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The influence of three different solvents including lactic acid, formic acid, and acetic acid on the constant-voltage electrodeposition behavior of chitosan biopolymer was investigated. In this regard, charge density, viscosity, and some molecular parameters of chitosan solutions in aqueous acids were studied. The mechanism of chitosan film formation was investigated by fitting the current density–time experimental data to the Pierce and Miskovic film growth models. It was found that solvents have a significant influence on the molecular structure and electrodeposition behavior of chitosan. Using formic acid as the solvent caused the best electrophoretic mobility and resulted in a less porous film compared to acetic acid and lactic acid. [ABSTRACT FROM PUBLISHER]

The aim of this study was to produce a biosurfactant (rhamnolipid) from an autochthonousPseudomonas aeruginosaMM1011, which previously isolated from soil contaminated with crude oil over years. Produced biosurfactant subjected to different pressure 60–150 MPa, through high-pressure homogenization, for three cycles to produce nano-biosurfactant. Results showed that, homogenization was capable of producing nano-rhamnolipid (diameter as small as 631.4 nm). Homogenization pressure (about 90 MPa), were responding better than higher or lower pressures. Stability analysis supported a shelf life of up to one year at room temperature. This is the first report on stability of nano rhamnolipid using locally isolatedPseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

Vacuum residue obtained from Tehran oil refinery vacuum distillation tower and used in a bubble column fermentor as the sole source of carbon and energy in minimal salts medium and different aeration applied. The best results for bacterial growth obtained at 0.08–0.3 v.v.m. Specific gravity of vacuum residue after biodegradation also decreased from 0.98 to 0.95. Decreasing specific gravity could be an indication for bio-lightening. Gas holdup was in the range of 0.007 to 0.062 and was well fitted with Hugmark correlation. [ABSTRACT FROM PUBLISHER]