Recovery of precious metals by using chemically modified waste paper

Adhikari, Chaitanya Raj; Parajuli, Durga; Inoue, Katsutoshi; Ohto, Keisuke; Kawakita, Hidetaka; Harada, Hiroyuki

doi:10.1039/b802946f

Cited by 52 publications

(31 citation statements)

References 33 publications

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“…These results prove that gold particles formed on gel surface by the reduction process exhibit a certain sort of tendency to be detached from the gel surface forming clear aggregates. A similar observation was also found in our previous study (Adhikari et al 2008). …”

Section: Adsorption Isothermssupporting

confidence: 86%

Selective recovery of gold(III) using cotton cellulose treated with concentrated sulfuric acid

et al. 2011

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Novel utilization of cotton cellulose was developed by chemically modifying with concentrated sulfuric acid to prepare a novel kind of adsorption gel for gold. The adsorption behaviors of the gel were investigated for various metals from acidic chloride media. The gel was found to be highly selective for Au(III) over other precious and base metals tested over the whole concentration range of hydrochloric acid. The maximum adsorption capacity for Au(III) was evaluated as 6.21 mmol/g at 303 K. The amount of adsorbed Au(III) was increased with increasing temperature. A kinetic study for the adsorption of Au(III) at various temperatures confirmed the endothermic adsorption process following pseudo-first order kinetics. The activation energy was evaluated as 78.8 kJ/mol. Interestingly, it was found that the adsorbed Au(III) was reduced to elemental form which was evidenced by the clearly visible elemental gold particles which was further confirmed by means of the X-ray diffraction spectrum and optical microscope image of the gel after the adsorption of Au(III). The mechanism of Au(III) adsorption on the cotton gel and its reduction to elemental gold was proved from the results of IRspectra. The main mechanism could be explained in terms of the coordination of Au(III) to oxygen atom of C-O-C linkage of cross linked cotton gel and to the oxygen atoms of the hydroxyl groups at C 2 and C 3 atoms of pyranose ring of cotton cellulose followed by the reduction to metallic gold. The adsorbed gold in the cotton gel can easily be recovered by incineration.

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Section: Adsorption Isothermssupporting

confidence: 86%

Selective recovery of gold(III) using cotton cellulose treated with concentrated sulfuric acid

et al. 2011

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“…The presence of chloride or nitrate species basically facilitates the formation of palladium-chloride/nitrate anionic complexes and eases the ionic interaction between protonated amine groups present in the adsorbent [14,15]. However, the presence of an excess of such anions reduces the metal recovery because the metalanion complex and the anion itself compete for ionic interaction with the positively charged amine group.…”

Section: Adsorption Behavior Of Modified Cwp For Pd(ii)mentioning

confidence: 98%

Recovery of palladium using chemically modified cedar wood powder

Parajuli

Hirota

2009

Journal of Colloid and Interface Science

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“…Persimmon wastes were reported to be utilized for adsorption of heavy metals and precious metals from aqueous systems [15][16][17][18][19][20][21]. Nakajima et al reported that the persimmon tannin gel can adsorb vanadium effectively from aqueous solutions containing VOCl 2 and NH 4 VO 3 [15].…”

Section: Introductionmentioning

confidence: 98%