Hybrid photoactive materials from municipal sewage sludge for the photocatalytic degradation of methylene blue

To our knowledge this is the first manuscript describing a one step synthesis to produce an organic/inorganic hybrid material prepared by carbonization of municipal sewage sludge (AC(RM)) that shows photoactivity for the photocatalytic degradation of methylene blue (MB). The hybrid material (AC(RM)) exhibited a mesoporous texture while XRD and SEM-EDX showed Fe2O3 and Fe3C crystallites. Photodegradation of MB was studied under two different lamps and results were compared against those obtained with a commercial TiO2. The photocatalytic tests showed that the hybrid material is photoactive and the binary composite TiO2-AC(RM) showed higher apparent first-order rate constants for the degradation of MB than those obtained on pure TiO2. A synergy effect between TiO2 and ACRM was estimated at about 5 and 8 under lamps with UV-vis and almost pure visible light, respectively. It can be concluded that the photoactivity of TiO2-ACRM relative to neat TiO2 was up to one order of magnitude higher, suggesting that iron phases in the hybrid material photo-assist the TiO2 in the photodegradation of the methylene blue.