Seeking catalysts for organophosphate degradation: functionalized biopolymers and nanomaterials

Abstract

Organophosphates (OP) comprise toxic and chemically stable compounds commonly employed as agrochemicals and warfare agents. Pesticides overuse worldwide and potential terrorist chemical attacks require efficient, fast and secure actions to neutralize OP poisoning. Nucleophilic groups such as imidazole, thiol and hydroxamic acid can promote OP detoxification by catalysis of the dephosphorylation reaction that leads to less toxic products. However, the difficulty of disjoin these molecules from the medium to reuse enclose one of the challenges to develop catalysts. Herein, we propose the anchoring of hydroxamic acids in carboxymethyl cellulose (CMC-HDA) and the simultaneous anchoring of imidazole and thiol in graphene oxide (GOSHIMZ) aiming to acquire catalysts for OP degradation. In addition to enable reuse, the anchoring to polymeric templates can promote steric and synergic effects to the samples that contribute to catalysis, resembling the enzymes behavior. All the samples were characterized by several techniques in order to confirm the functionalization and analyze the materials properties. Then, the catalytic activity of samples was evaluated with OP-model diethyl 2,4-dinitrophenyl phosphate (DEDNPP) by UV-VIS spectroscopy. The results express that samples promote rate enhancements of 103-fold compared to spontaneous hydrolysis of DEDNPP. So, we achieved new and efficient catalysts for neutralizing hazardous compounds using mild conditions of synthesis (e.g., aqueous solvent and rational use of reagents). These functionalized materials enable several applications, such as the development of OP sensors and other detoxifying agents, promoting food monitoring and security against pesticides, healthier life for people, less damages and contamination to environment and sustainable economic progress.