title: Biosorption of gold from computer microprocessor leachate solutions using chitin.
abstract: The biosorption of gold from discarded computer microprocessor (DCM) leachate solutions was studied using chitin as a biosorbent. The DCM components were leached with thiourea solutions, and two procedures were tested for recovery of gold from the leachates: (1) biosorption and (2) precipitation followed by biosorption. For each procedure, the biosorption was evaluated considering kinetic, equilibrium, and thermodynamic aspects. The general order model was able to represent the kinetic behavior, and the equilibrium was well represented by the BET model. The maximum biosorption capacities were around 35 mg g(-1) for both procedures. The biosorption of gold on chitin was a spontaneous, favorable, and exothermic process. It was found that precipitation followed by biosorption resulted in the best gold recovery, because other species were removed from the leachate solution in the precipitation step. This method enabled about 80% of the gold to be recovered, using 20 g L(-1) of chitin at 298 K for 4 h.
authors.affiliation: Environmental Processes Laboratory, Chemical Engineering Department, Federal University of Santa Maria - UFSM, Santa Maria, RS, Brazil. Electronic address: leticiacortes@hotmail.com.
authors.forename: Letícia N
authors.initials: LN
authors.lastname: Côrtes
authors.affiliation: Environmental Processes Laboratory, Chemical Engineering Department, Federal University of Santa Maria - UFSM, Santa Maria, RS, Brazil. Electronic address: edutanabe@yahoo.com.br.
authors.forename: Eduardo H
authors.initials: EH
authors.lastname: Tanabe
authors.affiliation: Environmental Processes Laboratory, Chemical Engineering Department, Federal University of Santa Maria - UFSM, Santa Maria, RS, Brazil. Electronic address: dbertuol@gmail.com.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Bertuol
authors.affiliation: Environmental Processes Laboratory, Chemical Engineering Department, Federal University of Santa Maria - UFSM, Santa Maria, RS, Brazil. Electronic address: guilherme_dotto@yahoo.com.br.
authors.forename: Guilherme L
authors.initials: GL
authors.lastname: Dotto
mesh_terms: D000327:Adsorption; D002686:Chitin / Q000737:chemistry*; D059029:Electronic Waste / Q000032:analysis*; D006046:Gold / Q000737:chemistry*; D008838:Microcomputers; D008855:Microscopy, Electron, Scanning; D059027:Recycling / Q000379:methods*; D013052:Spectrometry, X-Ray Emission; D018505:Waste Management / Q000379:methods*
chemical_list: D002686:Chitin; D006046:Gold
keywords: Biosorption; Chitin; Computer microprocessors; Gold; Precipitation