title: Platinum and rhenium extraction from a spent refinery catalyst using Bacillus megaterium as a cyanogenic bacterium: statistical modeling and process optimization.
abstract: The present study evaluated the potential of Bacillus megaterium as a cyanogenic bacterium to produce cyanide for solubilization of platinum and rhenium from a spent refinery catalyst. Response surface methodology was applied to study the effects and interaction between two main effective parameters including initial glycine concentration and pulp density. Maximum Pt and Re recovery was obtained 15.7% and 98%, respectively, under optimum conditions of 12.8 g/l initial glycine concentration and 4% (w/v) pulp density after 7 days. Increasing the free cyanide concentration to 3.6 mg/l, varying the pH from 6.7 to 9, and increasing the dissolved oxygen from 2 to 5mg/l demonstrated the growth characteristics of B. megaterium during bioleaching process. The modified shrinking core model was used to determine the rate limiting step of the process. It was found that diffusion through the product layer is the rate controlling step.
authors.affiliation: Biotechnology Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Motaghed
authors.affiliation: Biotechnology Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, Iran. Electronic address: mousavi_m@modares.ac.ir.
authors.forename: S M
authors.initials: SM
authors.lastname: Mousavi
authors.affiliation: Biotechnology Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, Iran.
authors.forename: S O
authors.initials: SO
authors.lastname: Rastegar
authors.affiliation: Biotechnology Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, Iran.
authors.forename: S A
authors.initials: SA
authors.lastname: Shojaosadati
mesh_terms: D001410:Bacillus megaterium / Q000378:metabolism*; D019149:Bioreactors; D018929:Cell Culture Techniques; D006856:Hydrogen Cyanide / Q000378:metabolism*; D015233:Models, Statistical; D010578:Petroleum; D010984:Platinum / Q000302:isolation & purification* / Q000378:metabolism; D012211:Rhenium / Q000302:isolation & purification* / Q000378:metabolism; D014866:Waste Products / Q000032:analysis*
chemical_list: D010578:Petroleum; D014866:Waste Products; D006856:Hydrogen Cyanide; D010984:Platinum; D012211:Rhenium
keywords: Bacillus megaterium; Kinetics; Process optimization; Pt and Re recovery; Spent refinery catalyst