Investigating pyrite tailings-based mineral admixtures with photocatalytic activity
Thanks to a novel mineral admixture, cementitious materials have obvious photocatalysis and greater compressive strength.
The researchers prepared the mineral admixture by acid leaching-hydrolysation and single calcination method, using industrial waste pyrite tailings and high titanium slag as raw materials in which pyrite tailings were substrate and high titanium slag was the source of titanium.
Superior crystallinity of anatase
The results demonstrated that the optimum conditions for preparing admixture were that the mass ratio of acid and slag is 8:1; the temperature of acid leaching is 85 °C; the time of acid leaching is 250 min; the content of distilled water is 40%; the mass ratio of filtrate and tailings is 8:1; the loading temperature is 105 °C; the loading time is 3.5 h; at last, the precursor of admixture is calcined in 800°C for 2h. The admixture prepared in this method showed a superior crystallinity of anatase with the particle size of about 100 nm.
Perfect photocatalytic performance
Comparing with the cement paste without the admixture, the 3, 7 and 28 days compressive strength of the cement paste with 30% admixture were found to be increased by 40.92%, 44.57% and 37.74%, respectively. The photocatalytic degradation rate of methylene blue reached 95.28% after irradiation for 5h, and white cement with the admixture manifested perfect photocatalytic performance under irradiation by 300W high-pressure mercury lamp.
The study is published in: Construction and Building Materials, Volume 138, 1 May 2017, Pages 26–34
