Abstract
Abstract The removal of sulphate ions constitutes one of the main challenges in mining, metallurgical and other industries. This work evaluated sulphate removal from aqueous solutions by an electrocoagulation (EC)/raw straw activated carbon (RSAC) adsorption coupled process. The process parameters affecting sulphate removal efficiency were investigated: current density (0–100 mA/cm2), RSAC dosage (0–0.8 g/L), initial pH (4–9) and reaction time (0–40 min). A central composite design coupled with response surface methodology (RSM) was used to construct a mathematic model of EC/RSAC process that considers three key variables, namely current density, RSAC dosage and reaction time. Under optimum conditions (current density of 75 mA/cm2, dosage of 0.46 g/L and reaction time of 19.2 min), the removal efficiency of sulphate reached 95.2%. The RSM predictive value was 94.08% with a small deviation (1.12%). Thus, the fundamental data and results can provide some useful information for further studies and applications of the EC/RSAC coupled system in sulphate-containing wastewater treatment.
Highlights
Mine water is a source of sulphate contamination of natural water and industrial wastewater (Najib et al )
The results showed that the removal efficiency significantly increased with increasing current density
The findings of this study show that sulphate can be efficiently removed from aqueous solutions using EC/raw straw activated carbon (RSAC) technology
Summary
Mine water is a source of sulphate contamination of natural water and industrial wastewater (Najib et al ). Several technologies are available for the removal of SO42À, including chemical precipitation (Iii & Trahan ), biological degradation (Greben et al ; Martins et al ), ion exchange (Guimarães & Leão ), electrochemical method (Gärtner et al ; PazGarcía et al ) and adsorption methods (Namasivayam & Sangeetha ). Some of these methods are limited because sulphate removal is a complex problem due to the high solubility and stability of SO42– in aqueous solutions (Namasivayam & Sangeetha ; Silva et al ; Runtti et al ).
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