Investigation and optimization of the performance of sono-photo-electro-Fenton process for removal of Acid Black 172 and Disperse Blue 56 from polluted water: comparison of the degradation activity with electro-Fenton-based processes

Abstract

This study investigates the decolorization of two widely used textile dyes (Acid Black 172 (AB172) and Disperse Blue 56 (DB56) by using a combined sono-photo-electro-Fenton (SPEF) process. The effects of dye structure and processing factors on dye degradation from contaminated water and COD removal efficiency were determined by adopting response surface methodology. The results confirmed that current density, irradiation time, pH, ${\raise0.7ex\hbox{${{\text{H}}_{{2}} {\text{O}}_{{2}} }$} \!\mathord{\left/ {\vphantom {{{\text{H}}_{{2}} {\text{O}}_{{2}} } {{\text{C}}_{{0}} }}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{${{\text{C}}_{{0}} }$}}$, and AB172 concentration had the most impacts on COD removal, respectively, whereas DB56 removal efficiency was highly dependent on the initial dye concentration and ${\raise0.7ex\hbox{${{\text{H}}_{{2}} {\text{O}}_{{2}} }$} \!\mathord{\left/ {\vphantom {{{\text{H}}_{{2}} {\text{O}}_{{2}} } {{\text{C}}_{{0}} }}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{${{\text{C}}_{{0}} }$}}$, compared to other processing factors. The dye degradation efficiency of 95.5% and COD removal efficiency of 91.6% for DB56 were obtained at optimum conditions of pH = 3, current density = 2 mA.cm⁻², dye concentration = 200 ppm, ${\raise0.7ex\hbox{${{\text{H}}_{{2}} {\text{O}}_{{2}} }$} \!\mathord{\left/ {\vphantom {{{\text{H}}_{{2}} {\text{O}}_{{2}} } {{\text{C}}_{{0}} }}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{${{\text{C}}_{{0}} }$}}$ of 0.78 and irradiation time of 30 min. In the case of AB172, the same optimum conditions were found unlike reaction time of 50 min and ${\raise0.7ex\hbox{${{\text{H}}_{{2}} {\text{O}}_{{2}} }$} \!\mathord{\left/ {\vphantom {{{\text{H}}_{{2}} {\text{O}}_{{2}} } {{\text{C}}_{{0}} }}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{${{\text{C}}_{{0}} }$}}$ of 0.33, which resulted in the optimal dye degradation efficiency and COD removal of 97.4% 94.5%, respectively. These results verified that the type of dye and its structure can be a key factor in the Fenton-based degradation process. The comparison of the performance of different Fenton-based processes confirmed that the removal efficiency of electro-Fenton, sono-electro-Fenton, photo-electro-Fenton, and SPEF was 82–88%, 89.5–91%, 91.5–92.3% and 95.5–97.4%, respectively. The Fenton-based processes are highly effective methods that can be applied for water and wastewater treatment.

Graphic Abstract