Removal of Trace Metal Impurities from Pretreated Phosphoric Acid by Foam Fractionation

Demands for phosphoric acid are growing rapidly in various industries. This has highlighted the importance of optimizing its production and purification methods. Phosphoric acid can be produced by a wet process. However, due to the presence of many organic and inorganic impurities in the wet product, purification of the resulting product is a major concern in this industry. Removal of trace metal impurities (such as magnesium, cadmium, chromium, zinc, etc.) from produced phosphoric acid in a wet process was investigated by foam fractionation in a semi-batch setup using sodium dodecyl sulfate (SDS) as the surfactant. Effects of inlet air velocity, surfactant concentration, and surfactant selectivity were investigated. The optimum air velocity and surfactant concentration were obtained as 0.020 cm/min and 0.7 g/L, respectively. At the optimum condition, the total removal efficiency and enrichment factor reached were 70.2% and 4.39, respectively, while the acid loss was 8.3%. The total metal removal efficiency was increased to 95.3% in a two-stage experimental run.     

“长株潭”地区湘江底泥重金属含量调查研究

通过调查分析湘江＂长株潭＂段表层底泥的锌、铜、镉、铬、铅、汞、锰等重金属含量,将底泥样品中重金属的含量分别与土壤环境质量标准、污水排入城市下水道水质标准、以及生活饮用水卫生标准中重金属含量进行比较,从而发现重金属在湘江＂长株潭＂段的污染严重程度。根据调查结果分析,对湘江＂长株潭＂段底泥重金属污染问题提出减排含重金属废水,有关部门应关注底泥重金属含量变化,和修复河床表层重金属含量高的底泥等建议。     

污泥中重金属去除的技术

介绍了污泥中重金属存在的形态,综述了污泥中重金属去除的常用的四种技术化学浸出、生物浸出、电分离和超临界流体萃取,重点介绍了化学浸取技术的原理和特点,并对诸项技术的优点以及存在的问题进行了评述。     

生物淋滤去除污泥中重金属铬的试验研究

比较研究了皮革废水处理厂的剩余污泥在生物淋滤除铬过程中,由于添加辅助基质的种类、浓度及反应温度不同,重金属铬溶出效果的差异。结果表明:与对照相比,添加单质硫或硫酸亚铁作辅助基质可明显提高重金属铬的溶出效果;添加七水硫酸亚铁比添加单质硫的效果更好;其它反应条件相同,中温(35℃)条件下重金属铬的溶出效果比常温(25℃)和高温(45℃)都要好。控制反应温度可明显提高铬的溶出效果。     

Removal of Organic Impurities from Polymer Pellets

An investigation into the behavior of removing low molecular organics from polymer pellets in a countercurrent extraction column is presented. A mathematical model is developed, describing it in terms of intraparticle diffusion, adsorption, interphase equilibrium, convection and dispersion. The corresponding parameters are determined using nonlinear regression. The resulting partial differential equations are solved using a numerical method. The validity of the model is verified by means of experimental data.     

微电解法去除聚合氯化铝中金属铅的研究

以铝炭床微电解法去除聚合氯化铝中的铅。研究了电场、流速和铝炭的配比对聚合氯化铝中重金属铅的去除效果的影响,其结果：（1）当铝炭比为1：10的情况下,对于铅的去除有着更为理想的效果。而且在前10min的时间内铅的浓度有很明显的下降;（2）当流速越慢时,表明处理液在反应器中停留的时间越长,反应的也就越充分,较优的流速为5mL／min。且在10min内效果很明显;（3）弱电场会对处理效果有促进作用。     

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.     

河道底泥重金属的修复技术

河道底泥是河道水环境的重要组成部分,一旦底泥受到污染,整个河流水环境都会受影响.针对重金属污染的底泥,介绍了底泥重金属的影响因素及危害,并全面综述了目前国内外对底泥重金属的修复技术包括物理、化学和生物修复等,同时也对这些修复技术的原理、动态和优缺点进行了分析,为河道底泥重金属的修复提供科学依据和技术支持.     

汽轮机蒸汽通流部分的盐类沉积物

论述了汽轮机蒸汽通流面积上盐类沉积物的沉积特性、分布规律及减少沉积物的方法,总结了5#汽轮机大修期间的化学检查工作。     

疏浚底泥的资源化利用研究

介绍了疏浚底泥资源化利用的途径,对其土地利用、作建筑材料和填方材料及污水处理材料等资源化利用进行了可行性分析.     

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.     

污染底泥重金属去除技术研究进展

文章介绍了我国河流底泥重金属污染的现状并概括了污染底泥的修复技术及各自的特点。分析了物理修复、化学修复、生物修复及联合修复技术的优缺点。最后指出将这三类技术联合使用,取长补短,可实现经济、有效生态清淤与处置,这也将是河湖底泥修复的发展方向。     

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。     

Selective Removal of Heavy Metal Ions from Aqueous Solutions by Diafiltration of Macromolecular Complexes

Abstract

A process for the selective removal of heavy metal ions with macromolecular chelating agents or emulsified liquid ion exchange materials in combination with ultrafiltration is described. The theoretical limitations of the procedure are discussed, and several practical applications are presented.     

天然水凝胶材料在水体中重金属离子处理的研究进展

水凝胶材料由于其良好的金属离子吸附性能,从而在废水处理和环境保护等领域起到了重要作用。本文综述了天然水凝胶材料的开发及其在水处理(重金属离子去除方面)应用上的研究进展。详细讨论了天然水凝胶类型及其不同结构对重金属离子处理性能的影响。最后,对废水处理的水凝胶材料进行了展望。     

Electron Beam Grafted Polymer Adsorbent for Removal of Heavy Metal Ion from Aqueous Solution

Abstract

An electron beam grafted adsorbent was synthesized by post irradiation grafting of acrylonitrile (AN) on to a non‐woven thermally bonded polypropylene (PP) sheet using 2 MeV electron beam accelerator. The grafted poly(acrylonitrile) chains were chemically modified to convert a nitrile group to an amidoxime (AMO) group, a chelating group responsible for metal ion uptake from an aqueous solution. The effect of various experimental variables viz. dose, dose rate, temperature, and solvent composition on the grafting extent was investigated. PP grafted with the amidoxime group (AMO‐g‐PP) was tested for its suitability as an adsorbent for removal of heavy metal ions such as Co²⁺, Ni²⁺, Mn²⁺, and Cd²⁺ from aqueous solution. Langmuir and Freundlich adsorption models were used to investigate the type of adsorption of these ions. The adsorption capacities of the adsorbent for the metal ions were found to follow the order Cd²⁺>Co²⁺>Ni²⁺>Mn²⁺. The kinetics of adsorption of these ions indicated that the rate of adsorption of Cd²⁺ was faster than that of other ions studied.     

玉米芯改性前后对水中重金属去除的研究

以玉米芯为吸附剂,经氢氧化钠(NaOH)和硫酸(H_2SO_4)改性得到改性吸附剂,研究改性吸附剂对镉、铬、铅吸附性能的影响。实验研究了吸附时间和吸附初始浓度对吸附效果的影响。结果表明,改性玉米芯吸附剂对Cd~(2+)、Cr~(3+)、Pb~(2+)三种重金属离子的吸附能力都增强,且对Pb~(2+)的吸附效果最好,其吸附顺序为Pb~(2+)Cr~(3+)Cd~(2+);在初始质量浓度为400 mg/L时,酸改性的玉米芯对Cd~(2+)、Cr~(3+)、Pb~(2+)吸附容量为15、26、37 mg/g,而碱改性的玉米芯对Cd~(2+)、Cr~(3+)、Pb~(2+)吸附容量分别为17、29、59 mg/g。相对酸改性,碱改性的吸附剂对Cd~(2+)、Cr~(3+)、Pb~(2+)吸附量提高了14.54%、11.22%、57.86%。     

淤渣磷酸除杂工艺研究

以湖北大峪口化工有限公司低品位磷矿生产的淤渣磷酸为原料,通过预净化处理、氨化除杂等步骤,得到的磷酸达到了生产工业级磷酸一铵产品的要求。通过加入分散剂HG,解决了淤渣磷酸过滤困难的问题,提高了生产效率。研究了分散剂用量、氨化终点p H值、氨化速率、氨化温度等对淤渣磷酸除杂工艺的影响,结果表明当分散剂用量为0.5%~1%,氨化终点p H值为4.6~4.8,氨化时间60 min,氨化温度60~80℃时,除杂效果最佳。     

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⁺.