Influence of calcination on the physical characteristics and nitrogen removal performance of clinoptilolites

The influences of roasting activation on the particle morphology, microscopic structure, and adsorption properties of natural clinoptilolites were investigated. The experimental results show that the optimal modified conditions include a calcination temperature at 400 °C, a roasting time of 0.5 h, and furnace cooling. The ammonia nitrogen removal rate from analog renewable water of the modified clinoptilolites reached 72% in the optimized conditions, which is 12% higher than that of natural ones. Scanning electron microscopy analysis showed that the surface morphology changed, the micro-hole size increased, and the surface became smoother and more uniform after calcination. The single-point total adsorption average pore width increased from 7.74 nm to 10.64 nm.