Adsorption removal of cationic dyes from aqueous solutions using ceramic adsorbents prepared from industrial waste coal gangue.

Industrial solid waste coal gangue has huge utilization potential. Low-cost ceramic microsphere adsorbents were prepared from coal gangue by spray drying and sintering method and applied to remove cationic red X-5GN and cationic blue X-GRRL from aqueous solutions. The structural properties of the adsorbents were characterized. Adsorption kinetics, adsorption isotherms and effect of solution pH were studied. Adsorption mechanism and disposal of the spent adsorbents were also discussed. The results showed that the adsorption capacity of the cationic red and cationic blue onto the ceramic adsorbents was 1.044 mg g-1 and 2.170 mg g-1 respectively, according to the Langmuir model. The adsorption equilibrium time was quickly reached with the removal of both dyes over 90% within 1 min. The adsorbents exhibited favorable applicability with varying solution pH. Electrostatic attractions, n-π interactions and hydrogen bonding were proposed to be involved in the adsorption process based on the adsorption behavior. Using coal gangue ceramic adsorbents to treat colored wastewater could achieve the purpose of treating wastes with wastes. Therefore, the gangue adsorbent has promising application prospects for its comprehensive economic and environmental benefits.