Adsorption of Fluoride on Zirconium(IV)-Impregnated Collagen Fiber

Abstract

A novel adsorbent, zirconium(IV)-impregnated collagen fiber, was prepared. Zr(IV) was uniformly dispersed in collagen fiber, mainly through chemical bonds, and was able to withstand the extraction of water. This adsorbent is effective for the removal of fluoride from aqueous solutions. The adsorption capacity was 2.29 mmol/g at pH = 5.5 when 5.00 mmol/L fluoride solution was adsorbed by use of 0.100 g of adsorbent, and the extent of removal was 97.4% when the adsorbent dose was 0.300 g. The adsorption isotherms were well fitted by the Langmuir equation, and the maximum adsorption capacities calculated by the Langmuir equation were close to those determined by experiment. The adsorption capacity increased with rising temperature. These facts imply that the mechanism of chemical adsorption might be involved in the adsorption process of fluoride on the absorbent and that fluorides are adsorbed in the form of monolayer coverage on the surface of the adsorbent. The adsorption kinetics of fluoride onto Zr(IV)-impregnated collagen fiber could be described by Lagergren's pseudo-first-order rate mode. The investigation on desorption indicated that this adsorbent is easily regenerated by use of dilute NaOH solution.

Adsorptive Removal of Trace Concentration of Fluoride Using Orange Waste Treated Using Concentrated Sulfuric Acid

“…hydrofluoric acid (HF), which was hardly adsorbed onto these adsorbents, the adsorption is ultimately decreased. Similar observations have been also reported on the adsorption behavior of other Zr(IV) loaded adsorbents, such as Zr(IV) loaded leather fiber [21], Zr(IV) loaded cross-linked seaweed [22] and Zr(IV) loaded carboxylated chitosan [23], which is attributable to the fact that all of these adsorbents employ Zr(IV) as the loaded metal ion, as mentioned earlier. Consequently, the adsorption mechanism of fluoride on Zr-ATOJR can be clearly interpreted similarly to the case of Zr-SOJR by the following reactions.…”

Removal of fluoride from aqueous media by Fe3O4@Al(OH)3 magnetic nanoparticles

“…Fluoride contamination in the drinking water due to natural reasons and human activities is a major problem worldwide [1,2]. According to World Health Organization (WHO) norms, the upper limit of fluoride concentration in drinking water is 1.5 mg L −1 [3].…”

“…According to World Health Organization (WHO) norms, the upper limit of fluoride concentration in drinking water is 1.5 mg L −1 [3]. Long-term ingestion of high-fluoride drinking water can cause fluorosis [4,5], which is a chronic disease manifested by mottling of teeth in mild cases, softening of bones ossification of tendons and ligaments and neurological damage in severe cases [2,6]. Millions of people in the world are affected by fluorosis, especially in Asian countries such as China, India, Pakistan, and Thailand [6][7][8].…”

“…Several methods have been applied to remove excessive fluoride from aqueous environments, such as adsorption [2,[8][9][10], precipitation [6], ion-exchange [11], electrodialysis [12] and electrochemical methods [13]. Among them, precipitation and adsorption are two most important techniques used for water defluoridation.…”

“…Various low-cost materials such as activated alumina [7,8], clay [14], soil [15], bone char [8,12], light weight concrete [16], fly ash and other materials [2,13] have been tested for removing fluoride from drinking water, but the fluoride adsorption capacities of those materials are not high enough for wide application [8]. In the past few years, novel adsorbents with strong affinity towards fluoride have been developed for fluoride removal, such as synthetic ion exchangers calcined Mg-Al-CO 3 layered double hydroxides (LDH) [7], zirconium-impregnated collagen fiber [2], Fe-Al-Ce trimetal oxide [17] and iron-aluminum mixed oxide [9]. Rare earth elements also have been investigated as potential adsorbents because of their selective affinity to fluoride, high adsorption capacity, cause little pollution, and easy preparation [18].…”