Influence of ZnO Nanoparticles on Mechanical Properties and Photocatalytic Activity of Self-cleaning ZnO-Based Geopolymer Paste

Abstract

The influence of zinc oxide (ZnO) nanoparticles on the mechanical properties and photocatalytic degradation of methylene blue (MB) of ZnO-based geopolymer material was investigated under the illumination of ultraviolet (UV) radiations. In this work, ZnO-based geopolymer paste was manufactured using class F fly ash (FA) and ZnO nanoparticles powders with different mass percentages (0, 2.5, 5.0, 7.5 and 10 wt%). The FA-ZnO dry mix was activated by alkaline activator solution made from sodium silicate and sodium hydroxide with a ratio of 2.5. The mechanical properties were investigated by performing a compressive strength test at 28 days. The photocatalytic activity of ZnO nanoparticles was evaluated by measuring the photodegradation level of methylene blue under sunlight rays. The results showed a substantial influence of ZnO on the compressive strength, which decreased with the increase of ZnO amounts ranging from 2.5 to 7.5 wt% then a slightly increased at 10 wt% of ZnO. The addition of ZnO nanoparticles to a geopolymeric material showed a satisfactory efficiency of photocatalytic degradation of methylene blue after 150 min of exposure to sunlight. Phase analysis revealed that the addition of ZnO nanoparticles in the geopolymeric system develops a new ZnO crystalline phases.