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

Abstract

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 (EEM = 4.7 kW h/kg) were calculated and these results indicated a promising future for the MCO-UV process.