Synthesis and adsorption performance of ultra-low silica-to-alumina ratio and hierarchical porous ZSM-5 zeolites prepared from coal gasification fine slag.

Since the human consumption of coal is increasingly growing and coal-based solid wastes are discharged in large quantities, the resource utilization of coal-based solid wastes has been paid more attention. In the present work, for the first time, the coal gasification fine slag is subjected to prepare ZSM-5 zeolites with ultra-low n (SiO 2)/ n (Al 2 O 3) ratios (less than 20) and hierarchical pore structures. The increase in the concentration of the alkaline extract leads to the decrease of the crystallinity, the irregularity of the microscopic morphology, and the decrease of the specific surface area, resulting in the in-situ generation of mesopores within ZSM-5. Moreover, adsorption experiments demonstrate that ZSM-5-2M exhibits the best methylene blue adsorption performance at the pH of 9 with a removal rate of up to 82.07%, and it also has good adsorption performance in simulated real water samples. Furthermore, the adsorption performance of ZSM-5-2M on the malachite green, Rhodamine B, Congo red, and methyl orange has been investigated and it is found to be very effective for the adsorption of cationic dyes, and its adsorption performance for methylene blue and malachite green is reduced in the presence of anions. [Display omitted] • Hierarchical porous ZSM-5 zeolites were synthesized from coal gasification fine slag. • The obtained ZSM-5 zeolites possessed ultra-low silica-to-alumina ratios. • The morphology and textural properties can be tuned by varying alkaline conditions. • The maximum adsorption efficiency of MB by obtained ZSM-5 reached 82.07%. • The obtained ZSM-5 showcased selective adsorption performance for dyes in wastewater. [ABSTRACT FROM AUTHOR]