Construction And Study Of Biomass Aerogels With Superwetting/Superelasticity For The Removal Of Pollutants In Water

With the increasing of the types and quantity of wastewater in our living environment,the development of multifunctional,high-efficient,and long-life separating materials that can simultaneously remove a variety of pollutants from water is a promising topic in the field of wastewater treatment.In this project,according to the structure and composition of biomass aerogels,we regulate the three-dimensional network structure and skeleton composition of biomass aerogels in the microscopic level by the combination of ice templating method and in situ doping technology.The mechanical strength and toughness of the aerogel are improved,and given its underwater superoleophobicity,high adsorption efficiency,and photocatalytic activity.As a result,we obtain biomass aerogels with high-strength-toughness and multifunction that can simultaneously and high-efficiently remove a variety of pollutants from water.Through the research of the design,preparation,performance,and mechanism of biomass aerogels,the preparation method and regulation technology of biomass aerogels with high-strength-toughness and multifunction are mastered;the relationship between the composition and performance is confirmed;the multifunction synergistic effect mechanism for the removal of a variety of organic pollutants is revealed.These results can provide the theoretical and technical support for the development and application of biomass materials in the field of wastewater treatment.?1?To overcome the poor mechanical properties of biomass aerogels in oil/water separations,three different freeze-casting methods were used including direct freezing,unidirectional freezing,and bidirectional freezing with sodium alginate?SA?aerogels reinforced with cellulose nanofibrils?CN?.After chemical crosslinking and silane modification,compression testing revealed that the SA/CN aerogels with parallel lamella microstructures prepared by bidirectional freezing exhibited super-elasticity,the original shape can be recovered effectively when dealing with large compression strain,with the minimal energy dissipation of⁰.04 in each cycle,a maximum compressive stress of 80.4 kPa,and minimal plastic deformation at⁴.15%.Additionally,the water and oil contact angle of the surface of the lamellar SA/CN aerogel was 148.7°and 0°,respectively.By combining the super-elasticity and hydrophobicity/superoleophilicity,the lamella SA/CN aerogels could be reused for the separation of oil/water mixture with oil absorption capacities up to 34 times its weight.Furthermore,the lamellar SA/CN aerogel could realize the continuous separation of oil/water mixture with the assistance of a pump.Therefore,the present study offered a simple and environmentally friendly method for fabrication of super-elastic and hydrophobic/superoleophilic biomass aerogels that are applied to continuous removal of oil from water.?2?In this study,the biomass aerogel is prepared through incorporating Typha orientalis fibers?TOFs?and graphene oxide?GO?into sodium alginate?SA?matrix by using a facile combined bidirectional freezing technique and ionic cross-linking method.The SA/TOFs/GO aerogel possesses large parallel lamellar layers and honeycomb-like cellular pores between lamellas microstructures,in which SA flakes and GO nanosheets with 2D structure were intimately grown along TOFs through hydrogen bonds.Under the cyclic compression test condition,the distinctive structure makes the stress spread over the entire lamellar layer to avoid stress concentration and endows the SA/TOFs/GO aerogel with excellent mechanical compressibility.Furthermore,the aerogel could be used for the separation of various oils?e.g.,kerosene,crude oil,and n-hexane etc.?with high oil separation efficiency?>98.2%?due to its excellent underwater superoleophobicity,and simultaneous removal of water-miscible contaminants with high dye removal efficiency?>98.0%?by the electrostatic interaction and?-conjugation between the dye and the oxygen-containing groups/nonoxidized regions.More importantly,the SA/TOFs/GO aerogel is demonstrated to possess dramatically reusability and maintain excellent dye adsorption capacity?>86.9%?for100 cycles of adsorption-desorption,thus achieving high efficiency and simultaneous removal of insoluble oil and water-soluble organic pollutants in water.?3?In this study,the biomass aerogel is prepared through incorporating BFs and CaCO₃ into chitosan?CS?matrix by using a facile combined bidirectional freezing technique.After 10000 cycles of constant strain 60%repeated compression/release,the plastic deformation of CS/BFs/CaCO₃ aerogel is negligible.Furthermore,the obtained aerogel feature excellent underwater superoleophobicity which could removal of insoluble oils,soluble dyes,and heavy metal ions in water through hydrogen bonds interaction between the dye and-OH/-NH₂,ionic exchange interaction between the heave metals and CaCO₃.Various pollutants in water achieved with very high removal efficiencies in a short time by simply passing through aerogel.We believe that the underwater superoleophobic aerogel are very promising for removal of various pollutants in water.