Dicyandiamide: Applications in Leather Production and its Electrochemical Detection

General Description

Dicyandiamide plays a key role in eco-friendly leather production by forming a biomass-derived retanning agent with Dialdehyde sodium alginate, eliminating the need for formaldehyde. The resulting leather exhibits superior quality with enhanced properties such as hydrothermal stability, thickening ratio, and mechanical strength. By replacing traditional formaldehyde-containing resins, Dicyandiamide helps create a formaldehyde-free product, aligning with sustainability goals. Additionally, in electrochemical detection, dicyandiamide can be precisely detected through oxidative polymerization on a carbon electrode, offering high sensitivity and a low detection limit. This method proves effective for detecting dicyandiamide in various samples, showcasing its potential for environmental monitoring.

Figure 1. Dicyandiamide

Applications in Leather Production

Dicyandiamide plays a pivotal role in the creation of environmentally friendly leather production methods, specifically through its application in the formulation of a biomass-derived retanning agent (BDR) developed in combination with Dialdehyde sodium alginate (DSA). This innovative approach aims to eliminate the hazardous use of formaldehyde, commonly found in traditional leather processing. Dicyandiamide's utility in this context stems from its ability to react with DSA, thus preserving the desirable properties of DSA while enhancing the functionality of the final leather product. The interaction between Dicyandiamide and DSA leads to the formation of a new compound that retains the structural integrity and molecular weight characteristics of DSA. Specifically, the resulting BDR has molecular components ranging from 1424 to 1462 g/mol, which are crucial for its effectiveness in leather treatment. The application of Dicyandiamide in this process results in several notable improvements in leather quality. For instance, leather treated with the DSA-bonded Dicyandiamide showcases superior hydrothermal stability, with a measured stability of 82.4 °C. Additionally, this treatment enhances the thickening ratio to 13.93%, indicating a denser and more robust material. Mechanical strengths are also significantly improved, with tensile strength reaching 17.2 N/mm2 and tear strength peaking at 120 N/mm. These enhancements are attributed to the Dicyandiamide-infused BDR, which effectively replaces traditional amino resin formulations that typically contain formaldehyde. One of the most significant benefits of incorporating Dicyandiamide into the leather retanning process is the achievement of a formaldehyde-free product. While conventional dicyandiamide-formaldehyde resin (DFR) treated leathers contain up to 591.5 mg/kg of formaldehyde, leather treated with DSA-bonded Dicyandiamide contains none. This stark contrast highlights Dicyandiamide's role in reducing toxic substance use in leather manufacturing, aligning with broader environmental and health safety goals. Overall, Dicyandiamide's integration into leather processing through DSA not only advances the performance characteristics of the leather but also contributes to the sustainability and safety of the manufacturing process. This novel application of Dicyandiamide offers significant potential to expand into large-scale industrial applications, providing a safer, cleaner alternative to traditional leather tanning methods. ¹

Electrochemical Detection

Electrochemical detection of dicyandiamide, a nitrification inhibitor, involves a precise process utilizing electrogenerated chlorine-assisted polymerization through azo bonds in acidic conditions. The procedure is executed on a preanodized screen printed carbon electrode. The presence of a chloride-containing support electrolyte in the acidic medium is critical for the successful oxidative polymerization of dicyandiamide. Additionally, oxygen functionalities and edge sites on the electrode surface play vital roles in the adsorption of the oxidized dicyandiamide products. The polymer film formation, crucial for detecting dicyandiamide, is characterized using scanning electron microscopy (SEM), cyclic voltammetry, and X-ray photoelectron spectroscopy. These techniques confirm the integrity and functionality of the polymer layer which captures and signals the presence of dicyandiamide. This detection system is highly sensitive, offering a linear response range from 20 to 170 μM and a low detection limit of 3 μM for dicyandiamide, ensuring precise quantification even at low concentrations. The method's effectiveness extends to real-world applications, having been tested for dicyandiamide detection in both dairy and water samples. Furthermore, it demonstrates the capability to detect dicyandiamide concurrently with other compounds like melamine. This robust approach underscores the potential of direct electrochemical methods in environmental monitoring and quality control in agricultural practices. ²

Reference

1. Ding W, Wang Y, Sun J, Bao L, Pang X. Dialdehyde sodium alginate bonded dicyandiamide for formaldehyde-free leather production with enhanced properties. Carbohydr Polym. 2022; 295: 119838.

2. Natarajan T, Gopinathan M, Thiruppathi M, et al. Detection of nitrification inhibitor dicyandiamide: A direct electrochemical approach. Food Chem X. 2023; 18: 100658.

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