Facile Synthesis of Diatomite/β-Cyclodextrin Composite and Application for the Adsorption of Diphenolic Acid from Wastewater

Diphenolic acid (DPA) is a kind of endocrine-disrupting compound, which brings serious health problems to humans and animals. An eco-friendly and cost-effective adsorbent was prepared through a simple method, in which the β-Cyclodextrin(β-CD) was crosslinked onto the surface of diatomite (DA), the as-prepared DA/β-CD composite showed higher adsorption efficiency for DPA than DA as the host–guest interaction between DPA and β-CD. DA is a kind of biosilica with a hierarchical pore structure that provides enough surface area for the DA/β-CD. The surface area and pore size of DA/β-CD were investigated by nitrogen adsorption and desorption. The DA/β-CD composite illustrated a good adsorption capability, and was used for removing DPA from wastewater. The adsorption ratio of DPA could achieve 38% with an adsorption amount of 9.6 mg g⁻¹ under room temperature at pH = 6. The adsorption isotherm curves followed the Langmuir (R² = 0.9867) and Freundlich (R² = 0.9748) models. In addition, the regeneration rate of the DA/β-CD was nearly at 80.32% after three cycles of regeneration. These results indicated that the DA/β-CD has the potential for practical removal of the EDC contaminants from wastewater.