Synthesis of Chitosan-Polyvinyl Alcohol Biopolymers to Eliminate Fluorides from Water

The fluoride content in groundwater varies depending on geological configuration. Fluoride problems tend to occur in places where these minerals are most abundant in rocks. The objective of the present work was to synthesize four biopolymers based on chitosan-polyvinyl alcohol (Ch-PVA) cross-linked with sodium tripolyphosphate pentabasic (TPP) and ethylene glycol diglycidyl ether (EGDE) and determine their ability to remove fluoride from water. The characterization of the Ch-PVA beads was performed by way of Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The percentage of humidity and the point of zero charge were determined. The Ch-PVA beads showed a surface area of 63.87 m2 g−1, a pore size of 7.6 nm, a point of zero charge of 7.4, and 98.6% humidity. The kinetic adsorption study was adjusted to the pseudo-second-order model and the adsorption equilibrium data were adjusted to the Freundlich adsorption isotherm, showing a maximum fluoride adsorption capacity of 12.64 mg g−1 at pH 7 and 30 °C, for the beads of Ch-PVA-NaOH-TPP. According to the thermodynamic parameters: −∆G°, +∆H° and −∆S°, fluoride adsorption is spontaneous, endothermic in nature and there is no random energy change in the solid/liquid interface during the adsorption process.

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Thermodynamic Study on the Adsorption of Pb2+and Zn2+From Aqueous Solution by Human Hair

E-Journal of Chemistry ◽

10.1155/2010/849239 ◽

2010 ◽

Vol 7 (4) ◽

pp. 1296-1303 ◽

Cited By ~ 2

Author(s):

A. S. Ekop ◽

N. O. Eddy

Keyword(s):

Aqueous Solution ◽

Human Hair ◽

Contact Time ◽

Metal Ion ◽

Ion Concentration ◽

Optimum Conditions ◽

Batch System ◽

Freundlich Adsorption Isotherm ◽

Equilibrium Data ◽

Adsorption Equilibrium Data

Adsorption of Pb(II) and Zn(II) ions from aqueous solutions was studied in a batch system using modified human hair. The optimum conditions for the adsorption of Pb(II) and Zn(II) ions from aqueous solution by human hair were investigated by considering the extent of adsorption with respect to contact time, initial metal ion concentration and temperature. The results obtained indicates that the extent of metal ions removed decreases with increasing contact time but increased with increase in the initial metal ion concentration. The adsorption equilibrium data best fitted Freundlich adsorption isotherm. The adsorption of Pb(II) and Zn(II) ions onto human hair is endothermic, spontaneous and is characterised by increasing degree of orderliness.

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Removal of Fluoride and Arsenate from Aqueous Solutions by Aluminum-Modified Guava Seeds

Applied Sciences ◽

10.3390/app8101807 ◽

2018 ◽

Vol 8 (10) ◽

pp. 1807 ◽

Cited By ~ 6

Author(s):

Sarai Ramos-Vargas ◽

Ruth Alfaro-Cuevas-Villanueva ◽

Rafael Huirache-Acuña ◽

Raúl Cortés-Martínez

Keyword(s):

Aqueous Solutions ◽

Adsorption Equilibrium ◽

Order Model ◽

Freundlich Model ◽

Equilibrium Time ◽

Fluoride Adsorption ◽

Batch Type ◽

Equilibrium Data ◽

Pseudo Second Order ◽

Adsorption Equilibrium Data

The contamination of groundwater by arsenic and fluoride is a major problem worldwide, causing diseases in the population that uses these waters for their consumption. Therefore, the removal of these types of pollutants from groundwater is a very important issue. In this work, the removal of arsenate and fluoride from aqueous solutions by using aluminum-modified guava seeds (Al-GSs) was evaluated. Batch-type adsorption experiments were carried out with aqueous solutions of As(V) and F− and Al-GSs. The kinetic and equilibrium parameters of adsorption were determined, as well as the effects of adsorbent dose and pH. The adsorbent was characterized by scanning electron microscopy and infrared spectroscopy in order to determine its morphology and the functional groups present in the material. The results showed that hydroxyl and carboxyl are the main groups involved in the adsorption of As(V) and F−. The fluoride adsorption kinetics indicate that the equilibrium time was reached at 150 min and it can be described by the Lagergren model, while for As(V) the equilibrium time was lower (120 min) and the kinetic data were fitted well to the pseudo-second-order model. The Langmuir-Freundlich model can describe the adsorption equilibrium data in all cases. The fluoride adsorption capacity by Al-GS was 0.3445 mg/g, and for As(V) it was 4 mg/g. It can be established that the removal of arsenates and fluoride in Al-GSs is due to chemisorption on a heterogeneous surface.

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Effective Poly (Cyclotriphosphazene-Co-4,4′-Sulfonyldiphenol)@rGO Sheets for Tetracycline Adsorption: Fabrication, Characterization, Adsorption Kinetics and Thermodynamics

Nanomaterials ◽

10.3390/nano11061540 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1540

Author(s):

Muhammad Ahmad ◽

Tehseen Nawaz ◽

Mohammad Mujahid Alam ◽

Yasir Abbas ◽

Shafqat Ali ◽

...

Keyword(s):

Adsorption Capacity ◽

Surface Area ◽

High Surface ◽

High Surface Area ◽

High Adsorption ◽

Clean Environment ◽

Equilibrium Data ◽

Langmuir Isotherm Model ◽

High Adsorption Capacity ◽

Adsorption Equilibrium Data

The development of excellent drug adsorbents and clarifying the interaction mechanisms between adsorbents and adsorbates are greatly desired for a clean environment. Herein, we report that a reduced graphene oxide modified sheeted polyphosphazene (rGO/poly (cyclotriphosphazene-co-4,4′-sulfonyldiphenol)) defined as PZS on rGO was used to remove the tetracycline (TC) drug from an aqueous solution. Compared to PZS microspheres, the adsorption capacity of sheeted PZS@rGO exhibited a high adsorption capacity of 496 mg/g. The adsorption equilibrium data well obeyed the Langmuir isotherm model, and the kinetics isotherm was fitted to the pseudo-second-order model. Thermodynamic analysis showed that the adsorption of TC was an exothermic, spontaneous process. Furthermore, we highlighted the importance of the surface modification of PZS by the introduction of rGO, which tremendously increased the surface area necessary for high adsorption. Along with high surface area, electrostatic attractions, H-bonding, π-π stacking and Lewis acid-base interactions were involved in the high adsorption capacity of PZS@rGO. Furthermore, we also proposed the mechanism of TC adsorption via PZS@rGO.

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