Defluoridation Proficiency of Ocimum tenuiflorum Based Bioadsorbent against Fluoride Toxicity in Drinking Water

Abstract

From the past century, the global attention shifted towards fluoride toxicity through drinking water due to its severity in important health concerns. Many researchers made an attempt to resolve the issue to potable drinking water through many chemical and mechanical methods. Among them adsorption is one of the acceptable cheap and cost-effective method to remove the fluoride from its contaminated waters. This article presents a remarkable defluoridation techniques and approach by preparing efficient bioadsorbent from Holy Basil Ocimum tenuiflorum L. leaves. Thermo-charring method was followed to prepare bioadsorbent from holy basil and avoided acid charring method. With this bioadsorbent, batch equilibrium adsorption method was followed by varying the adsorbent and adsorbate (fluoride) concentrations, its contact time, different adsorbent dose and its different sizes. As a sum up, the best contact time was identified as 90 minutes for all fluoride concentrations. As known, the smaller size adsorbent has shown good absorptivity and the quantity of 1.5 g/L found to be optimal amount for the effective defluoridation. The interference of co-existing anions like nitrates, chlorides, sulphates and carbonates were also studied to identify the applicability of prepared bioadsorbent at real water environment. The co-ions nitrates and chlorides did not affect the adsorptive efficiency, but sulphates and carbonates suffered lot due to its bulky structured binding on adsorbent and lacked the fluoride adsorption onto it. The spectral and morphological characterizations such as FTIR, XRD and SEM-EDAX spectral studies carried out to confirm the surface variations of bioadsorbent and their corresponding reports reveal the notable observations. The best optimal defluoridation capacity for Ocimum tenuiflorum based bioadsorbent was found to be 1766 mg/kg.