Factors that influence degradation of acetaminophen by Fenton processes

• The effect of organic acids on the degradation of ACT molecules was also studied.
• Acetic acid improved ACT degradation efficiency.
• The inhibition of oxalic acid in the EF process was less than in Fenton process.
• The semi-batch addition of H2O2 would be an effective practice in industry.

The effects of important parameters, Fe2+, H2O2 and initial acetaminophen concentrations, on the initial rate and efficiency of ACT degradation in the electro-Fenton (EF) and photoelectro-Fenton (PEF) processes were investigated. The effect of organic acids on the degradation of ACT molecules was also studied. Experimental results show that the initial rate and removal efficiency of ACT in the EF and PEF processes varied insignificantly with Fe2+ concentration. The initial rate and removal efficiency of ACT in the PEF process were higher than those in the EF process. At a high initial ACT concentration, the initial rate of ACT degradation in the EF process was lower than that in the PEF process. Acetic acid improved ACT degradation efficiency while malonic and oxalic acids reduced it. Oxalic acid exhibited the strongest inhibitory effect, reducing ACT degradation efficiency by 18%. In the presence of oxalic acid in solution, EF yielded a degradation efficiency of 79%, which should be compared to efficiencies of 9% and 3%, for the fluidized-bed and conventional Fenton processes, respectively, showing that the EF process involves beneficial Fe2+ regeneration.