Modelling and optimisation of p-nitrophenol removal process using homogeneous photo-periodate (UV/KPI) advanced oxidation process

Abstract

ABSTRACT In this study, removal of P-Nitrophenol (PNP) as a nitro-aromatic contaminant from the aqueous medium have been investigated using the photochemical oxidation process by UV-activated periodate. The experiments were performed in a photochemical reactor with a volume of one litre. The central composite design (CCD) as a response surface method was applied for the experimental design and optimisation of the process parameters by design expert software. The aim of this study was to distinguish the optimum level of independent variables intended for the dependent variable. The selected independent variables were the initial concentration of PNP, initial pH, and the amount of initial concentration of KIO4 that could affect the degradation efficiency (DE) as response (dependent variable). The CCD demonstrated an excellent relationship between the independent and dependent variables. The mathematical equations and response surface plots were utilised to determine the interactions and explain the results. The optimum conditions were found to be at pH = 5.8, [KIO4] = 83.3 ppm, [PNP] = 10 ppm, and after 30 min of the process, 88% degradation efficiency was obtained. To verify the adequacy and prediction power of the model, the predicted optimum conditions were validated by the actual experiments. Furthermore, p-nitrophenol mineralisation was also examined under optimal conditions and displayed the ability of the process to mineralise 35% of p-nitrophenol after 30 min. Also electrical energy consumption of the process was obtained about 102.74 kWh/m3.