3.5. Batch adsorption experiments
The maximum oil sorption capacities of RP, AP and SP for diesel and lubricating oil were evaluated by batch adsorption experiments in oil/water mixture. The results were displayed in Fig. 4. It is observed that RP, AP and SP show a fast adsorption rate during the initial 15 s, and the maximum oil sorption capacity for diesel and lubricating oil can be reached within 9 min, for example, the maximum oil sorption capacity of RP is about 6.39 and 9.04 g/g for diesel and lubricating oil, respectively. Furthermore, the sorption capacity of SP for diesel and lubricating oil can reach 18.91 and 26.36 g/g, respectively. Also, the sorption capacity of AP is 16.50, 19.39 g/g for above two kinds of oils. It indicates that the surface modification of RP is very effective for improving its oil sorption capability. In addition, the oil sorption capacity of SP is superior to that of AP probably due to the different rough surface for AP and SP. The surface is very important for effective oil sorbent, which could affect the oil retention capability of sorbent, resulting in the change of oil sorption capacity. This surface not only increases the surface area of the fiber, but also improves the oil adhesion property on the fiber surface, which is beneficial for oil retention of RP.