Renewable conversion of coal gangue to 13‐X molecular sieve for Cd <sup>2+</sup> ‐containing wastewater adsorption performance
Le Kang, Sifan Liu, Dawei Yi, Kai Wang, Huiling Du, Haoqi Huang, Peng Chen
Abstract
Abstract Using coal gangue (CG) as raw material, a new type of all solid‐waste‐based 13‐X molecular sieve material was controllably prepared by alkali fusion‐hydrothermal method. The synthetic molecular sieve was used as a solid adsorbent to treat Cd 2+ ‐containing wastewater, and its adsorption behavior on Cd 2+ in aqueous solution was studied and analyzed. The microstructure and morphology of the molecular sieve were investigated by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and specific surface area analyzer. The results show that the synthesized 13‐X molecular sieve has higher Brunauer–Emmett–Teller (BET) specific surface area with higher crystallinity and higher adsorption capacity for the heavy metal Cd 2+ . The adsorption process of Cd 2+ by molecular sieve conforms to the Langmuir isotherm adsorption equation and Lagergren pseudo‐second‐order rate equation. Combined with thermodynamic calculation, it can be concluded that the adsorption process is physically monolayer, spontaneous and exothermic. In this study, a low‐cost and naturally available synthesis method of 13‐X molecular sieve is reported. Combined with its adsorption mechanism for Cd 2+ , it provides a feasible and general method for removing heavy metal ions from coal gangue and also provides a new way for the utilization of coal gangue with high added value.