Development of an eco-efficient CaMoO4/electroconductive geopolymer composite for recycling silicomanganese slag and degradation of dye wastewater

A novel and eco-efficient CaMoO4/electroconductive geopolymer composite (CaMoO4/ECC) was synthesized for the first time to realize double goals of high-value recycling of silicomanganese slag (SS) and effective treatment of dye wastewater by photocatalytic degradation. The XRD and XPS results demonstrated that the CaMoO4 active phase was formed by the reaction between silicomanganese slag based geopolymer and (NH4)(6)Mo7O24 center dot 4H(2)O. The BET specific surface areas of CaMoO4/EGC samples increased with increasing content of CaMoO4. The FESEM results indicated that the elements of S, Mn, Mo and Ca evenly distributed in the matrix of 4CaMoO(4)/EGC. The photoluminescence (PL) spectrum showed that 4CaMoO(4)/EGC possessed the lowest PL peak at 469 nm and could have the highest photocatalytic activity. The response surface methodology (RSM) was employed to evaluate the main influence factors on the degradation rate of Basic Violet 5BN (BV5) dye and to predict the optimal condition of photocatalytic degradation. The variance analysis results of F-value (75.33), p-value (<0.0001) and coefficient of determination (R-2 = 0.9999) testified that the regression model was highly efficacious. The RSM optimized results indicated that the degradation rate of BV5 approached to 100% under the conditions of 0.54 g of catalyst, 3.78 wt% of CaMoO4 loading and 5.64 mg/L of dye concentration in accord with the verified experiment results. (C) 2018 Elsevier Ltd. All rights reserved.