槽边循环电解法回收电镀废水中Ni的研究

对槽边循环电解法回收电镀废水中Ni进行了分阶段实验研究,包括小型试验、扩大试验以及系统扩大试验。试验结果表明,适合工业生产中使用的操作条件如下:Ni离子浓度可在0.5～2.5g/L变化,电流密度40～80 A/m2,槽电压3～6 V,pH=4.5～5.5;当Ni离子浓度保持在1.0～2.5g/L,若连续操作电流密度采用100～150 A/m2,则电流效率仍大于40%;若从高浓度操作到低浓度,每次回收到0.5 g/L,电流密度应取40～80 A/m2,操作10次后,可回收到使浓度小于0.1 g/L,弃掉,则回收槽的回收率大于99%;由3类不同规模试验的对比中可以看出,在相同条件下,电流效率几乎相等。研究表明,采用槽边循环电解法回收电镀废水中的Ni是完全可行的,且可保证较高回收效率。     

Recovery of H2SO4 from waste acid solution by a diffusion dialysis method

A diffusion dialysis method using anion exchange membrane was used to recover H2SO4 from waste sulfuric acid solution produced at the diamond manufacturing process. Effects of flow rate, operation temperature, and metal ion concentration on the recovery of H2SO4 were investigated. The recovery of H2SO4 increased with the concentration of H2SO4 and operation temperature. It also increased with the flow rate ratio of water/H2SO4 solution up to 1, above which no further increase was observed. The flow rate did not affect the rejection of Fe and Ni ions. About 80% of H2SO4 could be recovered from waste sulfuric acid which contained 4.5M free-H2SO4 at the flow rate of 0.26x10(-3) m3/hm3. The concentration of recovered H2SO4 was 4.3M and the total impurity was 2000 ppm. Preliminary economic evaluation has revealed that the dialysis system is highly attractive one that has payback period of only few months.     

Recovery of sulfuric acid from waste aluminum surface processing solution by diffusion dialysis

Diffusion dialysis with anionic ion exchange membranes was employed to recover sulfuric acid from the waste acid solution of aluminum surface processing plant. Experiments were conducted to examine the dialyzer performances under various operating conditions, including feed flow rates, sulfuric acid concentration in the feed solution, temperature and number of pieces of ion exchange membrane. Diffusion dialysis was found very efficient for this purpose. Based on the test results, optimum operating conditions of these variables were identified. Preliminary economic evaluation of the process indicated that diffusion dialysis is highly viable for sulfuric acid recovery due to its short payback period.     

2×300MW汽轮机双机循环水余热供热系统

针对现有余热供热技术仅能回收典型双机配置热电厂一台机组余热的问题,定量分析了湿冷机组余热量和现有各余热供热技术回收循环水余热能力,提出吸收式热泵与低压缸光轴技术串联的余热供热系统以及低压缸光轴改造后给水泵汽轮机余热利用系统。实现了典型配置热电厂双机余热全部回收供热,为湿冷机组双机余热供热改造和设计提供参考。     

纳滤膜处理酸洗废液新工艺

用纳膜法处理钢厂酸洗废液,对影响纳滤过程的因素,如操作压力,操作时间和废酸液流量进行分析。此方法既回收硫酸亚铁,母液又返回酸洗工序循环使用,回收了资源,保护了环境。     

极稀醋酸废水处理的双极性膜电渗析法

探索了用双极性膜电渗析法处理含质量分数为 0 .2 %醋酸废水的可行性 .初步实验验证废水中的醋酸可以得到有效清除 ,并且可以回收得到 3 6%以上的浓缩醋酸 .应该进一步解决的问题是设法提高过程的电流效率 ,降低过程的能耗 .     

Simultaneous removal of nickel and cobalt from aqueous stream by cross flow micellar enhanced ultrafiltration

Nickel and cobalt were simultaneously removed from aqueous feed using cross flow micellar enhanced ultrafiltration. Twenty kiloDalton polysulfone membrane was used and the rejection more than 99% was obtained. The effect of operating variables like inlet flow rate, inlet pressure, feed metal ions concentration, surfactant to metal ion (S/M) ratio and pH on the rejection of metal ions was investigated. Gel layer formation and concentration polarization was insignificant under the present experimental condition. Presence of salt in the aqueous feed results in drop in rejection from 99% to 88%. The distribution coefficient of solutes in the micellar phase and aqueous phase was estimated from ultrafiltration data. The loading of micelles was also estimated for both the nickel and cobalt ions which confirmed the reproducibility of the micellar enhanced ultrafiltration (MEUF) experiments.     

液膜法从金矿贫液中除氰及回收氰化钠的小型工业化试验

本文提出了一种用乳化液膜法处理金矿含氰废水的新工艺,建立了规模为日处理量10～20m~3的一套小型工业化试验的液膜装置。研究了传质的影响因素及操作参数对除氰和回收氰化钠的影响。经运转操作证明,用该工艺流程能有效地从锌粉置换后的含氰贫液中将氰化钠浓缩回收并可重复使用,同时,使排放液中的游离氰根离子浓度低于0.5mg/L,达到国家排放标准。整个过程,氰的去除率达99％以上,氰化钠的回收率高于90％。经三个月的运转操作进行了经济估算,证明液膜法较其它方法优越。     

Application of nanofiltration for the rejection of nickel ions from aqueous solutions and estimation of membrane transport parameters

The present work deals with the application of a thin-film composite polyamide nanofiltration membrane for the rejection of nickel ions from aqueous wastewater. The operating variables studied are feed concentration (5-250ppm), applied pressure (4-20atm), feed flowrate (5-15L/min) and pH (2-8). It is observed that the observed rejection of nickel ions increases with increase in feed pressure and decreases with increase in feed concentration at constant feed flowrate. The maximum observed rejection of the metal is found to be 98% and 92% for an initial feed concentration of 5 and 250ppm, respectively. The effect of pH on the rejection of nickel ions and permeate flux are studied, and found that the variation in pH is having more effect on the latter than the former. The experimental data are analyzed using membrane transport models; combined-film theory-solution-diffusion (CFSD), combined-film theory-Spiegler-Kedem (CFSK) and combined-film theory-finely porous (CFFP) models; to estimate membrane transport parameters and mass transfer coefficient, k. Also, enrichment factor, concentration polarization modulus and Peclet number are found from various parameters. From CFFP model the effective membrane thickness and active skin layer thickness are found.     

特殊分离膜在铜箔漂洗水处理中的应用

针对铜箔生产中的漂洗水处理问题,结合实际工程经验,详细介绍了铜箔漂洗水膜法处理工艺.原水经一级RO膜处理后,淡水作为漂洗水回用,浓水进入二级特殊RO分离膜装置,经进一步浓缩后铜离子浓度达8.8 g/L,返回溶铜罐回用,透过的淡水经离子交换后作漂洗水回用,从而实现了铜箔漂洗水的零排放.实际运行结果表明该工艺处理铜箔漂洗水经济可行.     

Ultrasonic recovery of copper and iron through the simultaneous utilization of Printed Circuit Boards (PCB) spent acid etching solution and PCB waste sludge

A method was developed to recover the copper and iron from Printed Circuit Boards (PCB) manufacturing generated spent acid etching solution and waste sludge with ultrasonic energy at laboratory scale. It demonstrated that copper-containing PCB spent etching solution could be utilized as a leaching solution to leach copper from copper contained PCB waste sludge. It also indicated that lime could be used as an alkaline precipitating agent in this method to precipitate iron from the mixture of acidic PCB spent etching solution and waste sludge. This method provided an effective technique for the recovery of copper and iron through simultaneous use of PCB spent acid solution and waste sludge. The leaching rates of copper and iron enhanced with ultrasound energy were reached at 93.76% and 2.07% respectively and effectively separated copper from iron. Followed by applying lime to precipitate copper from the mixture of leachate and rinsing water produced by the copper and iron separation, about 99.99% and 1.29% of soluble copper and calcium were settled as the solids respectively. Furthermore the settled copper could be made as commercial rate copper. The process performance parameters studied were pH, ultrasonic power, and temperature. This method provided a simple and reliable technique to recover copper and iron from waste streams generated by PCB manufacturing, and would significantly reduce the cost of chemicals used in the recovery.     

Extraction and recovery of methylene blue from industrial wastewater using benzoic acid as an extractant

Liquid-liquid extraction (LLE) of methylene blue (MB) from industrial wastewater using benzoic acid (extractant) in xylene has been studied at 27 degrees C. The extraction of the dye increased with increasing extractant concentration. The extraction abilities have been studied on benzoic acid concentration in the range of 0.36-5.8x10(-2) M. The distribution ratio of the dye is reasonably high (D=49.5) even in the presence of inorganic salts. Irrespective of the concentration of dye, extraction under optimal conditions was 90-99% after 15 min of phase separation. The extracted dye in the organic phase can be back extracted into sulphuric acid solution. The resultant recovered organic phase can be reused in succeeding extraction of dye with the yield ranging from 99 to 87% after 15 times reused, depending on the concentration of the initial feed solution. Experimental parameters examined were benzoic acid concentration, effect of diluent, effect of pH, effect of initial dye concentration, effect of equilibration time, various stripping agents, aqueous to organic phase ratio in extraction, organic to aqueous phase ratio in stripping and reusability of solvent.     

连续法合成己二酸二甲酯的膜反应过程研究

以己二酸二甲酯的连续合成为目标反应,考察渗透汽化膜反应过程中的反应温度、进料流量、渗透汽化膜面积、进料中醇酸摩尔比等主要参数对己二酸转化率的影响.实验表明:温度越高,进料流量越小,膜面积越大,进料中醇酸比越高,酯化反应转化率越高;在醇酸比为4,流量0.24 mL/min,膜面积291.6 cm2,反应温度60℃条件下,...     

两相电解电渗技术浓缩回收乙酸的研究

在两相电泳的基础上,针对含乙酸稀溶液的处理提出了两相电解电渗的技术．利用饱和水的正丁醇为有机相,以AM203阴离子交换膜为介质,开展普通电解电渗和两相电解电渗的研究工作,考察了浓度、电流密度等因素对电流效率、浓缩比以及水的电渗量的影响、结果发现较普通的电解电渗技术和两相电解电渗技术在浓缩比、水的电渗量的控制方面具有明显的优势,在本实验范围内,在两相电解电渗过程中基本没有发现水的电渗现象的发生,同样乙酸的回收率也可以达到100％．由此可以说明新的两相电解电渗技术对于环境稀溶液的处理是一种较为理想的方法．     

饱和钢纤维再生混凝土氯离子扩散特性研究

利用废弃骨料制作再生混凝土是建筑固废弃物的再生资源利用途径之一,其在氯盐侵蚀环境条件下的耐久性规律与普通混凝土不同。本文以模拟海洋侵蚀环境,通过改变水灰比及NaCl溶液浓度,分析各因素对钢纤维再生混凝土氯离子扩散行为的影响规律。结果表明:浸泡液浓度越大,进入混凝土内部的氯离子越多,随着深度的增加氯离子含量逐渐减少;较低的水灰比与适量钢纤维的掺入均可以有效降低氯离子扩散系数,提升钢纤维再生混凝土的抗氯盐侵蚀能力;氯离子扩散系数随着NaCl溶液浓度的增加而增大。     

Enhanced biosorption of nickel(II) ions by silica-gel-immobilized waste biomass: biosorption characteristics in batch and dynamic flow mode

Batch and dynamic flow biosorption studies were carried out using the waste biomass entrapped in silica-gel matrix for the removal of nickel(II) ions from synthetic solutions and real wastewater. Batch biosorption conditions were examined with respect to initial pH, S/L ratio, contact time, and initial nickel ion concentration. Zeta potential measurements showed that immobilized biosorbent was negatively charged in the pH range of 3.0-8.0. The immobilized biomass was found to possess relatively high biosorption capacity (98.01 mg g(-1)), and biosorption equilibrium was established in a short time of operation (5 min). The equilibrium data were followed by Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. Scanning electron microscope analysis was used to screen the changes on the surface structure of the waste biomass after immobilization and nickel(II) biosorption. Sorbent-sorbate interactions were confirmed by Fourier transform infrared spectroscopy. The applicability of sorbent system was investigated in a continuous mode, and column studies were performed under different flow rate, column size, and biosorbent dosage. Also, the proposed sorbent system was successfully used to remove the nickel ions from industrial wastewater in dynamic flow treatment mode. The results showed that silica-immobilized waste biomass was a low-cost promising sorbent for sequester of nickel(II) ions from synthetic and real wastewater.     

Residence Time Distribution of Segregating Sand Particles in a Rotary Drum

Leaching, which is described as the extraction of soluble constituents from a solid by means of a solvent, is an important separation technique in the refining of precious metals from their matte. It is, therefore, important to investigate the extraction behavior of metals from the matte, which is the focus of this study. This study reports the influence of concentration of the solvent (ammonia), leaching temperature, leaching time, and pH on the recovery of nickel and copper from the matte. The elemental composition analysis of the matte indicated that it contains 23% copper, 37% nickel and 1.1% ferrous compound. The analysis also showed that the major mineral phases present in the matte were heazlewoodite (Ni₃S₂), chalcocite (Cu₂S), djurleite (Cu1.9S), and nickel alloy. The leaching parameters studied were concentration of ammonia (1.5, 2.0, 2.5, and 3.0 M), leaching time (0–270 min, at 15 min sampling interval), leaching temperatures (50°C, 60°C, and 70°C), and pH (9.3–11.2). The results obtained revealed that the recovery of nickel and copper from the matte was greatly influenced by the concentration of ammonia, leaching time, leaching temperature, and pH. It was established from this study that the highest dissolution of nickel and copper was obtained at 3 M and 2 M ammonia concentration, respectively. The results also revealed that a decrease in the pH of the solution resulted in a decrease in both nickel and copper recovery, with maximum leaching time of 270 min. It was observed that less than 50% of both nickel and copper was leachable due to the presence of metal alloys. The analyses of the results also showed that as the leaching temperature increased from 50°C to 60°C, the amount of nickel and copper that was recovered from the matte significantly increased. However, there was reduction in the amount of nickel and copper recovered from the matte as the temperature was increased from 60°C to 70°C, due to loss of ammonia by evaporation. The shrinking core model was used to explain the behavior of the recovery of these metals at different temperatures, and both metals were found to be favored by diffusion controlled reaction.     

超声波在线监测卷式反渗透膜污染及清洗

应用超声时域反射法和信号拟合及量化模型在线监测卷式反渗透膜元件污染及清洗过程.实验采用三个2.25 MHz高频聚焦探头和商业卷式反渗透膜组件,污染液为1.0 g/L硫酸钙.清洗阶段包括纯水冲洗、浸洗与酸洗三部分.结果表明,超声信号能够穿透组件外壳而进入多层膜结构.观察发现随膜表面污染物沉积而超声信号发生系列有序变化.此外,随膜表面污染物沉积、结构变化以及污染层形成,声强不断减小至最低,后期趋于稳定.研究还发现,沿进料液流动方向,信号变化诱导期趋于变短,而且,污染物优先靠近出口处沉积;越靠近料液出口,信号变化幅度越大,污染越严重.这是由于沿轴向不断加剧的浓差极化所致.在清洗阶段,随着膜通量恢复超声信号变化表现出一致性.     

集成膜法回收硫酸稀土溶液中硫酸

对减压膜蒸馏浓缩硫酸稀土溶液和与扩散渗析联合回收低浓度的硫酸做了研究．结果表明,水通量随着溶液中稀土及硫酸浓度的增大而减小,随温度升高、减压侧压力降低及料液流速增大而增大;先用减压膜蒸馏法浓缩硫酸稀土溶液,再用扩散渗析法回收硫酸对稀土截留率基本无影响,但大大增高了回收液硫酸的浓度,减少了扩散渗析的处理量,而浓缩倍数越大则效果越明显．     

Polymeric composites based on polystyrene and cement dust wastes

Due to the economical and environmental concern, polymer mortar and polymeric composites were prepared by mixing recycled polystyrene waste and cement dust waste as a filler. Virgin polystyrene and portland cement were used for comparison. Cement dust was treated by the reaction with stearic acid to increase the adhesion between the filler and the polymer matrix. The composites were prepared by mixing different concentration of treated and untreated cement dust (30, 50, 70 and 90 wt.%) with either virgin or recycled polystyrene. The suitability of the prepared polymeric composites as building materials in terms of mechanical properties, water absorption and chemical resistance was studied. After 1 week immersion in water, 10% sodium chloride (NaCl) and 10% sodium sulfate (Na₂SO₄) solutions, it was found that the chemical resistance and the mechanical properties were enhanced and the water absorption was retarded. The recycled polystyrene composites filled with treated cement dust gave the highest abrasion resistance and the lowest weight loss, also the best compressive and bending strength.