Portugaliae
Electrochimica Acta

The widespread use of HMDE for multi-ionic analysis is mainly explained by the following factors: excellent reproducibility, due to the electrode surface ease of renewal, for preventing hysteresis; wide Ec; ability to forming amalgams with many redox-active metal ions; and (sub)nanomolar detection limits, which have unique capabilities for multi-metal determination. In this research, selectivity and sensitivity for Pb, Cd and Zn simultaneous determination, by DPAdSV, using HMDE as WE and CCA as a ligand, were tested. This method is based on the deposition of CCA-metals on Hg electrodes. The instrumental and chemical parameters that could improve measurements were obtained under optimal conditions, including: CCA concentration (0.05 mmol/L), pH (7), Edep (-0.3 V) tdep (60 s), AB concentration (0.5 mol/L), scan rate (150 mV/s), pulse height (80 mV), Hg drop size (4 mm2) and linearity (Ip vs concentration), which was in the range from 5 to 170, 5 to 140 and 5 to 190 M, for Pb, Cd and Zn, respectively). The LOD (S/N = 3) values were 0.05, 0.03 and 0.05 µg/L for Pb, Cd and Zn, respectively. The repeatability and intermediate precisions were tested as RSD of 0.44, 1.21 and 1.23% for Pb, Cd and Zn, respectively. The recovery values were 98, 99 and 101% for Pb, Cd and Zn, respectively. As result, the DPAdSV method with CCA ligands was successfully applied for heavy metals determination in the seawater of a former bauxite mining area. Keywords: bauxite, DPAdSV, HMDE, CCA, heavy metals and voltammetry.

SLE (Melastoma candidum D. Don) was tested as an inhibitor of St-37 S corrosion in a HCl solution, using WL, PDP and SEM analysis methods. CR has decreased with SLE addition, according to the WL method. The highest IE(%) was 67%, with 0.8% SLE addition. Rise in T had a decreasing effect on IE(%). PDP showed that the extract was a mixed inhibitor. SEM analysis showed changes in the St-37 S surface immersed in HCl, without and with the inhibitor. SLE adsorption onto the steel surface obeyed Langmuir’s isotherm. Keywords: corrosion IE(%), Langmuir’s isotherm, PDP, SEM, SLE, St-37 S and WL.

Medical forensics and homeland security have been focusing on the food and beverage industries, for water quality remote sensing, drug residue determination in food, etc. NT is playing a growing role in BS development. NT-based BS, also known as NBS technology, are reshaping the medical field. They are used in metabolite measurement, diabetes monitoring, and other applications, such as environmental protection. Pesticide and heavy metal ions detection in river water, as well as genomes sequencing the use of NM in BS design have increased their sensitivity and ability to also develop NP special properties, such as high electrical conductivity, improved shock resistance, sensitive response and flexibility. These advances result from the confluence of NP characteristics, allowing for the presentation of numerous modern flag transduction innovations in BS, such as the development of devices, and forms for manufacturing them and enhancing their measurement capability. Imaging the nanoscale objects has improved sensors connected with tiny atoms. Many mechanical devices, optical resonators and bi-functional architecture based on NBS have been developed. BS have also been discussed in this research, in order to highlight their critical applications in a variety of fields. This study discusses the various types of BS that depend on multiple types of NM, as well as their biological and implicational factors and analytical techniques, such as amperometric, CV potentiometric optical techniques, and other measurements methods that use enzyme and non-enzymatic BS. Keywords: NT application, NBS, BS analytical techniques, enzyme BS and nanoenzymatic sensors.

Two novel synthesized compounds (FD and ACP) have been applied as inhibitors for MS corrosion in HCl and H2SO4 solutions. Gravimetric, PDP, EIS, SEM and theoretical approaches were employed for the investigation of FD and ACP synthesized compounds IE%. Their corrosion IE% and calculated quantum chemical properties were comparable to each other, and indicated that ACP is a slightly less effective inhibitor than FD in HCl and H2SO4 solutions. Langmuir’s, Temkin’s, Frumkin’s and Freundlich’s adsorption isotherms were used for describing the inhibitors adsorption behavior. The adsorption was spontaneous and followed a mixed mechanism, but with initial physisorption. Polarization data revealed that the inhibitors were more cathodic, because they tended to enforce MS HER retardation. The inhibitors decreased the electrolyte impedance, while Rct increased. The adsorption mechanism was influenced by the protonation and solvation environment, and it was concentrated within the heteroatoms and the aromatic systems. Calculated quantum parameters agreed effectively with the obtained experimental results, while FF indices were useful for predicting the nucleophilic and electrophilic attacks positions. Keywords: ACP, adsorption isotherm, corrosion, EIS, FD, IE (%), MS and PDP.

In this research, TiO2 NP were prepared by MW-R and conventional SG methods, using TTIP as Ti precursor, in the presence of different mixtures of distilled H2O and ETG (0 < H2O/ETG < 100%), as a solvent. The prepared samples were characterized by XRD, Raman, FTIR, EDX/ SEM, N2 physisorption, DLS and UV/visible DRS techniques. XRD and Raman analyses showed that Ant phase dominated, with traces of Rt or Brk phases, in some samples. According to K-M curves, TiO2 calculated EG decreased with an increase in Rt phase percentage. PC performance of the prepared samples was tested on E131 VF. Kinetic evaluations showed that Rt percentage and surface area had a significant role in TiO2 NP PC performance. E131 VF degradation high RC were obtained in an AU by 0% ETG SG (0.130 (AU)) and 0% ETG MW-R (0.113 (AU)), due to the high surface area and Rt absence. The samples (x% ETG) synthesized by the MW-R method showed low pore volume and PC performance that might have been be due to a blockage of the pores and screening effect of some combustion products or residual ETG, which carried UV irradiation to the catalyst surface. Keywords: MW-R, SG, TiO2, ETG and PC degradation.