Formation of high-valent cobalt-oxo phthalocyanine species in a cellulose matrix for eliminating organic pollutants

The selective elimination of recalcitrant organic pollutants in high backgrounds of complex constituents has proven a significant challenge. Inspired by the naturally occurring oxidation reactions catalyzed by metalloporphyrin-based enzymes, where the target substrates can be oxidized selectively due to the specific enzyme environment and the axial fifth ligands of metalloporphyrins, we developed a bioinspired catalytic system based on cellulosic fiber-boned cobalt phthalocyanine for capturing and oxidizing dyes by H2O2 activation in the presence of high additive concentrations. In this system, the cellulosic fibers provided the amorphous regions, functioning as cavities in the same manner as the protein backbones of enzymes for the selective accessibility of dyes; cobalt phthalocyanine was introduced as the catalytic entity; and linear alkylbenzene sulfonate (one of the most widespread surfactants in industrial and domestic wastewater) was employed as the fifth ligand to help generate high-valent cobalt-oxo intermediates by the heterolytic cleavage of the peroxide O-O bond. According to detailed density functional theory calculations, the spin populations are predominantly located around the cobalt-oxo center, achieving an electrophilic attack on the electron-rich azo bond and the aromatic ring of the target model dyes. (C) 2014 Elsevier B.V. All rights reserved.