Study of supercritical carbon dioxide pretreatment processes on green coconut fiber to enhance enzymatic hydrolysis of cellulose.

Green coconut fiber was treated by supercritical CO with the aim to enhance hydrolysis of its enzymatic cellulose. To this end, different static conditions of CO contact times (3 and 5 h) and polarity modifiers (NaOH, NaHSO, ethanol) were evaluated at 20 MPa, 70 °C and 1 h of dynamic extraction followed by fast depressurization. After supercritical CO exposition, SEM images showed fiber damage and FTIR spectra showed decreases of phenolic and wax contents, including a reduction in the degree of the hydrogen bond established between lignin and cellulose.