Statistical modeling of photocatalytic degradation of synthetic amoxicillin wastewater (SAW) in an immobilized TiO2 photocatalytic reactor using response surface methodology (RSM)

The present research deals with degradation of amoxicillin (AMX) in an immobilized TiO2 photocatalytic reactor under UVA irradiation (365 nm). Enhancement of photocatalysis by sequence aeration and addition of ozone and H2O2 was also evaluated. Relationship between three numerical independent variables (chemical oxygen demand (CODin), reaction time and initial pH) and four process responses (COD removal efficiency, specific COD removal rate (SRR), BOD5/COD ratio, and final pH) for the synthetic amoxicillin wastewater (SAW) photocatalyst oxidation process were analyzed and modeled using response surface methodology (RSM). The region of exploration for the process was taken as the area enclosed by CODin concentration (400-2000 mg/L), initial pH (3-11) and reaction time (20-240 min) boundaries. As a result, initial COD showed different impact at different pH on the COD removal efficiency. The maximum BOD5/COD ratio found 0.43 at initial COD 2000 mg/L and pH of 3. The maximum COD removal efficiency for the photocatalytic reaction alone was 20%, while the value could be improved up to 38% by sequence aeration. The photocatalytic process induced by O3 and O3/H2O2 showed COD removal efficiencies of 53 and 58%, respectively. As a conclusion, the photocatalyst process induced by O3 and O3/H2O2 could be an appropriate pretreatment method prior to a biological treatment process.