Microbial oxidation of graphite by Acidithiobacillus ferrooxidans CFMI-1

Abstract

A simple and environmentally-friendly bio-oxidation approach to produce graphite oxide nanosheets is described.

Extracellular electron uptake from carbon-based π electron surface-donors: oxidation of graphite sheets by Sulfobacillus thermosulfidooxidans probed by Raman and FTIR spectroscopies

“…The measured I D /I G of pure graphite sheets is 0.07 in full agreement with previous measurements and remains constant in the control experiment which is consisted of the growth medium of the S. thermosuldooxidans-graphite sheets (spectrum B) indicating that the bacteria growth material has no effect on the surface properties of graphite sheet. 9 In spectra C, D, and E there is a 2-3 cm À1 frequency up-shi of both the D and G bands. The presence of the D 0 at 1620 cm À1 in spectra C, D, and E indicates that there are some randomly distributed impurities or surface charges on the surface of graphite sheets and thus the G-peak splits into two peaks, the G-peak at 1582 cm À1 and the D 0 peak at 1620 cm À1 .…”

“…The frequencies, intensity ratio and FWHM of both the D and G Raman bands are in agreement with those previously reported. 9,14,15 A ratio of the intensities of D and G bands (I D /I G ) determines the relative defect content in the carbon lattice. The measured I D /I G of pure graphite sheets is 0.07 in full agreement with previous measurements and remains constant in the control experiment which is consisted of the growth medium of the S. thermosuldooxidans-graphite sheets (spectrum B) indicating that the bacteria growth material has no effect on the surface properties of graphite sheet.…”

“…7,8 Thiobacillus ferrooxidans is involved in electricity generation in microbial fuel cell systems acting as the cathode and by an unknown mechanism, oxidize graphite powder. 9 It was proposed that the oxidation of graphite occurred in the periplasm space by the copper protein rusticyanin acting as the electron acceptor. 9 In terms of the electron transfer mechanisms, direct and indirect mechanisms concerning the action of T. ferrooxidans with sulde minerals have been proposed in the eld of hydrometallurgy.…”

“…9 It was proposed that the oxidation of graphite occurred in the periplasm space by the copper protein rusticyanin acting as the electron acceptor. 9 In terms of the electron transfer mechanisms, direct and indirect mechanisms concerning the action of T. ferrooxidans with sulde minerals have been proposed in the eld of hydrometallurgy. 7,8 Members of the genus Sulfobacillus are Gram-positive bacteria, moderately thermophilic acidophiles, metal-tolerant that promote sulde mineral dissolution and occur in acidic habitats, hydrothermal vents, and in industrial hydrometallurgy operations.…”

“…We provide experimental evidence that graphite is oxidized and forms GO with I D /I G ¼ 0.3 which represents the highest defect content in the carbon lattice by a bio-oxidation process in much shorter times compared to those previously reported. 9 The techniques illustrate the potential of the techniques to perform ultrasensitive chemical analysis on graphite sheets and bio-lms, including the detection of different components and the determination of their relative abundance on the surface of graphite. 7,8,12,13 The biolm formation which mediates the adhesion of the microorganism to the surface of graphite sheets is demonstrated by the presence of FTIR bands in the 1100-1300 cm À1 bands and the formation of GO is characterized by the bands at 3347 and 3463 cm À1 which are attributed to the stretching vibration of -OH groups (V O-H ) either from -OH groups of absorbed water or -OH groups formed during the oxidation.…”