Groundwater Medium Research Articles

Study on bioremediation of Lead by exopolysaccharide producing metallophilic bacterium isolated from extreme habitat

Lead released from manufacturing factories, recycling plants, automobile company and landfill leachate is abundantly found in wastewater. An efficient bioremediating agent for lead removal from wastewater is expected to ease the ever increasing problem. The present study reports Pseudomonas sp. W6 isolated from extreme habitat of hot water spring of North–East India evaluated for its Lead biosorption property. The bacterium showed capacity to resist 1.0mM lead in both solid and liquid minimal media. Epifluorescence microscopy reveal the viability of bacterial cells under metal stress condition. ICP-MS analysis revealed 65% and 61.2% removal of lead from the Synthetic Bangladesh Ground Water medium in batch culture and column study respectively which was higher when compared to biosorption capacity of P. aeruginosa MTCC2474, P. alcaligenes MJ7 from forest soil and P. ficuserectae PKRS11 from uranium rich soil. Exopolysaccharide released by the isolate which influenced biosorption revealed the presence of ligands assayed using microbial hydrophobicity and FTIR. The extremophilic isolate is proposed as a choice for efficient bioremediation of lead contaminated wastewater.

Corrosion inhibition by benzotriazole derivatives and sodium dodecyl sulphate as corrosion inhibitors for copper in ground water at different temperatures

1‐(2‐Pyrrole carbonyl) benzotriazole (PBTA) and 1‐(2‐thienyl carbonyl)‐benzotriazole (TBTA) were synthesized. Different concentrations of PBTA, TBTA, sodium dodecyl sulphate (SDS), and molybdate (Mo) were evaluated as corrosion inhibitors for copper in ground water medium at different temperatures. The obtained results were compared with the effect of benzotriazole (BTA) on the inhibition of copper corrosion at the same condition. The study was performed using potentiodynamic polarization, electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy investigations. A good inhibition is ensured at elevated temperatures. All measurements indicated that PBTA, TBTA, and BTA act as good corrosion inhibitors and their inhibition efficiency (IE%) increased with combining them with optimum concentration of SDS and Mo. Furthermore, the best performance was recorded for the compound PBTA + SDS + Mo, which was found to offer increased IE% in a synergistic manner, thereby acting as a good corrosion inhibitor for copper in ground water medium. Copyright © 2015 John Wiley & Sons, Ltd.

Experimental and theoretical investigations on the inhibition of mild steel corrosion in the ground water medium using newly synthesised bipodal and tripodal imidazole derivatives

Two new imidazole derivatives, namely 1,4-bis(N-imidazolylmethyl)-2-5-dimethoxybenzene (BIDM) and 1,3,5-tris(N-imidazolylmethyl)-2,4,6-trimethoxybenzene (TITM), were synthesised and their effects on the inhibition of mild steel corrosion in ground water medium are reported. The study was carried out using gravimetric and electrochemical techniques in order to determine the corrosion inhibition efficiencies of the bipodal and tripodal structured imidazoles. Further, the quantum chemical calculations using density functional theory (DFT) gave a profound insight into the inhibitory action mechanism of BIDM and TITM and their calculation parameters, such as EHOMO, ELUMO and ΔE were in good agreement with the results of the experimental studies. BIDM and TITM exhibited lowest corrosion current densities of circa 7.5 μA cm−2 and 4.1 μAcm−2 at the optimum concentrations of 0.67 and 0.49 mM, respectively. All measurements thus confirmed that both BIDM and TITM behaved as good inhibitors for mild steel corrosion in ground water medium.

Adsorption and inhibition properties of mild steel corrosion in ground water medium by 1‐(4‐methoxy benzyl)‐1H‐imidazole: experimental and theoretical investigations

Corrosion inhibitive performance of a newly synthesized imidazole derivative 1‐(4‐methoxy benzyl)‐1H‐ imidazole (MBI) on mild steel in ground water medium was investigated. Gravimetric and electrochemical measurements incorporated with quantum chemical calculation were used to study the corrosion inhibition characteristics of MBI in ground water medium. The inhibition efficiency increased with the increase of inhibitor concentration, while the adsorption followed the Langmuir isotherm. To clarify the inhibition efficiency of MBI for the corrosion prevention of mild steel in ground water medium, a density functional theory study was also carried out using 6‐31 G* basis set. Quantum chemical descriptors such as the energy of highest occupied molecular orbital, energy of lowest unoccupied molecular orbital, chemical potential (Pi), electronegativity (χ), global hardness (η), softness (σ), the energy gap (ΔE), and dipole moment (μ) were calculated. The quantum chemical calculations based on density functional theory results show that the new imidazole derivative can adsorb on the mild steel surface, which forms a barrier against corrosion. Thus, MBI acts as a good corrosion inhibitor for mild steel in ground water medium. Copyright © 2012 John Wiley & Sons, Ltd.

Surface and electrochemical characterization of pitting corrosion behaviour of 304 stainless steel in ground water media

The effectiveness of aminotrimethylidene phosphonic acid (ATMP) as a corrosion inhibitor in association with a bivalent cation like Zn2+ and non-ionic surfactant like polyoxyethylene sorbitan monooleate (Tween 80) were investigated by measuring corrosion losses using electrochemical techniques. The corrosion of 304 stainless steel in the ground water medium was inhibited by complexation of the inhibitor. A combined inhibition effect was achieved by adding both ATMP and Zn2+ along with Tween 80. The formulation functioned as a mixed type inhibitor. The synergistic effect of the inhibitor compound is calculated. Luminescence spectra, FTIR spectra, XRD, XPS and scanning electron microscopic studies were carried out to understand the mode of corrosion inhibition and also the morphological changes on the metal surface.