fulltext.study @t Gmail

An integrated process: Ester synthesis in an enzymatic membrane reactor and water sorption

Paper ID Volume ID Publish Year Pages File Format Full-Text
25294 43565 2007 10 PDF Available
Title
An integrated process: Ester synthesis in an enzymatic membrane reactor and water sorption
Abstract

In the case of such reactions as ester synthesis, water is produced during the reaction. Because these reactions are carried out in hydrophobic solvents an additional (water) phase in the system must not be allowed, i.e. the concentration of water saturation in the organic solvent should not be exceeded. In such a case, the reaction kinetics and product equilibrium concentration undergo undesirable changes because of the partition coefficient of the components and hampered process of product separation. Hence, removal of the water produced in the reaction determines whether the process is successful or not. For this purpose, the integrated process with water sorption in the column with molecular sieves was applied.Integration of the process of synthesis and dehydration of a reaction phase, in which a biocatalyst is suspended and not dissolved as in water solutions, requires holding up of the catalyst in the reactor before directing the stream of reaction mixture to dehydration process. This hold-up and a possibility of multiple use of the catalyst may be accomplished by using a separating barrier, e.g. an ultrafiltration membrane or by permanent fixing of the catalyst to the matrix, e.g. a polymeric membrane.The efficiency and activity of a biocatalyst (lipase CAL-B) immobilized on a polymer membrane by sorption and chemical binding, were determined. A subject of study was the synthesis of geranyl acetate, one of the most known aromatic compound. A hydrophobic (polypropylene) matrix was shown to be a much better carrier in the reactions performed in an organic solvent than a hydrophilic (polyamide) membrane being tested.The reaction kinetics of geranyl acetate synthesis with the use of geraniol and acetic acid as substrates, was described by the equation defining the “Ping-Pong Bi Bi  ” mechanism that was related additionally to the inhibition of a substrate (acetic acid). The following constants of kinetic equation were obtained k3'=0.344 mol g−1 h−1, KmA = 0.257 mol l−1, KmG = 1.629 and KiA = 0.288 for the native enzyme and vmax,Gel=111.579 mol l−1 h−1vmax,Gel=111.579 mol l−1 h−1, KmA = 0.255 mol l−1, KmG = 1.91 mol l−1, KiA = 0.238 mol l−1 for the one immobilized by sorption on a polypropylene membrane. Half-life time of the native enzyme activity was 204 h and stability of the immobilized preparation was 70 h.With respect to the reaction kinetics and stability of the native enzyme and immobilized preparation, from both types of membrane bioreactor more attractive appears to be the one in which the membrane is used not as a catalyst layer but only as a barrier that immobilizes the native enzyme within the bioreactor volume. When an integrated process proceeds, the method to collect water in the sorption column during the process, appeared to work very well. The reaction proceeded with a very high efficiency (after 120 h α = 98.2% for native enzyme and 83.2% for immobilized enzyme) and due to low water concentration in the system (≈0.000% v/v) the second phase was not created.

Keywords
Membrane bioreactor; Organic solvent environment; Enzyme immobilization; Catalytic membrane; Geranyl acetate; Enzymatic kinetics
First Page Preview
An integrated process: Ester synthesis in an enzymatic membrane reactor and water sorption
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 130, Issue 1, 31 May 2007, Pages 47–56
Authors
, ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us