Adsorption Behavior of Mercury and Precious Metals on Cross-Linked Chitosan and the Removal of Ultratrace Amounts of Mercury in Concentrated Hydrochloric Acid by a Column Treatment with Cross-Linked Chitosan

Oshita, Koji; Oshima, Mitsuko; Gao, Yunhua; Lee, Kyue-Hyung; Motomizu, Shoji

doi:10.2116/analsci.18.1121

Cited by 44 publications

(19 citation statements)

References 19 publications

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“…[1][2][3][4][5][6][7] Previously, one of the authors reported that persimmon tannin (PT) gel, a newly developed biosorbent, adsorbed large amounts of gold from a solution containing hydrogen tetrachloroaurate(III). 8 The gold adsorption by the gel was rapid, endothermic, and obeyed the Langmuir isotherm.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Gold Adsorption by Persimmon Tannin Gel

et al. 2003

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IntroductionRecently, attention has been focused on the recovery of gold from aqueous solutions from the standpoints of gold recovery from industrial resources, such as electronics parts and plating materials. [1][2][3][4][5][6][7] Previously, one of the authors reported that persimmon tannin (PT) gel, a newly developed biosorbent, adsorbed large amounts of gold from a solution containing hydrogen tetrachloroaurate(III). 8 The gold adsorption by the gel was rapid, endothermic, and obeyed the Langmuir isotherm. On the other hand, the gel also adsorbed large amounts of uranium, 9 iron, 10 and vanadium. 11 The gel contained a number of adjacent hydroxyphenyl groups, which are suitable ligands for hard acids, such as uranyl, iron(III), and vanadyl ions, based on the HSAB idea. 12,13 Because Au(III) ion is softer than these cations, hydroxyphenyl groups in the gel are not suitable.Preliminary experiments revealed that colloidal Au(0) was formed in a HAuCl4 solution containing PT gel. In this note, therefore, further experiments were conducted to analyze the mechanism of gold adsorption. ExperimentalThe persimmon tannin (PT) solution used throughout this study was obtained from Tomiyama Shoten, Kyoto. PT gel was prepared as previously described. 8,11 Hydrogen tetrachloroaurate(III) tetrahydrate and other chemicals used for this study were obtained from Nacalai Tesque, Inc. (Kyoto, Japan). Gold adsorption experiments in a column system were conducted as follows: 1000 ml of a solution (pH 3) containing 0.1 mM HAuCl4 was passed through a column (diameter 8 mm, bed volume 8.9 ml) of PT gel at 150 and 300 ml/h, collecting 100 ml for each fraction. The pH of the gold solution was adjusted to 3 by 0.1 M HCl and 0.1 M NaOH. To avoid an optical reduction of Au(III) ion, adsorption experiments were conducted under dark conditions. The gold content in each fraction was determined by a inductively coupled plasma quantometer (Shimadzu ICPQ 1000II). A colloidal Au(0) solution was prepared by adding 20 µM of formaldehyde to a solution containing 0.05 mM HAuCl4. After adjusting the pH to the desired value by 0.1 M HCl and 0.1 M NaOH, the mixture solution was allowed to stand. The time when the gold solution became colored purplish red was recorded as the time for colloid formation. Fifty milliliters of the resulting colloidal Au(0) solution were passed through a column (diameter 8 mm, bed volume 5 ml) of PT gel at 100 ml/h. The gold adsorption ratio (%) was estimated from the gold content in each elute. The optical absorption spectra were measured using an absorption spectrophotometer (Japan Spectroscopic Co. Ltd., JASCO V-550). Powder X-ray diffraction (XRD) patterns of PT adsorbed gold were recorded with a powder X-ray diffractometer (Shimadzu XD-D1) using Cu Kα1 radiation (λ = 1.54056 Å) over a 2θ range from 1˚ to 80˚. Results and DiscussionThe effect of the flow rate on gold adsorption by PT gel was examined in a column system, the results of which are listed in Table 1. When the HAuCl4 solution (pH 3) was passed through the PT g...

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Section: Introductionmentioning

confidence: 99%

Mechanism of Gold Adsorption by Persimmon Tannin Gel

et al. 2003

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“…Guibal et al (1998) found that enhancing the solubility of chitosan in acidic wastewater (e.g., due to acidic mine drainage) results in low porosity, low hydraulic conductivity and low permeability that can clog pore structures in a wastewater treatment. Acidic wastewater may also cause dissolution of chitosan, resulting in a loss of mass that could lead to structural failure of the chitosan sorbent (Oshita et al 2002). Hence, the structure and functional groups of chitosan must be optimized to enhance its stability and metal sorption capacity.…”

Section: Chitosan Modificationmentioning

confidence: 99%

Environmental Applications of Chitosan and Its Derivatives

Yong

Shrivastava

Srivastava

et al. 2014

Reviews of Environmental Contamination and Toxicology Volume 233

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Chitosan originates from the seafood processing industry and is one of the most abundant of bio-waste materials. Chitosan is a by-product of the alkaline deacetylation process of chitin. Chemically, chitosan is a polysaccharide that is soluble in acidic solution and precipitates at higher pHs. It has great potential for certain environmental applications, such as remediation of organic and inorganic contaminants, including toxic metals and dyes in soil, sediment and water, and development of contaminant sensors. Traditionally, seafood waste has been the primary source of chitin. More recently, alternative sources have emerged such as fungal mycelium, mushroom and krill wastes, and these new sources of chitin and chitosan may overcome seasonal supply limitations that have existed. The production of chitosan from the above-mentioned waste streams not only reduces waste volume, but alleviates pressure on landfills to which the waste would otherwise go. Chitosan production involves four major steps, viz., deproteination, demineralization, bleaching and deacetylation. These four processes require excessive usage of strong alkali at different stages, and drives chitosan's production cost up, potentially making the application of high-grade chitosan for commercial remediation untenable. Alternate chitosan processing techniques, such as microbial or enzymatic processes, may become more cost-effective due to lower energy consumption and waste generation. Chitosan has proved to be versatile for so many environmental applications, because it possesses certain key functional groups, including - OH and -NH2 . However, the efficacy of chitosan is diminished at low pH because of its increased solubility and instability. These deficiencies can be overcome by modifying chitosan's structure via crosslinking. Such modification not only enhances the structural stability of chitosan under low pH conditions, but also improves its physicochemical characteristics, such as porosity, hydraulic conductivity, permeability, surface area and sorption capacity. Crosslinked chitosan is an excellent sorbent for trace metals especially because of the high flexibility of its structural stability. Sorption of trace metals by chitosan is selective and independent of the size and hardness of metal ions, or the physical form of chitosan (e.g., film, powder and solution). Both -OH and -NH2 groups in chitosan provide vital binding sites for complexing metal cations. At low pH, -NH3 + groups attract and coagulate negatively charged contaminants such as metal oxyanions, humic acids and dye molecules. Grafting certain functional molecules into the chitin structure improves sorption capacity and selectivity for remediating specific metal ions. For example, introducing sulfur and nitrogen donor ligands to chitosan alters the sorption preference for metals. Low molecular weight chitosan derivatives have been used to remediate metal contaminated soil and sediments. They have also been applied in permeable reactive barriers to remediate metals in soil and groun...

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“…Among those biomass, chitosan has been proved to be an extremely promising material due to its high chelating ability, higher hydrophilicity, environmentally safe, and abundant base material. Chitosan also has been proposed as biopolymers for mercury removal [12][13][14]. However, the application of chitosan to Hg determination is less reported.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of chitosan-based resins modified with tris(2-aminoethyl)amine moiety and its application to collection/concentration and determination of trace mercury by inductively coupled plasma atomic emission spectrometry

Hakim

Sabarudin

Oshita

et al. 2008

Talanta

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(Shoji Motomizu) A novel chitosan-based chelating resin modified with tris(2-aminoethyl)amine was synthesized, and the resin capability in the collection/concentration of mercury was examined.The synthesized resin showed good adsorption toward mercury in wide pH range, and the adsorbed mercury can be easily eluted by using 2 M HNO 3 without any addition of complexing agent. The resin was then packed in a mini-column and the mini-column was installed on an automated pretreatment system coupled with ICP-AES (Auto-Pret AES system). The proposed method had demonstrated that CCTS-TAA along with Auto-Pret AES system can be applied to the on-line concentration/collection and determination of mercury in aqueous solution.

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Adsorption Behavior of Mercury and Precious Metals on Cross-Linked Chitosan and the Removal of Ultratrace Amounts of Mercury in Concentrated Hydrochloric Acid by a Column Treatment with Cross-Linked Chitosan

Cited by 44 publications

References 19 publications

Mechanism of Gold Adsorption by Persimmon Tannin Gel

Mechanism of Gold Adsorption by Persimmon Tannin Gel

Environmental Applications of Chitosan and Its Derivatives

Synthesis of chitosan-based resins modified with tris(2-aminoethyl)amine moiety and its application to collection/concentration and determination of trace mercury by inductively coupled plasma atomic emission spectrometry

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