Chalcopyrite ores are usually processed by means of hydrometallurgical or pyrometallurgical processes, but due to environmental aspects and the possibility of increased exploitation of mixed and lower grade ores and relatively small isolated deposits, there has been a worldwide upsurge of interest in the hydrometallurgical processes of this ore as compared to pyrometallurgy. The different concentrates obtained through differential flotation in pyrometallurgy are usually of poor quality with low metal recovery. This further makes pyrometallurgical processing of chalcopyrite very difficult and costly and rendered them difficult to commercialize. As a result, the metal value is preferably extracted directly from low grade ores through hydrometallurgical process. A detailed review of chalcopyrite deposits, production and consumption, mining, ore processing, steps involved in the pyrometallurgical and hydrometallurgical processing of copper as well as the dissolution kinetics and microbial studies of chalcopyrite ore were discussed.

In this study, bamboo impregnated with nanoscale zero-valent iron (nZVI) and nanoscale manganese (nMn) were prepared by the aqueous phase borohydride reduction method and characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and PIXE analysis. The synthesized nMn-bamboo and nZVI-bamboo composites were subsequently applied to the sorption of methylene blue (MB) dye from aqueous solution. The adsorption of MB dye was investigated under various experimental conditions such as pH, contact time, initial concentration of MB dye and adsorbent dosage. The results showed that the synthesized nZVI-bamboo composite was more effective than nMn-bamboo composite in terms of higher MB dye adsorption capacity of 322.5 mg/g compared to 263.5 mg/g of nMn-bamboo composite. At a concentration of 140 mg/L MB dye, 0.02 g of nZVI-bamboo and nMn-bamboo composites resulted in 79.6% and 78.3% removal, respectively, at 165 rpm, contact time of 120 min and at a solution pH of 7.6. The equilibrium data was best represented by Freundlich isotherm model and the pseudo-second order kinetic model better explained the kinetic data for both nZVI-bamboo and nMn-bamboo composites.

This study presents a detailed review on the advanced hydrometallurgical treatment involving the extraction and separation of Cobalt (Co) and Nickel (Ni) by Cyanex® extractants. The structures, properties and applications of various Cyanex® extractants such as Cyanex®272, Cyanex®301, Cyanex®921, Cyanex®923 and Cyanex®421X were discussed and compared. Cyanex®272 thus proved to be the most appropriate solvent extractant for the separation of Co and Nickel from sulphate and chloride media due to its stability to common oxidant, better physicochemical properties and its ability to avoid gypsum crystallization in stripping-electrowinning circuit. Finally, various solvent extraction (SX) techniques for the extraction and separation of Co and Ni using Cyanex® extractants were discussed as well as newer processes of extraction and separation. Key words: Hydrometallurgy, Cobalt, Nickel, solvent extraction, Cyanex® extractants, Cyanex®272, Cyanex®301, Cyanex®921, Cyanex®923, Cyanex®421X.

In this study, nano iron (nano-Fe) was successfully synthesized by sodium borohydride reduction of ferric chloride solution to enhance the ultrasonic degradation of phenolsulfonphthalein (PSP). The nano-Fe was characterized by scanning electron microscopy - energy dispersive spectroscopy (SEM-EDX), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), attenuated total reflection - Fourier transform infrared spectroscopy (ATR-FTIR), and Brunauer, Emmett and Teller (BET) surface area determination. Experimental results demonstrated that a combined ultrasonic/nano-Fe/H2O2 system was more effective for PSP removal in combination than they were individually and there was a significant difference between the combined and single processes. The ultrasonic/nano-Fe/H2O2 degradation follows the Langmuir-Hinshelwood (L-H) kinetic model. The addition of nano-Fe and H2O2 to the ultrasonic reactor greatly accelerated the degradation of PSP (25 mg/L) from 12.5% up to 96.5%. These findings indicated that ultrasonic degradation in the presence of nano-Fe and H2O2 is a promising and efficient technique for the elimination of emerging micropollutants from aqueous solution.