Mechanistic approach on comparative biosorption of dyes by extracellular polymer of Ochrobactrum pseudintermedium C1 utilizing waste mineral lubricating oil

Abstract

Dyes are widely used in manufacturing of various consumer products for their ability to impart characteristic color. However, dyes are also one of the most important hazardous pollutants in this present day. Presence of hydroxyl, phosphate, ether, carbonyl and alkyl groups also enable bacterial extracellular polymers to function as biosorbent. In this study, negatively charged biosorbent EP-C1 produced by Gram-negative bacterium Ochrobactrum pseudintermedium C1 utilizing waste mineral lubricating oil has given different decolorization percentages for triphenylmethane cationic Malachite Green and azoic anionic Congo Red at neutral pH. Time wise absorbances from Ultraviolet-Visible Spectrophotometry has estimated maximum biosorption of Malachite Green after 300 min. Biosorption capacities have differed with initial dye concentrations, biosorbent dosages and contact time. Time taken by each dye to reach saturation has depended upon their charged bearing groups of each dye and biosorbent. Kinetic (pseudo first and pseudo second order) and diffusion (intra particle and liquid film) parameters in presence of different dye concentrations and biosorbent dosages were studied for understanding the biosorption mechanism. Morphological differences in chemical structure, chemical functional groups of EP-C1 and EP-C1 loaded dye was studied by Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy and Zeta potential measurements. A compiled overview on comparative mechanistic biosorption of Malachite Green and Congo Red dyes by a bacterial extracellular polymer in miniature laboratory shake flask experiments was done in this study. Newer advents on biological remediation of dyes with mineral lubricating oil as sole carbon source can add a new feather to the already available bioremediation techniques in mitigation of hazardous wastes.