Adsorption and inhibitive properties of Tryptophan on low alloy steel corrosion in acidic media

AbstractThe inhibition efficiency of Tryptophan (Trp) has been studied for the corrosion of low alloy steel ASTM A213 grade T22 in sulfamic (HSO3NH2) and hydrochloric (HCl) acid solutions.Corrosion inhibition was studied using electrochemical methods (electrochemical impedance spectroscopy; EIS and the new technique electrochemical frequency modulation; EFM) and weight loss measurements. The influence of inhibitor concentration, solution temperature, and immersion time on the corrosion resistance of low alloy steel (LAS) has been investigated. Trp proved to be a very good inhibitor for low alloy steel acid corrosion. EFM measurements showed that Trp is a mixed type inhibitor. Trp behaved better in 0.6M HCl than in 0.6M HSO3NH2. Moreover, it was found that the inhibition efficiency increased with increasing inhibitor concentration, while a decrease was detected with the rise of temperature and immersion time. The associated activation energy (Ea) has been determined. The values of Ea indicate that the type of adsorption of Trp on the steel surface in both acids belongs to physical adsorption. The adsorption process was tested using Temkin adsorption isotherm

Corrosion Inhibition of Mild Steel in Acidic Medium by Salvadora Persica (Miswak) -Part 1: in Sulfamic Acid

Abstract: Aqueous root extract of Salvadora persica (ARESP) was studied as a new green corrosion inhibitor for mild steel (MS) in 1.0 N sulfamic acid solutions by using mass loss and electrochemical techniques at temperatures ranging from 303 to 333 K. Appropriate equivalent circuit model was used to calculate the impedance parameters. The electrochemical impedance spectroscopy (EIS) measurements showed that the charge transfer resistance increases with an increase in the concentration of ARESP. The results obtained from the new technique electrochemical frequency modulation (EFM) indicated that ARESP acts as mixed type of inhibitor. The protection efficiency increases with the increase in inhibitor concentration and decreases with temperature. The results of the study revealed that ARESP inhibits the corrosion of MS through adsorption process following Temkin adsorption isotherm model. The apparent activation energy (E a ) and the equilibrium constant of adsorption (K ads ) were calculated. Scanning electron microscopy (SEM) was used to investigate the adsorbed film of ARESP on the steel surface

Low cost chemical oxygen demand sensor based on electrodeposited nano-copper film

A commercially available copper electrical cable and pure Cu disk were used as substrates for the electrodeposition of copper nanoparticles (nano-Cu). The surface morphology of the prepared nano-Cu/Cu electrodes was investigated by scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDX). The bare copper substrates and the nano-copper modified electrodes were utilized and optimized for electrochemical assay of chemical oxygen demand (COD) using glycine as a standard. A comparison was made among the four electrodes (i.e., bare and nano-Cu coated copper cable and pure copper disk) as potential COD sensors. The oxidation behavior of glycine was investigated on the surface of the prepared sensors using linear sweep voltammetry (LSV). The results indicate significant enhancement of the electrochemical oxidation of glycine by the deposited nano-Cu. The effects of different deposition parameters, such as Cu2+ concentration, deposition potential, deposition time, pH, and scan rate on the response of the prepared sensors were investigated. Under optimized conditions, the optimal nano-Cu based COD sensor exhibited a linear range of 2–595 mg/L, lower limit of detection (LOD) as low as 1.07 mg/L (S/N = 3). The developed method exhibited high tolerance level to Cl− ion where 1.0 M Cl− exhibited minimal influence. The sensor was utilized for the detection of COD in different real water samples. The results obtained were validated using the standard dichromate method

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially