Developing a solar photothermal method for peroxydisulfate activation for water purification: Taking degradation of sulfamethoxazole as an example

Persulfate activation is a promising advanced oxidation processes to remove micropollutants for the water purification. Persulfate could be activated by heat efficiently, but the continuous energy input limited its application. In this study, a novel photothermal method was developed to activate peroxydisulfate (PDS) to degrade sulfamethoxazole, a widely detected antibiotic in aqueous environments, for water purification. Using the carbon black as the photothermal conversion agent, both heating rate and equilibrium temperature of the solution were enhanced under the simulated sunlight, which was beneficial for PDS activation. By using the developed photothermally-activated PDS method, about 95% of sulfamethoxazole in the aqueous solution could be removed within 180 min, which was 3.28 times faster than that using the individual PDS activated by solar irradiation. Quenching experiment and the electron paramagnetic resonance proved that ·OH and SO4·- were the main species for pollutant degradation, and PDS decomposition at high temperature was the main mechanism for the PDS activation by photothermal method. In addition, this photothermally-activated PDS method also showed a great capacity for degrading SMX in the actual water. This work provides a novel and low cost persulfate activation technology for the contaminant removal from the aqueous solution, which shows a great application potential for water purification.