title: Selective recovery of precious metals by persimmon waste chemically modified with dimethylamine.
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.
authors.affiliation: Department of Applied Chemistry, Saga University, 1-Honjo, Saga 840-8502, Japan.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiong
authors.forename: Chaitanya Raj
authors.initials: CR
authors.lastname: Adhikari
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Kawakita
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ohto
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Inoue
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Harada
mesh_terms: D000327:Adsorption; D003247:Conservation of Natural Resources; D004123:Dimethylamines / Q000737:chemistry*; D019652:Extraction and Processing Industry; D007700:Kinetics; D008670:Metals / Q000302:isolation & purification*
chemical_list: D004123:Dimethylamines; D008670:Metals; C034516:dimethylamine