Combined Biological and Photocatalytic Degradation of Dibutyl Phthalate in a Simulated Wastewater Treatment Plant

Abstract

The removal of organic pollutant in wastewater has become a major priority in water treat-ment. In this study, organic pollutant dibutyl phthalate (DBP) has been biologically and photocatalyt-ically degraded in wastewater using modified transition metal dichalcogenides. The as-synthesized nanoparticles were characterized using various characterization techniques, which includes XRD, Raman, FT-IR, SEM, TEM, UV-Vis, XPS, PL, EIS, and photocurrent responses. The nanoparticles synthesized by slightly modified hydrothermal method depicted a hexagonal phase, as evidenced by XRD and Raman analyses. The biological degradation of 69% dibutyl phthalate was achieved. Moreover, the total organic carbon removal efficiency of 70% was further achieved. Incorporating biological and photocatalytic systems significantly improved dibutyl phthalate removal in secondary effluent by three folds when compared to the unilateral operating setup. The optimized parameters such as pH = 7, 5 ppm and DBP concentration with the addition of 10 mg catalysts loading were employed for the photocatalytic degradation of dibutyl phthalate in water. Pristine WS2 exhibited photocatalytic efficiencies of 46% after 60 min illumination. The use of dual system 3% Ce/Gd-WS2 exhibited the highest photodegradation of 85%, with a chemical oxygen demand of 80% and total organic carbon of 77%. The enhanced activity by the composite is attested to the formation of hetero-junction exhibiting excellent charge separation and low rate of recombination. The 3% Ce/Gd-WS2 can be used up to seven times and still achieve a degradation of 56%.