Hydrolysis kinetics characteristic of recycled fiber in subcritical water

Recycled fiber hydrolysis was conducted to evaluate the feasibility of reducing sugar accumulation for biofuel products during hydrolysis in subcritical water. The hydrolysis conversion of recycled fiber was reaching to approximate 90% within 3 min at 280–320 °C, while the glucose decomposed simultaneously within 0.5 min. The FTIR wave variation and the crystalline index of hydrolysis residue indicated that the intermolecular, intramolecular hydrogen bond and the crystalline was a constraint for recycled fiber hydrolysis. The kinetics analysis demonstrated the cylindrical shape model is proper at low temperature for recycled fiber hydrolysis, while sphere shape model is suitable at high temperature. The apparent activation energies of recycled fiber on both kinetics models were 58.19 kJ mol−1 and 53.18 kJ mol−1, which were lower than that the glucose with 79.59 kJ mol−1. Therefore, the conclusion is drawn that the high yield of glucose during recycled fiber hydrolysis is achievable by reducing the cellulose crystalline through proper indispensible pretreatments.

► Recycled fiber hydrolysis characteristic was investigated under subcritical condition.
► We identified hydrolysis residues to elucidate the changing of recycled fiber.
► Cylindrical shape model is proper at low temperature for recycled fiber hydrolysis.
► Apparent activation energies affirmed the feasibility for reducing sugar accumulation.
► High glucose yield is achievable by reducing crystallinity of recycled fiber.