Rapid phenol mineralisation in a low-pressure dead-end light transmitting photocatalytic membrane reactor (LT-PMR)

Photocatalytic membrane reactors (PMRs) are widely studied for wastewater decontamination but reactions are too slow for scaled up application. This PMR study proposes a novel operation involving rapid decontamination in just one pass through the confined space within the membrane. This approach was demonstrated for the first time by light transmitting PMR (LT-PMR) conveniently receiving UV LED light (λpeak = 365 nm) via the permeate side to the photocatalyst P25 TiO2 microfiltration membrane coated on porous glass. A 93 % reduction in model contaminant phenol concentration from a 10 mg/L feed occurred at a flux of 4.7 L/m2/h. The phenol degradation occurred without any residence time from external vessels or recirculation. Phenol was almost entirely mineralised confirmed by total organic carbon (TOC) measurements, with trace by-products identified by high pressure liquid chromatography (HPLC) analysis. Mass transfer and reaction rate constants from Langmuir-Hinshelwood modelling were comparable to literature. Highest reaction rates occurred at lowest permeate phenol concentrations highlighting potential to destroy recalcitrant pollutants persisting through established treatments. LT-PMR is therefore an effective and practical process that very rapidly destroys phenol. Further work to explore improved flux by enhanced light transmission, tailored catalytic materials and demonstration on other pollutants and water matrices is warranted.