The application of chloroquine (CLQ) due to its antibacterial/antiviral
nature and high potential of being persistent and bioaccumulative
poses a significant environmental threat. In this study, the electro-Fenton
(EF) process with pyrite (FeS2)-modified graphite felt
(FeS2/GF) as the cathode (EF-FeS2/GF), capable
of providing a stable acidic environment with a solution pH of 3.0
was constructed and found to (i) achieve 83.3 ± 0.4% 60 min CLQ
removal and (ii) maintain about 60.0% CLQ removal during consecutive
batch tests. FeS2 loading amount, current density applied,
and spacing between electrodes all influenced the efficacy of EF-FeS2/GF, with the optimum CLQ removal obtained at 10 mg, 150 mA,
and 2.0 cm, respectively. Adsorption and electrocatalysis were both
observed to contribute to the CLQ removal while the EF process with
the verified functioning of ·OH played a dominant
role. Based on the detected intermediates with identified ecotoxicities,
two main paths were postulated to describe the degradation processes
which led to the mineralization of CLQ. These findings supported that
the EF-FeS2/GF could be an efficient technology to treat
wastewater contaminated with CLQ.