New and Green Corrosion Inhibitor Based on New Imidazole Derivate for Carbon Steel in 1 M Hcl Medium: Experimental and Theoretical Analyses

In this research work, a new and green corrosion inhibitor based on new imidazole derivate (IMD) was introduced for carbon steel in 1 M HCl medium. Its inhibition properties were fully characterised by the gravimetric, electrochemical, surface and quantum chemical analyses. The experimental results confirmed that the inhibition efficiency of IMD was over 99% at 150 mg/L, forming a protective hydrophobic film on the metal surface, which maximally blocked the cathodic and anodic corrosive processes by adsorption. The electrochemical results suggested that the IMD is a mixed-type inhibitor. The adsorption behaviour of IMD was obeyed by Langmuir isotherms. The gravimetric results show that the inhibition efficiency depends on the change of concentration and temperature. The experimental tests were supported by the DFT (density functional theory) measurements, and a good relationship was found among these tests. The observed results of the surface analysis indicated that the metal surface was seriously improved with the presence of IMD.

Dissolution Study on Grape Polyphenol Hard Gelatin Capsule Dietary Supplements

Methods for a dissolution study by ultra-high performance liquid chromatography/triple quadrupole mass spectrometry (UHPLC-QqQ/MS) analysis of grape polyphenol dietary supplements, namely, grape seed extract (GSE) and resveratrol (RSV) capsules, were developed following the guidance of United States Pharmacopeia (USP) <2040>. Two dissolution media, 0.1 N hydrochloric acid (pH 1.2) and 0.05 M acetate buffer (pH 4.6), were evaluated with dissolution apparatus (USP 1), 100 rpm rotation speed, and 900 ml dissolution medium volume. Dissolution profiling was performed over 120 min. Major phenolic compounds of gallic acid, catechin, epicatechin, and procyanidin B2 were quantitated to obtain the dissolution profile of GSE capsules, and trans-RSV was used for RSV capsules. Results indicated that the released trans-RSV for RSV capsules in both of the dissolution media meets the USP standards, and that for the GSE capsules, all the four marker compounds passed the dissolution test in the HCl medium but did not reach a 75% release within 60 min in the acetate buffer. These promising results suggest that the general USP dissolution protocols are adequate for the successful release of RSV capsules in HCl medium and acetate buffer and GSE capsules (in HCl medium), but may be inadequate for GSE capsules in acetate buffer. These results showed that under a low pH of 1.2 (simulated stomach environment), bioactive compounds were released on time from the GSE capsules and met the USP guidelines; however, under a higher pH of 4.6 (simulated duodenum environment), the same biomarkers failed, suggesting the need to further improve the dissolution of GSE over a wider range of pH environments to enhance bioavailability and efficacy.

Green Approach to Corrosion Inhibition of Carbon Steel by Fucus spiralis extract in 1 M HCl Medium

The extract of Fucus spiralis (FS) was tested as a corrosion inhibitor of carbon steel in a 1M HCl medium. The anti-corrosion properties were analyzed by gravimetric and electrochemical techniques such as potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). The surface characterization of carbon steel submerged in the optimal solution was carried out using UV-Visible, UV-Vis-NIR, and Optical microscopy analyses. Electrochemical and gravimetric results demonstrated that inhibitory efficiencies increase with increasing inhibitor concentration and the efficiency reaches 87% at a concentration of 0.5 g/L. According to Tafel extrapolated polarisation measurements, the FS also worked as a mixed-type corrosion inhibitor and changed the mechanism of anodic reactions. EIS analysis showed that a depressed capacitive loop dominates the Nyquist plot of impedance and enhances the polarization resistance (Rp) to 161.9 Ω cm2 with a reduction of the double layer capacity (Cdl) of carbon steel to 61.8 μF/cm2. This protection is assured by an adsorption mechanism based on the isothermal Langmuir adsorption model, which positively affects the thermodynamic parameters. UV-Visible, UV-Vis-NIR analyses exhibited that inhibitor decreases the iron oxides like hematite, Magnetite, and Goethite, Maghemite, Lepidocrocite, δ-FeOOH of the metal surface and delays the dissolution of the bare metal of iron to the ferrous ions, notably that optical morphology showed that FS extract decreases the aggressivity of HCl.