Synergistic adsorption and photocatalytic properties of AC/TiO2/CeO2 composite for phenol and ammonia–nitrogen compound degradations from petroleum refinery wastewater

Abstract

This study focuses on the utilization of AC/TiO2/CeO2 composite on the removals of phenol and ammonia–nitrogen (NH3-N) compounds from petroleum refinery wastewater (PRW) through a combination of adsorption and photocatalytic process. The composite was prepared by hydrothermal method with the composite formulation of 53.43%-wt of AC, 21.96 %-wt of TiO2, and 24.61 %-wt of CeO2. Characterization results revealed that the surface micromorphology, elemental, and oxide contents on synthesized composite significantly changed with the addition of TiO2 and CeO2. Optical UV–vis analysis showed that the estimated bandgap energy of the synthesized composite was 2.60 eV, which is lower than pristine TiO2 or CeO2, indicating that the photocatalysis is easier to perform that reflecting the successful combination of TiO2 and CeO2 as the photocatalyst in the composite. The Langmuir isotherm and pseudo-second order kinetic showed to be the most favorable isotherm and kinetic model for the adsorption process. The photocatalytic activity and kinetic evaluations showed that the photocatalytic process remarkably improved the removal performance and was followed the pseudo-first order kinetic. Moreover, the rate constants of photocatalysis were higher than the adsorption process, indicating that the rate of photocatalysis on the pollutant degradations is faster than the adsorption process. The final pollutant removals by using AC/TiO2/CeO2 composite were 50.91% for phenol removal and 65.83% for NH3-N removal. Three consecutive cycles test showed that the AC/TiO2/CeO2 composite has excellent durability and can nicely maintain the phenol and NH3-N removals from PRW.