Conversion of lignocellulosic biomass to nanofiber by microfluidization and its effect on the enzymatic hydrolysis

Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Turkey

Approval Date: 2010

Thesis Language: English

Student: Sinem Yavaş



Lignocellulosic biomass is under extensive investigation as a bioethanol and bio-based materials feedstock. However, the complex structural and chemical mechanisms of lignocellulosic plant, which cause resistance to deconstruction during saccharification, require a pretreatment process. In this study, raw materials (corn bran, wheat bran and wheat straw) were selected because of their production and consumption in Turkey and also their accessibilities to be used as bioethanol source. Microfluidization pretreatment (high-pressure fluidization), which stands as a new approach for nano-cellulosic fibers production, was studied at 500 bar and 2000 bar to observe the qualitative and quantitative modifications in enzymatic hydrolysis depending on its effects on lignocellulosic structure. Optimum cellulase concentrations were determined for microfluidized samples as 4.5 U/g dry biomass for wheat bran, corn bran and 6.0 U/g dry biomass for wheat straw samples for the first 150 min interval. Effective usage of solid loads were found as 5.0 %, 2.5 %, and 7.5 % (dw/v) for wheat bran, wheat straw and corn bran, respectively. X-ray diffraction and SEM results of the microfluidized samples have indicated that the pretreatment has increased crystallinity index of all the samples and resulted in a scattered structure. Comparisons with other methods (softening, dilute-acid and lime pretreatments) have shown that microfluidization is advantageous over others by reducing the time required for enzymatic hydrolysis and thus can be a promising alternative pretreatment.