Unveiling New Product Formations beyond Conventional Pathways in De-Halogenation of Halo-Acetic Acids Using Ni-Encapsulated Sol-Gel Catalysts †

The urgency of water remediation and the conversion of toxic pollutants into non-toxic compounds is increasingly crucial in our industrialized world. Heterogeneous catalysts based on metal nanoparticles, which are cost-effective, non-toxic, and readily available, have garnered significant attention in the market due to their unique catalytic properties. This study presents sol–gel-based hybrid silica matrices that encapsulate nickel, designed for the efficient reductive de-halogenation of tri-bromoacetic acid (TBAA), di-bromoacetic acid (DBAA), mono-bromoacetic acid (MBAA), tri-chloroacetic acid (TCAA), mono-chloroacetic acid (MCAA), and Chloroacetanilide (CAA). A detailed study of the product distribution from each halo-acetic acid (HAA) is presented. The study points out that other products are formed from Ni-catalyzed reduction reactions of HAAs, breaking the conventional rules of stepwise reduction mechanisms. The plausible mechanisms of the catalytic processes are discussed.