Titanium(IV) hydrate based on chitosan template for defluoridation from aqueous solution

Abstract

a b s t r a c tA cost effective bio-adsorbent, titanium(IV) hydrate based on chitosan template (Ti-CHI), was synthesized using Ti(SO 4 ) 2 and chitosan for defluoridation from aqueous solutions. The Ti-CHI material was characterized using FTIR, SEM with EDX, XRD, XPS and Zeta potential. The adsorption kinetics of fluoride onto Ti-CHI followed pseudo-second-order and intra-particle diffusion models. The Ti-CHI was effective for defluoridating systems with low fluoride concentrations (4.52 mg/L), exhibiting a 87.50% removal rate and permitting a residual fluoride concentration (0.55 mg/L). The most stable pH range for fluoride removal was from 4 to 9. After combining the results of pH effects, FTIR and Zeta potential, the NH groups and Ti OH groups were revealed as the fluoride adsorption sites on Ti-CHI. In addition, the carbonate ions present in the aqueous solutions adversely impact the fluoride adsorption. The Langmuir, Freundlich, and Langmuir-Freundlich models were used to illustrate the isotherms of the adsorption process. The adsorption of fluoride onto Ti-CHI fits the Langmuir and Langmuir-Freundlich isotherm models well. The maximum adsorption capacity for fluoride on the Ti-CHI was 16.12 mg/g. Thermodynamic studies revealed that the adsorption process was spontaneous.

Removal of Fluoride from Aqueous Solutions Using Chitosan Cryogels

“…In other articles materials of chitosan have been used in order to remove fluoride and under similar conditions used in this study, such is the case of the chitosan beads modified by carboxylation followed by chelation with Fe 3+ (4.23 mg F − /g), the chitosan modified with a mixed of rare earths (3.72 mg F − /g), a bioadsorbent of titanium(IV) hydrate based on chitosan template (11.44 mg F − /g), and an Aldoping chitosan-Fe(III) hydrogel (3.9 mg F − /g). The sorption capacity in equilibrium time is similar to or lower than sorption capacity obtained in this work: 13.10 mg F − /g and 23.20 mg F − /g at 303 K for the QE and QEFe cryogels, respectively [13,34,54,55].…”

“…Epidemiological studies prove detrimental to the bone tissue (bones and teeth) and the spinal cord and brain. The degeneration of neurons and alteration of the metabolism of free radicals in the liver, kidney, and heart and lesions on the thyroid and the endocrine glands interfere with DNA synthesis, and metabolic disorders in soft tissues and some cancers are also associated with the exposure to fluorine [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The World Health Organization (WHO) classifies fluorine as a public health risk and recommends a maximum concentration of 1.5 mg/L of fluorine in drinking water.…”

Enhanced removal of fluoride by tea waste supported hydrous aluminium oxide nanoparticles: anionic polyacrylamide mediated aluminium assembly and adsorption mechanism

“…Corresponding signal peaks were detected on the surface of the biosorbent samples. 9 Such observation was direct evidence of hydrous aluminium oxide loading in tea waste. 2a), as found elsewhere.…”

“…9 Therefore, the effect of fluoride concentration on 10 the uptake of fluoride from solution by Tea-Al and Tea-APAM-Al was studied at different initial fluoride concentration from 5 to 200 mg/L with an incubation of 180 min. 9 Therefore, the effect of fluoride concentration on 10 the uptake of fluoride from solution by Tea-Al and Tea-APAM-Al was studied at different initial fluoride concentration from 5 to 200 mg/L with an incubation of 180 min.…”

“…7 Elevated fluoride concentrations in the groundwater occurs in various parts of the world, such as some regions in Argentina, Morocco, Algeria, 30 Turkey, Kenya, Tanzania, S. Africa, China, Australia, New Zealand, Canada, and India. [9][10][11][12] Various 35 materials, including alumina-based adsorbents, 13,14 agricultural waste, [15][16][17] calcium-based materials, 6,18 ion-exchange resins, 4 carbon, 19, 20 zeolite 21 and biopolymer-based adsorbents, 22 have been employed as adsorbents for fluoride removal, with many available reagents yet to be tested. [9][10][11][12] Various 35 materials, including alumina-based adsorbents, 13,14 agricultural waste, [15][16][17] calcium-based materials, 6,18 ion-exchange resins, 4 carbon, 19, 20 zeolite 21 and biopolymer-based adsorbents, 22 have been employed as adsorbents for fluoride removal, with many available reagents yet to be tested.…”