ABSTRACT
Fluoride in small concentrations prevents tooth decay, but its exposure in higher concentration causes fragile bones and decrease in fertility. Nitrate is among the chief factors in eutrophication, and perchlorate causes hindrance of iodine uptake by the thyroid gland. This chapter includes factors affecting the adsorption of anions such as fluoride, nitrate, perchlorate, and sulfate. Fluoride is a common contaminant existing in a number of minerals like fluorspar, cryolite, and fluorapatite. In addition to natural sources, various industries such as glass, semiconductor, electroplating, and aluminum also contribute to the release of fluoride into the environment. The effect of sulfate on the reduction of fluoride’s adsorption on akaganeite was more pronounced as compared to chloride and nitrate. The more pronounced effect of sulfate is attributed to the inner sphere complex formation by sulfate ions in comparison to outer sphere complex formation by chloride and nitrate.
