Evaluation of oil sorption kinetics behavior and wetting characteristic of cattail fiber

In this study, the effect of packing density, oil type and temperature on the sorption kinetics behavior of cattail fiber was investigated based on Washburn theory by capillary rise test. It was found that higher packing density resulted in lower oil sorption capacity due to the less available space among fibers. The sorption coefficient to different oils which represented the sorption rate exhibited large difference with various packing densities. The results illustrated that when the packing density was 0.04 g/cm3, the cattail fiber showed higher oil sorption capacity and faster oil sorption rate. With regards to the temperature, results revealed that at the packing density of 0.06 g/cm3, the oil sorption capacity of cattail fiber showed little difference when the temperature ranged from 20 to 80 °C. However, the sorption coefficient depicted almost linear enhancement when higher temperature was applied. Moreover, the wetting characteristics of single cattail fiber to three test oils were performed by drop-on-fiber test. It was concluded that three test oils all displayed barrel-shaped droplets on single fiber with the smallest size for diesel oil and the largest for engine oil. Oil drops of vegetable oil and engine oil on single cattail fiber presented a dynamic flow process where smaller droplets converge into large ones. The unique wetting characteristic of cattail fiber was supposed to result from the open-cavity surface structure of cattail fiber.