Synthesis of ZrP–C using MOF-808 as a template and investigation of its fluoride ion adsorption

This work describes the synthesis of a ZrP–C composite adsorbent using MOF-808 as a template via one-step, high-temperature carbonization. The adsorption performance of ZrP–C material toward fluoride ions was investigated as a function of time, solution concentration, temperature, pH, and coexisting anions. After 3 h, the ZrP–C-3 adsorbent achieved saturation in fluoride uptake, demonstrating a final uptake of 37 mg/g at equilibrium. Fit the adsorption process using kinetic and isothermal adsorption models. The study revealed that adsorption was dominated by monolayer chemical adsorption. Adsorption was found to be endothermic, according to thermodynamic studies, with higher temperatures favoring increased uptake. Combined XPS, XRD, and FT-IR studies revealed that ion exchange, surface complexation, and electrostatic interactions jointly governed fluoride removal. For low-concentration fluoride-containing water bodies, typically those with concentrations below 20 mg/L, adding an appropriate amount of adsorbent could effectively reduce the wastewater concentration to meet national standards. These results highlight the strong potential of ZrP–C-3 for practical applications in fluoride removal from wastewater.