Optimization of AC/TiO2/CeO2 composite formulation for petroleum refinery wastewater treatment via simultaneous adsorption-photocatalytic process using D-optimal mixture experimental design

Abstract

This study aims to optimize the formulation of activated carbon/titanium oxide/cerium oxide (AC/TiO2/CeO2) composite for petroleum refinery wastewater (PRW) treatment via simultaneous adsorption and photocatalytic process. D-optimal mixture experimental design was applied to predict the optimal formulation of the composite. The experimental data were assessed to generate empirical models for analyzing the effects of components fraction on individual responses. The fitted models were statistically examined (through the standard error of design), considerably validated (via analysis of variance (ANOVA) and model adequacy indicators), and experimentally verified (by estimating errors, root-mean square error (RMSE), and standard error of prediction (SEP) between the predicted and actual values). Finally, the optimized formulation was accepted to have 36.85% total dissolved solid (TDS) removal, 49.23% chemical oxygen demand (COD) removal, treated PRW with pH = 7.22 and electrical conductivity (EC) = 2937.11 µS/cm, 53.76% phenol removal, and 52.86% NH3-N removal, by applying 53.43%-wt of AC, 21.96%-wt of TiO2, and 24.61%-wt of CeO2 with reasonably high desirability score of 0.8874. Based on the characterization results, it can be concluded that the optimized AC/TiO2/CeO2 composite was successfully synthesized. From the diffuse reflectance spectrometry (DRS), the estimated bandgap energy of the synthesized AC/TiO2/CeO2 composite was successfully reduced through the use of CeO2. Our findings show the efficiency, reliability, and feasibility of the D-optimal mixture experimental design from modeling, predicting, and optimizing the formulation of AC/TiO2/CeO2 composite. Overall, our findings prove that the optimized AC/TiO2/CeO2 composite is a prominent and effective material for PRW treatment.