Statistical Evaluation and Optimization of Factors Affecting the Leaching Performance of Copper Flotation Waste

Copper flotation waste is an industrial by-product material produced from the process of manufacturing copper. The main concern with respect to landfilling of copper flotation waste is the release of elements (e.g., salts and heavy metals) when in contact with water, that is, leaching. Copper flotation waste generally contains a significant amount of Cu together with trace elements of other toxic metals, such as Zn, Co, and Pb. The release of heavy metals into the environment has resulted in a number of environmental problems. The aim of this study is to investigate the leaching characteristics of copper flotation waste by use of the Box-Behnken experimental design approach. In order to obtain the optimized condition of leachability, a second-order model was examined. The best leaching conditions achieved were as follows: pH = 9, stirring time = 5 min, and temperature = 41.5°C

Adsorption of neutral red dye from an aqueous solution onto natural sepiolite using full factorial design

The main objective of factorial design is to construct an empirical model to understand complex phenomena such as a purification process up to a given level of accuracy. The present study aimed to investigate the adsorption of Neutral Red dye (NR) from an aqueous solution onto sepiolite using 2 full factorial design. The combined effect of initial dye concentration, adsorbent dosage, pH, and particle size on adsorption of the dye was studied. The results were analyzed statistically using the student's t-test, analysis of variance (ANOVA), and an F-test to define important experimental factors and their relative levels of importance. A regression model which may be used to estimate the removal efficiency of NR without performing any experiments was suggested. The coefficient of determination (R = 0.9938) indicated that adsorbent dosage > particle size > initial concentration. The magnitude of the effects measured in this work can be used as a guide for how to adapt the adsorption process for different process conditions. The results also indicated that natural sepiolite is a suitable adsorbent for NR