Corrosion inhibition performance of 4-(prop-2-ynyl)- [1,4]-benzothiazin-3-one against mild steel in 1 M HCl solution: Experimental and theoretical studies

4-(prop-2-ynyl)-2H [1,4]-benzothiazin-3(4H)-one (PBO) was synthesized and evaluated on corrosion resistance for mild steel (MS) in1 M HCl environment. The molecular and crystal structure of PBO has been determined by single-crystal X-ray crystallography, Hirshfeld surface (HS) analysis was carried out by using Crystal Explorer 17.5. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques were used to find corrosion rate (CR) and corrosion inhibition efficiency (η) in the presence and absence of PBO. These techniques were supported with energy dispersive X-ray (EDX) and scanning electron microscope (SEM). Molecular Dynamics Simulation (MDS) and Frontier Molecular Orbital (FMO) are realized by means of the Density Functional Theory (DFT) method. The results show that PBO could offer an inhibition efficiency of 92% at 303 K. The type of inhibition mechanism of PBO was mixed-type. The Langmuir isotherm proved the highest compliance with experimental data, representing the generation of protective mono-layer of inhibitors on the MS substrate. The SEM pictures displayed a metallic substrate covered with a highly compact protective layer covered. The theoretical findings suggested by electronic/atomic computer simulations supported the inhibitive chemicals interfacial adsorption through reactive centres.     

Inhibition effect of newly synthesized benzoxanthonesderivative on hydrogen evolution and Q235 steelcorrosion in 15% HCl under hydrodynamic condition: Combination of experimental,surface and computational study

The investigation of this study deals with the synthesis using green synthetic approach, characterization and application of benzoxanthones derivative namely 9,9-Dimethyl-12-p-tolyl-8, 9,10, 12-tetrahydrobenzo[a]xanthen-1-one (TBX) for the inhibition of Q235 steel corrosion in 15% HCl under dynamic condition. The results of EIS confirmed towards the increment in R_ct values with rise in concentration. Additionally, results of PDP reveals that TBX is cathodic type inhibitor. The maximum inhibitive excellency of TBX was given at 200 mg/L with the value of 92.3%. The increasing temperature tends to increase in corrosion rate. Langmuir adsorption isotherm provides the excellent fitting. The surface morphology and adsorption of TBX molecules were confirmed using scanning electron microscopy (SEM) and X-photo electron microscopy (XPS). Density functional theory (DFT) and Molecular dynamic simulation (MD) confirmed that corrosion inhibition efficiency ranking obtained for studied molecules is TBXH⁺> TBX.     

Inhibitive effect of onion mesocarp extract-nickel nanoparticles composite on simultaneous hydrogen production and pipework corrosion in 1 M HCl

Nanoscale nickel is prepared from ethanol extracts of Allium cepa and characterized. Zerovalent face centred cubic (fcc) nickel nanoparticles oriented mainly at Ni (111) plane formed rapidly within 30–45 min. The nanoparticles are stabilized by negative surface potential, non-agglomerated, monodispersed, round-shaped and distributed between sizes of 39.5–53.1 nm. The nanoparticles are used to simultaneously regulate the rates of hydrogen gas production and X80 steel corrosion in 1 M HCl solution for the first time. The nanoparticles efficiently inhibit hydrogen gas evolution and X80 steel corrosion rates especially at increased concentration. Inhibition efficiency increases as temperature increases from 303 to 323 K, remains fairly constant from 323 to 343 K and decreases drastically from 343 to 363 K. By means of O–H, N–H and C=C sites, the nanoparticles are spontaneously physically adsorbed on X80 steel surface and act as mixed type corrosion inhibitor with dominant influence on cathodic reaction involving hydrogen gas evolution. In the presence of the nanoparticles, surface roughness (measured by AFM) reduces by 76.0% and heights of peaks from the mean plane reduces by 58.2%. Comparatively, even 100 ppm of the nanoparticles showed higher inhibition efficiency at all temperatures than 1000 ppm concentration of the crude extract.     

Inhibition effect of natural polysaccharide composite on hydrogen evolution and P110 steel corrosion in 3.5 wt% NaCl solution saturated with CO2: Combination of experimental and surface analysis

For the analysis of corrosion and hydrogen production inhibition, we have synthesized Guar gum and methylmethacrylate (GG-MMA) composite. The synthesized composite was used as an eco-friendly corrosion inhibitor for P110 steel in 3.5% NaCl solution saturated with carbon dioxide at 50 °C. The primary corrosion techniques like weight loss, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) was used to analyze the corrosion inhibition process. EIS study reveals the kinetically controlled corrosion inhibition process. The results of PDP proposed that GG-MMA composite is the cathodic type of inhibitor. The corrosion inhibition performance of GG-MMA alone is 90% at 400 mg/L, and that of formulation with KI (5 mM) + GG-MMA (300 mg/L) is 96.8%. The adsorption of GG-MMA over P110 steel is spontaneous and mixed type i.e., both physical and chemical. The conformation of GG-MMA molecule adsorption was done using a scanning electron microscope (SEM), Contact angle measurement, Atomic force microscopy (AFM), Scanning Electrochemical Microscopy (SECM) and X-ray photoelectron spectroscopy studies.