Removal of cadmium ions from aqueous solution via micellar-enhanced ultrafiltration

To separate cadmium ions from aqueous solution efficiently, micellar-enhanced ultrafiltration(MEUF) of hollow ultrafiltration membrane was used, with sodium dodecyl benzene sulfonate (SDBS) and sodium dodecylsul fate (SDS) as surfactants. The important parameters affecting the rejection of cadmium, the permeate flux and the secondary resistance were investigated, including surfactant species, surfactant concentration, operating time,trans-membrane pressure, the addition of electrolyte and solution pH. The results show that the rejection rate of cadmium reaches 97.8%. Trans-membrane pressure and the addition of electrolyte (NaCI) are less influential while surfactant species, surfaetant concentration and pH value are important for micellar-enbanced ultrafiltration. The optimum concentration of surfactant is the critical micelle concentration, and SDBS is better than SDS. Micellarenhanced ultrafiltration with SDBS can separate cadmium ions from aqueous solution efficiently.     

采用锰矿从水溶液中吸附铅和镉离子(英文)

采用低成本的本地可得的天然锰矿作为吸附剂,研究吸附工艺从水溶液中脱除铅离子和镉离子。利用伪一级、伪二级动力学和颗粒内扩散模型检验动力学吸附数据,计算和比较这些动力学模型的吸附速率常数,发现用伪二级动力学模型能最佳地描述吸附动力学。将 Langmuir 和 Freundlich 等温吸附模型用来拟合不同温度下的平衡数据,发现实验数据与 Langmuir 模型拟合得更好。采用 Langmuir 等温吸附模型计算出锰矿吸附铅离子和镉离子的最大容量分别为 98 和 6.8 mg/g。计算了热力学参数,如吸附吉布斯自由能的变化、焓变与熵变。结果表明,锰矿作为吸附剂对铅和镉的吸附反应是自发的吸热反应。因此,锰矿作为一种天然的矿物吸附剂,可以替代现有的吸附剂来脱除水溶液中的铅离子和镉离子。     

Biosorption of cadmium(Ⅱ) from aqueous solutions by industrial fungus Rhizopus cohnii

An important filamentous industrial fungus, Rhizopus cohnii (R. cohnii), was used as an efficient biosorbent for removing cadmium from wastewater. The sorption conditions, such as pH, the dose of biomass and the initial concentration of cadmium were examined. Two kinds of adsorption models were applied to simulate the biosorption data. The uptake of cadmium was higher in weak acid condition than in strong acid condition. Nearly no sorption of cadmium occurred when the pH value was lower than 2.0. Biosorption isothermal data could be well simulated by both Langmuir and Freundlich models. Langmuir simulation of the biosorption showed that the maximum uptake of cadmium was 40.5 mg/g (0.36 mmol/g) in the optimal conditions, which was higher than many other adsorbents, including biosorbents and activated carbon. In addition, the reusability results showed that after five times of sorption and desorption process, the sorption capacity of R. cohnii could still maintain nearly 80%, confirming its practical application in cadmium treatment. Fourier transform infrared spectrum revealed that carboxyl, amino and hydroxyl groups on biosorbent R. cohnii surface were responsible for the biosorption of cadmium.     

Selective separation of copper and cadmium from zinc solutions by low current density electrolysis

Copper and cadmium ions were selectively separated from zinc sulphate aqueous solution or zinc ammonia/ammonium sulphate aqueous solution by low current density electrolysis.It was shown that the concentration of cadmium ion in zinc sulphate solution decreased from 4.56 g/L to 0.18 g/L in an electrolysis time of 8.5 h,whilst it decreased from 5.16 g/L to lower than 0.005 g/L in zinc ammonia/ammonium sulphate aqueous solution.On the other hand,the deposition rate of copper was so low that it was difficult to...     

Removing cadmium from electroplating wastewater by waste saccharomyces cerevisiae

The appropriate condition and scheme of removing cadmium from electroplating wastewater were investigated by adsorption-precipitation method using waste saccharomyces cerevisiae（WSC） as sorbent. Effect factors on biosorption of cadmium in cadmium-containing electroplating wastewater by waste saccharomyces cerevisiae and precipitation process of waste saccharomyces cerevisiae after adsorbing cadmium were studied. The results show that removal rate of cadmium is over 88% after 30 min adsorbing under the condition of cadmium concentration 26 mg/L, the dosage of waste saccharomyces cerevisiae 16.25 g/L, temperature 18℃, pH 6.0 and precipitation time 4 h. Biosorption-precipitation method is effective to remove cadmium in cadmium-containing electroplating wastewater by waste saccharomyces cerevisiae. The SEM, infrared spectroscopy and Zeta-potential of the cells show that chemical chelating is the main adsorption form; electrostatic attraction, hydrogen bonding and van der Waals force all function in adsorption process; and -NH2-,-C=O-,-C=O-NH-,-CH3, -OH are the main adsorption groups.     

壳聚糖固定化枯草芽孢杆菌水溶液中铜离子的吸附(英文)

研究了壳聚糖固定化枯草芽孢杆菌吸附铜离子的性能,分析了pH、吸附剂投加量、温度、铜离子初始浓度和时间对铜离子吸附的影响。结果表明,pH对铜离子的吸附有较大的影响。此外,固定化枯草芽孢杆菌吸附剂比空白吸附剂具有更强的吸附性能。整个吸附过程符合朗缪尔吸附模型(R2=0.994),最大吸附量为100.70mg/L。动力学模型拟合结果表明,实验符合准二级动力学模型,线性相关指数大于0.999。吸附剂能在0.1mol/LNaOH溶液中被成功解吸。     

采用水泥制粒的赤泥脱除水溶液中的镉离子(英文)

采用湿赤泥添加水泥作为粘结剂的方法制备出一种新型粒状吸附剂材料,并评价这种粒状赤泥材料脱除水溶液中镉离子的潜力。直接向湿赤泥中添加 2%-8%的水泥,研究不同水泥添加量和保养时间对粒状赤泥基吸附剂材料的粉化率和比表面积的影响。结果表明,在 2%的水泥添加量下保养 6d 后的粒状赤泥的结构特性和强度等参数达到了较好的水平。在pH为6.5,温度分别为 30、40 和 50℃及不同 Cd2+浓度溶液的条件下,进行吸附实验研究。结果表明,随着温度的升高吸附性能提高,并以此采用伪二级动力学模型进行吸附动力学模拟,得到了相关的模型参数。     

Removal of cobalt from zinc sulphate solution using rude antimony trioxide as additive

1　ＩＮＴＲＯＤＵＣＴＩＯＮＲｏａｓｔ ｌｅａｃｈ ｐｕｒｉｆｉｃａｔｉｏｎ ｅｌｅｃｔｒｏｗｉｎｎｉｎｇｐｒｏｃｅｓｓｉｓｔｈｅｍｏｓｔｃｏｍｍｏｎｍｅｔｈｏｄｆｏｒｚｉｎｃｐｒｏｄｕｃｔｉｏｎｉｎｔｈｅｗｏｒｌｄ[1 ] .Ｔｈｅｒｅｍｏｖａｌｏｆｃｏｂａｌｔｆｒｏｍｚｉｎｃｓｕｌｐｈａｔｅｓｏｌｕ ｔｉｏｎｂｙｃｅｍｅｎｔａｔｉｏｎｈａｓｂｅｅｎｔｈｅｆｏｃｕｓｏｆｒｅｓｅａｒｃｈｆｏｒｍｏｒｅｔｈａｎ 2 0ｙｅａｒｓｉｎｔｈｅｈｙｄｒｏｍｅｔａｌｌｕｒｇｙｏｆｚｉｎｃ[1 ,2 ] .Ｔｈｅｐｒｅｓｅｎｃｅｏ…     

Thermodynamics and kinetics of fluoride removal from simulated zinc sulfate solution by La(III)-modified zeolite

To understand the mechanism of fluoride removal from the simulated zinc sulfate solution by the La(III)-modified zeolite, the adsorbent was characterized by XRD, SEM and EDS. The effects of absorbent dose and contact time, the adsorption isotherms and the sorption kinetics were investigated. The experimental results were compatible with the Langmuir isotherm model. The theoretical maximum adsorption capacities are 20.83 and 23.04 mg/g at 303 and 313 K, respectively. And the physisorption is revealed using the Temkin isotherm model and the D–R isotherm model. The sorption process is more suitable by the pseudo-second-order kinetic models. Thermodynamic parameters such as standard free energy change (ΔG^Θ<0 kJ/mol), standard enthalpy change (ΔH^Θ=8.28 kJ/mol) and standard entropy change (ΔS^Θ=0.030 kJ/(mol·K)) indicate the spontaneity of adsorption and endothermic physical sorption. Furthermore, the fluoride concentration in the industrial zinc sulfate solution decreases from 98.05 to 44.09 mg/L with the adsorbent dosage of 15 g/L.     

Adsorption and removal of cadmium （ Ⅱ ） from aqueous solutions by bio-formulation

A novel sorbent, bio-formulation（BF）, was prepared and employed for the adsorption of cadmium（Cd） ion from aqueous system. The process of adsorption follows the pseudo second-order kinetic equation and the adsorption behavior is fitted with a Freundlich isotherm. The removal rate of Cd is slightly dependent on the initial pH value over a wide range of 4-11. The addition of Zn^2＋ and Cu^2＋ ions hardly affects the Cd adsorption, whereas the coexisting Pb^2＋ ion greatly interferes with the adsorption. The adsorption mechanism is supposed as a cation-exchange process between Cd^2＋ and calcium and Mg^2＋ present on the surface of BF, and somewhat as adsorption in a hydrolyzed form. The adsorbed Cd ions are desorbed effectively by a 0.1 mol/L HCl solution.     

高炉尘泥化学除锌

为了降低经物理分选后的高炉精泥中锌的含量,对高炉精泥进行化学浸出除锌研究,考察浸出剂、浸出时间、温度、液固比和搅拌速度等对浸出的影响,并进行理论分析。结果表明：硫酸对锌的浸出率最高,氯化铁次之,氨水最低;在合适的浸出条件下：液固比8-1,温度20℃,硫酸浓度125 g/L,浸出时间35 min和搅拌速度150 r/min,锌浸出率为73.9%,高炉精泥中的锌含量从1.46%降低到0.38%。对硫酸浸出脱锌的动力学和反应机制的研究表明,浸出过程遵从1-2α/3-（1-α）2/3=kt,浸出反应的活化能为8.89 kJ/mol,属于扩散控制过程。     

锌蒸气高温气相氧化动力学

用热重法测定了锌蒸气在不同温度和气氛下的氧化动力学曲线,用扫描电镜观察分析产物的结晶形貌.结果表明:氧化动力学遵守直线规律时,产物的结晶形貌是无定形、颗粒状和单针状;氧化动力学曲线为抛物线规律时,产物的结晶形貌是四针状和多针状.氧化动力学转变规律的原因是锌蒸气中存在超细锌微粒与气态锌原子的动态平衡.应用动力学理论和上述结果推断了相关条件下的动力学机理函数和动力学常数,研究了锌微粒的氧化过程并求出了锌原子通过氧化膜层的扩散系数.     

Selective extraction of zinc from sulfate leach solution of zinc ore

1　INTRODUCTIONSolventextractionwasregardedasahighlyeffi cienttechniqueofseparationandpurification .Ithasbeenwidelyappliedinmetalextractionandrecoveryduringhydrometallurgicalprocessandenvironmentalprotection[14 ] .Solventextractionhasbeencommer ciallyusedintheextractionofuranium ,rarenoblemetals ,copper ,cobaltandnickel,whichwastypical lypresentedbythetechniqueofleach solventextrac tion electrowinning .Presently ,thecopperproductionfromsolventextractionhasbeenaccountedformorethan 2 0 %oft…     

一株抗镉真菌的分类学鉴定和镉吸附

研究一株高抗镉真菌M1的分类学鉴定和镉吸附影响因素。通过分子生物学方法获得ITS 和β-微管蛋白的基因序列,并进行测序和分析;采用摇瓶振荡培养方法研究影响镉生物吸附能力的因素;采用傅里叶红外光谱对菌丝的镉吸附机理进行初步分析。基因序列相似性比较和系统发育树构建均表明该真菌与淡紫拟青霉的关系最近,表明真菌M1在分类学上属于淡紫拟青霉菌。活的和失活菌丝体分别在起始pH值为6~7和5~7的范围内表现出较好的吸附能力,镉溶液浓度为100 mg/L 时吸附效率最好。锌和锰对菌体的镉吸附有些许影响,而铜和铅对它的镉吸附影响明显。红外光谱分析表明：菌体吸附镉主要与羰基、羟基和氨基等基团有关。实验结果表明：真菌M1在重金属的生物修复中具有较好的应用前景。     

Removal of cadmium from cadmium-contaminated red soils using electrokinetic soil processing

1 INTRODUCTIONElectrokinetic soil processing(ESP) is one ofthe newly developed techniques for the remediationof soils . It use low-level direct current of cross-sectional area betweenthe electrodes placedin soilsto be treated[1]. Three transport phenomena ,elec-trophoresis , electroosmosis and electromigration,will occur in soils when an electric field is appliedto a soil system[2]. Contaminants in fine-grainedsoils can be transported toward the anode or cath-ode by means of the electrom…     

Corrosion inhibition of 304 stainless steel by Paecilomyces variotii and Aspergillus niger in aqueous environment

The presence of microorganisms influences corrosion of metallic materials by either an accelerating or an inhibiting effect. While most studies have focused on corrosion influenced by bacteria, especially sulphate-reducing bacteria, fungus (or mould) is another form of microorganisms which can significantly affect corrosion processes. This study investigated the effects of two common fungi, Paecilomyces variotii and Aspergillus niger, on corrosion of 304 stainless steel immersed in aqueous environment for up to 28 days. Biofilm formation was observed by SEM. Instead of accelerating corrosion, electrochemical studies such as potentiodynamic polarisation and electrochemical impedance spectroscopy have shown inhibitive effects of these fungi to corrosion of 304 stainless steel.     

Effects of additives on zinc electrodeposition from alkaline zincate solution

The effects of additives on the surface and cross-sectional morphologies of zinc deposits on iron substrate from alkaline zincate solution were characterized by scanning electron microscope (SEM). The cathodic reaction mechanisms under various concentrations of additives were investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. It is found that with increasing the additive A content in the bath solution, the nucleation overpotential (NOP) value is obviously increased and the inhibition effect is strengthened. This may be mainly due to the adsorption of additive A on the cathodic electrode surface, which can cover the active sites and block the discharge reduction. The results of EIS analysis indicate that the rate-determining step of zinc electrodeposition process is changed from mixed control step into electrochemical reduction step in the presence of additive A. However, any quantity of additive B has little effect on the NOP value and the inhibition effect is not obvious. Furthermore, addition of additive A and additive B at the same time displays the strongest inhibition effect and shows a strong synergism because of their co-adsorption on the cathodic electrode surface.     

Tolerance and removal of chromium（Ⅵ） by Bacillus sp. strain YB-1 isolated from electroplating sludge

Four chromium（Ⅵ）-resistant bacteria named YB-1, YB-2, YB-3 and YB-4 were isolated from Cr-electroplating sludge. YB-1 and YB-2 were identified as a member of Bacillus sp. based on morphology and Biolog Microstation System. The strain of YB-1 was selected to test for its resistance and ability to remove Cr（Ⅵ） from aqueous solution. The results indicate that YB-1 exhibits high MIC value which can almost reach 140 mg/L and the growth of YB-1 in liquid medium containing 60 mg/L Cr（Ⅵ） is affected especially in the late exponential phase and stationary phase. Furthermore, the potential of living and freeze-dried YB-1 biomass to remove Cr（Ⅵ） was studied in different pH, biosorbent dose, contact time and initial concentration using the batch method. At the optimal conditions, living and freeze-dried biomass are capable of absorbing 34.5 mg/g and 17.8 mg/g chromium（Ⅵ） at initial concentration of 60 mg/L, respectively. The adsorption data were fitted to Langmuir isotherm model for these two sorbents. Kinetic studies show that the rates of sorption all follow the pseudo-second order kinetics.     

络合-超滤技术处理含镉废水

用丙烯酸-马来酸共聚物(PMA-100)作络合剂采用络合-超滤技术处理模拟含镉(Cd2+)废水,研究聚合物/金属离子质量比(P/M)、溶液pH、盐浓度、操作压力(TMP)和运行时间等对镉离子截留率和膜通量的影响。结果表明:在一定P/M下,pH在3~7范围内,适当提高溶液pH值有利于镉离子的截留;在一定pH条件下,镉离子截留率R随P/M的增加而增加;当pH=5.8、P/M=6时,镉离子的截留率可达99%以上;溶液pH值在3~7范围内时,NaCl和Na2SO4的存在使镉离子的截留率有所降低。当溶液pH<5.8时,酒石酸钾钠的存在使Cd2+的截留率有所下降。