Recyclable methodology over bimetallic zero-valent Mg:Zn composition for hexavalent chromium remediation via batch and flow systems in industrial wastewater: an experimental design

Abstract The bimetallic zero-valent magnesium: zinc composition was used as a suitable reductant agent to remove hexavalent chromium from industrial wastewater. The efficiency of the proposed bimetallic composition in removal process was inspected in both batch and flow systems. Response surface methodology was employed in a batch system to investigate the effects on the removal efficiency of different operational conditions. Central composite design was used for process optimization and evaluation of process effects and interactions parameters including weight percentages and amount of bimetallic composition, pH, contact time, stirring rate, temperature of solution and the primary concentration of hexavalent chromium that the optimum conditions were 25:75% (WMg/WZn), 1 g, pH 3, 10 min, 750 rpm, 40 °C and 50 ppm, respectively. Efficiency of hexavalent chromium pollutant elimination for the batch and flow systems at optimum conditions that optimized for batch system and the used optimized parameters for flow system, was 97.10% and 94.50%, respectively. Moreover, wastewater of barium chromate production line was applied as a real sample containing of hexavalent chromium, while the removal efficiency in batch and flow systems was 91.70% and 91.20% for this real sample, respectively.