No abstract

No abstract

No abstract

The efficiency of three new synthesized Gemini surfactants (namely, A312, A314, and A316) of the type 4,4-[1,4phenylenebis(azanylylidene)bis(N,N-dimethyl-N-alkylaminium] bromide is evaluated as corrosion inhibitors for carbon steel API 5L X52 grade in 1M HCl. The relation between the experimental inhibition efficiency and theoretical chemical parameters obtained by computational calculation in order to predict the behavior of the organic compounds as corrosion inhibitors was instigated. The chemical structures were elucidated using 1HNMR spectra. Inhibition performance was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and weight loss tests. The polarization curves show that applied surfactants act as mixed type inhibitors. Nyquist plots showed the semicircle capacitive loop with different surfactants and concentrations. The inhibition efficiency orders are A312 > A314 > A316 with the highest efficiency of 94.87% for A312. Adsorption of inhibitors on API X52 steel surface was found to obey Langmuir isotherm. Theoretical evaluation of the inhibitory effect was performed by computational quantum chemical calculations. The molecule structural parameters (EHOMO), (ELUMO), energy gap (ΔE), and the dipole moment (μ) were determined. The results of experimental inhibition efficiency and theoretical calculated quantum parameters were subjected to correlation analysis.

I n this study cross-linked biocomposite with a high adsorption capacity was prepared by incorporating amorphous carbon thin film (ACTF); synthesized from rice straw by catalytic acid spray method; into the chitosan biopolymeric matrix by microwave irradiation precipitation technique. The new technique improves the polymeric cross-linking effect between ACTF and chitosan without catalyst and does not affect the spatial structure of chitosan. The physicochemical properties of the resulting biocomposite were evaluated by FTIR, SEM, XRD, Raman. The chitosan/ACTF biocomposite analyses refer to the presence of cave-shaped pores, high electron density and ion exchange active sites on internal and external surfaces in addition to high thermal stability. The adsorption study summarizes the potential of novel chitosan/ACTF biocomposite for the removal of Ca 2+ and Ba 2+ from water by batch adsorption. Freundlich isotherm model was best fitted to equilibrium data as well as the pseudo-second-order kinetic model was best fitted to adsorption kinetic data. Thermodynamic parameters (ΔG, ΔH, and ΔS) suggested the exothermic nature of Ca 2+ and Ba 2+ adsorption. The removal efficiency for Ca 2+ and Ba 2+ were 80% and 87.85 % at initial concentration of 100 mg/l, respectively. The results indicated that the chitosan/ACTF biocomposite has a high adsorption capacity and excellent water compatibility.