Removal of diclofenac by UV-B and UV-C light-emitting diodes (LEDs) driven advanced oxidation processes (AOPs): wavelength dependence, kinetic modelling and energy consumption

In this study, the degradation of diclofenac (DCF), a frequently detected non-steroidal pharmaceutical, was evaluated by using UV-B and UV-C (265, 285, 310 nm) light-emitting diodes (LEDs) alone in combination with hydrogen peroxide (UV/H2O2) free chlorine (UV/FC). The DCF followed pseudo first-order kinetic, their trend reflected pattern molar absorption coefficients oxidants. A positive synergistic factor found for UV-LED driven advanced oxidation processes almost all cases, but despite higher rates, overall electricity demand is similar to UV due oxidants’ energy cost. rigorous kinetic mechanisms at different wavelengths were proposed two processes, UV/H2O2 UV/FC, where predicted values respectively kHO = 9.12 · 109 M-1 s-1 kCl 1.30 1010 s-1. No significant synergy (p>0.05) dual-wavelength system (265 + 285 nm), time-based constants cases changed linearly lamp intensity. Finally, dissolved organic carbon phytotoxicity analysis revealed low mineralisation (around 20-30%) associated formation stable dimers decrease toxicity towards tomato radish seeds. main, work shows great potential implementing wavelength-specific LEDs water treatments effectively designing reactor playing adjustable intensities rates.