Green Recovery of Kapok by Partial Dissolution Regeneration for Constructing High-Strength Fiber Membrane to Achieve Oily Wastewater Purification

Recently, the recovery and reuse of natural fibers have gained much attention. However, kapok fiber as a kind of natural cellulose fiber is difficult to recycle because of its poor mechanical property. In this study, a facile, universal, and brand new strategy was proposed by taking the partial dissolution and self-assembled regeneration of cellulose for fabricating regenerated kapok fibers (R-KFs). The R-KFs exhibit compact fiber structure, and the structural densification obtained in the cellulose dissolution and self-assembled regeneration process make the fibers possess high strength. Then, the tensile strength of R-KFs is enhanced 37 times compared to the original kapok fibers, which can efficiently break through the limitation of weak mechanical property of kapok fibers for constructing functional material to broaden its application in other fields. Furthermore, the regenerated kapok cellulose fibers achieve strong hydrogen bonding networks and unique multilayer structures so as to exhibit the remarkable properties of superhydrophilicity and stability. Thus, under gravity-driven filtration, the as-prepared R-KFs showed excellent purification efficiency of 99.9% for oily wastewater, and furthermore, the R-KFs achieved superior flux (3.8 × 104 L m–2 h–1) and favorable reusability (30 cycles). It is the first time to achieve the regeneration and recycling of waste kapok fibers, and moreover, such a green, simple, and highly efficient strategy developed in this study for the recovery and reapplication of kapok fibers can be extended to recycle and reuse other natural fibers and cellulose materials similar to kapok fibers.