Cofactor-embedded nanoporous activated carbon matrices for the immobilization of intracellular enzymes and degradation of endocrine disruptor.

ABSTRACT

The mixed intracellular enzyme (MICE) from Citrobacter freundii, capable of degrading o-phenylene diamine (OPD), was extracted and characterized. Cofactors such as zinc and copper ions enhanced the MICE activity. The functionalized nanoporous-activated carbon (FNAC) matrix, zinc-impregnated FNAC matrix (Zn2+ -FNAC), copper-impregnated FNAC matrix (Cu2+ -FNAC), and zinc- and copper-impregnated FNAC matrix (Zn2+ -Cu2+ -FNAC) were prepared and characterized to immobilize MICE. The parameters such as time (0-240 Min), pH (1-10), temperature (20-50 ºC), amount of MICE (1-5 mg), particle size of carbon (100-600 µm), and mass of carbon (0.5-2.5 g) were optimized for immobilization of MICE on different FNAC matrices. The carrier matrices in the free and MICE immobilized form were characterized using SEM, FT-IR, XPS, XRD, thermogravimetric analysis (TGA), and DSC analyses. The kinetic and adsorption models for the immobilization of MICE on FNAC matrices were studied. The parameters such as time, pH, temperature, concentration of OPD, and agitation speed were optimized for the degradation of OPD using FNAC-MICE and MICE-immobilized metal-impregnated FNAC matrices. The maximum amount of pyruvic acid formed was found to be 133 µg/mg of OPD using Zn2+ -Cu2+ -FNAC-MICE matrix. The kinetic models were studied for the formation of pyruvic acid on OPD degradation and confirmed using FT-IR spectroscopy.