Facile preparation of tannic acid functionalized phosphogypsum for efficient removal of heavy metal in wastewater

Phosphogypsum (PG) as a by-product is produced by the industrial wet phosphoric acid production process. The environmental-friendly disposal and recycling of PG holds significant importance within the domain of solid waste management. In this research, due to its unique property of versatile molecular glue and the strong metal-chelating ability, polyphenol tannic acid (TA) was employed as an organic modifier to functionalize inert PG to prepare TA@PG adsorbent for effective removal of heavy metal in wastewater. The morphology, structure, thermal stability and surface charge of TA@PG adsorbent was characterized and tested. The effects of adsorption conditions, adsorption isotherms and adsorption kinetics were also studied in detail. In addition, the adsorption mechanisms were also discussed by XPS analysis, which might involve in electrostatic interaction, ion exchange and complexation interaction. The prepared TA@PG adsorbent exhibited excellent adsorption performance with removal rate up to 100% and maximum adsorption capacity up to 221.72 mg·g −1 for heavy metal Cr (VI). The adsorbent preparation method in this study is simple, cost-effective, environmental-friendly without using organic solvent. It holds significant promise for large-scale production. This study provides a novel approach for the resource utilization of industrial solid waste PG, achieving the dual objectives of waste recycling and value addition.