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| Author(s): |
Cintia Maria Rodrigues Rosa
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Lorena. |
| Institution: | Universidade de São Paulo (USP). Escola de Engenharia de Lorena (EEL/ASDI) |
| Defense date: | 2019-10-04 |
| Examining board members: |
Larissa de Freitas;
Leandro Gonçalves de Aguiar;
Rita de Cássia Lacerda Brambilla Rodrigues
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| Advisor: | Larissa de Freitas |
| Abstract | |
The aim of the present work was to synthesize and characterize styrene based particles magnetised by co-precipitation of Fe2+ and Fe3+ ions in basic media, to be used as support for enzyme immobilization. The synthesis of 4 magnetic copolymers (STY-DVB-M, STYEGDMA-M, STY-TEGDMA-M and STY-TMPTA-M) obtained by suspension polymerization employing azobisisobutyronitrile (AIBN) as the initiator was studied with the aid of the methodology statistics of complete orthogonal arrangement (L9 - Taguchi). The factors analyzed were: monomer / solvent ratio; % crosslinker in the total monomer mass; proportion of solvent with high affinity / solvent with low affinity in the mixture (toluol / heptane) and % of magnetite in the total mass of monomer, being evaluated in 3 levels. The responses variable were established as: total polymerization yield and yield in useful particles (particles between 80-24 mesh). From the statistical analysis it was possible to determine the best fit condition for the polymerization process, aiming at the total particle yield, being the 4 factors at the maximum level. For the yield of the useful particles, the settings indicated varied for each type of copolymer. Further tests were performed to confirm the statistical notes. The synthesis of the different copolymers, employing the best experimental conditions for maximum obtainment in useful particles, was also performed employing benzoyl peroxide as the initiating agent. The obtained magnetized copolymers were characterized by EDX, FTIR, Raman, ICP-OES, XRD, Hysteresis, DSC, TGA, contact angle, Density, SEM, OM, BET and swelling. Through the SEM, OM and BET analyzes, it was possible to observe the influence of the initiating agents on the characteristics of the copolymers, being observed differences in the morphologies and roughness of the particles. In the analysis of FT-IR, DSC, TGA, Density, BET, contact angle and degree of swelling, it was possible to observe the influence of the different crosslinking agents, noting different temperatures of thermal decomposition, densities, surface areas and percentage of heptane absorption. The insertion of magnetite into polymer matrices was confirmed by the EDX, ICP-OES, Hysteresis and Raman analyzes, with magnetization saturation between 4 and 7 emu.g-1 and the limit of incorporation of magnetite around 35 to 40% of all Fe2O3 supplied during the polymerization. In order to determine the suitability of synthesized polymer matrices for immobilization of enzymes, Lipase B from Candida antarctica was immobilized by physical adsorption in the different copolymers, quantifying its hydrolytic and synthetic activities. The stability of the biocatalysts that presented the best catalytic performance (obtained by the STY-EGDMA-M and STY-TEGDMA-M supports) was evaluated, with residual activity higher than 97% after incubation for 4 h at 50 ° C, and half-life equal to 21.6 h for STY-EGDMA-M immobilized lipase, which presented a Kd value 14 times higher than that obtained by its free form, proving that the immobilization process provided greater thermal stability to the enzyme. The experimental work allowed to obtain different solid matrices suitable for use as substrates for immobilization of lipases, expanding the range of these materials and contributing to the viability of replacing conventional chemical catalysts with biocatalysts using clean technology. (AU) | |
| FAPESP's process: | 17/04934-9 - Synthesis and characterization of magnetized poly (styrene-co-divinylbenzene) particles to be used as support for enzyme immobilization |
| Grantee: | Cintia Maria Rodrigues Rosa |
| Support Opportunities: | Scholarships in Brazil - Master |