| With the development of industry,the environmental damage caused by oily wastewater has become more and more serious.The treatment of oily wastewater caused by the leakage of oil and insoluble chemical organic pollutants has become an urgent problem to be solved.The use of superhydrophobic/superoleophilic sponge adsorbents for oil-water separation has the advantages of economy,ease of operation,and environmental protection.It is an effective means of treating oily wastewater.Melamine sponge is a typical sponge absorbent material.It not only has the advantages of high porosity,flame retardancy,acid and alkali resistance,light weight,and high elasticity,but also contains many secondary amine groups(-NH)on the surface,which is easy to its modification,so melamine sponge is an ideal matrix for preparing superhydrophobic/superoleophilic materials for oil-water separation.In this study,melamine sponge(MS)was used as the matrix,and methyl trichlorosilane(MTS)and octadecyl trichlorosilane(OTS)were used as modifiers.The melamine sponge was hydrophobically modified,and the best superhydrophobic modification conditions for the melamine sponge were determined,the changes of the surface morphology and chemical composition of the melamine sponge before and after modification were discussed,the effect of modification on the wettability and oil absorption capacity of the sponge was discussed,the oil absorption performance and stability under typical working conditions of the modified superhydrophobic sponge were studied.The main research contents and conclusions are as follows:(1)The melamine sponge was hydrophobically modified with two silane coupling agents,OTS and MTS.The silane hydrolyzed to produce silanol(Si-OH)and grafted it on the sponge skeleton,building a rough structure on the sponge surface and reducing the surface energy.The influence of modification conditions on the hydrophobic properties of sponges was investigated,and the best modification conditions were determined as follows:Step method,toluene is used as the solvent.In the first stage,OTS was used as modifier with a volume concentration of 0.5%and the modification time was 10 min;in the second stage,MTS was used as a modifier with a volume concentration of 0.5%and the modification time was 10 min.The water contact angle of the prepared OTS-MS-MTS is 155.4±0.9°.(2)The sponge before and after modification was characterized.The micro morphology of the sponge before and after modification was analyzed by scanning electron microscope(SEM)and laser confocal scanning microscope(CLSM).It was found that after modification,the sponge surface appeared rough structure,and the surface mean square error height increased from 0.2 mm to 0.494 mm;The chemical composition of the sponge surface before and after the modification was analyzed by X-ray photoelectron spectroscopy(XPS),X-ray energy spectroscopy(EDX)and Fourier transform infrared spectroscopy(FT-IR).The results showed that the composition and content of the element on the surface of the sponge have changed,which prove that the modifier is successfully loaded on the sponge skeleton;combined with the test results of the contact angle tester,it can be determined that the modification has changed the wettability of the sponge.(3)Oil-water separation experiments show that OTS-MS-MTS can quickly absorb 68-120 times its own weight of oil,and after 20 repeated adsorption-extrusion processes,it still retains more than 76.6%of the adsorption capacity,showing a good recycling performance;OTS-MS-MTS has oil-water selectivity in the oil-water separation process,and the recovered oil-water mixture has an oil mass fraction of more than 99%,which has recycling value.(4)OTS-MS-MTS has excellent chemical stability and physical stability.After immersed in aqueous solutions of different pH,sea water and various organic solvents,as well as ultrasonic and tape experiments,the wettability of the OTS-MS-MTS has not been significantly affected,the static water contact angle remains above 145°. |
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