Dimethylamine-Modified Waste Paper for the Recovery of Precious Metals

Abstract

Waste newsprint paper was modified with dimethylamine (DMA) to obtain a tertiary amine type adsorption gel called DMA-paper gel. This new derivative was investigated for adsorption, from hydrochloric acid medium, of gold, palladium, and platinum as well as some base metals. The gel exhibited selectivity only for precious metals with a remarkably high capacity for Au(III), i.e., 4.6 mol/kg dry gel and comparable capacities, i.e., 2.1 and 0.9 mol/kg for Pd(II) and Pt(IV), respectively. Also, Au(III) was reduced to the elemental form during adsorption. Furthermore, column adsorption and subsequent elution of the adsorbed metal ions by acidic thiourea revealed encouraging recoveries (approximately 90%), thus enhancing the scope of the gel for effective preconcentration, separation, and recovery of precious metals. The effectiveness of recovery of precious metals from real industrial liquor was also tested, and it showed highly encouraging results with respect to the stability of the gel in the harsh medium, and selectivity for the targeted metal ions in the presence of excess of other metal ions.

Hydrometallurgical Recovery of Precious Metals and Removal of Hazardous Metals Using Persimmon Tannin and Persimmon Wastes

“…It is easy to chemically modify persimmon tannin extract and persimmon waste including persimmon peel by immobilizing a variety of functional groups which exhibit special affinities for some metal ions onto their surface similar to other biomass wastes [41,42]. In our research works, persimmon waste was chemically modified by immobilizing functional group of dimethylamine (DMA) to prepare the adsorption gel functioning as a typical weak base type of anion exchange material and investigated its adsorption behavior for some precious and base metals from hydrochloric acid solutions [35,36].…”

Study on the adsorption behavior of modified persimmon powder biosorbent on Pt(IV)

“…It can be seen that when the temperature increases from 293 to 333 K, the Pt(IV) adsorption by GPP increases slowly. Further increasing modified temperature, the Pt(IV) adsorption tends to decrease, which can be ascribed to the dissolution and decomposition of active ingredients in persimmon, thus hindering the Mannich reaction occurrence (Adhikari et al 2008). …”

N-(2-(2-Pyridyl)ethyl)chitosan (PEC) for Pd(II) and Pt(IV) sorption from HCl solutions

“…Thiourea is a ligand that was frequently used for the recovery of precious metals from loaded sorbents and resins. This ligand is generally used in acidic solutions for enhancing metal recovery (Sanchez et al 2001;Adhikari et al 2008;Donia et al 2005). Tables 5 and 6 show the results obtained varying both thiourea and HCl concentration These solutions were used for testing the recycling of the resins.…”

“…However, recently a number of alternative materials have been investigated for the recovery of PGMs from dilute acid solutions. These new materials issued from renewable resources are part of the new class of biosorbents, including algal, bacterial or fungal biomass (Turner et al 2007), biopolymers (Laudenslager et al 2008;Dang et al 2008;Jaworska et al 2003;Ruiz et al 2001Ruiz et al , 2002Guibal et al 1999a, b;Kondo et al 1997;Inoue et al 1993), waste materials from agriculture (Parajuli et al , 2009, and even modified waste materials such as waste newspaper (Adhikari et al 2008). These biosorbents are generally binding metal ions through sorption mechanisms comparable to those used for ion exchange and chelating resins, with the major interest of using low cost materials, with, in most cases, more environmentally friendly properties (i.e., renewable, more benign thermal degradation at the end of life cycle) than conventional resins.…”