Preparation And Properties Of Super Hydrophilic Membrane Materials For The Treatment Of Oily Wastewater From Iron And Steel Processing

With the rapid development of the iron and steel industry,the oily wastewater discharged from the iron and steel processing process is increasing day by day,and the resulting environmental problems seriously affect the ecological balance and human health.Moreover,the oily wastewater from iron and steel processing is complex in composition and difficult to treat.At present,the membrane separation method is widely used in the treatment of various types of oily wastewater due to its high efficiency,energy saving and convenient operation.However,when using the membrane separation method to treat oily wastewater from iron and steel processing,there are still problems such as membrane fouling,membrane cleaning and high cost.Based on this,this paper proposes to modify the melamine foam by regulating metal ions to cross-link the natural polymer biomass sodium alginate,so as to obtain a superhydrophilic-superoleophobic film material,which is highly suitable for the field of steel processing and treatment of oily wastewater.In order to realize the above process,in this paper,the superhydrophilic membrane materials were prepared by adjusting the concentration of sodium alginate solution and changing the type of cross-linked ions.The effect of sodium alginate modification amount on the properties of superhydrophilic membranes prepared by cross-linking of Ca²⁺and Cu²⁺was mainly investigated.Tests and evaluations were carried out,and different types of oily wastewater from iron and steel processing were simulated in the laboratory to evaluate the oil-water separation effect.The main conclusions are as follows:（1）Taking melamine foam（MS）as the matrix,the melamine foam was first soaked in different concentrations of sodium alginate（SA）solution by the method of solution immersion,and then immersed in the same concentration of Ca Cl₂ solution for cross-linking modification.For Ca-SA/MS superhydrophilic membrane,the effect of SA modification amount,that is,the concentration of SA solution,on the performance of superhydrophilic membrane was investigated,and the optimal conditions were determined.By studying the effect of SA modification amount on its macroscopic properties and microstructure,the results show that when the SA solution concentration is between 0.5%and 2.0%,the change of SA solution concentration has an effect on the underwater oil contact angle（UWOCA）had a greater impact,and showed a trend of increasing first and then decreasing.When the concentration of SA solution is 1.5%,the UWOCA of Ca-SA/MS is the largest,the oleophobicity is the best,and it exhibits good oil-water separation efficiency（98.6%）,antifouling performance,self-cleaning performance and recyclability,but its The water flux is small and the acid and alkali resistance is poor.（2）In view of the shortcomings of the above-mentioned Ca-SA/MS,such as the small water flux,after consulting the literature,Cu²⁺with better affinity for SA was selected for cross-linking,and the modified MS was optimized to prepare superhydrophilic membranes.The Cu-SA/MS superhydrophilic membrane was prepared by immersing MS in SA solutions of different concentrations by solution immersion,and then immersing in Cu SO₄ solution of constant concentration for cross-linking optimization and modification.By investigating the effect of SA modification amount on its macroscopic properties and microstructure,the results show that the SA modification amount has a great influence on the UWOCA of Cu-SA/MS superhydrophilic membrane,which shows a trend of first increasing and then decreasing.When the amount of SA modification is 1.5%,the UWOCA of Cu-SA/MS is the largest,the oleophobicity is the best,and the water flux is larger.performance,self-cleaning properties,acid and alkali resistance and recyclability.Compared with Ca-SA/MS,the performance of Cu-SA/MS is better than that of Ca-SA/MS,and the performance of Cu-1.5%SA/MS is better than that of Ca-1.5%SA/MS.（3）The above-mentioned preferred Cu-1.5%SA/MS with SA concentration of 1.5%was placed in the oily wastewater of iron and steel processing with different salt concentrations,different corrosiveness,different heavy metal contents,and its oil-water separation effect was evaluated.The results show that the prepared Cu-1.5%SA/MS membrane material has good salt resistance,corrosion resistance,and more importantly,good stability in the above-mentioned complex environment.It is an oil-water separation membrane material with good application prospects in the treatment of oily wastewater from iron and steel processing,and is of great significance for realizing ultra-clean discharge in the iron and steel industry.