Reclamation of Hexavalent Chromium from Electroplating Effluents by Electroextraction.

This investigation aims at the reclamation of Cr(VI) from synthetic electroplating industrial effluent by electroextraction process namely electrochemical ion exchange (EIX). An electrochemical ion exchange reactor of desired dimensions was fabricated with the help of ion-permeable membranes, stainless steel cathode and PbO2 coated Ti expanded mesh anode. The performance of the reactor was studied in batch recirculation mode, continuous flow mode at different experimental conditions. The influence of various experimental factors, for instance, initial metal ion concentration (20, 300, 1000 mg/L of Cr(VI)), applied voltages (2.5 V, 5 V, 7.5 V, 10 V) and flow rates of the process stream (2, 4, 6, 8, 10, 12 and 14 ml/min) on removal/reclamation efficiency was deliberated. For comparison purposes, an electrodialysis process was conducted at the same optimal conditions. It was found that the EIX process with three compartments has more removal efficiency at optimum experimental conditions than the electrodialysis process. The continuous flow process of the reactor with 300 mg/L of Cr(VI) as inlet concentration has studied to predict the breakeven point of the reactor. It was noted that Cr(VI) ion concentration in the treated wastewater is almost zero up to the discharge of 20 liters of treated rinse water.

Modeling electrowinning process in an expanded bed electrode.

A theoretical model has been developed to describe the flow behavior of conducting particles in a fluidized bed electrode for electro winning of metal ions present in the dilute solution. Model equations have been developed for potential and current distributions and mass transfer rates. The influence of operating parameters on particle growth has been critically examined. It has been observed from the present investigation that the particle size increased with electrolysis time. The present model simulations have been compared with the experimental data reported in the literature and observed that the model predictions satisfactorily match with the reported experimental findings.

Heavy metal removal from copper smelting effluent using electrochemical cylindrical flow reactor.

The purpose of this study is mainly to evaluate the performance of the continuous recirculation flow cell at low current density and pH (the pH at which the effluents are available) in removing heavy metals from copper smelting effluent by cathodic reduction. During the electrolysis at different pH, % removal of heavy metals removal, energy consumption and heterogeneous reaction rate constants were investigated at given flow rate and current density on the selected industrial effluent. The overall specific energy consumption at the pH 0.64 was observed to be lowest, which is 10.99kWh/kg of heavy metal removal.

Photocatalytic and electrochemical combined treatment of textile wash water.

Various chemical and physical processes for treatment of textile effluent are not destructive but they only transfer the contaminants from one form to another. The presence of high concentration of organic dye and total dissolved solids (TDS) in the effluent that are not removed by biological treatment must be eliminated by an alternative method to the conventional ones is the advanced oxidation process (AOP). A procion blue dye effluent was treated by photo and electrochemical oxidation process as well as by combining photocatalytic degradation using TiO2 suspensions. Chemical oxygen demand (COD) and colour removal can be used to follow the degradation of the organic pollutant. The effects of pH, current density, flow rate of effluent that passes into the reactor and supporting electrolyte were studied. Comparative studies were carried out on photocatalytic and electrochemical process to degrade the procion blue. The maximum COD reduction and colour removal were 96 and 100%, respectively. Photodegradation efficiency of dye was high when photolysis was carried out in the presence of 40 mg/l of TiO2.

Chemical or electrochemical techniques, followed by ion exchange, for recycle of textile dye wastewater.

This paper examines the use of chemical or electrocoagulation treatment process followed by ion-exchange process of the textile dye effluent. The dye effluent was treated using polymeric coagulant (cationic dye-fixing agent) or electrocoagulation (iron and aluminum electrode) process under various conditions such as various current densities and effect of pH. Efficiencies of COD reduction, colour removal and power consumption were studied for each process. The chemical or electrochemical treatment are indented primarily to remove colour and COD of wastewater while ion exchange is used to further improve the removal efficiency of the colour, COD, Fe concentration, conductivity, alkalinity and total dissolved solids (TDS). From the results chemical coagulation, maximum COD reduction of about 81.3% was obtained at 300 mg/l of coagulant whereas in electrocoagulation process, maximum COD removal of about 92.31% (0.25 A/dm2) was achieved with energy consumption of about 19.29 k Wh/kg of COD and 80% (1A/dm(2)) COD removal was obtained with energy consumption of about 130.095 k Wh/kg of COD at iron and aluminum electrodes, respectively. All the experimental results, throughout the present study, have indicated that chemical or electrocoagulation treatment followed by ion-exchange methods were very effective and were capable of elevating quality of the treated wastewater effluent to the reuse standard of the textile industry.