Fabrication And Studies Of Special Wettable Biomass Materials For Oil/Water Separation

With the increase of people's demand for material life and the development of industry technology,the emissions of industrial and sanitary wastewater are also growing year by year.The wastewater is often a mixture of oil and water,which contains highly toxic oil that may be extremely damaging to water and atmosphere environment.Besides,oil spill accidents occur frequently,seriously threatening marine ecological environment and life.Due to the worsening oil pollution crisis,oil-water separation materials have received a great deal of attention and have been developed greatly these years.Scientists change materials'wettability toward water and oil through regulating materials'surface chemical composition and physical structure,significantly improving the performance of oil-water separation materials.A most representative research direction is endowing oil-water separation materials superwettability.Based on this background,in this thesis,we are committed to developing special wettable biomass materials for oil/water separation through using low-cost and eco-friendly biomass materials as raw materials.By probing the performance of these materials and analyzing the basic scientific problems during oil-water separation,we comprehensively assess the application value of these materials.This thesis revolves around three issues,namely,wettability,oil-water separation property and the scope of application.The main research contents are as follows:1.Preparationofsuperhydrophilic/underwatersuperoleophobicand superhydrophobic/superoleophiliczero-dimensionalbiomassmaterials.Superhydrophilic/underwater superoleophobic carbon and superhydrophobic/superoleophilic magnetic carbon were synthesized by using corn straw as raw material through the processes of high-temperature pyrolysis,immersion,hydrothermal synthesis,etc.Superhydrophilic carbon can be made into laminated membranes for further separation of oil-in-water emulsions.The laminated membranes possess high separation efficiency?the oil content in the filtrates is below 40 ppm?and low flux(<250 L m^-2 h^-1).Superhydrophobic magnetic carbon can be used in three ways:?i?it can be made into laminated membranes for further separation of water-in-oil emulsions.The laminated membranes possess high separation efficiency?the oil purity of all filtrates is above 99.97%?,low flux(<250 L m^-2 h^-1)and stable separation efficiency in the15 cycles of oil-water separation.?ii?It can be directly used for separation of simple oil-water mixture.It possess high oil absorption capacity(9.5¹6.7 g g^-1),can be manipulated by external magnetic field and be recycled through distillation and in-situ combustion without the degradation of oil absorption performance.?iii?It can be used for fast separation of surfactant-free oil-in-water emulsions under stirring.2.Preparation of superhydrophilic/underwater superoleophobic and hydrophobic/underoil high-hydrophobictwo-dimensionalbiomassmaterials.Superhydrophilic/underwater superoleophobic and hydrophobic/underoil high-hydrophobic nylon/filter paper composite membranes were synthesized by using filter paper as a raw material through the processes of immersion,immersion precipitation phase-inversion,etc.These two kinds of membranes can be used for separation of oil-in-water and water-in-oil emulsions,respectively.Both the membranes possess high separation efficiency?the oil content in the filtrates of oil-in-water emulsions is below 60 ppm;the oil purity of the filtrates of water-in-oil emulsions is above99.97%?,low flux(<400 L m^-2 h^-1)and long-term stable separation performance.3.Preparation of superhydrophobic/superoleophilic three-dimensional biomass materials.Superhydrophobic/superoleophilic magnetic carbonized cotton was synthesized by using cotton as raw material through the processes of high-temperature pyrolysis,immersion,etc.It possesses good mechanical strength,low magnetism?the saturation magnetization=6.4 emu/g,still can be driven by external magnetic field for absorbing randomly distributed floating oil on water?and high absorption capacity(27.2⁴6.2 g g^-1)for both organic solvents and oils.