Selective recovery of precious metals by persimmon waste chemically modified with dimethylamine.

Department of Applied Chemistry, Saga University, 1-Honjo, Saga 840-8502, Japan.
Bioresource Technology (Impact Factor: 5.04). 05/2009; 100(18):4083-9. DOI: 10.1016/j.biortech.2009.03.014
Source: PubMed

ABSTRACT Persimmon waste was chemically modified with dimethylamine (DMA) to obtain a tertiary-amine-type gel, named DMA persimmon waste gel (DMA-PW). It was found to be effective for the adsorption of Au(III), Pd(II), and Pt(IV) in hydrochloric acid medium. In contrast, base metals such as Cu(II), Zn(II), Fe(III), and Ni(II) were not practically adsorbed. The formation of ion pairs of the metal chloro complex anions with the protonated adsorption gels was proposed as the main adsorption process. The gel exhibited selectivity only for precious metals with a remarkably high capacity for Au(III), i.e., 5.63 mol/kg dry gel and comparable capacities, i.e., 0.42 and 0.28 mol/kg for Pd(II) and Pt(IV), respectively. According to the kinetic and electrochemical studies, the adsorption rate of Au(III) was greatly enhanced by the chemical modification. Also, its excellent adsorption characteristics for the precious metals were confirmed by adsorption and elution tests using a column packed with the DMA-PW gel.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Various types of protein-rich biomass were examined as selective and environment-friendly absorbents for precious metal ions. In the presence of base metal ions, Au3+, Pd2+ and Pt4+ ions were selectively adsorbed to samples of protein-rich biomass. Among the biomass samples tested, egg-shell membrane exhibited the highest adsorption ability and had high selectivity for Au, Pd and Pt ions. The maximum adsorption amount of Au, Pd and Pt ions to egg-shell membrane was approximately 250, 110 and 50 mg/g, respectively, in the presence of 0.1 M HCl. Microscopic observations and metal-ion desorption studies suggested that the precious metal ions were adsorbed and a portion of them was reduced to form metal nanoparticles on the egg-shell membrane, leading to high adsorption ratios. Investigations using glycoproteins indicated the importance of sugar chains in the adsorption of Au ions to the egg-shell membrane. Successful recovery of Au, Pd and Pt ions from industrial waste solutions was also demonstrated using egg-shell membrane. Biomass sheets (1 mm thick) made from egg-shell membrane also exhibited adsorption abilities for precious metal ions.
    PROCESS BIOCHEMISTRY 05/2014; · 2.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A low cost bio-sorbent, named "PPF resin", was prepared by crosslinking the persimmon residual with formaldehyde. The adsorption behavior of PPF resin towards Au(III) from varied HCl and HNO3 concentration solutions was studied. PPF resin could adsorb almost complete Au(III) from high acidic systems. The influence of dilution ratio, solid-liquid ratio and time towards Au(III) from aqua regia leached PCBs liquor was censored in detail by batch and continuous adsorption methods. The PPF resin before and after adsorption was characterized by FT-IR, XRD and XPS spectra which provided evidences for the reduction of Au(III) to Au(0) with a proposed mechanism of Au(III) adsorption-reduction process. After saturated column adsorption of 0.1g PPF resin, 0.0506g gold (purity: 99.9%) was obtained by the method of incineration. The present results provide a new approach for gold recovery from the secondary resources.
    Bioresource Technology 04/2014; 163C:167-171. · 5.04 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A novel type of adsorption gel was prepared from filter paper by treating it with concentrated sulfuric acid to investigate the efficient adsorption of Au(III) from aqueous acidic chloride media. Various parameters have been examined for the recovery of gold such as effects of hydrochloric acid concentrations, contact time, initial Au(III) concentrations, and temperature. The adsorption of gold was fitted with the Langmuir type adsorption model, and the maximum adsorption capacity of gold was evaluated as 5.05 mmol·g−1. The kinetics of gold adsorption was interpreted in terms of the pseudofirst-order kinetic model, and the activation energy was evaluated as 61.3 kJ·mol−1. The gold adsorbed by the paper gel was measured by means of X-ray diffraction spectrum, scanning electron microscope (SEM), and an optical microscope. The inferred mechanism for the adsorption of Au(III), followed by its reduction to elemental gold, was proposed based on the observation of infrared spectroscopic analysis. It was inferred that Au(III) was adsorbed by the coordination to oxygen atom of C−O−C linkage formed after the cross-linking with concentrated sulfuric acid, as well as the oxygen atoms of hydroxyl groups of pyranose
    Journal of Chemical & Engineering Data 02/2012; 57:796-804. · 2.00 Impact Factor


Available from
May 29, 2014