A sorbent of carboxymethyl cellulose loaded with zirconium for the removal of fluoride from aqueous solution

• A new method to load Zr(IV) on carboxymethyl cellulose sodium.
• CMC-Zr shows a good adsorption capacity for fluoride.
• Characterizations of FT-IR, SEM-EDX and XPS are used to research the adsorption mechanism of CMC-Zr.

A novel sorbent for the removal of fluoride is prepared by immobilizing Zr(IV) on carboxymethyl cellulose sodium (CMC-Zr). Batch adsorption experiments are performed on factors of pH, temperature, initial fluoride concentration, adsorbent dosage and contact time to evaluate the adsorption capacity. The results show that the saturation adsorption capacity is 47 mg/g at pH 4.0, 25 °C, concentration 300 mg/L for 24 h. Adsorption process could be well described by Langmuir isotherm model. The adsorption kinetic data is fitted well with pseudo-second-order model. Thermodynamic parameters are also evaluated and the results indicate that adsorption of fluoride on CMC-Zr is a spontaneous and endothermic process. The mechanism of modification and adsorption process on CMC-Zr is analyzed by FT-IR, SEM-EDX and XPS. Results show that Zr(IV) is loaded on CMC through ion exchange of sodium of CMC and surface adsorption, coordination reaction happened during the adsorption process between CMC-Zr and fluoride. CMC-Zr adsorbent is a promising adsorbent for the removal of fluoride from aqueous solutions.