Photocatalyst production from wasted sediment and quality improvement with titanium dioxide to remove cephalexin in the presence of hydrogen peroxide and ultrasonic waves: A cost-effective technique

Abstract

In this study, wasted sediment (sludge waste from shipping docks) was coupled with titanium isopropoxide by the thermal and sol-gel method as a new photocatalyst. The sediment-titanate catalyst alongside ultrasonic and UV was activated hydrogen peroxide to produce OH radicals and decompose cephalexin (CEP). The photocatalyst was crystalline with 52.29 m2/g BET area. The best destruction rate of 87.01% based on COD test was achieved at optimal conditions (pH: 8, cephalexin concentration: 100 mg/L, H2O2: 1.63 mg/L, UV: 15 W/m2, ultrasonication time: 100 min at 40 kHz, photocatalyst quantity: 1.5 g/L). The trend of anions effect was NO3− ≤ SO42− ≤ Cl−. Decomposition of cephalexin in water solution followed the first-order kinetics (k > 0.01 min−1, R2 > 0.9). The percentage of cephalexin removal from urban water (76%) and hospital wastewater (63%) has decreased compared to the distilled water solution (87%), which is probably due to the presence of radical inhibitors. The consumed electrical energy of the studied system was calculated by 0.031 kW/h. The developed system is a promising and economical method to remove cephalexin.