Enhanced mineralization of reactive brilliant red X-3B by UV driven photocatalytic membrane contact ozonation

The partial oxidation on refractory organics in ozonation process and the poor performance of mass transfer between ozone (O₃) phase and liquid phase by common O₃ distribution techniques inhibit the practical application of O₃. To overcome these defects, hollow fiber membrane was applied in membrane contact ozonation (MCO)-UV process for the reactive brilliant red X-3B (RBRX-3B) degradation. The efficiency of mass transfer was guaranteed due to the enormous gas/liquid contact area supplied in this bubble-less O₃ transfer process. UV photolysis not only significantly improved the O₃ utilization efficiency but also accelerated the mineralization of RBRX-3B by promoting O₃ to decompose to hydroxyl radicals (OH). When 15 mg/L of O₃ was supplied at flow rate of 0.2 L/min, and a liquid velocity of 0.453 m/s, the chemical oxygen demand (COD) removal and total organic carbon (TOC) removal reached 90 % and 77 %, respectively. The rate constant for TOC removal in the MCO-UV process (7.89 × 10^-3 min^-1) was 3.08 and 6.12 times higher than that in MCO and UV photolysis processes, respectively. Furthermore, the mineralization efficiency (ΔCOD/ΔO₃ = 0.84 mg/mg) and electrical energy per mass (E_EM = 4.7 kW h/kg) were calculated and these results indicated a promising future for the MCO-UV process.