Ultrasonic-assisted ionic liquid treatment of chemithermomechanical pulp fibers

Scientific Achievement

  The IL treatment led to a small change in the kink index of fibers and noticeable alternations in the surface charge density (from -0.8 to -14.7 leq/g),CSF (from 760 to 580 ml) and WRV (from 1.45 to 1.75 g/g) of fibers, which provided evidence for improved swelling and flexibility of the fibers. The content of lignin and hemicellulose of fibers was also reduced via IL treatment, which facilitated the swelling and brightness increases of fibers, as well as the surface area of dried fibers. The ultrasonic treatment changed the surface charge density of fibers to -17.9 leq/g, CSF to 530 ml and the WRV to 1.8 g/g. The ultrasonic-assisted IL treatment of fibers improved the tensile, tear and burst indices as well as the folding endurance of cellulosic networks by 41, 36, 12 and 150%, respectively.

Significance and Impact

  The pretreatment with ultrasonic treatment for 20 min reduced its CSF to 545 ml. The tensile, tear and burst indices as well as the folding endurance of the handsheet increased by 41, 36, 12 and 150%, respectively after the ultrasonic-assisted IL treatment. The surface charge density and area of fibers were improved via ultrasonic-assisted IL treatment.As IL could effectively be recovered after the treatment, the ultrasonic-assisted IL treatment can be implemented to broaden the application of CTMP fibers in packaging industry.

Research Details

  Enhancing the swelling of chemithermomechanical pulp is essential for improving its physical properties and thus broadening its end-use applications. In this work, ionic liquid (IL) using 1-allyl-3-metheylimidazolium chloride ([Amim]Cl) was used for reducing hydrogen bonding within the fiber wall, and ultrasonic treatment was used for improving the performance of IL treatment. Mixing IL with pulp fibers at 5 ml/g concentration decreased the Canadian standard freeness (CSF) of pulp from 760 to 570 ml at room temperature, and the pretreatment with ultrasonic treatment for 20 min reduced its CSF to 545 ml. The ultrasonic-assisted IL treatment improved the tensile, tear and burst indices as well as the folding endurance of the cellulosic network by 41, 36, 12 and 150%, respectively. The surface charge density and area of fibers were improved, but the lignin and hemicellulose contents of the fibers were reduced via ultrasonic-assisted IL treatment.

DOI:10.1021/ef502462p