Regression and mathematical modeling of fluoride ion adsorption from contaminated water using a magnetic versatile biomaterial & chelating agent: Insight on production & experimental approaches, mechanism and effects of potential interferers

Abstract

Fluoride is one of the chemicals that enter the human body through drinking water and, at higher concentrations, can cause various long-term health effects. Owing to remove the pollutant from aqueous solutions on large-scale, researchers are always exploring efficient, inexpensive, and easily recoverable adsorbents. In this research study, a versatile magnetic biomaterial & chelating agent (Chitosan) is used as an adsorbent for fluoride removal. In the present research, chitin was extracted from discarded shrimp shells. The obtained Chitosan was characterized based on its yielding, moisture and ash content, degree of acetylation and water binding capacity according to standard protocols. Also, in this study, differential evolution optimization is used to evaluate isotherm and kinetic model parameters using nonlinear model expressions, thus depicting inherent mechanisms. The isotherm and kinetic studies revealed that the adsorption process follows Langmuir and the pseudo 2nd order kinetic model. The interactive effect of process variables is investigated, and their optimal conditions for higher removal efficiency are estimated using response surface methodology. A quadratic model was used to predict removal efficiency at different operating conditions, which resulted in R2 of 0.9949. Optimum adsorption efficiency (93.1%) was observed at an adsorbent rate of 1 g/L, initial concentration of 1 mg/L, pH of 3, and contact time of 25 min. The thermodynamic study is indicating that the process is exothermic and spontaneous. The effect of interventions such as chloride, acidic, and sulfate on fluoride removal was also investigated, and results indicated that Chitosan-Fe3O4 is also efficient in their presence. A hybrid model of ANN and GA predicted the fluoride removal at different operating conditions, and results indicated that prediction values result in R2 of 0.9825. Thus, these results confirm the remarkable ability of Chitosan-Fe3O4 nanocomposite for fluoride removal.