Preparation Of Polyacrylic Acid-Polyethylene Glycol/Ethanolamine Polycondensate And Surface Modification Of Nanometer Ferroferric Oxide And Application

1.Most of the dye industrial wastewater contains complex organic amine aromatic compounds.At present,there are many methods for treating wastewater,and the adsorption method is widely used because it is fast,efficient,and inexpensive.Methylene blue?MB?is a nitrogen-containing heterocyclic aromatic compound whose aqueous solution can be used as a model for simulating wastewater.In this paper,polyacrylic acid-polyethylene glycol?PAA-PEG?polycondensate and polyacrylic acid-ethanolamine?PAA-ETA?polycondensate were prepared by using polyacrylic acid?PAA?aqueous solution as raw material and polyethylene glycol?PEG?and ethanolamine?ETA?as crosslinking agents,respectively.Explore the kinetics and thermodynamics of the polycondensate for MB adsorption.The specific work is as follows:?1?The mixing aqueous solution of PAA and PEG unders go an intermolecular dehydration condensation reaction upon heating at 180°C for 80 min.Infrared spectrum proved that PAA-PEG contains ester group.Its specific surface area reached3953.19 m² g^-1;When the addition is 0.75 g L^-11 and pH is 7.0,PAA-PEG possesses good adsorption capacity and removal rate in 200 mg L^-11 MB solution.The adsorption process of PAA-PEG for MB conforms to the quasi-second-order kinetics,and the process follows the Langmuir adsorption law and classified as monolayer adsorption and the average value of its saturated adsorption capacity is 407.2 mg g^-1.The Gibbs free energy??35?G?become negative during the adsorption process,indicating that the adsorption process can proceed spontaneously.Under acidic conditions,the adsorbed MB can be desorbed from the surface of the polycondensate,so that the adsorption and degradation of MB can be achieved.After three cycles,the removal rate of MB(200 mg L^-1)is still up to 87.7%in the aqueous solution.?2?The mixing aqueous solution of PAA and ETA also occurred an intermolecular dehydration condensation reaction upon heating at 150°C for 90 min.Infrared spectroscopy verified that PAA-ETA contains ester groups with a specific surface area of 4308.62 m² g^-1.The effects of dosage and pH on the adsorption performance of MB in aqueous solution were investigated.Under different dosages,the adsorption process of MB by PAA-ETA accorded with quasi-second-order kinetics,and the process complied with the Langmuir model as well.The average value of its saturated adsorption capacity is 427.8 mg g^-1.?35?G becomes negative,suggesting that the adsorption process can proceed spontaneously.The desorption of adsorbed MB can achieve under acidic conditions.After three adsorption-desorption,the removal rate of MB(300 mg L^-1)in aqueous solution is still as high as 87.62%,which demonstrate its excellent recyclability.2.Because of small size,superparamagnetism and low toxicity,Nano-Fe₃O₄ is widely used in biomedicine,material science and other fields.However,the application range of Nano-Fe₃O₄ has also been limited due to its poor dispersibility in water.In our work,the nano-Fe₃O₄ is treated with sodium hydrogen tartrate and further activated,then its dispersibility in aqueous medium is improved,resulting in the coupling of protein molecules and chelation of Ni²⁺.The details are as follows:?1?Nano-Fe₃O₄ was prepared by coprecipitation method.The transmission electron microscope showed that the particle size was about 10 nm.X-ray diffraction also proved the formation of Fe₃O₄.Adding sodium hydrogen tartrate into the Fe₃O₄solution,the above solution was treated under ultrasonic to give rise to a complex of sodium hydrogen tartrate-Fe₃O₄?SHT-Fe₃O₄?.The carboxyl group of surface is activated by N-hydroxysuccinimide and can be covalently coupled with bovine serum albumin?BSA?and alpha-amylase containing primary amino groups.Fe₃O₄ coupled with BSA is almost non-toxic to MB231 cells.The Fe₃O₄ coupled with?-amylase has a catalytic effect on starch hydrolysis.?2?After alkalizing SHT-Fe₃O₄,the chelation of Ni²⁺can be achieved.The SDS-PACE gel electrophoresis experiment shows that the surface-chelated Ni²⁺can coordinate with histidine-tagged protein.Therefore,the separation and purification of his-tagged proteins can be achieved by using the magnetic characteristics of nano-Fe₃O₄.