Electrolytic Removal of Cadmium, Lead and Copper from Wastewater

The respective compounds of copper, cadmium and lead, owing to their strong toxic potential, as a result of industrial effluent, have left a trail of contamination in humans and the environment. This paper aimed to study the electrode position on the removal of aqueous solutions of cadmium, lead and copper, using an electrolytic cell with a metallic screen cathode of carbon steel and platinum anode. Removal efficiencies were obtained by analysis of the solutions before and after treatment, using the methodology of cathodic-stripping voltammetry with a mercury drop electrode to quantify the concentrations of Cd2+, Pb22+ and Cu2+. Removal efficiencies were obtained of 94.07% for cadmium, 94.71% for lead and 96.19% for copper, demonstrating that electrolytic removal is an effective technique for the removal of these metals from simulated industrial wastewater.

Electrolytic Sampling from Pure Copper and Common Brasses Ⅰ: Calculation of the Mass Dissolved from the Samples according to Faraday's Law

In a procedure for electrolytic dissolving pure copper and common brasses, the approximate electrochemical mole mass(k) of the sample was determined in accordance with the brand of the sample, a stitable electrolyte was selected to make the current efficiency equal to 100%, and then the dissolved mass of samples was calculated according to Faraday's law(m=klt).Three representative samples were sampled by the electrolytic dissolution method and the calculated dissolved amounts were equal to the values by weighing the anode.The cxperimental results of zinc and copper in the anode liquor are in agreement with certified values.

ELECTROLYTIC REMOVAL OF COPPER FROM GUANYL-O-ALKYL-ISOUREA COPPER COMPLEX

A facile method for removing copper from guanyl-0-alkylisourea copper complex was found by using electrolysis.The complex was electrolyzed at a copper cathode in dilute hydrochloric or nitric acid to give guanyl-O- alkylisourea salt in high yield and current efficiency.

ON-LINE ELECTROLYTIC DISSOLUTION OF SOLID METAL SAMPLE AND DETERMINATION OF COPPER IN ALLOY BY AAS

On-line dissolution of solid metal sample can be carried out by electrolysis under the control of flow injection analyzer(FIA),and the dissolved sample can be transferred to atomic spectrometer for the direct analysis.The hyphenated technique of FIA on-line electrolytic dissolution of alloy and atomic absorption spectrometer(AAS)detection is developed.The research is focused on the effects of electrolyte composition and electrolysis parameters on the sample dissolving,as well as the quantitative analysis of Cu in Al alloy samples.

Separation and recovery of Cu and As during purification of copper electrolyte

Cu, As, Sb and Bi in copper electrolyte could be efficiently removed by reducing with SO2 followed by evaporative crystallization. As2O3 and CuSO4·5H2O were obtained after crystallized product was treated by dissolution, oxidation, neutralization, sedimentation, filtration and evaporative crystallization. The removal rates of Cu, As, Sb and Bi are 87.1%, 83.9%, 21.0% and 84.7%, respectively, when As （Ⅴ） in copper electrolyte is fully reduced to As （Ⅲ） by SO2, and the H2SO4 in concentrated copper electrolyte is 645 g/L. The removal rate of As is 92.81% when 65 g crystallized product is dissolved in 200 mL water at 30 ℃. The CuSO4·5H2O content is 98.8% when the filtrate is purified under the conditions that n（Fe）：n（As） is 1.2, the dosage of H2O2 is 19 times the stoichiometric needed, temperature is 45 ℃, time is 40 min, pH is 3.7, and then is evaporation crystallized.

Role of Sb(V) in removal of As, Sb and Bi impurities from copper electrolyte

The function mechanism of Sb（V） in As, Sb and Bi impurities removal from copper electrolyte was investigated by adding Sb（V） ion in a synthetic copper electrolyte containing 45 g/L Cu2＋, 185 g/L H2SO4, 10 g/L As and 0.5 g/L Bi. The electrolyte was filtered, and the precipitate structure, morphology and composition were characterized by chemical analysis, SEM, TEM, EDS, XRD and FTIR. The results show that the precipitate is in the shape of many irregular lumps with size of 50-200 μm, and it mainly consists of As, Sb, Bi and O elements. The main characteristic bands in the FTIR spectra of the precipitate are As-O-As, As-O-Sb, Sb-O-Bi, Sb-O-Sb and Bi-O-Bi. The precipitate is the mixture of microcrystalline of AsSbO4, BiSbO4 and Bi3SbO7 by XRD and electronic diffraction. The removal of As, Sb and Bi impurities by Sb（V） ion can be mainly ascribed to the formation of antimonate in copper electrolytes.

Effects of direct current electric field on corrosion behaviour of copper, Cl- ion migration behaviour and dendrites growth under thin electrolyte layer

Effect of direct current electric field （DCEF） on corrosion behaviour of copper printed circuit board （PCB-Cu）, Cl-ion migration behaviour, dendrites growth under thin electrolyte layer was investigated using potentiodynamic polarization and scanning electron microscopy （SEM） with energy dispersive spectrometer （EDS）. Results indicate that DCEF decreases the corrosion of PCB-Cu;Cl-ions directionally migrate from the negative pole to the positive pole, and enrich on the surface of the positive pole, which causes serious localized corrosion; dendrites grow on the surface of the negative pole, and the rate and scale of dendrite growth become faster and greater with the increase of external voltage and exposure time, respectively.

Separation and recovery of Cu and As from copper electrolyte through electrowinning and SO_2 reduction

Cu and As were separated and recovered from copper electrolyte by multiple stage electrowinning, reduction with SO2and evaporative crystallization. Experimental results showed that when the current density was 200 A/m2, the electrolyte temperature was 55 °C, the electrolyte circulation rate was about 10 mL/min and the final Cu concentration was higher than 25.88 g/L, the pure copper cathode was recovered. By adjusting the current density to 100 A/m2 and the electrolyte temperature to 65 °C, the removal rate of As was 18.25% when the Cu concentration decreased from 24.69 g/L to 0.42 g/L. After As（V） in Cu-depleted electrolyte was fully reduced to As（Ⅲ） by SO2, the resultant solution was subjected to evaporative crystallization, then As2O3 was produced, and the recovery rate of As was 59.76%. The cathodic polarization curves demonstrated that both Cu2＋ concentration and As（V） affect the limiting current of Cu2＋ deposition.

Reduction and deposition of arsenic in copper electrolyte

The influences of temperature, H2SO4 concentration, CuSO4 concentration, reaction time and SO2 flow rate on the reduction of arsenic（V） with SO2 were studied and the deposition behavior of arsenic （III） under the effect of concentration and co-crystallization was investigated in copper electrolyte. The results indicate that reduction rate of arsenic （V） decreases with increasing temperature and H2SO4 concentration, but increases with increasing SO2 flow rate and reaction time, and it can reach 92% under appropriate conditions that reaction temperature is 65 °C, H2SO4 concentration is 203 g/L, CuSO4 concentration is 80 g/L, reaction time is 2 h and SO2 gas flow rate is 200 mL/min. To remove arsenic in the copper electrolyte, arsenic （V） is reduced to trivalence under the appropriate conditions, the copper electrolyte is concentrated till H2SO4 concentration reaches 645 g/L, and then the removal rates of As, Cu, Sb and Bi reach 83.9%, 87.1%, 21.0% and 84.7%. The XRD analysis shows that crystallized product obtained contains As2O3 and CuSO4·5H2O.

Deep removal of copper from nickel electrolyte using manganese sulfide

Copper is difficult to separate from nickel electrolyte due to low concentration of copper (0.53 g/L) with high concentration of nickel (75 g/L). Manganese sulfide (MnS) was used to deeply remove copper from the electrolyte. Experimental results show that the concentration of copper (ρ(Cu)) decreases from 530 to 3 mg/L and the mass ratio of copper to nickel (RCu/Ni) in the residue reaches above 15 when the MnS dosage is 1.4 times the theoretical valueDt,MnS (Dt,MnS=0.74 g) and the pH value of electrolyte is 4?5 with reaction time more than 60 min at temperatures above 60 °C. The concentration of newly generated Mn2+(ρ(Mn)) in the solution is also reduced to 3 mg/L by the oxidation reaction. The values ofρ(Cu),ρ(Mn)andRCu/Ni meet the requirements of copper removal from the electrolyte. It is shown that MnS can be considered a highly effective decoppering reagent.

Role of trivalent antimony in the removal of As, Sb, and Bi impurities from copper electrolytes

The role of trivalent antimony was investigated in removing As, Sb, and Bi impurities from a copper electrolyte. Puri- fication experiments were carried out by adding a various concentrations of Sb（III） ions in a synthetic electrolyte containing 185 g/L sulfuric acid, 45 g/L Cu2＋, 10 g/L As, and 0.5 g/L Bi under stirring at 65℃ for 2 h. The electrolyte was filtered, and the structure, morphology and composition of the precipitate were analyzed by means of chemical analysis, scanning electron mi- croscopy （SEM）, X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and IR spectroscopy. The precipitate is composed of irregular lumps which are agglomerated by fine dendritic and floccus particles, and it mainly consists of As, Sb, Bi, and O elements. Characteristic bands in the IR spectra of the precipitate are As-OX （X=As, Sb, Bi）, Sb-OY （Y=Sb, Bi）, O-As-O1 As-OH, Sb-OH, and O-H. The precipitate is a mixture of microcrystalline SbAsQ, （Sb,As）203, and amorphous phases. As, Sb, and Bi impurities are effectively removed from the copper electrolyte by Sb（III） ions attributing to these pre- cipitates.

Di(2-ethylhexyl) phosphoric acid-coconut oil supported liquid membrane for the separation of copper ions from copper plating wastewater

Permeation of Cu（Ⅱ） from its aqueous solution through a supported liquid membrane （SLM） containing di（2-ethylhexyl）phosphoric acid （D2EHPA） carrier dissolved in coconut oil has been studied. The effects of Cu（Ⅱ）, pH （in feed）, H2SO4 （stripping） and D2EHPA （in membrane） concentrations have been investigated. The stability of the D2EHPA-coconut oil has also been evaluated. High Cu（Ⅱ） concentration in the feed leads to an increase in flux from 4.1 × 10^-9 to 8.9 × 10^-9 mol/（m^2·s） within the Cu（Ⅱ） concentration range 7.8×10^-4-78.6×10^-4 mol/L at pH of 4.0 in the feed and 12.4 × 10^-4 mol/L D2EHPA in the membrane phase. Increase in H2SO4 concentration in strip solution leads to an increase in copper ions flux up to 0.25 mol/L H2SO4, providing a maximum flux of 7.4 × 10^-9 mol/（m^2·s）. The optimum conditions for Cu（Ⅱ） transport are, pH of feed 4.0, 0.25 mol/L H2SO4 in strip phase and 12.4 × 10^-4 mol/L D2EHPA （membrane） in 0.5 μm pore size polytetrafluoroethylene （PTFE） membrane. It has been observed that Cu（Ⅱ） flux across the membrane tends to increase with the concentration of copper ions. Application of the method developed to copper plating bath rinse solutions has been found to be successful in the recovery of Cu（Ⅱ）.

Sb(Ⅴ) removal from copper electrorefining electrolyte: Comparative study by different sorbents

Removal of Sb（V） from copper electrolyte by different sorbents such as activated carbon, bentonite, kaolin, resin, zeolite and white sand was investigated. Adsorption capacity of Sb（V） removal from copper electrolyte was as follows： white sand 〈 anionic resin 〈 zeolite 〈 kaolin 〈 activated carbon 〈 bentonite. Bentonite was characterized using FTIR, XRF, XRD, SEM and BET methods. The results show specific surface area of 95 m2/g and particles size of 175 nm for bentonite. The optimum conditions for the maximum removal of Sb are contact time 10 min, 4 g bentonite and temperature of 40 ° C. The adsorption of Sb（V） on bentonite is followed by pseudo-second-order kinetic （R2=0.996 and k=9×10？5 g/（mg· min））. Thermodynamic results reveal that the adsorption of Sb（V） onto bentonite from copper electrolyte is endothermic and spontaneous process （ΔGΘ=？4806 kJ/（mol· K）. The adsorption data fit both the Freundlich and Langmuir isotherm models. Bentonite has the maximum adsorption capacity of 10000 mg/g for adsorption of Sb（V） in copper electrolyte. The adsorption of Zn, Co, Cu and Bi that present in the copper electrolyte is very low and insignificant.

Synthesis of novel silica-supported chelating resin containing tert-butyl 2-picolyamino-N-acetate and its properties for selective adsorption of copper from simulated nickel electrolyte

A novel silica-supported tert-butyl 2-picolyamino-N-acetate chelating resin (Si-AMPY-1) was successfully synthesized and characterized by elemental analysis, FT-IR, SEM and 13 C CP/MAS NMR. The adsorption behaviors of the Si-AMPY-1 resin for Cu(Ⅱ) and Ni(Ⅱ) were studied with batch and column methods. The batch experiments indicated that the Si-AMPY-1 resin adsorbed Ni(Ⅱ) mainly via physisorption, while adsorbed Cu(II) via chemisorption. The column dynamic breakthrough curves revealed thatthe Si-AMPY-1 resin can efficiently separate Cu(Ⅱ) from the simulated nickel electrolyte before the breakthrough point. Moreover, the concentration of Cu(Ⅱ) in the column effluent was decreased to be less than 3 mg/L within the first 43 BV (bed volumes), and the mass ratio of Cu/Ni was 21:1 in the saturated resin, which completely satisfied the industrial requirements of the nickel electrorefining process. Therefore, it was concluded that the Si-AMPY-1 resin can be a promising candidate for the deep removal of Cu(Ⅱ) from the nickel electrolyte.

Industrial experiment of copper electrolyte purification by copper arsenite

Copper electrolyte was purified by copper arsenite that was prepared with As2O3.And electrolysis experiments of purified electrolyte were carried out at 235 and 305 A/m2,respectively.The results show that the yield of copper arsenite is up to 98.64% when the molar ratio of Cu to As is 1.5 in the preparation of copper arsenite.The removal rates of Sb and Bi reach 74.11% and 65.60% respectively after copper arsenite is added in electrolyte.The concentrations of As,Sb and Bi in electrolyte nearly remain constant during electrolysis of 13 d.The appearances of cathode copper obtained at 235 and 305 A/m2 are slippery and even,and the qualification rate is 100% according to the Chinese standard of high-pure cathode copper(GB/T467-97).

Separation and recovery of Ni from copper electrolyte by crystallization of nickel ammonium sulfate double salt

The separation and recovery of Ni from the copper electrolyte by crystallization of nickel ammonium sulfate double salt were studied.It is found that the solubility of copper sulfate at the same temperature is less than that of nickel sulfate,while the solubility of copper ammonium sulfate is greater than that of nickel ammonium sulfate.So,by adding(NH_(4))_(2)SO_(4),the Ni can be selectively crystallized from the copper electrolyte.By adding(NH_(4))_(2)SO_(4)at the molar ratio of(NH_(4))_(2)SO_(4)/NiSO_(4)≤0.8,and crystallizing at−15℃for 10 h,the Ni in the copper electrolyte can be crystallized in the form of Ni(NH_(4))_(2)(SO_(4))_(2)×6H_(2)O.The qualified product of NiSO_(4)×6H_(2)O can be obtained by pyrolyzing the crystals,dissolving the pyrolysis product in water,and then concentrating the dissolved solution for crystallization.The method of double salt crystallization is a clean,environmentally-friendly,cost-effective and efficient method for separating and recovering nickel from copper electrolyte.

Nanosized copper powders prepared by gel-casting method and their application in lubricating oil

Nanosized copper powders were prepared by a gel-casting method using copper nitrate, acrylamide（AM） and N, N′-methylenebisacrylamide（MBAM） as the main raw materials. The as-prepared copper powders were characterized by X-ray diffractometry and scanning electron microscopy, and then added into a 48# industrial white oil. Dispersion and wear properties of the compounded lubricating oil were tested. The results show that the copper powders prepared are of high purity, fine dispersibility with mean particle size of about 60 nm and with a narrow particle size distribution. The nanosized copper powders can be well dispersed in the lubricating oil. The addition of the copper powders obviously improves the anti-wear properties of the lubricating oil owing to their good self-repairing performance. Compared with 48# industrial white lubricating oil, the friction coefficient of GCr15 steel with the compounded oil containing 0.6% copper powders reduces by 0.07 and nearly no wear chippings are found in the scratches of the friction counter parts.

Fixed-bed column study for deep removal of copper(Ⅱ) from simulated cobalt electrolyte using polystyrene-supported 2-aminomethylpyridine chelating resin

This study presents the deep removal of copper (Ⅱ) from the simulated cobalt electrolyte using fabricated polystyrene-supported 2-aminomethylpyridine chelating resin (PS-AMP) in a fixed-bed.The effects of bed height (7.0–14.0 cm),feed flow rate (4.5–9.0 mL/min),initial copper (Ⅱ) concentration of the feed (250–1000 mg/L),feed temperature (25–40 ℃) and the value of pH (2.0–4.0) on the adsorption process of the PS-AMP resin were investigated.The experimental data showed that the PS-AMP resin can deeply eliminate copper (Ⅱ) from the simulated cobalt electrolyte.The bed height,feed flow rate,initial copper (Ⅱ) concentration of the feed,feed temperature and feed pH value which corresponded to the highest removal of copper (Ⅱ) were 7.0 cm with 35 mm of the column diameter,4.5 mL/min,40℃,1000 mg/L and 4.0,respectively.The breakthrough capacity,the saturated capacity of the column and the mass ratio of Cu/Co (g/g) in the saturated resin were correspondingly 16.51 mg/g dry resin,61.72 mg/g dry resin and 37.67 under the optimal experimental conditions.The copper (Ⅱ) breakthrough curves were fitted by the empirical models of Thomas,Yoon-Nelson and Adam-Bohart,respectively.The Thomas model was found to be the most suitable one for predicting how the concentration of copper (Ⅱ) in the effluent changes with the adsorption time.

Copper Release Kinetics and Ageing of Insulation Paper in Oil-Immersed Transformers

The paper provides a general overview of chemical processes leading to the degradation of oil-paper insulation in oil-immersed electrical current transformers. Previous knowledge available in literature is complemented by new results placing a specific emphasis on the physicochemical factors which affect the copper release in the insulation oil and the oil oxidation kinetics. It is demonstrated that various ageing processes interact with each other, with one or another process dominating under specific conditions. Comprehensive but disjoint studies focusing on separate sub-processes may produce rather misleading results, and occasionally, lie behind rather irrelevant quality demands imposed on the insulating liquids.

Novel technology of purification of copper electrolyte

The effects of arsenic with different valence states on the purification of copper electrolyte were studied and a novel technology of purification of copper electrolyte by copper arsenite was proposed. The results show that the purification performance of As(Ⅲ) compounds is better than that of As(Ⅴ) compounds. The purification technology by copper arsenite has the advantages of simple operation, high purification performance and low cost in comparison with other technologies and its appropriate purification conditions are that copper arsenite concentration is 18 g/L, reaction temperature is 65 ℃ and reaction time is 8 h. The removal rates of Sb and Bi are 53.22% and 58.67% respectively under these conditions. The purification principle show that a kind of yellow precipitate mainly composed of arsenic, antimony (Ⅴ), bismuth and oxygen forms in electrolyte after copper arsenite is added, and consequently antimony and bismuth are removed from electrolyte.