Effect of composite photo-catalysts prepared with recycled clay brick sands and nano-TiO2 on methyl orange and NOx removal

Abstract

This research aims to develop a composite photo-catalyst using recycled clay brick sands (RCBS) and nano-TiO2. The RCBS was sourced from construction and demolition wastes (C&DW). For comparison, river sands (RS) were also used. Both RCBS and RS were soaked in 0%, 0.5%, 1.0%, 2.5%, and 5.0% (by weight) nano-TiO2 solutions to produce RCBS based composite and RS based composite photo-catalysts. The amount of nano-TiO2 absorbed by RCBS and RS was then determined. The photocatalytic methyl orange removal and NOx removal activities of the prepared composite photo-catalysts were investigated. The results showed that the amount of nano-TiO2 absorbed by RCBS and RS increased with increasing the concentration of nano-TiO2 solution. However, a non-linear relationship between the photocatalytic activities and the amount of TiO2 absorbed by RCBS and RS was observed. The highest methyl orange and NOx removal were observed on the composite photo-catalysts soaked in 1.0% nano-TiO2 solutions. Interestingly, the optimal RCBS based composite photo-catalysts were even superior to pure nano-TiO2 in terms of both methyl orange removal (60%) and NOx removal (50%) under the same conditions. Overall, the developed composite photo-catalysts not only possess an enhanced photocatalytic activity, but also generate value-added recycling of RCBS in construction materials.