Preparation Of Fe₃O₄/SBA-16 Magnetic Composites And Their Adsorption Properties

Compared with the traditional M41S series molecular sieve,SBA-16 molecular sieve not only inherits the advantages of the traditional M41S series molecular sieve,such as larger pore size,higher specific surface area and higher pore capacity,but also has the advantages of more stable skeleton structure,easier modification of the inner surface,thicker pore wall,etc.As an emerging mesoporous material,SBA-16 is widely used in environmental energy,separation and doping,chemical technology,catalysis,etc.Fe₃O₄has high saturation magnetization strength and coercivity,which are not available in mesoporous molecular sieves.In order to combine the advantages of both,in this study,Fe₃O₄/SBA-16 nanomagnetic composites（hereafter referred to as Fe₃O₄/SBA-16）were prepared by making nano-Fe₃O₄modified on the surface of SBA-16 particles using SBA-16 as a shell.This method maintains the advantages of the magnetic material itself and does not adversely affect the performance of SBA-16 molecular sieve.The main work is as follows:1.The Fe₃O₄/SBA-16 magnetic composites were prepared by hydrothermal synthesis using F127 as a template agent n-butanol as an auxiliary.The results of the large-angle XRD characterization of the samples showed that they have an ordered three-dimensional stereo structure consistent with the structure of SBA-16 molecular sieve.The FT-IR based characterization results showed that the chemical bonds in the tested samples were all consistent with the chemical bonding characteristics of SBA-16 molecular sieve.SEM characterization showed that the Fe₃O₄nanoparticles were successfully modified on the surface of SBA-16 molecular sieve.Nitrogen adsorption-desorption test can see that the range of specific surface area of the samples is 150.4647～1000.8298 m²/g,the range of pore volume is 0.2211～0.5839 cm³/g,most of the pore size does not change much,the one with large deviation is the sample with crystallization temperature 110℃,crystallization time 24h,Fe₃O₄dosage of 0.8 g,this sample may have large error.Finally,the Fe₃O₄/SBA-16 magnetic composite sample with a crystallization temperature of 100°C,a crystallization time of 30 h and a dosage of 0.8 g Fe₃O₄has the best overall performance when combined with the test results of the M?ssbauer spectroscopy.2.The Fe₃O₄/SBA-16 magnetic composites were prepared by hydrothermal synthesis using P123 and F127 as template agents.The results of the large angle XRD characterization of the samples showed that they have an ordered three-dimensional stereo structure consistent with the structure of SBA-16 molecular sieve.The FT-IR based characterization results show that the chemical bonds in the tested samples are all consistent with the chemical bonding characteristics of SBA-16 molecular sieve.SEM characterization shows that the Fe₃O₄nanoparticles are well modified on the surface of SBA-16 molecular sieve.The nitrogen adsorption-desorption test shows that the specific surface area of the sample ranges from165.0258 to 1048.7783 m²/g,the pore volume ranges from 0.1736 to 0.6491 cm³/g,and the pore size ranges from 2.2743 to 5.2506 nm.Finally,combined with the test results of the M?ssbauer spectroscopy,it is found that the Fe₃O₄/SBA-16 magnetic composite material with0.5 g Fe₃O₄dosage has the best comprehensive properties when the ratio of F127 to P123 is2.51 and the crystallization temperature is 120℃.3.The benzene adsorption performance of the samples was basically consistent with the pattern of the nitrogen adsorption analysis score.The best benzene adsorption performance was obtained for Fe₃O₄/SBA-16 magnetic composite samples prepared under the environment of single template agent F127 n-butanol as an additive,with Fe₃O₄dosage of 0.5 g,crystallization time of 36 h and crystallization temperature of 100℃;for Fe₃O₄/SBA-16magnetic composite samples prepared under the environment of double template agent P123and F127,with double template agent The best benzene adsorption performance was achieved when the ratio of F127 to P123 was 2.51,the amount of Fe₃O₄was 0.5 g,and the crystallization temperature was 120℃.