Catalytic degradation of diverse azo dyes using Eucommia ulmoides bark-mediated gold nanocatalyst

Abstract

In the absence of any hazardous substances, colloidal gold nanoparticles (AuNPs) were synthesized through the reduction and stabilization of corresponding metal cations by a simple Eucommia ulmoides bark extract (EUBE). Employing these AuNPs as catalysts, at least ten distinct azo compounds were catalyzed and analyzed. The findings reveal outstanding catalytic performance across a diverse range of azo dyes, regardless of structural complexity, the count of azo bonds, the presence of various functional groups in the side chains, differences in molecular weight, degrees of water solubility, ionic characteristics of the dyes, and the particular class of dyes, whether reactive or acidic. Regardless of these varieties, azo dyes achieved over 90% degradation within 16 min, following a first-order pseudo-kinetic reaction. This report systematically explains the mechanics of AuNPs synthesis using EUBE and the step-by-step azo dye degradation. It signifies an advancement in azo-contaminated wastewater treatment, transcending the varied types and structural complexities of azo compounds.