Mechanism of adsorption of gold and silver species on activated carbons

Jia, Yongfeng; Steele, Carl J.; Hayward, Ian; Thomas, K. Mark

doi:10.1016/s0008-6223(98)00091-8

Cited by 85 publications

(38 citation statements)

References 22 publications

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“…Aqueous metal ions have different affinities for various functional groups such as carboxylic and phenolic groups present on the carbon surface [24]. Although they are considered to be adsorbed via complex mechanisms [25][26][27] ion exchange seems to be the predominant mechanism of the removal process [5,24]. Moreover it is well known that several factors including the pH value, initial concentration, the speciation of metal ions and surface charge affect the adsorption of metal species from aqueous solutions [28].…”

Section: Introductionmentioning

confidence: 99%

Investigation of factors affecting adsorption of transition metals on oxidized carbon nanotubes

Gao

Bandosz

Zhao

et al. 2009

Journal of Hazardous Materials

225

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Section: Introductionmentioning

confidence: 99%

Investigation of factors affecting adsorption of transition metals on oxidized carbon nanotubes

Gao

Bandosz

Zhao

et al. 2009

Journal of Hazardous Materials

225

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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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“…Table compares the maximum Ag(I) ion adsorption capacities of the LS‐PPY nanocomposite with those of different biomass‐based adsorbents reported in recent years . It can be easily seen that the LS‐PPY nanocomposite displayed a high adsorption capacity for Ag(I)ions.…”

Section: Resultsmentioning

confidence: 97%

Controllable preparation and heavy‐metal‐ion adsorption of lignosulfonate‐polypyrrole composite nanosorbent

Luo

Lü

2014

Polymer Composites

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Lignosulfonate‐polypyrrole (LS‐PPY) composite nanospheres were prepared facilely via an in situ polymerization of pyrrole monomers in the presence of lignosulfonate as a dispersant and ammonium persulfate as an oxidant. The LS‐PPY composite was characterized with Fourier Transform infrared spectroscopy (FTIR), thermogravimetric analysis, wide‐angle X‐ray diffraction (XRD), scanning electron microscopy (SEM), field‐emission SEM, and transmission electron microscopy. Uniform LS‐PPY solid composite nanospheres with an average diameter of 154 nm were obtained. The LS‐PPY composite nanospheres were applied to adsorption of Ag(I) and Pb(II) ions from aqueous solutions. Maximum adsorption capacities of Ag(I) and Pb(II) were up to 759.3 mg g−1 and 207.5 mg g−1, respectively. Furthermore, the silver ions can be reduced to metallic silver nanowires through a redox reaction between the LS‐PPY composite nanospheres and the silver ions. A productive no‐template route to fabrication of LS‐PPY composite nanospheres with controllable size and heavy‐metal‐ion adsorption ability was achieved. POLYM. COMPOS., 36:1546–1556, 2015. © 2014 Society of Plastics Engineers

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Mechanism of adsorption of gold and silver species on activated carbons

Cited by 85 publications

References 22 publications

Investigation of factors affecting adsorption of transition metals on oxidized carbon nanotubes

Investigation of factors affecting adsorption of transition metals on oxidized carbon nanotubes

Mechanism of Gold Adsorption by Persimmon Tannin Gel

Controllable preparation and heavy‐metal‐ion adsorption of lignosulfonate‐polypyrrole composite nanosorbent

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