Adsorption of Fluoride from Aqueous Solutions Using Graphene Oxide Composite Materials at a Neutral Ph

Adsorption methods have garnered significant attention for fluoride removal from water bodies owing to their superior selectivity, simple operations, and wider applicability. However, the development of adsor-bents with higher adsorption performances requires significant attention. Here, graphene oxide is endowed with excellent affinity towards fluoride by doping polyhydroxy complexes onto its surface structure and regulating the potential charge. Multiple detection measurements involving scanning elec-tron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD), and transmission electron microscopy (TEM) were employed to demonstrate the textural properties of graphene oxide (GO) modified by polyaluminium chloride (HAO@GO). Conversely, the effects of parameters including the preparation conditions, co-existing competitive ions, recyclability, contact time, and initial concentration on the adsorption behav-iors were systematically determined. The adsorption experimental data were fitted well by the Langmuir isotherm model and pseudo-first-order model. The calculated maximum adsorption capacity was 129.23 mg/g at room temperature (25 degrees C) and a pH of 7.00, which is greater than that of most reported adsorbents. The existence of competitive anions, such as NO -3 , SO2-4 , and PO3- 4 , unavoidably interferes with fluoride adsorption. TEM, zero point of charge test, adsorption isotherm, and X-ray photoelectron spec-troscopy (XPS) tests indicated that chemical adsorption and ligand exchange are responsible for the adsorption of fluoride onto HAO@GO. (c) 2023 Elsevier B.V. All rights reserved.