title: Biogenic nanopalladium production by self-immobilized granular biomass: application for contaminant remediation.
abstract: Microbial granules cultivated in an aerobic bubble column sequencing batch reactor were used for reduction of Pd(II) and formation of biomass associated Pd(0) nanoparticles (Bio-Pd) for reductive transformation of organic and inorganic contaminants. Addition of Pd(II) to microbial granules incubated under fermentative conditions resulted in rapid formation of Bio-Pd. The reduction of soluble Pd(II) to biomass associated Pd(0) was predominantly mediated by H2 produced through fermentation. X-ray diffraction and scanning electron microscope analysis revealed that the produced Pd nanoparticles were associated with the microbial granules. The catalytic activity of Bio-Pd was determined using p-nitrophenol and Cr(VI) as model compounds. Reductive transformation of p-nitrophenol by Bio-Pd was ∼20 times higher in comparison to microbial granules without Pd. Complete reduction of up to 0.25 mM of Cr(VI) by Bio-Pd was achieved in 24 h. Bio-Pd synthesis using self-immobilized microbial granules is advantageous and obviates the need for nanoparticle encapsulation or use of barrier membranes for retaining Bio-Pd in practical applications. In short, microbial granules offer a dual purpose system for Bio-Pd production and retention, wherein in situ generated H2 serves as electron donor powering biotransformations.
authors.affiliation: Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam 603102, Tamil Nadu, India.
authors.forename: E
authors.initials: E
authors.lastname: Suja
authors.affiliation: Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam 603102, Tamil Nadu, India.
authors.forename: Y V
authors.initials: YV
authors.lastname: Nancharaiah
authors.affiliation: Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam 603102, Tamil Nadu, India. Electronic address: vpv@igcar.gov.in.
authors.forename: V P
authors.initials: VP
authors.lastname: Venugopalan
mesh_terms: D018533:Biomass; D002384:Catalysis; D002857:Chromium / Q000737:chemistry; D004785:Environmental Pollutants / Q000737:chemistry*; D052918:Environmental Restoration and Remediation; D005285:Fermentation; D006859:Hydrogen / Q000378:metabolism; D053768:Metal Nanoparticles; D059013:Microbial Consortia; D008855:Microscopy, Electron, Scanning; D009596:Nitrophenols / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D004785:Environmental Pollutants; D009596:Nitrophenols; D002857:Chromium; D010165:Palladium; D006859:Hydrogen; C024836:4-nitrophenol
keywords: Aerobic granular biomass; Bio-Pd; Cr(VI); Microbial granules; Palladium; p-nitrophenol