Optimization of Toluenediamine degradation in synthetic wastewater by a UV/H2O2 process using full factorial design

Toluene diamine (TDA) is a major carcinogenic aromatic contaminant that is usually utilized as an intermediate in the formation of toluene diisocyanate (TDI) and dyes in several industrial processes. Advanced oxidation processes (AOPs) are one of the very efficacious and reliable solutions for the degradation and mineralization of the extensive ranges of organic refractory contaminants from industrial wastewater. Almost no research work has been conducted to explore the reaction mechanisms of TDA degradation utilizing UV/H2O2 process. Hence, in this novel experimental work, the degradation of TDA in synthetic wastewater with the UV/H2O2 process as an effective AOP was inspected. The Full Factorial Design (FFD) was utilized to study the effect of operating parameters, including initial TDA dosage, pH, and initial H2O2 dosage, on the TDA removal performance. The statistical optimization demonstrated a highly satisfactory determination coefficient (R2 = 0.9445, R2adj = 0.9150, and R2pred = 85.33). The underlying reasons and mechanism of each major parameter on the TDA degradation were comprehensively discussed. The H2O2 decomposition under different pH conditions directly governs the mechanistic aspects of the UV/H2O2 process for the TDA degradation. The optimal situations expected by the experimental design were as follows: the initial TDA dosage at 37.0365 mg/L, pH at 7.04919, and initial H2O2 dosage at 44.1792 mM. At optimum points, the expected and real TDA degradation was 104.661% and 98.5%, respectively. The outcomes of this work obviously substantiated that the UV/H2O2 AOP can successfully degrade TDA in wastewater.