Alireza Mohadesi; Rasool Roohparvar; Nahid Yaghoobi
Abstract
The use of additives is a standard method in both electrowinning and electrorefining of copper. They have multiple roles in the electrodeposition of copper. They are diffusion barriers and/or complexing agents for copper. In addition, they can perform other important roles as well. Thiourea has been ...
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The use of additives is a standard method in both electrowinning and electrorefining of copper. They have multiple roles in the electrodeposition of copper. They are diffusion barriers and/or complexing agents for copper. In addition, they can perform other important roles as well. Thiourea has been extensively used as an additive in industrial copper electrorefining processes. The effect of thiourea on anode passivation, nodule formation in the cathode, and polarization of copper reduction has been investigated. In this study, we reviewed the most important studies conducted on the mechanism of thiourea effect in the copper electrorefining process, as well as the methods of determination and monitoring thiourea in real samples of copper refinery.
Suprapto Suprapto; Yessy I. Riwayati; Yatim L. Ni’mah
Abstract
In this study, the differential pulse voltammetry (DPV) method was used to simultaneously determine bismuth and copper concentrations. A 25 bismuth and copper mixtures at the designed ratio were measured using the DPV technique. However, the overlapping differential pulse voltammograms obtained made ...
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In this study, the differential pulse voltammetry (DPV) method was used to simultaneously determine bismuth and copper concentrations. A 25 bismuth and copper mixtures at the designed ratio were measured using the DPV technique. However, the overlapping differential pulse voltammograms obtained made it difficult to quantitatively analyze the concentrations based on adaptive peak current selection. To address this issue, the voltammograms were preprocessed using derivatization and peak subtraction. The second derivative voltammogram was found to be highly correlated with the copper-bismuth concentration ratio, resulting in improved fit and prediction accuracy. To further improve the accuracy and precision of the training and prediction results, XGBoost and Gradient Boosting regression models were applied. The XGBoost and Gradient Boosting regression models showed high accuracy and precision with r-squared values of 0.877 and 0.993 for copper, and 0.879 and 0.993 for bismuth, respectively. The mean recoveries of copper were 99.84% and 98.07%, while bismuth recoveries were 93.17% and 90.85% for XGBoost and Gradient Boosting, respectively. Additionally, cross-validation using 10 splits produced a mean score of 45.565 and a mean absolute error of 13.051 for copper, and a mean score of 13.600 and a mean absolute error of 10.920 for bismuth. Overall, the results indicate that the proposed method is an accurate and precise way to simultaneously determine bismuth and copper concentrations.
Khaled Elsherif; Ashraf El Hashani; Ibrahim Haider
Volume 5, Issue 2 , September 2018, , Pages 31-38
Abstract
Biosorption of Cu(II) ions from aqueous solutions onto waste Tea and Coffee powder (WTCP) has been investigated in a batch biosorption process. The biosorption process was found to be dependent on pH of solution, initial metal ion concentration, biosorbent dose, and contact time. The experimental equilibrium ...
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Biosorption of Cu(II) ions from aqueous solutions onto waste Tea and Coffee powder (WTCP) has been investigated in a batch biosorption process. The biosorption process was found to be dependent on pH of solution, initial metal ion concentration, biosorbent dose, and contact time. The experimental equilibrium biosorption data were analyzed by Langmuir, Freundlich, Temkin and Dubinin ̶ Radushkevic isotherms models. The Langmuir model gave a better fit than the other three models by higher correlation coefficient, R2. The maximum biosorption capacities calculated from the Langmuir isotherm model were 526 and 417 mg/g, for coffee and tea, respectively at optimum conditions. The kinetic studies indicated that the biosorption process of the metal ions followed well pseudo-second-order model. According to the biosorption capacity, waste coffee and tea powder considered as an effective, low cost, and environmentally friendly biosorbent for the removal of Cu (II) ions from aqueous solutions.
