Mussel-Inspired Functionalization Of Polyurethane Sponge And Study For Instantaneous Clean-Up Of Microcontaminants In Waste Water

Water pollution has a serious impact on human health and economic development.According to statistics,more than 25 million people die from water pollution every year.Sewage contains a variety of harmful substances,among which the teratogenicity and carcinogenicity of toxic solvents,dye molecules and heavy metal ions are the most serious.These toxic pollutants can be stable in the presence of sewage,which increases the difficulty of removal.Although some works have been reported on the removal of these toxic molecules,the preparations of these materials were relatively complex and the remova efficiencies were still unsatisfactory.Therefore,it is urgently needed to develop a simple,efficient and rapid method to adsorb these toxic molecules.In this thesis,a series of multi-functional polyurethane sponge adsorbents were prepared by using polyurethane sponge with good mechanical properties,excellent adsorption properties and unique three-dimensional multi-space structure as the substrate,which was chemically modified by mussel-inspired chemical technology and in-situ polymerization.The adsorption performance and adsorption mechanism of the modified sponges were studied systematically.The work of this thesis is divided into following three aspects:Part one,polyurethane sponges with super hydrophobic/super oil-wet properties were prepared based on mussel-inspired chemical and polymerization in situ method for adsorbing toxic solvents from sewage.We synthesized 3,4-dihydroxy benzene-acrylamide（DHBAA）from dopamine molecules and coated the DHBAA with dopamine on the surface of polyurethane sponge to prepare mussel-inspired modified polyurethane sponge（PUSD）.Subsequently,the PUSD was modified with1-hexadecene by polymerization in-situ,and superhydrophobic and superoleophobic sponge of PUSD-16ene was got.The experimental results showed that the PUSD-16ene can quickly adsorb a variety of toxic solvents,including n-hexane,petroleum ether,acetone,toluene,dimethyl sulfoxide,dichloromethane and chloroform.And the adsorption capacities of the PUSD-16ene were 99,101,104,118,128,152and 181 g.g^-1,respectively.What’s more,the PUSD-16ene could also quickly adsorb wax oil which was produced in actual industrial production.Meanwhile,the PUSD-16ene showed good mechanical properties and excellent reusability.Importantly,the PUSD-16ene had excellent adsorption/separation performance for a variety of different layered water/oil mixed solutions and uniformly dispersed oil/water mixed emulsions.Hence,the PUSD-16ene has a great practical application potential for adsorbing oil and toxic organic solvents.Part two,in view of the above method of preparing super-hydrophobic/super-oil-wet sponge and its excellent performance,we constructed a fast adsorbent for cationic pollutants（organic dyes and heavy metal ions）in sewage by similar method.We used acrylic acid to modify PUSD sponge and prepared carboxylized functional sponge（PUSDA）.For further increasing its negative surface charge,we used triethylamine solution to deprotonize PUSDA and prepare functional carboxylized sponge（PUSDAD）.The PUSDAD had the good ability of water absorption and rapid recovery the morphology after water absorption.The results of adsorption experiments showed that PUSDAD could quickly adsorb the cationic dye of methylene blue in sewage only by simple absorbing and squeezing,what’s more,the whole process only need one second.Meanwhile,PUSDAD could also adsorb other cationic dyes and heavy metal ions in sewage,and the adsorption capacities of methyl violet,Cu²⁺,Cr³⁺,Co²⁺and Ag⁺were 775.9,208.5,523.3,137.6,247.5 and 107.2 mg g^-1,respectively.We investigated the adsorption mechanism and adsorption process of PUSDAD,at the same time.The adsorption mechanism included mainly the electric charge interaction between the surface of the PUSDAD and dye molecules or heavy metal ions,including strong electrostatic attraction and weak electrostatic attraction,and the pi-pi accumulations between the aromatic ring skeleton of dye molecules and aromatic ring structure of the PUSDAD.It is important that the PUSDAD could be used to quickly adsorb dye molecules and floc impurities in the actual sewage.Part three,in view of the PUSDAD must be stored in water and cannot be used for selective removal of mixed dyes.Hence,we used compounds with other functional groups that were less affected by the environment to modify the PUSD sponge for fabricating new portable and intelligent adsorption materials.Functional polyurethane sponges（PUSDS）were prepared by in-situ polymerization of the PUSD sponge with sodium p-vinyl benzene sulfonate.The experimental results showed that the PUSDS had good mechanical properties and compression recovery,and the pH values barely influenced on the performance of adsorption.The PUSDS could maintain a high removal efficiency in a wide range of pH values.Moreover,the PUSDS could not only quickly absorb cationic pollutants in sewage,but also selectively absorb mixed dyes.What’s more,the PUSDS could be used to quickly and extensively remove dyes from sewage,with a flow rate of up to 22.2 L/（m³·s）.In a word,the PUSDS has a good application prospect.