American Chemical Society, Environmental Science and Technology, 17(47), p. 9928-9933, 2013
DOI: 10.1021/es4019892
Full text: Download
NaOH-modified ceramic honeycombs (Na-CH) were simply prepared by impregnating ceramic honeycombs (CH) into NaOH aqueous solution. It was clearly shown that the surface modification incurs higher specific surface area and smaller grain sizes of the CH without destruction of their integrity. Moreover, the introduced surface NaOH can trigger Cannizzaro disproportionation of surface-absorbed formaldehyde (HCHO) on Na-CH, resulting in catalytic transformation of HCHO into nontoxic formate and methoxy salts. NaOH concentration during impregnating treatment has a great influence on HCHO adsorption and removal efficiency, while the impregnation time and temperature have little influence on the efficiency. When the CH was impregnated in 1 M NaOH aqueous solution for 0.5 h at room temperature, the HCHO removal efficiency at ambient temperature can reach about 80% with an initial HCHO concentration of 250 ppm. Moreover, the used Na-CH can be facilely regenerated via 1-min blow using a common electric hair dryer, with the generation of less toxic HCOOH and CH3OH and recovery of NaOH. Using such a mild, fast and practical regeneration method, the regenerated Na-CH showed slight degradation in adsorption and removal capability towards HCHO. The enhanced performance of Na-CH obtained was attributed to the presence of NaOH and increase of specific surface area and surface hydroxyl groups. Considering no demand of noble-metal for HCHO removal at ambient temperature and practical reusable capability of Na-CH under mild conditions, this work may provide some new insights into the design and fabrication of advanced catalysts for indoor air purification.