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The present study dealt with the interaction of dichloromethane (DCM) with other non-chlorinated organic solvents such as methanol, acetone, toluene, and benzene, which are commonly present in the pharmaceutical wastewater, during biodegradation by mixed bacterial consortium. Non-chlorinated solvents were easily degradable even at an initial concentration of 1,000 mg/L, whereas only 20 mg/L of DCM was degraded when used as sole carbon source. The Monod Inhibition model appears to simulate the single pollutant biodegradation kinetics satisfactorily. In dual substrate systems, low concentrations (100 mg/L) of non-chlorinated solvents did not interfere with the DCM degradation. Non-interaction sum kinetics model was able to simulate the experimental results well in this case. However, high concentrations of non-chlorinated solvents (1,000 mg/L) affected the DCM degradation significantly. There was severe competition between the chlorinated and the non-chlorinated solvents. In this case, competitive inhibition model predicted the experimental results better compared to co-metabolism model. In multiple substrate system also, presence of DCM prolonged the degradation of the other non-chlorinated solvents. However, the presence of non-chlorinated compounds accelerated the degradation of DCM. The results of the present study may be helpful in optimal design of biological systems treating mixed pollutants.

The inhibitive effect of Abelmoschus esculentus seed extract on the corrosion of mild steel in sulphuric acid was investigated using gravimetric, potentiodynamic and electrochemical impedance spectroscopy (EIS) techniques. The results obtained showed that Abelmoschus esculentus seed extract could serve as an effective inhibitor for the corrosion of mild steel in sulphuric acid. The percentage inhibition increased with increasing concentration of the extract at room temperature. Maximum inhibition efficiency of 90 % was obtained with 0.5 % v/v concentration. The inhibition efficiencies obtained from impedance and polarization measurements were in good agreement. Poteniodynamic polarization studies clearly revealed that the extract behave as mixed type inhibitor. The inhibition efficiency was significantly affected by the temperature of the medium. The synergism parameters (S) obtained was found to be greater than unity which indicates that the enhanced inhibition efficiency caused by the addition of halides is only due to synergism.

The synergistic effect of halide ions such as KCl, KBr and KI on the corrosion inhibition of mild steel in 1 N sulphuric acid by [Formula: see text]-2,c-6-diphenyl-t-3-methyl piperdin-4-ones with semicarbazone (01[Formula: see text]SC), [Formula: see text]-2,c-6-diphenyl-N-methyl-t-3-ethyl piperdin-4-ones with semicarbazone (02[Formula: see text]SC) and 2,6-diphenyl-t-3-ethyl piperdin-4-one with semicarbazone (03[Formula: see text]SC) has been examined by weight loss method, potentiodynamic polarization measurements and electrochemical AC impedance spectroscopy. Results show that substituted [Formula: see text]-2,c-6-diphenyl piperidin-4-ones with semicarbazone act as the perfect corrosion inhibitors and their inhibition efficiency increases with the addition of halide ions. The inhibitor (01[Formula: see text]SC) shows the inhibition efficiency of 78.28% (0.2[Formula: see text]mM) by using a weight loss method. The influence of I[Formula: see text], Br[Formula: see text] and Cl[Formula: see text] anions raises the inhibition efficiency of the substituted 2,6-diphenyl piperidin-4-ones with semicarbazone due to the synergistic effect. The synergistic effect of halide ions was formed in the following order: KI [Formula: see text] KBr [Formula: see text] KCl.

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The acid corrosion inhibition technique of mild-steel in 1N sulfuric acid by a part of alkyl substituted 2,6-diphenyl piperidin-4-one with thiosemicarbazone has been observed by quantum chemical calculations, electrochemical AC impedance measurements, weight loss process and potentiodynamic polarization studies. Results show that substituted γ-2,c-6-diphenyl piperidin-4-ones with thiosemicarbazone act as perfect corrosion inhibitors and their inhibition efficiency increase with the addition of inhibitors. The potentiodynamic polarization curves pointed the studied inhibitors are mixed type of character and cathodic nature in 1 N H2SO4 media. The impedance spectroscopy shows a change in the value of charge transfer resistance (Rct) and double layer capacitance (Cdl) indicating the adsorption of the some substituted piperidin-4-ones with thiosemicarbazones on the mild steel surface. For all the three types of alkyl substituted 2,6-diphenyl pipieridin-4-one with thiosemicarbazone, the inhibition efficiency raised to increment in the inhibitor concentration and the performance of the three inhibitors are 01TS> 02TS> 03TS. The adsorption of the alkyl substituted 2,6-diphenyl piperidin-4-one with thiosemicarbazone on the mildsteel metallic surface pursued the Langmuir's adsorption isotherm. Quantum chemical calculations were executed by adopting density functional theory (DFT) to conclude whether a clear link exists among the inhibiting outcome of the inhibitor and the electronic characteristics of its main fundamentals.

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