Preparation And Characterization Of P(DEA-co-AA) Microgels And Its Role In Horseradish Peroxidase Immobilization

A series of temperature-sensitive microgels were synthesized with N, N-diethylacrylamide(DEA) as main monomer,acrylic acid(AA) as comonomer by surfactant-free emulsion polymerization(SFEP).The structure,morphology and phase transition behavior were studied in detail.Furthermore,the microgels were used as carriers of horseradish peroxidase(HRP),and the conditions and properties of enzyme immobilization had been studied.And then,the catalytic performance of the immobilized HRP applied in the treatment of phenolic wastewater and enzymatic reaction mechanism were also studied in detail.The main contents including:1.A series of temperature-sensitive microgels poly(N,N-diethylacrylamide-co -acrylilcacid)(P(DEA-co-AA)) were synthesized by surfactant-free emulsion polymerization(SFEP).The microgels were characterized by infra-red spectrometer (IR),turbidimetric method,scanning electron microscope(SEM) and dynamic light scattering analysis(DLS).The result show that the microgels P(DEA-co-AA) were monodispersed as spherical particles.The average size of the microgels increased with the content of AA.The dispersions versus temperature(VPTT) increased with the increasing AA content at pH 7.0,while at pH 4.0 the change of VPTT is significant with the AA content.The swell ratios of the microgels also increased with the AA content.2.The P(DEA-co-AA) microgels was feasible material for enzyme immobilization.The IR spectra show that the enzyme was immobilized mainly by hydrogen bond force with the microgel.In spite of the pH value of system affected enzyme immobilization yield greatly,it is needless to adjust the pH value of system. The enzyme immobilization process normally finished after 60 minutes.Based on an overall consideration of various factors,the amount of carrier should be 0.82 mg per enzyme active unit.And the experiment of enzyme immobilization had a good repeatability.3.At appropriate situation,the immobilized HRP achieved a high removal efficiency of over 96%phenol in wastewater.The reaction mechanism of oxidation of phenolic compound catalyzed by HRP could be considered as ping-pong kinetics. Free enzyme exhibited higher affinity to substrate than immobilized enzyme. However,the maximum reaction velocity of oxidation of phenol catalyzed by bound HRP was greater than obtained form free HRP.At the same time,compared with free enzyme,the immobilized HRP on the P(DEA-co-AA) microgels is more thermostable.