TiO2-carbonized medium-density fiberboard for the photodegradation of methylene blue

TiO2-carbonized medium-density fiberboard (TiO2-cMDF), prepared by carbonization of MDF treated with 50% (v/v) titanium tetraisopropoxide (Ti-tip) in isopropyl alcohol (IPA) as a precursor, was investigated for adsorption and photodegradation in aqueous methylene blue (MB) solution under UV-C (254 nm) irradiation. After full adsorption of MB, four successive cycles of photodegradation were conducted. After the second cycle, the TiO2-cMDF was rinsed with water, dried, and subjected to photodegradation again. For every photodegradation cycle, the TiO2-cMDF practically removed MB. The photodegradation results of the second (unrinsed) and third (rinsed) cycle were similar, however, the result of the fourth (rinsed) cycle was lower than the third cycle. The rate constant of adsorption was 3.3 x 10(-3)/h and followed pseudo-first-order kinetics. The rate constant of photodegradation decreased from 11.0 x 10(-3)/h (first cycle) to 5.9 x 10(-3)/h (fourth cycle) and likewise followed pseudo-first-order kinetics. A reduction in Ti content on the surface of TiO2-cMDF was observed after photodegradation based on scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS) analysis; nonetheless, photodegradation of MB was still accomplished. Although TiO2-cMDF in aqueous system exhibited slow photodegradation, it is due to the limited number of TiO2-cMDF slabs. The number of slabs must be increased to improve the photocatalytic performance.