OPTIMIZATION OF BARLEY HUSKS ACID HYDROLYSIS PROCESS USING THE RESPONSE SURFACE METHODOLOGY

Barley husks were submitted to a two-step acid hydrolysis process able to conduct to a material with high content of fermentable sugar (31.77 g/L). The first hydrolysis stage was conducted in "mild" conditions with diluted sulphuric acid and aimed to recover monosaccharides from hemicellulose content. More "aggressive" conditions were employed in the second stage of hydrolysis targeting the cellulose content in order to obtain glucose which is known as highly suitable to be transformed in biomass. The most important parameters of the developed process (temperature, sulphuric acid concentration, hydrolysis time) were optimized using the Response Surface Methodology. According to the obtained results the first hydrolysis step can be properly conducted at 323.35 K with diluted sulphuric acid (3.02 g/L) for 282 min. For the second hydrolysis step, the temperature set at 368.65 K and the use of concentrated sulphuric acid (75.2 g/L) for 26.7 min seemed to be adequate.