Treatment of hypersaline industrial wastewater from salicylaldehyde production by heterogeneous catalytic wet peroxide oxidation on commercial activated carbon

• The AC/H2O2 process was applied to tread hypersaline industrial wastewater.
• TOC removal up to 91.27% was achieved under optimal reaction conditions.
• AC exhibited efficient and stable catalytic activity during repeated use.
• Impregnation in the wastewater does not effect on the textural properties of AC.

In this work, a heterogeneous catalytic wet peroxide oxidation process combined activated carbon (AC) and hydrogen peroxide (H2O2) was applied for the removal of organic matter from the salicylaldehyde industry wastewater with high organics content, strong acid and ultrahigh salinity. The effects of different crucial factors such as temperature, initial pH, H2O2 concentration and AC dose on the removal efficiency were investigated. It was found that the degradation of organic matter was inhibited by the high salinity at room temperature. Excess AC was unfavorable to the removal of organic matter. The TOC removal efficiency was significantly dependent on the pH, which could be explained in terms of the electrostatic forces among AC, H2O2, and organics in the solution. The optimal operating conditions established through the experiments were as follows: reaction temperature 60 °C, initial pH of 3, H2O2 concentration of 21.7 g/L, AC dose of 15 g/L and reaction time of 1 h. Under such operation conditions, the removal efficiency of TOC, COD, phenol and formaldehyde were 91.21%, 88.52%, 99.54% and 97.18%, respectively. Furthermore, the catalytic stability of AC was evaluated through the continuous reuse experiments, and the structure and chemical features of AC were analyzed by using ASPS 2020 and SEM/EDS before and after using.