Cartap removal from simulated water matrices by fluidized-bed Fenton process: optimization of process parameters.

Abstract

Cartap is a thiocarbamatepesticide widely-usedto protect rice crops, one of the most mass-produced cereals worldwide. Effluents containing cartap pose serious environment and health risks due to the acute toxicity of this emergingcontaminant. This work evaluates the capabilities of the Fenton process to efficiently removecartapfrom water matrices. Process parameters such as hydrogen peroxide dosage, ferrous ion concentration and operating pH were optimized using Box-Behnken design.Results showed complete cartap removal with Fenton oxidation in a fluidized-bed reactorwhile eliminating sludge generation during treatment. Fluidized-bed Fentonprocess had improvedreduction in chemical oxygen demand and total organic carbon due to the contribution ofheterogeneous Fenton catalysis to the overall degradation of cartap species compared to conventional Fenton in abatch reactor. Furthermore, competitivereactions and scavenging effects in complexnatural water matrices were simulated withthe use of inorganic ions such asnitrate, chloride, and phosphate. Results demonstrated the detrimental effect of phosphateions onFenton oxidation due to the precipitation of soluble catalysts as iron phosphates, which stops the catalytic Fenton cycle and thus the production of oxidantsfor contaminant degradation.