Recovery of Valuable Metals from Aqueous Systems Using Microbial Thermophilic Proteins as the Biosorbents

  • 柯 迷諾

Student thesis: Master's Thesis


The global demands and market prices of noble metals (e g Aurum (or gold) Platinum and Rhodium) have markedly increased Because of special physical and chemical characteristics of noble metals the process of noble metal mining requires employment of expensive technology making the cost of mining process higher than received economic benefits One of the ways to collect rare earth metal with low mining process cost and high selectivity is using microorganisms or their derived products (such as proteins) to directly adsorb the metals Literature shows that some proteins possess functional groups that can provide specific metal binding sites (metal-binding domains) to chelate metal ions In this study noble metals such as Aurum (or gold) Rhodium and Platinum in aqueous system were recovered via biosorption using proteins produced from an isolated bacterial strain Thermophilic strain Modified Thermus Enhanced Medium was found to be a suitable medium to improve the protein production of the thermophilic strain The optimal conditions of protein production were temperature 55oC; agitation rate 200 rpm; initial pH 7 Sucrose with a concentration of 0 5 g/L was selected as carbon source and urea as nitrogen source A carbon to nitrogen ratio (C/N ratio) of 2 was considered as the best composition of carbon and nitrogen concentration to increase the protein production Finally the microbial protein produced from thermophilic strain showed effective adsorption ability for Platinum (Pt) Aurum (Au) and Rhodium (Rh) The optimum adsorption condition for Pt occurred at pH 2 with an adsorption capacity of 231 6 mg/g protein For Au the optimum adsorption condition occurred at pH 1 with an adsorption capacity of 482 0 mg/g protein For Pd metal the optimum adsorption condition occurred at pH 3 with an adsorption capacity of 395 5 mg/g protein For Rh metal the adsorption optimum condition occurred at pH 3 with an adsorption capacity of 712 7 mg/g protein The metal adsorption capacity increased with an increase in temperature When the temperature was increased to 100oC the metal adsorption capacity for Pt Au Pd and Rh reached 252 2 483 2 727 4 and 386 0 mg/mg protein The adsorption isotherm was conducted at room temperature The adsorption of Pt Au Pd and Rh could be well fitted by the Freundlich isotherm equation Among the desorption agents examined combination of 1 5 M Thiourea with 1 N HCl can effectively desorb the Pt Au Pd and Rh metal ion from microbial protein with over 90% metal recovery
Date of Award2014 Aug 4
Original languageEnglish
SupervisorJo-Shu Chang (Supervisor)

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