α-calcium sulfate hemihydrate with a 3D hierarchical straw-sheaf morphology for use as a remove Pb2+ adsorbent

作者：Zhang, Genlei; Cao, Dongjie; Wang, Xianshun; Guo, Shiyu; Yang, Zhenzhen^*; Cui, Peng^*; Wang, Qi; Dou, Yan; Cheng, Sheng; Shen, Hao

来源：Chemosphere, 2022, 287: 132025.

DOI：10.1016/j.chemosphere.2021.132025

• Synthesis
• alpha-calcium sulfate hemihydrate
• 3D hierarchical
• Straw-sheaf
• Pb2+ removal

Novel three-dimensional hierarchical alpha-calcium sulfate hemihydrate with a straw-sheaf morphology (3D alpha-HH straw-sheaves) are synthesized successfully in glycerin aqueous solution by a simple one-pot method, using as an efficient adsorbent for Pb2+ removal from water. The 3D straw-sheaf morphology, that closely depends on the glycerin/water volume ratio (V-Gly/V-H2O), can be accurately fabricated only when V-Gly/V-H2O is not lower than 3/1. 3D alpha-HH straw-sheaves are generated via multistep-splitting growth coupled with self-assembly. The obtained 3D alpha-HH straw-sheaves are further used as an adsorbent to remove Pb2+ from water, exhibiting excellent Pb2+ removal performance with an equilibrium adsorption capacity of 79.19 mg(Pbg alpha-HH)(-1) and removal efficiency of 98.98%, that both higher than those of plate- and columnar-like alpha-HH. Moreover, the experimental adsorption data for the 3D alpha-HH straw-sheaves is well fitted with pseudo-second-order kinetic model, and the adsorption isotherm is in good agreement with Langmuir model. The Pb2+ adsorption mechanism is thought to be a chemical adsorption process enforced by chemical bonding and ion exchange. This work demonstrates that 3D alpha-HH straw-sheaves are highly promising in removing Pb2+ from wastewater, thereby broadening the research field for the practical application of gypsum-based materials.