Preparation And Properties Of Biomass-based Oil/water Separation Materials With Special Wettability

With the fast economy growth,the dramatic increasing production of oily wastewater generated by industries,including steel,petrochemical,and manufacturing,and so on,have imparted serious environmental threats to ecology and our life.However,traditional oil/water separation technology has some disadvantages such as secondary pollution,high energy consumption and low efficiency,which makes it difficult to effectively treat oily wastewater.Since oil/water separation is an interfacial problem,the special wetting materials with opposite affinities toward oil and water has been considered as efficient materials for oily water treatment.For the application prospects in the field of oil/water separation.Biomass-based materials with special wettability were fabricated.The contents are as follows:(1)A hydrophobic sponge for highly efficient oil/water separation and high oil absorption capacity were fabricated by a simple,eco-friendly,economical,and scalable dip-coating of hydrophilic melamine sponges in urushiol(a naturally biomass)solution.Because of the unique catechol group and a long alkyl side chain with unsaturated double bonds,urushiol molecules easily adhered on the sponge wall surface and self-polymerized to form a thin hydrophobic coating layer with the assistance of heat treatment.The urushiol-modified melamine sponge(UMS)displayed a water contact angle of?139^o and a 3D highly porous structure,so it could effectively separate oil from dynamic oil/water mixtures.The separation flux of n-hexane from an n-hexane/water mixture was as high as 18,356±2200 L·m^-2·h^-1·bar^-1.It could quickly absorb various oils and common organic solvents with an absorption capacity of up to 181 g·g^-1 and had excellent recyclability.UMS also displayed robust mechanical stability,flexibility,elasticity,and thermal stability.Therefore,the facile preparation process,low cost,and superior oil separation/absorption would endow UMS with high potential when dealing with oily wastewater.(2)In nature,shrimp has an outstanding antifouling behavior since its shell possesses underwater superoleophobicity.As a major component of the shrimp shell,chitin might have the potential of self-cleaning and can be exploited for dealing with oily water.Hence,novel filtration membranes derived from shellfish wastes were constructed via filtration of chitin nanofiber suspension.The resultant chitin nanofibrous membrane(CNM)was evaluated as a highly efficient oil/water emulsion separation material for the first time.Similar to shrimp shell,CNM with excellent superhydrophilicity and underwater superoleophobicity displayed extremely low underwater oil adhesion and self-cleaning performance.With controllable thickness and nanoscale pore size,CNM could effectively separate micrometer-and nanometer-sized oil/water emulsions with a high separation efficiency(>95%)and water flux(>1500 L?m^-2?h^-1?bar^-1).Furthermore,CNM displayed multifunctional water remediation characteristics,i.e.it could simultaneously remove heavy metal ions from water phase in the course of oil/water emulsion separation.The CNM also exhibited excellent mechanical strength,recyclable performance,thermal stability,and p H-resistance.Therefore,CNM with unique characteristics e.g.sustainability,chemical and thermal resistance,multifunctionality and excellent oil/water separation efficiency has the high potential in the practical oily water treatment.