Elimination of Gaseous Dichloromethane in a Coated Mesh Photocalytic Reactor

PASSALIA, C.; ALFANO, O. M.; BRANDI, R. J.

San Diego

Congreso; The 20th International Conference on Advanced Oxidation Technologies for Treatment of Water, Air and Soil (AOTs-20).; 2014

Dichloromethane (CH2Cl2) is a simple chlorinated volatile organic compound used as a solvent. It is an airborne pollutant usually found indoors. A possible way of its elimination from the gas phase is by means of TiO2 photocatalysis. In this work we present a study of the oxidation of DCM from air stream in a photocatalytic wall reactor. The reactor is made in acrylic and holds inside a stainless steel mesh (size 20) coated with titanium dioxide (Aeroxide P25). Near UV radiation is provided by two sets of actinic lamps (Sylvania F15W T12) which provide a uniform flux over the reactor windows. In order to avoid mass transfer limitations to the catalyst surface the reaction space is only 5 mm in width and the mesh is located at the midpoint between windows. A continuous air stream feeds the reactor from two inlets with a known concentration of DCM and relative humidity. Concentrations of DCM at the inlet and outlet of the reactor are determined from syringe extracted samples by gas chromatography. DCM is generated online by controlled evaporation of pure liquid DCM (Sintorgan, reagent grade). A set of experimental tests are conducted by variation of the fundamental operating variables: inlet DCM concentration, RH, total flow rate and radiation flux. Conversions of DCM are recorded for each experimental point. Based on many studies of the photocatalytic oxidation of volatile organic compounds over TiO2, a modified Langmuir-Hinshelwood type expression for the reaction rate is proposed. Preliminary essays indicate the feasibility of the photocatalytic destruction of gas phase dichloromethane in a continuous coated mesh reactor. This study is intended to be a starting point towards the intrinsic kinetic of DCM destruction from a kinetic pathway and, ultimately, to a scaling up of the reactor for the treatment of larger air volumes.