Data-driven modeling and optimization of oil spill sorption by wool fibers: retention kinetics and recovery by centrifugation

Oil spills have provoked negative environmental impacts for decades. To combat such accidental pollutions, the exploiting of the low-cost sorbents is of real interest. We report herein the valorization of coarse grade wool fibers (biomass waste) as sorbents for the uptake of oily products. Response surface methodology was employed for modeling and optimization of the oil-uptake process. The optimal conditions were found to be (1) the sorbent dosage of 2.80 g/dm2; (2) the initial thickness of the oil layer of 3.0 mm (on the water surface), and (3) the dripping time equal to 10 s. The established optimal conditions yielded the maximum oil removal efficiency of 98.28%. In addition, the microscopy investigations revealed that the oil can be retained by the wool fibers as (1) adhered films, (2) ellipsoidal droplets, and (3) oil-bridges filling the voids between fibers. Kinetic data of liquids retention and dripping were modeled using the unsteady-state retention theory. According to the model parameters, the maximum sorption capacities of wool fibers were found to be 6.65, 17.86, and 22.54 g/g for the uptake of dodecane, motor oil 5 W, and 15 W, respectively. The desorption isotherm of cyclohexane disclosed the predominant role of the capillary phenomena in the retention of liquids. Ultimately, the used sorbents were centrifuged in order to recovery the oily liquids in an advanced mode (98.33 ± 0.42%—recovery efficiency).