Aluminium alloys have a good strength-to-weight ratio and low density, but they are not impervious to corrosion. Therefore, it is necessary to evaluate their corrosion performance in the atmospheric environment. Paints are typically used to prevent corrosion on aluminium alloys. A conversion or anodized layer, an inhibitor/metal-doped primer, and a polyurethane topcoat are used as 3-layer coatings for aluminium alloy corrosion protection in the aerospace industry. However, major modi­fications have been made to the protection of aluminium alloys against corrosion as a result of environmental issues. REACH, a European regulation, has significantly altered some finishing procedures for aluminium alloys by prohibiting or restricting the use of Cr(VI)-based compounds, such as chromate conversion, chromic acid anodizing, and chromate sealing. Searching for alternatives to Cr has yielded intriguing results. For many years, sol-gel-based hybrid coatings have been a promising alternative to pretreatment and primer layers, with promising results. This review discusses the current development and advancement in chrome-free corrosion-resistant layer coating systems for aluminium alloys.

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-DPAA) is commonly used in agricultural practices. Unfortunately, it has a high toxicity level and is known to be a carcinogenic substance. Therefore, developing an analytical technique capable of detecting this com­pound is crucial. Electrochemical methods offer a viable solution for the rapid and on-site analysis of 2,4-DPAA residues in real samples. The detection of 2,4-DPAA can be achieved through electrochemical redox electron transfer reactions, making voltammetry an effective approach. Various studies have explored the use of carbon electrodes, such as glassy carbon electrodes (GCE), carbon paste electrodes (CPE), and screen-printed electro­des (SPE), for voltammetric detection of 2,4-DPAA. However, researchers have encountered challenges in detecting 2,4-DPAA using these carbon electrodes. Consequently, modifi­cations have been made to the carbon materials by incorporating chitosan hierarchical porous silica, Fe3O4-polyaniline nanocomposites, silver, manganese oxide nano­particles, alizarin yellow R polymer, hierarchical porous calcium phosphate, and molecularly im­printed polypyrrole with TiO2 nanotubes. In this comprehensive review, we have examined the effectiveness of each modified electrode, considering factors such as the limit of detection, precise linear range, and recovery rate for detecting 2,4-DPAA in real samples.