Optimization of ZVAl based oxidation and reduction process conditions: Selection of the most suitable process by multiple-criteria decision-making approach

Abstract

The use of zero valent aluminum (ZVAl) has attracted attention as an effective agent in the oxidation and reduction of pollutants due to its electron donor nature. In this study, the removal of the target pollutant Sunfix red S3B (SR-S3B) azo dye with ZVAl based processes was investigated. For maximum dye removal efficiency, the operating conditions of the processes are optimized with Box Behnken Design. With the optimum conditions of the (PS+ZVAl) oxidation process (PS dose of 12.5 g anion/L, duration of 134 min, pH of 2, ZVAl dose of 3.5 g/L) 94.95% dye removal, and with the optimum conditions of the (H2O2+ZVAl) oxidation process (H2O2 dose of 0.20 M, duration of 180 min, pH of 2, ZVAl dose of 1.44 g/L) 55% dye removal efficiency was obtained. In the (O2 status+ZVAl) reduction process, 77.27% dye removal efficiency was obtained under optimum conditions (anaerobic conditions, duration of 14.8 min, pH of 2, ZVAl dose of 1.43 g/L). With the Pareto analysis of (PS+ZVAl), (O2 status+ZVAl) and (H2O2+ZVAl) processes, the parameters with the highest effect were determined as (ZVAl dose)2 (37.42%), O2 status (29.56%), and (H2O2xpH) (28.38%) respectively. The optimized processes were evaluated by the PROMETHEE method, taking into account the criteria of dye removal efficiency, operating cost and possible residues of oxidizing/reducing agents. The preference ranking of the processes was determined as (O2 status+ZVAl)> (PS+ZVAl)> (H2O2+ZVAl).