Oxidation 4-chlorophenol immobilized on the modified dioxide of the titanium horse–radish peroxidase

In this work synthesis and investigation of the catalytic properties of the multicomponent biocatalyst based on the horseradish peroxidase immobilized on the modified titanium dioxide (TiO2) were carried out. Hydrochloric acid, chitosan, aminopropyltriethoxysilane and glutaric dialdehyde were used to modify the titanium dioxide. The horseradish peroxidase was obtained by extraction of the horseradish root (Armoracia rusticana), followed by centrifugation and separation of the filtrate. Immobilization of enzyme was performed by sequential application method with intermediate washing with distilled water from the non–specifically bounded reagents. Enzymatic activity of the enzymatic extract and of the synthesized biocatalyst in the reaction of oxidation of 4-chlorophenol in the presence of hydrogen peroxide was investigated. Monitoring the reaction was carried out by changing of the optical density of the reaction mixture containing 4‑aminoantipyrine, at a wavelength of 506 nm. Biocatalyst component composition was optimized, and the basic kinetic parameters of the synthesized biocatalyst was determined based on the results of experiments on variation of the process conditions and of the number of components of the reaction mixture. The article expediency of physic–chemical modification of titanium dioxide with chitosan, and aminopropyltriethoxysilane to increase the strength of covalent bonding of the enzyme with the carrier was first experimentally confirmed received. Also, new effective immobilized biocatalyst based on the titanium dioxide which is suitable for repeated use in the liquid phase oxidation of chlorophenols was obtained. The results show high prospects of synthesized biocatalyst using in the process of chlorophenol pollutants removing from the water. All hypotheses and conclusions expressed in this article are based on scientific and technical literature on methods of immobilization of enzymes, methods of inorganic carriers modifying, the calculation of the kinetic parameters of enzymatic reactions and the basic laws of spectrophotometric analysis.