f) 2020 - 82 Documents
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Item TRANSITION METAL COMPLEXES OF NOVEL BINUCLEAR SCHIFF BASE DERIVED FROM 3,3′-DIAMINOBENZIDINE: SYNTHESIS, CHARACTERIZATION, THERMAL BEHAVIOR, DFT, ANTIMICROBIAL AND MOLECULAR DOCKING STUDIES(Taylor & Francis Online, 2020-03-21) Venkittapuram, Palaniswamy Radha; Subramanian, Chitra; Suyambulingam, Jonekirubavathi; Ill-Min, Chung; Seung-Hyun, Kim; Mayakrishnan, PrabakaranA series of binuclear Co(II), Ni(II), Cu(II), and Zn(II) complexes were prepared with a novel bidentate Schiff base ligand derived by condensation of 3,3′-diaminobenzidine with creatinine. The prepared compounds were characterized by elemental analysis, magnetic susceptibility measurements, molar conductivity, FT-IR, UV-vis, 1H NMR, 13C NMR and mass spectra and thermal analysis (TGA/DTG). From spectral analysis, an octahedral geometry was proposed for the complexes except Zn(II) complex which had tetrahedral geometry. The microcrystalline nature of the complexes has been confirmed by powder XRD and SEM analyses. The molecular structures of the Schiff base L and its Zn(II) complex were fully optimized and also their quantum chemical parameters were calculated. The synthesized ligand and their metal complexes were screened against two gram-positive, gram-negative bacterial and fungal species. The results revealed that the metal complexes exhibited higher antimicrobial activity than the free ligand. The antioxidant activity of the synthesized ligand and their metal complexes was carried out by DPPH method.Item FLOXACINS: AS MEDIATORS IN ENHANCING THE CORROSION INHIBITION EFFICIENCY OF NATURAL POLYMER DEXTRIN(Springer Link, 2020-01-11) Gowraraju, Nirmala Devi; Chan, Basha Nusrath Unnisa; Selvaraj, Mohana Roopan; Venkatesan, Hemapriya; Subramanian, Chitra; Ill-Min, Chung; Seung-Hyun, Kim; Mayakrishnan, PrabakaranThree different floxacins (Ciprofloxacin, Levofloxacin, and Norfloxacin) were used to enhance the inhibition property of Dextrin (Dex) against the dissolution of mild steel in acid medium. Substantial increase in the inhibition property was observed against mild steel dissolution by the addition of floxacins than with pure Dex. Weights loss experiments proved the potential of Fluoroquinolones (FQs) in enhaning the corrosion inhibition property of Dex on metal by proving its best ability at lower concentrations. Adsorption of Dex and floxacins on metal surface was observed to accept with Langmuir adsorption isotherm. The results from EIS studies add to the enhancing property of floxacins on Dex. While the mixed type behavior of inhibitors were confirmed by polarization studies, images from SEM, EDS and AFM gathers strength to propose the formation of protective layer.Item ECOFRIENDLY GREEN INHIBITOR FROM HEMEROCALLIS FULVA AGAINST ALUMINUM CORROSION IN SULPHURIC ACID MEDIUM(Taylor & Francis Online, 2020-01-15) Ill-Min, Chung; Ramalingam, Malathy; Seung-Hyun, Kim; Kathirvel, Kalaiselvi; Mayakrishnan, Prabakaran; Mayakrishnan, GopiramanThis research work aims to identify a non-toxic, cheap, and effective greener inhibitor from Hemerocallis fulva (H. fulva) for corrosion of aluminum in a 1 M H2SO4 medium at different concentrations and temperatures. We investigated the inhibitive effect of H. fulva extract in a 1 M H2SO4 solution on aluminum using weight loss measurements with various concentrations and temperatures. Evaluations of the mechanism of corrosion inhibition by potentiodynamic polarization and AC-impedance analysis were also performed. The nature of the adsorption and morphology on the surface of aluminum were performed by atomic force microscopy (AFM) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) studies. The results suggested that the H. fulva extract can be used on aluminum as an efficient eco-friendly corrosion inhibitor in 1 M H2SO4 solution as identified using weight loss because the maximum corrosion inhibition efficiency η (%) was found to be 89% at 600 ppm at 303 ± 1 K. It was found that maximum η (%) was obtained at 303 ± 1 K compared to other temperatures (313, 323, and 333). The activation energy (Ea) was higher in the presence of inhibitor than in the absence of inhibitor, showing the temperature dependency of inhibition. The positive values of enthalpy of activation ΔH° and entropy of activation ΔS° reflect the endothermic and disordered nature of the reaction. Physical adsorption was proposed for the inhibition and the process followed the Langmuir adsorption isotherm. The negative value of ΔGoads indicates spontaneous adsorption. Polarization measurements clearly indicated that the H. fulva acts as a mixed inhibitor and the η (%) increases with inhibitor concentration. SEM-EDX, AFM, and XPS studies confirmed the formation of a protective layer over the surface of the aluminum specimen.Item INHIBITION OF MILD STEEL CORROSION USING MAGNOLIA KOBUS EXTRACT IN SULPHURIC ACID MEDIUM(Elsevier, 2020-12) Ill-Min, Chung; Ramalingam, Malathy; Rameshkumar, Priyadharshini; Venkatesan, Hemapriya; Seung-Hyun, Kim; Mayakrishnan, PrabakaranMagnolia kobus DC. (M. kobus), a prominent Southeast Asian flowering plant species, was investigated for its inhibition efficiency against mild steel corrosion in 1 M H2SO4. The extract (M. kobus) was identified to have 145.80 μg/g of myricetin and 102.32 μg/g syringic acid as prominent components, with a total phenolic content (TPC) of 95.26 mg/g and a total flavonoid content (TFC) of 25.38 mg/g. The mass-loss measurements showed that 500 ppm of M. kobus extract was able to inhibit corrosion, with an efficiency of 95.01% at 303 ± 1 K. Reduction of dissolved iron content in the inhibited solution than in the inhibitor free solution observed in Atomic Adsorption Spectroscopy (AAS) revealed the corrosion mitigating effect of inhibitor on mild steel. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) analysis of the protected and unprotected mild steel samples indicate adsorption of M. Kobus on the electrode surface. UV–vis and FT-IR studies complement the above results. The electrochemical studies indicated that M. kobus functioned as a mixed-type indicator and myricetin along with other plant components present in the plant extract contributed to the inhibition process.Item UTILIZATION OF BIOWASTE AS AN ECO-FRIENDLY BIODEGRADABLE CORROSION INHIBITOR FOR MILD STEEL IN 1 MOL/L HCL SOLUTION(Elsevier, 2020-12) Venkatesan, Hemapriya; Mayakrishnan, Prabakaran; Subramanian, Chitra; Manoharan, Swathika; Seung-Hyun, Kim; Ill-Min, ChungThis report focuses on the application of a biodegradable biowaste [human hair-(HHR)], to produce a mild steel corrosion inhibitor. The performance of HHR extract in inhibiting metallic corrosion in 1 mol/L HCl was investigated. The analysis of the metal corrosion behavior using electrochemical and weight loss techniques revealed that HHR exhibits an efficient corrosion-mitigating effect via adsorption on the metal surface following a Langmuir isotherm. Tafel-plot results revealed the mixed-mode corrosion protection behavior of HHR. Surface analysis using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and Fourier transform infrared (FT-IR) spectroscopy provided evidence for the precipitation of a protective HHR film on the metal surface.