Supramolecular Gelator Modified Melamine Sponge For Efficient Oil/Water Separation

Frequent organic pollutants leakage and marine oil spills pose serious threats to the ecosystem,and the development of efficient and environmentally friendly methods for oil spill treatment has become the focus of current study.In this paper,a series of halogen-free phase-selective gelators An(n=6,12)and ANn(n=6,12)were designed and synthesized.The relationship between the gelator structures and the gelation properties was analyzed,and the application of gelators was studied.Further more,the supramolecular phase-selective gelator was used as a surface modification material to prepare the gel modified melamine sponge due to its hydrophobicity,oleophilicity and self-assemble,and the application and mechanism of the modified sponge were explored in this paper.It was found that the structure of gelator had an important effect on the properties of modified sponges,and the modified sponges prepared by A12,A18 and AN12 with long alkyl chain are hydrophobic,with a water contact angle of 129±0.5°.The prepared sponges could selectively absorb oil from the oil-water mixture quickly and efficiently up to 79.3-142.1g/g,and can also collect oil microdroplets from surfactant-free oil-in-water emulsion.The recyclability of the modified sponges is mainly related to the solubility of gelator in organic solvents.MS-AN12 with a amino group at the terminal position of long alkyl chain has the best recycling performance with 120 cycles.The structure of modified sponge was characterized by IR and SEM,and a possible combination mechanism of gelator and sponge was proposed.The gelator attached to melamine sponge fibers through hydrogen bonding(between the hydroxyl groups and amide groups of gelator and the secondary amine group on the surface of the melamine sponge),exposing its hydrophobic part.The rough hydrophobic coating formed by the self-assembly of gelators further covers the hydrophilic sponge and improves the surface roughness of the fibers,thus changing the surface wettability of the sponge.Compared with traditional modified materials such as inorganic nanoparticles and graphene,the synthesis of supramolecular gels is simple and cost-effective,does not need complicated pretreatment.The hydrophobic sponge can be prepared by a simple and environmentally friendly dip coating method,avoiding high temperature conditions and complex chemical reactions,is suitable for large-scale industrial production,and provide an effective approach for oil spill containment and environmental remediation.