Full text
| |
| Author(s): |
Denise Silva de Aquino
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Química |
| Defense date: | 2010-10-18 |
| Examining board members: |
Telma Teixeira Franco;
Heizir Ferreira de Castro;
Helia Harumi Sato;
Victor Haber Pérez;
Cecília Sulzbacher Caruso
|
| Advisor: | Gustavo Paim Valença; Telma Teixeira Franco |
| Abstract | |
In this work the equilibrium and kinetics constants of the direct esterification of sucrose with acrylic acid catalyzed by lipase Candida antarctica (Novozym 435) were determined. The optimal conditions were studied such as: different amounts of enzyme and water, sucrose to acrylic acid molar ratio and molecular sieves content. Enzymatic esterifications are equilibrium reactions whose subproduct is water. The presence of this must be controlled to allow esterification of the lipase and to avoid hydrolysis of esters. The addition of molecular sieve 3 Å to the system was investigated to remove of produced water and to shift the equilibrium to the synthesis of ester. The interest in the sugar ester production is due the high capacity to absorb water. Renewable sugars are interesting alternative carbon sources for the production of chemicals by biotechnological routes. The highest sucrose conversion (76%) in sucrose acrylate was reached on the following conditions: 78 g/L of lipase, molar ratio 1:6 (sucrose:acrylic acid), without initial water and 400g/L of molecular sieve. The Ping-Pong Bi-Bi mechanism was proposed. Therefore, the equation represents the mechanism for the reaction sequence involved in the synthesis of sucrose acrylate was developed. The estimates of the parameters of the K1, K2, K3, K8, K9 and ? were obtained using the Taylos series expansion, set by a line equation and set non-linear by the computer program Polymath 6.0. The criterion used to value the quality of data fit was 95 % confidence level. (AU) | |