Water–Dispersible Magnetite Montmorillonite Encapsulated Cellulose Beads for Fluoride Removal and their Kinetics and Mechanism

Water is indispensable to life. The presence of toxic fluoride in water is a problem of grave concern. To address this problem, we have synthesized a water-dispersible magnetite low-cost clay montmorillonite impregnated with cellulose beads (MMTCB) by the dropping technique. Excellent surface chemistry, ease of separation, good swelling behaviour, and smooth operationality contribute to the novelty of the adsorbent. The presence of iron enables the nanoparticle adsorbent to be recovered easily by applying a magnetic field. Pseudo-second-order and Langmuir were found to be the best interpreting models for the experimental adsorption data. The adsorption capacity of MMTCB was found to be 409 mg/g due to the high specific surface area (SBET), i.e. 508.06 m2/g. Thermodynamics parameters predict that the adsorption process is spontaneous and endothermic. There was no significant loss of efficiency even after ten sequential adsorption-desorption cycles. The adsorption mechanism explained by FTIR analysis shows the exchange of the hydroxyl group with the fluoride ion through electrostatic interaction, ion exchange, and hydrogen bonding.