Study on dye wastewater treatment of tunable conductivity solid-waste-based composite cementitious material catalyst

Abstract

At present, dye wastewater pollution and solid wastes storage become the main environmental issues in China. Thus, it is of great significance to develop low–cost and efficient technologies to remove dyes from aquatic environment. In this paper, the mixture of magnesium slag and steel slag were used as the raw materials, Na SiO O as alkali activator, silica fume as toughening agent, conductive carbon black as conductive2 medium,3·9H2 a novel conductive alkali-activated-steel-slag-magnesium-slag-based composite cementitious material (CACCM) was successfully prepared and applied to dye wastewater treatment. The results indicated that the compressive strength of the prepared specimens with carbon black was decreased, and the electrically conductive property was improved significantly with growing of carbon black content. When carbon black content reached 4.5 wt%, the stable conductivity was 0.3997 S/m for the curing period of 28 d. PL spectrum revealed that the photoluminescence intensities progressively decreased with increasing of carbon black content. The incorporation of carbon black could improve the photo catalytic degradation rate of the composite cementitious material, and the conductivity was positively correlated with the degradation rate. 4.5CB/CACCM specimen showed the best photo catalytic degradation activity and the degradation rate of malachite green dye could reach 90.58% at 80 min. The photo catalytic degradation reaction belongs to the second-order reaction kinetics.