Removal of Some Heavy Metal Ions Using Grafted Polyurethane Foam

Polyurethane (PU) was modified by grafting a mixture of two monomers acrylonitrile/acrylic acid (AN/AAc) by gamma irradiation method. Effects of various parameters such as, concentration of comonomer composition, grafting yield, gamma irradiation doses, dose rates and pH of adsorbent on the adsorption capacity were studied. Characterizations of the grafted polyurethane (PU-g-AN/AAc) were investigated using infrared (IR) spectroscopic analysis, X-ray diffraction (XRD) and scanning electron microscope (SEM). Moreover, the adsorption capacities of some heavy metals such as, Zn(II), Fe(II), Ca(II), Ni(II), Cu(II) and Pb(II) onto PU-foam and PU-g-AN/AAc were studied. The efficiency of such grafted polyurethane foams for uptaking different previous metal ions was determined and compared with that of natural granular activated carbon (GAC). The uptaking of metal ions was remarkably affected by the pH of the solution, the valances of metal ions, atomic weight and its initial concentrations. Equilibrium isotherms and interruptible diffusivities were investigated through batch experiments in analyzing the uptaking of aqueous solutions of metal ions onto PU foam, grafted PU, and granular activated carbon. The Frundlich constants k and 1/n have been determined for each metal ion to represent both the ability and the affinity of that ions towards the uptaking materials, respectively.     

Competitive Removal of Heavy Metal Ions by Starch-Graft-Acrylic Acid Copolymers

Graft copolymerization of acrylic acid (AA) onto starch was carried out with ceric ammonium nitrate as initiator under nitrogen atmosphere. The structures of the synthesized graft copolymers were identified by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The grafting percentages (GP%) of starch-graft-acrylic acid (S-g-AA) copolymers were determined. Increasing the molar concentration of AA from 0.1 to 0.5 mol/L caused a significant increase in the GP%. The effect of GP% of S-g-AA copolymers on the competitive removal of Pb²⁺, Cu²⁺, Cd²⁺ ions from aqueous solution was investigated at pH 4.5. The concentrations of each ion in aqueous solution were equal to each other, which were kept constant at 4 mmol/L. Metal ion removal capacities were determined by atomic absorption spectrophotometer (AAS). Metal ion removal capacities of S-g-AA copolymers rose with the increase in GP% of the copolymers and the order of the removal of heavy metal ions was Pb²⁺ > Cu²⁺ > Cd²⁺.     

Removal of Heavy Metal Ions from Water by Cross-Linked Potato Di-Starch Phosphate Polymer

Potato di-starch phosphate polymer was synthesized by cross-linking potato starch with phosphorus oxy-chloride in basic medium and was then dispersed (0.2-1%) in aqueous solutions of divalent heavy metal ions (Cu²⁺, Ni²⁺, Zn²⁺, and Pb²⁺), to investigate their removal efficiency by the starch and was found to increase with increase in the polymeric starch content and increase in the heavy metal ion concentration. The removal order was found to be Pb²⁺ (78.1%) > Cu²⁺ (58.5%) > Zn²⁺ (20.5%) > Ni²⁺ (17.3%) against the constant polymeric starch content. UV-Visible, Fluorescence, FT-IR, SEM, and CHN techniques were used for characterization of different complexes formed.     

纤维素的改性及对重金属离子去除的研究进展

本文在对纤维素的性质、结构和来源进行介绍的基础上,重点阐述了近年来国内外对纤维素改性的方法,其中包括醚化反应、酯化反应、接枝共聚反应和模板合成等.同时进一步总结了纤维素基吸附材料在含重金属离子废水中应用的研究进展.     

MnO2改性赤泥基多孔陶瓷滤料去除重金属离子的研究

电镀废水中重金属对水体的污染日益严重,如何安全处置重金属已成重要的研究课题.本文采用溶胶-凝胶法,在赤泥基多孔陶瓷滤球上涂覆MnO2膜,用于去除电镀废水中的Pb^2＋、Cd^2＋.研究了滤料改性膜热处理制度对膜与赤泥基多孔陶瓷滤球的结合性及对重金属离子去除率的影响,探讨了pH值、吸附时间、赤泥基环境修复材料的用量对去除率的影响.结果表明,改性陶瓷滤料最佳热处理温度为650℃时,时铅离子、镉离子去除能力最强.当MnO2改性滤料的添加量为2g、Pb^2＋的浓度为2mg/L、pH值为7、吸附时间为120min时,对Pb^2＋去除率可达96.75％;当MnO2改性滤料的添加量为2g、Cd2＋的浓度为2mg/L、pH值为7、吸附时间为120min时,对Cd2＋去除率可达96.73％.采用SEM、TG-DTA等现代测试技术对样品的结构及性能进行了表征,探讨了赤泥基多孔陶瓷滤球上涂覆MnO2膜的赤泥基环境修复材料的成膜机理和去除重金属铅离子、镉离子的作用机理.     

Comparison of Electrocoagulation and Chemical Coagulation for Heavy Metal Removal

Copper (Cu), chromium (Cr), and nickel (Ni) removal from metal plating wastewater by electrocoagulation and chemical coagulation was investigated. Chemical coagulation was performed using either aluminum sulfate or ferric chloride, whereas electrocoagulation was done in an electrolytic cell using aluminum or iron electrodes. By chemical coagulation, Cu‐, Cr‐, and Ni‐removal of 99.9 % was achieved with aluminum sulfate and ferric chloride dosages of 500, 1000, and 2000 mg L^–1, respectively. Removal of metals by electrocoagulation was affected by the electrode material, wastewater pH, current density, number of electrodes, and electrocoagulation time. Electrocoagulation with iron electrodes at a current density of 10 mA cm^–2, electrocoagulation time of 20 min, and pH 3.0 resulted in 99.9 % Cu‐, 99.9 % Cr‐, and 98 % Ni‐removal.     

Removal of Heavy Metal Ions using New Chelating Material Containing N,O, and S Donor Sites

Abstract

A new chelating material (AT‐PHE‐HCHO) was synthesized by reacting 2‐aminothiazole‐phenol (AT‐PHE) azodye and formaldehyde (HCHO) in an alkaline medium. The materials were characterized by elemental analysis, FT‐IR and ¹H‐NMR spectroscopic studies. The chelating material was used for the adsorption of Cu(II), Zn(II), Mn(II), and Cr(III) from dilute aqueous solutions with variation of adsorption parameters. The adsorption was described quantitatively by fitting the equilibrium data to the Freundlich isotherm. The thermodynamic parameters ΔS and ΔH were calculated to be 86.02 J mol^?1 K^?1 and ?126.9 KJ mol^?1, respectively. The metal adsorption followed the sequence Cu(II)>Zn(II)～Cr(III)>Mn(II). The material was used for the removal of metal ions from synthetic as well as real samples.     

典型重金属离子对双污泥系统反硝化除磷的影响

为了研究和比较重金属对双污泥系统的影响,在双污泥系统稳定运行的基础上,通过调节进水重金属(Cd2+、Cu2+、Zn2+)含量,分别考察了3种重金属短期冲击和长期冲击对双污泥系统碳、氮、磷去除效果的影响.结果显示,Cd2+、Cu2+、Zn2+对硝化菌的短期急毒性和抑制作用关系为Cd2+>Zn2+>Cu2+,对硝化菌的累积...     

壳聚糖超滤膜的制备及在低含量重金属废水处理中的应用

报道了壳聚糖超滤膜的制备及主要性能,确定了壳聚糖溶液成膜的最佳条件,制备的超滤膜透水速度为3～4mL cm2·h,对0.1%牛血清蛋白溶液的截留率可达90%。用此膜对低含量重金属废水进行处理,结果表明:通过调节溶液的pH值,使重金属离子在水溶液中形成胶体,用壳聚糖超滤膜可有效地去除水中Pb2+、Cd2+、Zn2+、Cu2+等金属离子的氢氧化物。     

Synthesis of Amine-Functionalized MCM-41 and MCM-48 for Removal of Heavy Metal Ions from Aqueous Solutions

In this research amino functional mesoporous MCM-41 and MCM-48 materials were prepared in an attempt to develop efficient adsorbents for removal of heavy metals from aqueous solutions. The adsorbents were characterized by XRD, FTIR, and TG-DTG techniques. The synthesized adsorbents were used for the removal of Cu(II), Co(II), Cd(II), and Pb(II) from aqueous solutions for the first time, and the influence of some effective parameters including concentration, initial pH, contact time, and temperature on the sorption process was studied and optimized. Significant adsorption capacities were obtained at low concentrations. The kinetic studies showed that the adsorption process was fast and more than 90% of equilibrium capacity was achieved within 60 min. Experimental kinetic data was well fitted with the pseudo-second-order kinetic model. Thermodynamic parameters computed from the experimental data showed that the adsorption was endothermic and spontaneous.     

Mathematical Modelling for Removal of Mixture of Heavy Metal Ions from Waste-Water Using Micellar Enhanced Ultrafiltration (MEUF) Process

The micellar enhanced ultrafiltration (MEUF) was studied for the removal of heavy metals using a mixture of non-ionic surfactant TWEEN-80 and anionic surfactant sodium dodecyl sulphate (SDS). The gel polarization model and resistance-in-series model were used to estimate the mass transfer coefficient (3 x 10-6 m/s) and the permeate flux. The total metal ion concentration was varied from 1 mM-4 mM and the corresponding effect of the trans-membrane pressure and limiting fluxes were studied. The modified resistance-in-series model was applied to these experimental data to correlate the flux with the feed concentration and applied pressure.     

中和-电絮凝法脱除废水中重金属的研究

对中和法与电絮凝法相结合的工艺脱除废水中的重金属进行了研究。先采用中和法预处理原废水中的氨氮,氨氮含量降至7.8 mg/L,Pb、Fe、Zn完全脱除。再采用电絮凝法脱除残余重金属,考察了反应时间、电流强度、极板间距对重金属脱除效果的影响。结果表明:经中和-电絮凝法处理后的废液达到国家地表水环境质量Ⅲ类标准。     

Removal of Anionic Metal Ions from Wastewater by Hydroxide-type Adsorbents

Generally speaking, anionic metal concentrations in wastewater from industries and mineral processing plants are well above the allowed limits for effluent set by the Ministry of Environment of Japan. Nowadays, the removal of anionic ions has been considered difficult and development of new process is desperately needed. In this paper, we report the development of three hydroxide-type adsorbents, illustrating their adsorption efficiency in removing As, Se, Mo and Sb ions from aqueous solutions. The main finding of this work was that the adsorption behavior was influenced very much by both the pH and the adsorbent concentration. Nevertheless, the newly developed hydroxide-type adsorbents were very effective in reducing the concentration of those anionic ions.     

壳聚糖去除废水中重金属离子的研究

研究了壳聚糖对水中Cu^2＋、Zn^2＋的吸附作用.结果表明：重金属离子的吸附率与溶液的pH值、壳聚糖的用量、反应时间,吸附温度等有关.     

甲醇低压羰基合成中金属离子的去除

分析了甲醇低压羰基合成法生产金属离子的来源情况,介绍了金属离子在反应中的副作用及除去金属离子的过程,此项技术对低压羰基合成中催化剂稳定性和防止催化剂沉淀有重要意义。     

化学改性沸石对重金属离子去除的研究进展

随着工业的不断发展,重金属污染程度日益加深,严重危害人类的健康.近年来,化学改性沸石因具有较大的比表面积和较强的离子交换能力,在重金属离子处理领域被广泛应用.然而,在化学改性过程中,由于使用酸、碱、无机盐、有机试剂等改性剂,在能耗、成本以及可持续发展方面仍存在一定弊端.因此,开展沸石化学改性方法的研究,使其简单化、工业...     

一种处理含重金属离子有机废水的新工艺

采用新型微电解－电物膜法处理含重金属离子有机废水，同时，与单纯的微电解工艺、生物膜工艺进行了对比，Cr^3 离子去除率均提高15％。在实验过程中，废水中的有机物，由生物膜中的复合微生物菌群作为营养源而消耗；重金属离子（Cr^3 ）则通过电沉积去除一部分，同时生物膜吸附另一部分而去除，净化后的废水超过工业回用水标准。     

Removal of Toxic/Heavy Metal Ions Using Ion-Imprinted Aminofunctionalized Silica Gel

Abstract

The investigation reports the preparation and evaluation of Cr(III) and Fe(III)-imprinted amino-functionalized silica gel adsorbents (APTS-Cr(III)-Si and APTS-Fe(III)-Si) for selective solid-phase extraction of Cr(III) and Fe(III), respectively, from aqueous solutions. The adsorbent materials were prepared by a surface imprinting technique using 3-aminopropyltrimethoxysilane as the surface modifying ligand. The effects of solution pH, sorption time, temperature, and initial metal ion concentration upon adsorption characteristics were investigated. The adsorption isotherms for Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) were evaluated and the thermodynamics of the adsorption processes were correlated. By optimizing the parameters, the synthesized materials could be used successfully for selective removal of trivalent cations from a mixture of cations in dilute aqueous solution.     

一种处理含重金属离子电镀废水的新工艺

研究了用微电解-生物膜法复合工艺处理含重金属离子和氰离子的工业电镀废水,并与单一生物膜法处理进行了比较。结果表明,单一生物膜法对废水中的Zn2+、Cr6+和CN-的去除率分别为 50 5%、99 99%和95 8%。以不锈钢材料作阴、阳极,复合工艺相对于单一生物膜工艺对Zn2+、Cr6+和CN-的去除率均有不同程度的提高,最显著的是Zn2+的去除率由 50 5%提高到 72%;复合工艺最佳反应循环量和压缩空气用量分别为15~30mL/min和 0 3m3 /h。     

Simutaneous Removal of Heavy Metal Ions from Wastewater by Foam Separation Techniques

Abstract

The objective of the present work is to extend the application of adsorbing colloid flotation techniques to remove mixtures of metal ions. The systems studied are: 1) Co(II) and Cr(VI); 2) Co(II), Ni(II), and Cr(VI); 3) Cr(VI), Cu(II), and Zn(II); 4) Cr(VI), Cu(II), Zn(II), and Ni(II); 5) Cd(II), Pd(II), and Cu(II). Ferric hydroxide and aluminum hydroxide were used as the coprecipitant, and sodium lauryl sulfate was used as the collector and frother. The ionic strength of the solution was adjusted with NaNO₃ or Na₂SO₄. It was found that all the heavy metals can be removed effectively by a single step foam flotation treatment.