Synthesis of Single-Phase Zeolite A by Coal Gasification Fine Slag from Ningdong and Its Application as a High-Efficiency Adsorbent for Cu2+ and Pb2+ in Simulated Waste Water

Abstract

Coal gasification is a new direction for the clean utilization of coal, but it also brings huge environmental pressure on solid waste. In this paper, the high-crystallinity single-phase zeolite A was prepared by solid-phase alkali fusion synthesis from coal gasification fine slag (CGFS), without template agent, with low water consumption, and with low cost, and it was used to remove heavy metals such as Pb2+ and Cu2+ in simulated waste water. The main factors affecting the solid-phase and green synthesis methods were analyzed, and the optimum conditions for solid-phase synthesis of high-crystallinity single-phase zeolite A were determined as follows: NaOH/CGFS = 1.2; solid-phase alkali fusion temperature 823 K, solid-phase alkali fusion 90 min, liquid–solid ratio 4.5, and 353 K hydrothermal reaction for 12 h. The relative crystallinity, specific surface area, and ion-exchange capacity of single-phase zeolites A are 93.1%, 61.09 m2/g, and 268.4 mmol/100 g. The removal rates of Pb2+ and Cu2+ can reach more than 99%, especially for the removal efficiency of Pb2+, which is common in simulated waste water. This is an effective method with important application prospects, and it formed an effective way to recycle solid waste of coal chemical industry.