Efficient adsorption and performance optimization of coal fly ash/desulphurized manganese residue composite microspheres on dyes

Abstract

Coal fly ash (CFA) and desulphurized manganese residue (DMR), as industrial solid wastes featuring high storage capacity but low utilization rate and high environmental risk, were used to develop composite microsphere adsorbents for dye removal from industrial wastewater. The microspheres were prepared using spray drying combined with low-temperature sintering, facilitated by DMR, resulting in a uniform size distribution and quartz and mullite as the major phases. The microspheres have porous structures with abundant functional groups and those with 10 wt% DMR sintered at 800 °C have the optimal adsorption property. With 80 g/L dosage of the optimized microspheres, the removal efficiency of malachite green (MG) reaches 99.6 %. The adsorption process follows the pseudo-second-order kinetic and Langmuir isotherm adsorption models, with van der Waals force, hydrogen bond, and electrostatic attraction promoting the adsorption. After three regeneration cycles, the dye removal efficiency reaches up to 96 %, indicating broad prospects in filtration and adsorption.