DOI: 10.2174/2211550112666230719121415 ISSN: 2211-5501

A Mini Review on the Application of Chitosan Composites for the Adsorption of Fluoride from Aqueous Solution

Clint Sutherland, Beverly Chittoo, Abdel Islam
  • Applied Microbiology and Biotechnology
  • Bioengineering
  • Biotechnology

Background:

Exploration into the development of cost-effective and eco-friendly adsor-bents for the removal of fluoride continues to be unabated. The modification of chitosan through the development of composites and derivatives has shown great promise over the past decade. These modifications aim to overcome the limitation of chitosan, such as separability and adsorption capacity.

Objectives:

The objective of this study is to review various modifications to chitosan for defluorida-tion, the resulting adsorption capacities, operational parameters that appreciably influence the full-scale application of adsorption systems and, where reported, the mechanisms that influenced the ad-sorption process.

Results and Discussion:

Among the adsorbents reviewed, most of the processes were best modelled by the Langmuir isotherm and the pseudo-second order model. Chitosan composites were able to achieve significantly higher F- adsorption capacities and compared well to other adsorbents in the literature. Gamma degraded chitosan-Fe(III) beads, 10%-Lanthanum-incorporated chitosan beads and neodymium-modified chitosan were found to easily achieve the WHO drinking water limit of 1.5 mg/L. In all instances, the reactions were spontaneous and endothermic. Fluoride adsorption was shown to increase from the acidic region to near neutral pH followed by a decrease into the al-kaline range.

Conclusion:

The presence of competing ions is a major operational parameter for full-scale adsorp-tion applications. The presence of carbonate and bicarbonate ions has been a consistent hindrance in reported studies. Thus, future investigations are warranted in this area.

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