Fe₃O₄ loading affects the magnetic separation. The optimal loading of Fe₃O₄ on rGO is important parameter for the adsorption process and fast separation of adsorbent.