The defluoridation of water by acidic alumina

Goswami, A.; Purkait, Mihir Kumar

doi:10.1016/j.cherd.2012.05.002

Cited by 86 publications

(28 citation statements)

References 20 publications

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“…Effects of phosphate on fluoride removal were also reported by [146]. The tendency of the anions to form inner-sphere complexes was reported by [28,29,32,63,170,174,175,177,178,[180][181][182][183]. Chloride ions formed outer-sphere surface complexes and had a minor effect on fluoride adsorption; thus they are less absorbed on the absorbent surface [65].…”

Section: Effects Of Anion Cation and Organicmentioning

confidence: 81%

“…The adsorption of anions decreases by increasing pH due to the higher concentration of competitive anions, such as OH − and increases due to protonated surfaces. In aqueous solution, the adsorption process is primarily governed by the zero point charge (ZPC) of an adsorbent [31,32]. At zero point charge, the pHzpc is the characteristic that determines the pH at which the adsorbent surface has net electrical neutrality.…”

Section: Adsorption Methods For Arsenic and Fluoride Removalmentioning

confidence: 99%

“…At pH between 4.4 and 12, 500 mg/L of carbonate and bicarbonate ions concentration was reported to decrease the fluoride adsorption on acidic alumina [32]. Fluoride adsorption was reduced significantly as bicarbonate was acting as a pH buffering agent, and its existence in solution increases and buffered the pH; therefore, the adsorption of fluoride was decresed [4,155,166] Kamble et al [4] reported that the addition of CO 3 2− , SO 4 2− , and HCO 3 − ions increases pH of fluoride solution in adsorption of fluoride on alumina of alkoxide nature.…”

Section: Effects Of Anion Cation and Organicmentioning

confidence: 99%

“…Since the protonated surface is accountable for anions adsorption, the maximum fluoride adsorption for many adsorbents occurs at acidic pH [32,63] and decreases at higher pH values. For adsorbents like activated alumina, fluoride adsorption is controlled by pH at point zero charges (pHzpc) [32,73]. At a certain selected pH, the adsorption showed an increasing trend due to the positively charged alumina complexes AlF 2+ and AlF 2 + on fluoride removal by acidic alumina [32].…”

Section: Effects Of Ph On Fluoride Removalmentioning

confidence: 99%

“…For adsorbents like activated alumina, fluoride adsorption is controlled by pH at point zero charges (pHzpc) [32,73]. At a certain selected pH, the adsorption showed an increasing trend due to the positively charged alumina complexes AlF 2+ and AlF 2 + on fluoride removal by acidic alumina [32]. The fluoride adsorption decreased after pHzpc because the concentration of protonated surface sites decreases with increasing pH [4,73], which causes strong competition of hydroxide ions [57].…”

Section: Effects Of Ph On Fluoride Removalmentioning

confidence: 99%

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A Comparative Study on Removal of Hazardous Anions from Water by Adsorption: A Review

John

David

Mmereki

2018

International Journal of Chemical Engineering

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This paper presents a comparative review of arsenite (As(III)), arsenate (As(V)), and fluoride (F − ) for a better understanding of the conditions and factors during their adsorption with focus on (i) the isotherm adsorption models, (ii) effects of pH, (iii) effects of ionic strength, and (iv) effects of coexisting substances such as anions, cations, and natural organics matter. It provides an indepth analysis of various methods of arsenite (As(III)), arsenate (As(V)), and fluoride (F − ) removal by adsorption and the anions' characteristics during the adsorption process. The surface area of the adsorbents does not contribute to the adsorption capacity of these anions but rather a combination of other physical and chemical properties. The adsorption capacity for the anions depends on the combination of all the factors: pH, ionic strength, coexisting substances, pore volume and particles size, surface modification, pretreatment of the adsorbents, and so forth. Extreme higher adsorption capacity can be obtained by the modification of the adsorbents. In general, pH has a greater influence on adsorption capacity at large, since it affects the ionic strength, coexisting anions such as bicarbonate, sulfate, and silica, the surface charges of the adsorbents, and the ionic species which can be present in the solution.

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Section: Effects Of Anion Cation and Organicmentioning

confidence: 81%

Section: Adsorption Methods For Arsenic and Fluoride Removalmentioning

confidence: 99%

Section: Effects Of Anion Cation and Organicmentioning

confidence: 99%

Section: Effects Of Ph On Fluoride Removalmentioning

confidence: 99%

Section: Effects Of Ph On Fluoride Removalmentioning

confidence: 99%

See 3 more Smart Citations

A Comparative Study on Removal of Hazardous Anions from Water by Adsorption: A Review

John

David

Mmereki

2018

International Journal of Chemical Engineering

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On the Conversion of Bauxite Ores to Highly Activated Alumina Media for Water Remediation

Haddad

Pilgrim

Sawvel

et al. 2019

Advanced Sustainable Systems

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Good quality drinking water is necessary to maintain a high quality of life. Millions lack access to clean and safe drinking water, and current trends suggest that billions will face acute water shortages in the coming decades. Development of new materials has led to technological impacts on water purification, from desalination membranes to atmospheric water scavenging. However, the most challenging aspect of technological solutions is cost: if the community being serviced cannot afford the solution, it is not likely to be sustainable. Repurposing Earth‐abundant materials to replace highly engineered solutions is an atractive solution. Herein, minimal processing of bauxite rocks produces a high‐porosity and reactive activated alumina in situ, without purification directly from the ore. This acid‐treated, thermally activated bauxite (ATAB) exhibits a high surface area of 401 ± 6 m2 g−1, a 40‐fold increase relative to its parent ore, and a 2× increase relative to the state‐of‐the‐art fluoride adsorbent, activated alumina. The composition, preparation, and mechanism of adsorption are studied by X‐ray diffraction, X‐ray photoelectron spectroscopy, and multiple‐quantum magic‐angle spinning 27Al nuclear magnetic resonance (NMR). The maximum adsorption density of ATAB is comparable with that of activated alumina, but ATAB requires fewer processing steps, thus warranting future consideration as a primary adsorbent of choice for fluoride removal from water.

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Process development for the decoloration of Panax notoginseng extracts: A design space approach

Chen

Gong

Chen

et al. 2014

J of Separation Science

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A systematic, yet simple method for the decoloration of Panax notoginseng extracts has been developed by static adsorption tests and response surface methodology. Through static adsorption experiment screening, acidic alumina was selected because of its high decoloration ratio and saponin recovery ratios. Using response surface methodology, the correlation between the process parameters (i.e., sample volume and flow rate) and decoloration performance was modeled. A design space of the decoloration process was subsequently established through the proposed models. The verification experimental values were in good agreement with the predicted values. The design space was proven reliable, because all the verification experimental results attained the criteria for design space development. Moreover, most of the saponins adsorbed by the acidic alumina could be recovered through dynamic desorption using water and ethanol. The method developed in the current study is highly efficient, flexible, and easy to control, thus providing a promising approach for the decoloration of Panax notoginseng extracts with consistent decoloration performance.

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The defluoridation of water by acidic alumina

Cited by 86 publications

References 20 publications

A Comparative Study on Removal of Hazardous Anions from Water by Adsorption: A Review

A Comparative Study on Removal of Hazardous Anions from Water by Adsorption: A Review

On the Conversion of Bauxite Ores to Highly Activated Alumina Media for Water Remediation

Process development for the decoloration of Panax notoginseng extracts: A design space approach

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