Schiff Bases of Triethylenetetramine as Corrosion Inhibitors of Zinc in Hydrochloric Acid

Abstract

The performance of triethylenetetramine-tribenzylidene (TTTB) and triethylenetetramine-trisalicylidene (TTTS) as corrosion inhibitors for zinc in hydrochloric acid is investigated. At lower concentrations, both inhibitors accelerate the attack but inhibit corrosion at higher concentrations, e.g., 96-100% with 1.0% concentration in 0.5 M and 1.0 M HCl. The efficiency of TTTB decreases while that of TTTS remains almost constant (≥ 99.7%) up to 120 minutes and in the temperature range 35 -65 ºC. The activation energies are higher in inhibited than in plain acid with both inhibitors. The free energy of adsorption (∆G ads ) and heat of adsorption (Q ads ) are negative, which suggests that there is spontaneous adsorption on metal surface, and from the values of (∆G ads ) and (Q ads ), the values of entropy of adsorption (∆S ads ) were calculated. Galvanostatic polarization shows that corrosion is under mixed control with predominance of the cathodic part. In uninhibited 1.0 M HCl, complete cathodic protection is achieved at a current density of 4.2224 Adm -2 , but in presence of these inhibitors, much lower current densities are required. Plot of log (θ/1-θ) versus log C inh gives a straight line, suggesting that inhibitors cover both the anodic and cathodic regions through general adsorption following Langmuir isotherm. The mechanism of inhibition has been proposed.

Synthesis of Thiophene Derivative and its Use as Zinc Metal Corrosion Inhibitor in Hydrochloric Acid Solution

“…[19] IR spectra were recorded as KBr discs for solid materials or by applying droplets of liquid materials on NaCl plate. 1 H-NMR and 13 C-NMR spectra were recorded on a spectrometer operating at 400 MHz for 1 H and 100 MHz for 13 C measurements, respectively. Chemical shifts (δ) are reported in parts per million (ppm) relative to tetramethylsilane (TMS).…”

“…While corrosion inhibitors will not halt or completely prevent corrosion, they can reduce the rate at which corrosion occurs, and block early corrosion damage. A wide variety of chemicals can be used for this purpose, although many are toxic, and must therefore be used with care to protect the environment [13,14].…”

Evaluation of Impedance Measurements on Al-Pure Corrosion in 1.0 M HCl in the Presence of Organic Schiff

“…The Schiff bases used in the present work were synthesized from equimolar amounts of p-methoxy benzaldehyde and corresponding amines (o-chloroaniline and m-chloroaniline) through a condensation reaction in ethanol media as method described by Shah et al [33]. All the used chemicals for preparation of Schiff bases were AR grade (MERCK).…”

Synthesis and Characterization of Some Thiadiazole Compounds as New Corrosion Inhibitors for Mild Steel in Cooling Water

“…Potentiodynamic polarization measurements: The inhibition efficiency was evaluated from the calculated Icorr values using the relationship [23]: …”