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

Cartap is a thiocarbamate pesticide widely-used to 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 emerging contaminant. This work evaluates the capabilities of the Fenton process to efficiently remove cartap from 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 reactor while eliminating sludge generation during treatment. Fluidized-bed Fenton process had improved reduction in chemical oxygen demand and total organic carbon due to the contribution of heterogeneous Fenton catalysis to the overall degradation of cartap species compared to conventional Fenton in a batch reactor. Furthermore, competitive reactions and scavenging effects in complex natural water matrices were simulated with the use of inorganic ions such as nitrate, chloride, and phosphate. Results demonstrated the detrimental effect of phosphate ions on Fenton oxidation due to the precipitation of soluble catalysts as iron phosphates, which stops the catalytic Fenton cycle and thus the production of oxidants for contaminant degradation.

Automated summary

Cartap, a widely-used thiocarbamate pesticide for protecting rice crops, poses significant environmental and health risks in effluents due to its acute toxicity. The fluidized-bed Fenton process showed efficient removal of Cartap with improved reduction in chemical oxygen demand and total organic carbon. However, the presence of phosphate ions in natural water matrices can have a detrimental effect on Fenton oxidation, inhibiting the production of oxidants for contaminant degradation.