Optimizing Supercritical Carbon Dioxide in the Bacterial Inactivation and Cleaning of Sheep Wool Fiber by Using Response Surface Methodology

Abstract

ABSTRACT In the textile industry, sheep wool undergoes treatment with a lengthy water-based procedure. In the present study, supercritical carbon dioxide (scCO2) was applied as a waterless technology to clean sheep wool fiber and inactivate gram-positive bacteria (Bacillus Velezensis, Bacillus amyloliquefaciens, Exiguobacterium, Bacillus cereus) and gram-negative bacteria (Klebsiella pneumoniae and Enterobacter cloacae) present in sheep wool fiber. Response surface methodology (RSM) was used to determine the optimal experimental conditions of scCO2 parameters (pressure, temperature, and time) on the maximum inactivation of bacteria (log survival) and whiteness index (stensby) of treated sheep wool. The optimal experimental condition of scCO2 was determined as the pressure of 29 MPa, the temperature of 55°C for 75 min treatment time to obtain the complete inactivation of bacteria (−6.2 log survival), and 26 stensby of whiteness index. The results demonstrated that the second-order polynomial model was adequately fitted with experimental data. The analyses of the influences of scCO2 parameters reveal that the scCO2 pressure, temperature, time, their interection, and quadratic effects potentially influence the inactivation of bacteria and the whiteness index of sheep wool fiber.