Abstract
Cellulase was immobilized onto silica gel surfaces pretreated with (3-aminopropyl) triethoxy-silane (3-APTES), and glutaraldehyde (GA) was used as a cross-linker. A carboxymethyl cellulose sodium salt (CMC) solution was used for activity experiments. Protein assay was performed to determine the mass immobilized and compare with free enzyme. Cellulase was successfully demonstrated to be immobilized on the modified silica gel surface, and no detectable amount of enzyme was stripped off during the hydrolysis of the CMC solution. The specific activity of the immobilized cellulase is 7 ± 2 % compared to the similar amount of free cellulase. Significant activity over multiple reuses was observed. The seventh batch achieved 82 % activity of the initial batch, and the fifteenth batch retained 31 %. It was observed that the immobilized cellulase retained 48 % of its initial activity after 4 days, and 22 % even after 14 days.
Highlights
Bioethanol, biomethanol, biodiesel, etc. known as biofuels are an alternative energy source that will likely become more prevalent in the future (Nigam and Singh 2011)
The results show that the activities of both the free and immobilized cellulase have the same
In this study, cellulase was immobilized covalently on silica gel modified by (3-aminopropyl) triethoxy-silane (3-APTES) using glutaraldehyde as a cross-linker
Summary
Bioethanol, biomethanol, biodiesel, etc. known as biofuels are an alternative energy source that will likely become more prevalent in the future (Nigam and Singh 2011). Known as biofuels are an alternative energy source that will likely become more prevalent in the future (Nigam and Singh 2011). Bioethanol has been made from plants that produced high amounts of natural sugar—such as sugar cane or corn. The increased demand for these products increases the competition and the price of food products from these sources. Cellulose is one of the most abundant polysaccharide in the nature. Bioethanol from cellulose, is a very promising avenue of biofuel as it does not compete with food products (Kemppainen and Shonnard 2005; Sticklen 2008). Producing ethanol from cellulose usually contains two steps. The hydrolysis of cellulose to glucose; and second, its fermentation to ethanol. The first process can be performed by either chemical or enzymatic process, the later one is preferred because it is cleaner and the process can be controlled by adjusting the reaction conditions (such as pH, temperature, etc.) (Mabee and Saddler 2010)
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