The aim of this study was to investigate the utilization of a recycled rayon waste-kapok mixtures as an oil sorbent for the removal of diesel, motor oil and bunker C. The effects of the kapok fibers: rayon fibers ratio and the additional of sodium sulfate on RRWK sorbents properties were investigated through series of oil sorption tests. The ASTM 726-06 method was used to determine the oil sorption capacity of the sorbents under both static and dynamic conditions. The results showed the high sorption capacity of the recycled rayon waste-kapok mixture for difference kinds of oil. Oil, which has a high viscosity, tends to have a higher oil sorption ratio. RRWK sorbents had higher oil sorption capacity than commercial polypropylene. The presence of kapok fibers in RRWK increases the hydrophobicity and oil sorption capacity of the sorbents while the presence of rayon fibers improves the strength of the sorbents. The additional of sodium sulfate during sorbent preparation increases the surface area and pore size of RRWK sorbent and thus improves the oil sorption capacity. It can be concluded that RRWK, which can be produced by utilizing industrial waste, is effective low cost, environmentally friendly oil sorbent with comparable performance to commercial products

Optimal condition-based microemulsion is key to achieving great efficiency in oil removal. One useful empirical equation to predict an optimal condition is a hydrophilic–lipophilic deviation (HLD). However, the K constants of each surfactant should be the same to combine the HLD equations for the mixed surfactant. Recently, a normalized hydrophilic-lipophilic deviation (HLD_N) was presented to avoid this limitation. This work sought to determine the phase behaviors and predict the optimal salt concentrations, using HLD_N for the mixed surfactant. Sodium dihexyl sulfosuccinate (SDHS) as an anionic surfactant, and alcohol alkyl polyglycol ether (AAE(6EO4PO)) as a nonionic surfactant, were both investigated. Alkanes and diesel were used as a model oil. The results showed that AAE(6EO4PO) enforced both the hydrophilic and the hydrophobic characteristics. The Winsor Type I-III transition was influenced by the ethylene oxide, while the propylene oxide presence affected the Winsor Type III-II inversion. For the HLD_N equation, the average interaction term was 1.82 ± 0.86, which markedly showed a strong correlation with the fraction of nonionic surfactant in the mixed systems. The predicted optimal salt concentrations using HLD_N of SDHS-AAE(6EO4PO) in the diesel systems were close to the experimental results, with an error of <10% that is significantly beneficial due to the shorter time required for optimal determination.