Degradation of tricyclazole from aqueous solution and real wastewater by electron-beam irradiation

Abstract

In this study, electron-beam (EB) irradiation was employed for the degradation of tricyclazole (TC) in an aqueous solution and real pesticide industry wastewater (RPW). Acute toxicity tests revealed that TC exhibits low toxicity against Daphnia magna, with LC50 values of 52.81 mg/L, 32.68 mg/L, 24.35 mg/L and 14.56 mg/L for TC at 24 h, 48 h, 72 h and 96 h, respectively. In contrast, RPW exhibited high toxicity against D. magna, with LC50 values of 0.194%, 0.157%, 0.141% and 0.136% at 24 h, 48 h, 72 h and 96 h, respectively. Results revealed that the high-efficiency removal of TC in an aqueous solution and RPW are achieved by employing EB. Approximately 96.5% of TC in the solution was decomposed under the optimum conditions of an absorbed dose of 3.5 kGy, a pH of 7.0, and an initial TC concentration of 4 mg/L and a H2O2concentration of 4 mM with an operating cost of ∼0.92 $/m3, while 99.2% TC and 82.8% TOC from real wastewater was eliminated at an absorbed dose of 4 kGy, and a H2O2 concentration of 5 mM, with an operating cost of 1.13 $/m3. The degradation of EB apparently followed first-order kinetics, with an R2 of ∼0.998. In real wastewater, the central composite design was employed to optimize the absorbed dose and H2O2 concentration and predict the TC and TOC removal efficiencies. Good regression coefficients (RTC2 = 0.775 and RTOC2= 0.783) of the model revealed fitted correlation between observed and predicted values. In addition, the major degradation pathways of TC were suggested by density functional theory and natural bond orbital calculations.