Extraction and optimization of chitosan from shrimp shell: preparation, characterization and application in fluoride removal (isotherm, kinetic and thermodynamic studies)

Fluoride in low concentrations is useful for human health. However, high concentrations of this substance is associated with problems such as fluorosis and Alzheimers. Adsorption is efficient technique in removal of this pollutant. The aim of this study was to extraction and optimization of Chitosan as a natural biosorbent in fluoride removal.
In present study, magnetized chitosan-iron oxide nano particles was prepared by co-precipitation method and its characteristics were determined by SEM, XRD, TEM and FTIR analyzes. Subsequently, the effect of magnetized chitosan was assessed as an adsorbent in fluoride removal from water solution in the batch system with considering various parameters included pH, contact time, adsorbent dosage, initial Fluoride concentration and solution temperature. The Langmuir and Freundlich isotherm models and pseudo first-order and pseudo second-order kinetics were used to examine experimental data.
The results showed that the Fluoride adsorption have followed Langmuir (R2>0.982) and kinetic model of pseudo second-order (R2>0.931). The maximum adsorption capacity of Fluoride was 22.756 mg/g at optimized condition, pH 50 adsorbent dose of 1g/L at 500C. Investigation of thermodynamically parameters and positive value of ΔH0 indicatethat this process was endothermic.
Generally, we can report that t he magnetic chitosan was used as a useful sorbent for the removal of pollutants from water and wastewater due to advantages such as easy and rapid separation from solution and high removal efficiency.