Continuous degradation of BTEX in landfill gas by the UV-Fenton reaction

Abstract

The degradation of benzene, toluene, ethyl benzene and xylene (BTEX) in waste gas using the UV-Fenton reaction has been investigated. By employing a bubble column reactor, a suitable inlet gas flow-rate was found to be important in determining both the handling capacity and the interfacial area between the gas-phase and liquid-phase. Both the large gas–liquid interfacial area and the UV-Fenton reaction in the liquid-phase enhanced the gas–liquid mass transfer process, and thus improved the removal efficiency of BTEX in waste gas. Under the optimized initial conditions (i.e., pH = 3, H₂O₂ dosage = 5.6 mmol L⁻¹, Fe²⁺/H₂O₂ molar ratio = 0.091 and purified air as a carrier gas), dynamic treatment of a gaseous mixture of BTEX was performed and the removal efficiencies of benzene, toluene, ethyl benzene and o-xylene were always maintained above 84%, 92%, 96% and 97%, respectively, during a 240 min reaction time. After the degradation reaction, the removal effect of the UV-Fenton system could be effectively restored by adding 10% of the initial amount of hydrogen peroxide. The obtained results showed that the UV-Fenton process was an effective method for BTEX degradation in continuous waste gas treatment. Compared with other common waste gas treatment methods like physical absorption, photo-catalytic oxidation and biofiltration, the proposed UV-Fenton method had distinct advantages such as in its degradation ability, large handling capacity and low operational cost. Thus, it is considered to be a promising method for waste gas treatment of typical air pollution sources including landfills, livestock farms, pharmaceutical factories and so on.