Fluoride in Drinking Water and Nanotechnological Approaches for Eliminating Excess Fluoride

Abstract

Arising awareness of health hazards due to long-term exposure of fluoride has led researchers to seek for more innovative strategies to eliminate excess fluoride in drinking water. Fluoride-bearing chemicals in both natural and anthropogenic sources contaminate drinking water, which mainly cause for human fluoride ingestion. Hence, developing sustainable approaches toward alleviation is essential. Among many emerging techniques of defluoridation, nanotechnological approaches stand out owing to its high efficiency, and hence, as in many areas, nanotechnology for excess fluoride removal in water is gaining ground compared to other conventional adsorbents and process. The present review focuses on some of the advanced and recent nanoadsorbents including their strengths and shortcomings (e.g., CNT, LDH, graphene-based nanomaterials, and magnetic nanomaterials) and other processes involving nanotechnology while discussing basic aspects of hydrochemistry of fluoride and geological conditions leading for water fluoride contamination. Considering all the findings in survey, it is evident that developing more sustainable techniques is essential rather than conducting batch-type experiments solely.

A Mini Review of Recent Findings in Cellulose-, Polymer- and Graphene-Based Membranes for Fluoride Removal from Drinking Water

“…Table 4 shows the reviewed membranes when employed for the removal of fluoride from water and offers evidence about their applications in water treatment. As shown in this Table, most of the membrane applied for defluoridation exhibit greater efficiency at pH values close to that of drinking water (i.e., [6][7][8]. Maximum treatment capacity was obtained with the use of a cellulose modified membrane (Fe-Al-Mn@chitosan [72]) with a permeate flux of 2000 L m −2 h −1 similar to those obtained from the membrane produced by modification of hydroxyapatite with Al(OH) 3 nanoparticles [80] (1568 L m −2 h −1 ) and zirconium-based MOF [79] (1750 L m −2 h −1 ).…”

“…In particular, according to the International Standards Organization, the acceptable concentration values of fluoride in drinking water are usually 0.5-1.0 mg L −1 . According to the World Health Organization (WHO) and the EU Directive 98/83/EC [3,4] the guideline value for fluoride in drinking water is 1.5 mg L −1 , as at lower concentrations there is an increasing risk of prevention of teeth cavities and at progressively higher levels there is an increasing risk of dental and skeletal fluorosis [5,6]. The limit has remained constant also in the revised version of the drinking water directive of 16 December 2020 [7].…”

“…there is an increasing risk of dental and skeletal fluorosis [5,6]. The limit has remained constant also in the revised version of the drinking water directive of 16 December 2020 [7].…”

Carbon-Based Materials for De-Fluoridation of Water: Current Status and Challenges

“…Various carbonaceous materials can be used to prepare activated carbon via chemical or physical activation. Carbon-based nanomaterials are also fast emerging materials for defluoridation of the water because of their very small size, high surface area, remarkable electrical conductivity, unique structural dimensions, high mechanical strength, and high efficiency [27]. In this chapter all the reported studies are reviewed and applicability of carbon-based adsorbents in different conditions are analyzed.…”

Efficient Fluoride Removal from Aqueous Solution Using Zirconium-Based Composite Nanofiber Membranes

“…Fluoride-containing water bodies is a critical problem for tropical nations such as India, Sri Lanka, as well as various countries in Africa. An efficient approach to overcome this issue is de-fluoridation, which can be performed using ion-exchange processes, dialysis, adsorption, and membrane-based processes [ 11 , 12 , 13 ].…”