Degradation of Beneficiation Reagent Ester-105 by Light, Heat, and Microwave Activated Persulfate

The degradation of Ester-105 by potassium persulfate activation in three ways (light, heat and microwave) was studied by simulating organic pollutants in wastewater. The removal effects of different factors including concentrations of persulfate and pollutant, pH of the reaction solution, light intensity/heat temperature/microwave power, typical inorganic cations and anions on the three systems were investigated, and the dynamic simulation was also carried out to compare and analyze the influence mechanism of each factor. As the result, under the conditions of 20 mg/L Ester-105 and 1.5 mmol/L potassium persulfate, the optimum reaction conditions were 100 W mercury lamp, 60 ℃, and 260 W of microwave power for light, heat, and microwave system respectively. The strong alkali inhibited the photoactivation and reduced the reaction rate about 30%; both of the strong acid and strong alkali in the thermal activation system promoted the reaction, and their reaction rate constants are almost twice of the unregrulated pH (6.0); pH had little effect on the microwave activation. The addition of Fe²⁺ showed a very strong promoting effect on three reaction systems, especially in the photoactivation that higher than 90% of Ester-105 was removed in 1 min. SiO₃²⁻ was beneficial to the degradation of Ester-105 in the photoactivation system while other ainions almost played an inhibitory role in all systems. The main active free radicals involved in the reaction were SO₄^−● and ^●OH through the free radical trapping experiment. The TOC removal efficiency and the activated rate of persulfate were also in agreement with degradation effect of Ester-105. Varieties of intermediates such as carbonyl sulfide and 3-ethoxyacrylonitrile were detected by GC–MS.