Optimization of post-treatment variables to produce hierarchical porous zeolites from coal gangue to enhance adsorption performance

•Hierarchical porous zeolites are prepared by using coal gangue as the raw materials.•The post-treatment variables of zeolites have been optimized.•The adsorbabilities of Cu2+ and Rh-B have been improved to 83.5% and 95.1%.•Post treatments of zeolites are found to increase surface adsorption efficiencies.