Portugaliae
Electrochimica Acta

Concerns about environmental pollution and depletion of petroleum and coal supplies in the twenty-first century have prompted a shift towards more sustainable and environmentally friendly alternatives. Lignocellulosic biomass (LCB), which contains hemicellulose, lignin (Ln), and cellulose, is a widely available natural bioresource. Ln, a natural biopolymer, has become more recognized as a valuable material with economic uses. The current research provides in-depth information on the evolution of phenol, from an impediment to a bridge connecting many industries with diverse applications. Successful valorization of Ln for the production of bio-based platforms, fuels, and chemical products has been the subject of extensive investigation. Understanding Ln properties and factors that influence its conversion into useful products might help optimize biomass utilization. Improved bioprocessing processes can convert LCB components into value-added products, including Ln. This study summarises and compares current improvements in Ln extraction, along with depolymerization technologies that might improve bioprocessing cost-effectiveness. Commercial importance of Ln-derived goods, such as aromatics, biological polymers, and biofuels, including agrochemicals, is also addressed. Most recent trends in Ln conversion into value-added compounds, and current technical and commercial applications of Ln that have economic significance are herein discussed. Keywords: agricultural waste; Bf; Bm; LCB; Ln extraction.

The following work presents a new method that aims to study the quality of toothpastes, in particular, excessive presence of fluoride, which is a corrosive agent for dental alloys. Results showed that the proposed method allowed analysis of electrochemical properties from compounds that exist in these oral hygiene products, generally based on the concentration effect of fluoride present in toothpastes. Excess doses of fluoride can cause serious effects, such as corrosion of dental alloys. Cyclic voltammetry (CV), linear voltammetry (LV) and electrochemical impedance spectroscopy (EIS) curves were herein recorded to identify characteristic electrochemical signals of different ingredients, in particular, fluoride concentration Keywords: CV; EIS, fluor; LV; toothpastes.

Agricultural residues are being explored as sustainable energy sources to mitigate global warming and reduce greenhouse gas emissions. This study investigates biofuel production from a free-fall reactor using sugarcane bagasse (SCB) and cassava rhizome (CR) as feedstocks, employing both experimental and modelling approaches. Pyrolysis was conducted with varying SCB-CR blend ratios, from 400 to 650 °C, with a 30 min residence time, to analyse yields of biochar, bio-oil and biogas. Ultimate and proximate analyses were performed on feedstocks and biofuels, to determine their properties. Mathematical models for biofuel yields were developed using multi-expression programming (MEP), and validated against multilinear regression (MLR). Optimal 50:50 SCB-CR composition produced the highest bio-oil yield of 36.2%, with a heating value of 23.6 MJ/kg, at 550 °C, alongside with 16.2% biochar and 47.6% biogas. MEP models demonstrated superior accuracy, with R² values of 0.974, 0.917 and 0.774, for biochar, bio-oil and biogas, respectively, outperforming MLR models. Results indicate that co-pyrolysis of SCB and CR enhanced biofuel yield and quality, due to synergistic effects. Integration of experimental data with modelling provides a pathway in optimizing process parameters for large-scale biofuel production. Keywords: biofuel; CR; modelling; MEP; pyrolysis; SCB.

Nanocomposites (NC) derived from electrically conductive polymers have emerged as promising materials for advanced applications in sensors, semiconductors and supercapacitors. The performance of these materials is critically influenced by environmental factors, with humidity exposure (HE) playing a pivotal role in determining their thermal and electrical behaviours. PIN, recognized for its high redox activity, tunable conductivity and thermal stability, has been integrated with WC, a material known for its exceptional hardness, wear resistance, high electrical conductivity (σDC) and thermal resilience. In this study, a novel series of NC electro polymers with WC were synthesized via FeCl₃-initiated chemical oxidative polymerization of indole in CTAB presence. WC was incorporated at varying wt% (5, 10 and 15), to assess its impact on the composites’ properties. Influence of relative humidity (40%) on thermal stability and σDC of NC was systematically evaluated. Structural and morphological analyses were performed to elucidate composites’ conductivity, stability and reliability under fluctuating humidity conditions. Results revealed that inclusion of WC significantly enhanced thermal and electrical properties of PIN, while providing superior resistance to humidity-induced degradation. Notably, NC with 15 wt% WC exhibited highest σDC, achieving 36.4mS/cm after 6h of HE. These findings highlight NC’s potential as robust materials for diverse applications in industrial, environmental, medical and agricultural domains, where stability under variable humidity conditions is paramount. Keywords:band gap; conductivity; HE; nanocomposite; PIN; WC.

This work focused on the electrochemical behaviour of a silver (Ag) deposit, from a mirror factory effluent, on the surface of an aluminium electrode. To carry out this study, two samples were taken from the same location of the mirror factory, before and after copper plating. Different applied potentials were selected based on results obtained from linear sweep voltammetry (LSV) analysis (potential window). Based on chronoamperometry (CA) measurements and electrochemical impedance spectroscopy (EIS) results, it can be seen that applied potentials affected the Ag deposit’s electrochemical behaviour, proving that it tended to be favoured by cathodic potential. Keywords: Ag recovery; CA; electrochemical behaviour; electrodeposition; EIS; LSV; SEM; EDS; XRD; XRF.