Portugaliae
Electrochimica Acta

Gravimetric, electrochemical, surface investigation, RSM and theoretical computational studies, using DFT and MD, were employed to investigate Ecorr inhibition of MS surfaces in 0.5 M H2SO4, by a worm expelling drug (Wormin® MBZ). The results from computational and RSM optimization and experimental methodologies were all in good accord. After 24 h, IE(%) of 1.5 g/L MBZ on MS corrosion, calculated from WL data, was 96.610%. Maximum IE(%) of 1.0 g MBZ was 96.903% (303 K) and 99.998% (333 K). PDP confirmed MBZ mixed nature of adsorption. The impact of the inhibitor C and IT of MS on IE(%) of MBZ was revealed by statistical evaluation and optimization, using Design Expert software package (Stat-Ease). The optimized IE(%) of 96.6103% was obtained with the inhibitor C of 1.061 g/L, at MS 48.58 h IT. On the MS surface, MBZ behaved according to Langmuir’s adsorption isotherm. MD showed that MBZ had an Einteraction of -536.33 and -694.53 kcal/mol, at 303 and 333 K, respectively. Negative Einteraction forecasts confirmed MBZ-MS surface interaction capability, which reinforced the experimental investigations IE(%) findings. Keywords: adsorption; C7H6N2 derivative; DFT; MBZ; MD optimization; RSM; PDP.

Abstract MS is extensively used in oil and gas industries, but its inherent susceptibility to corrosive attack in marine environments with high C of Cl- is a shortcoming to its applications in such inevitable medium. Coating has been a popular means of mitigating steel structures corrosion. This work assessed the effect of Zn-ZnO based AW-SS composite as AC material on a MS substrate in a marine environment. The Zn-ZnO base was separately subject to CD with SS, DLFA and LSLA particulates on MS substrates. PDP method was used to ascertain corrosion behaviors of the coated samples in a simulated SW environment. The samples  and microstructural properties were studied by a microhardness tester and SEM, respectively. The results indicated that the samples  increased when they were coated by SS and LSLA higher C, which had the highest and lowest , respectively. The coatings CP improved visibly with SS, which had the highest value (61.4%), followed by DLFA (53.8%) and LSLA (44.3%). AW incorporated into Zn-ZnO is a potential AC material. Keywords: AW; CI; coatings; ED; environment; MS.

Abstract Metals can contaminate the environment and increasingly affect ecological systems and public health worldwide. Cu(II) and Pb(II) ions play a significant part in increasing the cancer rate, since their amounts are higher in cancerous patients than in healthy individuals. Electrochemical methods have been extensively used for analyzing biological, beverages and food samples to estimate Cu(II) and Pb(II). The present study has employed LSASV for Cu(II) and Pb(II) determination in female patients (suffering from breast-cancer) cancerous blood serum samples. Optimized conditions for analysis have required: Gc, with an eacc of -0.2 V and a tacc of 400 s, as WE; 0.1 M AB (pH 5.1) as SE, at a stirring rate of 9 rpm and SR of 100 mV/s-1; Ag/AgCl as RE; and a Pt wire as CE. Under the optimized conditions, the cost-effective procedure was successfully applied for Cu(II) and Pb(II) determination in cancerous human serum. LOD was in the range of ppb. The analysis indicated higher Cu(II) and Pb(II) levels in cancerous female patients than in the healthy ones. Therefore, a strictly controlled diet is recommended. Keywords: biological sample; Cu(II); healthy and cancerous serums; LSASV; Pb(II); public health.

Abstract The effective inhibition of MS corrosion in H2SO4 by CP and CP + KI was assessed by EIS. SM of MS was studied using SEM and AFM. The rise in Rct and decrease in Cdl, with higher C of CP and CP + KI, confirmed MS CI. IE(%) increased with higher C of CP only and CP + KI (from 10-3 to 10-1 M). CP maximum IE(%) was 93.9%, at 10-1 M. CP + KI, due to I- ions synergistic effect, showed an IE(%) of about 98.8%, at 10-1 M. CP only and CP + KI adsorption mechanism followed Langmuir’s isotherm. SM studies suggested that a barrier film of CP only and CP + KI, mitigated MS surface corrosion. CP + KI is an efficient inhibitor in H2SO4. Keywords: AFM; corrosion; CP; EIS; IE(%); KI; MS; SM; SEM.

Abstract A potentiostat is a device that enables to measure I that flows through one of the electrodes, by imposing a E. It was invented in 1942, by Hickling. Potentiostats available on the market offer a wide variety of functions. Unfortunately, their prices are high, which is mainly due to a sophistication that is not necessary for experiments such as those practiced at the undergraduate level. Therefore, this paper proposes the fabrication of a multi-channel potentiostat that is inexpensive, interdisciplinary, and enables to plot, for several Ec cells, a certain number of curves describing the evolution of the measured electrical quantities. Specifically, it allows to measure Icorr and analyze the solution chemical reactivity. Keywords: Al corrosion; Ec; electronic materials; potentiostat.