Effect of Inorganic Salt Mixtures on Phenol Mineralization by Photo-Fenton-Analysis via an Experimental Design

Effluents of resin production, petrochemicals, refineries, paper mills, and iron foundry industries may present high concentrations of phenol. The high toxicity, solubility, and stability of phenolic compounds hamper the treatment of this wastewater by conventional methods. In this work, the effect of inorganic ion mixtures, such as chloride, nitrate, sulfate, carbonate, and monophosphate on the phenol mineralization by the photo-Fenton process, was investigated. The kinetic of phenol mineralization was monitored with the analysis of total organic carbon. Two experimental designs were employed to evaluate the influence of inorganic ions on mineralization efficiency: fractional experimental design and central composite rotatable design (CCRD). The pollutant degradation reached 100 % at 60 min in the absence of salts, but in a saline medium, this value was reduced to 10 %. The sequence of the inhibitory effect was H2PO4 − ≫ Cl> SO4> NO3≈ CO3. The statistical data analysis showed that the phosphate and chloride ion concentrations were studied variables and statistically significant on the mineralization process. The analysis of variance showed: (1) good fit between the observed and prediction values for fractional experiment design and CCRD and (2) according to Fisher distribution, the models that were obtained were considered significant and predictive.