Abstract Carbon steel corrosion inhibition in a hydrochloric acid solution by 2-((5-methyl-isoxazol-3-yl)-methyl)-benzimidazole (MMB) has been studied by electrochemical techniques (PDP and EIS). Results showed that the inhibition efficiency increases with higher MMB concentration, and the maximum value of 86.6% was obtained at 10-3 M concentration. The prepared benzimidazole inhibitor showed higher inhibition efficiency upon raising the solution temperature from 303 to 333 K. Corrosion current density decreased from 660.9 µA cm-2 (blank) to 97.8 µA cm-2 (MMB) and charge transfer resistance increased from 20.2 Ω cm2 (blank) to 150.8 Ω cm2 (MMB). PDP studies showed that MMB is a mixed type inhibitor. The adsorption of this compound onto the carbon steel surface in a 1 M HCl solution followed the Langmuir adsorption isotherm, and the value of the standard free energy of adsorption () is associated to physisorption and chemisorption.

New corrosion inhibitors of benzimidazole derivatives, namely: 6-methoxy-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfinyl)-1-vinyl-1H-benzo(d)imidazole (EMSB), 6-Methoxy-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)) sulfinyl)-1-(prop-2-yn-1-yl)-1H benzimidazole (MSVB) and 6-methoxy-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfinyl)-1-(phenacyl)-1-H benzimidazole (MSBP), have been synthesized and their inhibiting action on the corrosion of carbon steel in acidic bath (1 M HCl) has been investigated by various corrosion monitoring techniques, such as weight loss measurement, potentiodynamic polarization, adsorption, electrochemical impedance spectroscopy (EIS) and basic computational calculations. The results of the investigation show that the inhibition efficiency of all the three inhibitors increases with increase in concentration of inhibitors and decreases with increase in temperature. The inhibitors, MSBP, MSVP, and EMSB show corrosion inhibition efficiency of 98, 97 and 93% respectively, at 10-3 M and 303 K. EIS measurements showed an increase of the transfer resistance with the inhibitors concentration. Polarization studies showed that the studied inhibitors are mixed type in nature and the adsorption of benzimidazole is described by the Langmuir isotherm. In addition, density functional theory (DFT) calculations and molecular dynamics simulations (MDS) were undertaken to describe the electronic and adsorption properties of the synthesized inhibitors constituents, including the synergistic/dispersive interactive effects of the multiple adsorptions of the various active constituents in the inhibitor film on the iron surface. Also DFT and Molecular dynamic (MD) simulations were employed to correlate the experimental findings.

Penicillium canescens 10-10c strain was cultivated on barley straw hydrolysate as a soluble nutrient source and as inducer for xylanase production. Barley straw hydrolysate was obtained by treatment of barley straw with NaOH or hot water. In shake flask cultures, NaOH treatment was found to increase the biomass production, but was not accompanied by an increase in xylanase production. The best xylanase production (54 U/ml) was observed on hydrolyzed extract from barley straw treated with hot water (100 ºC) for 3 hours. Enzyme production was further improved by scaling up the cultivation process to a 3-L stirred tank bioreactor. For batch cultivations in the bioreactor, the maximum xylanase productivity reached 1.31 and 0.46 U/ml/h, respectively, after 96 and 168 hours of cultivation. However, xylanase productivity reached 3.46 U/ml/h in the continuous culture. These results suggest that xylanase can be produced efficiently by Penicillium canescens 10-10c in continuous culture from an inexpensive source such as barley straw hydrolysate.