Preparation of high oil absorption microfiber cryogels by mechanical method

Abstract

Poplar alkaline peroxide mechanical pulp (APMP) was used as plant fiber raw material, and it was graded according to the lignin content. The graded raw materials were used to prepare lignin-containing microfibers (LCMFs) by micro-grinding, and then, the lignin-containing microfiber cryogels (LCMF-cryogels) were prepared by vacuum freeze-drying. The particle size distribution, micromorphology and dispersion stability of LCMFs were characterized by laser diffraction particle size analyzer, transmission electron microscopy and Zeta potentiometer. Then, the crystalline structure, pore structure, surface morphology and adsorption properties of LCMF-cryogels were analyzed. In addition, LCMF-cryogels were compared with the microfiber cryogels (MF-cryogels) which use commercial eucalyptus chemical bleaching pulp as raw material. It was proved that using poplar APMP as raw material to prepare cryogels is more advantageous. The results showed that the lower the lignin content in plant materials, the better the oil adsorption ability of cryogels. This is because the binding effect of lignin on the fiber is reduced, which makes the fibrillation of the fiber easier by external mechanical action. The maximum adsorption capacity of LCMF-cryogel for methyl silicone oil is 215 g/g, while that of MF-cryogel prepared from commercial eucalyptus chemical bleaching pulp is 102.5 g/g. The analysis of the properties of raw fiber and the gel pores shows that the change in the fiber morphology caused by different pulping methods has important influence on the development of LCMF-cryogels by mechanical refining. Poplar APMP is more suitable for preparing fiber-based cryogels oil-absorbing materials than commercial eucalyptus chemical bleaching pulp.