玉米秸秆油污吸附剂的制备及其在油水分离中的应用
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摘要
以玉米秸秆为原料,粉碎后浸涂ZnO溶胶并经辛基三甲氧基硅烷(OTS)修饰后呈超疏水性和超亲油性,水滴在其表面的接触角为158.6°,滚动角小于5°,而油滴在其表面则完全铺开.利用玉米秸秆粉表面的超疏水性和超亲油性,可将其用于水面油污的过滤、吸附、分离及循环利用,其对油水混合物中油、水的分离效率分别为98.0%和99.6%.相关研究有望为玉米秸秆的加工、利用及油污吸附剂的制备提供新的思路.
The leakage of crude oil at sea and the discharge of domestic oily wastewater are likely to cause environmental pollution and threaten human health. Therefore, the development of techniques for the collection and recovery of the large amount of oil from water is attracting worldwide attention. To deal with the polluted water by spilled oil, materials with special wettability have been designed and developed over the past decades. Currently, metal meshes, sponges and cotton fabrics as well as particles with superhydrophobicity/superoleophiliciy or superhydrophiliciy/superoleophobicity have often been employed to separate oil and water mixtures. However, how to remove the spilled oil from water via techniques of low operation cost, high separation selectivity and efficiency as well as good recoverability for reuse without causing secondary contamination to environment is still a big challenge. Consequently, it is highly desirable to develop a new and advanced oil-water mixtures separation material that can selectively absorb oil while completely repelling water. Cellulose is the most abundant organic polymer, which is mainly used as a raw material to produce paper and cotton fabrics. Plant-derived cellulose is an important structural component of the primary cell wall of green plants, and usually found in a mixture with hemicellulose, lignin, pectin and other substances. Corn is a very common crop and widely planted in the Zhangye district of Gansu Province in China, and the corn straw are very abundant after harvest in autumn. However, the unused and accumulated corn straw can be easily rotted and hence cause the waste of resources, and the traditional treatment of burning can also induce serious environment pollution. With the consideration of the wide source, low cost, light weight, high oil adsorption capacity, good floatability in water as well as easy recycling, the corn straw is an ideal raw material which can be employed to prepare oil sorbent. In this research, corn straw was employed to fabricate oil sorbent. Corn straw was first crushed and then immersed into ZnO sol for 24 h, subsequently, corn straw powders were taken out and dried in air at 80°C. Finally, the dip-coated corn straw powders were immersed in octyltrimethoxy silane(OTS) solution for 24 h, taken out and dried at 120°C, and then, the corn straw powders begun to exhibit superhydrophobicity and superoleophilicity. Water contact angle on the superhydrophobic corn straw powders is 158.6° and the sliding angle of water droplet is about 4°, but the oil droplets can spread out completely on the corn straw powders due to the superoleophilicity. Synergy effects between surface morphology and surface chemical composition are known as the crucial factors to realize the opposite wettability to oil and water. The surface morphology and surface chemical composition of the obtained corn straw powders with superhydrophobicity and superoleophilicity were characterized by scanning electron microscopy(SEM) and X-ray photoelectron spectrum(XPS), respectively, and the wettability were measured with an optical contact angle meter at ambient temperature. The research indicates that both the dip-coating ZnO sol and surface modification with OTS play an important role for the performance of superhydrophobicity and superoleophilicity of corn straw powders. Because water and many oils are intrinsically immiscible, and the corn straw powders with extremely different affinities towards oils and water can be employed to separate oil-water mixtures by ways of filtration, and the separation efficiency towards water and oil is up to 99.6% and 98.0%. In addition, the spilled oil on water can also be removed by adsorption. Compared with the adsorption capacity of the pristine corn straw powder to spilled oil, the adsorption capacity of superhydrophobic corn straw powder is much high, and the corresponding adsorption capacity is 2.1 and 3.8 g/g, respectively. Moreover, the corn straw and spilled oil adsorbed by superhydrophobic corn straw can be reused and recovered by treatment of high speed centrifugation. When the adsorption time increased from 1 to 10, the water contact angle on the recovered corn straw powders is still about 156°±1°, and the corresponding sliding angle of water is about 8°, and the average percentage of recovery of superhydrophobic corn straw to hexadecane is above 70%. The design and fabrication of oil sorbent of superhydrophobic-superoleophilic corn straw made by dip-coating ZnO sol and modifying with OTS are expected to provide a new idea for the processing and utilization of corn straw as well as preparation of oil sorbents.
The leakage of crude oil at sea and the discharge of domestic oily wastewater are likely to cause environmental pollution and threaten human health. Therefore, the development of techniques for the collection and recovery of the large amount of oil from water is attracting worldwide attention. To deal with the polluted water by spilled oil, materials with special wettability have been designed and developed over the past decades. Currently, metal meshes, sponges and cotton fabrics as well as particles with superhydrophobicity/superoleophiliciy or superhydrophiliciy/superoleophobicity have often been employed to separate oil and water mixtures. However, how to remove the spilled oil from water via techniques of low operation cost, high separation selectivity and efficiency as well as good recoverability for reuse without causing secondary contamination to environment is still a big challenge. Consequently, it is highly desirable to develop a new and advanced oil-water mixtures separation material that can selectively absorb oil while completely repelling water. Cellulose is the most abundant organic polymer, which is mainly used as a raw material to produce paper and cotton fabrics. Plant-derived cellulose is an important structural component of the primary cell wall of green plants, and usually found in a mixture with hemicellulose, lignin, pectin and other substances. Corn is a very common crop and widely planted in the Zhangye district of Gansu Province in China, and the corn straw are very abundant after harvest in autumn. However, the unused and accumulated corn straw can be easily rotted and hence cause the waste of resources, and the traditional treatment of burning can also induce serious environment pollution. With the consideration of the wide source, low cost, light weight, high oil adsorption capacity, good floatability in water as well as easy recycling, the corn straw is an ideal raw material which can be employed to prepare oil sorbent. In this research, corn straw was employed to fabricate oil sorbent. Corn straw was first crushed and then immersed into ZnO sol for 24 h, subsequently, corn straw powders were taken out and dried in air at 80°C. Finally, the dip-coated corn straw powders were immersed in octyltrimethoxy silane(OTS) solution for 24 h, taken out and dried at 120°C, and then, the corn straw powders begun to exhibit superhydrophobicity and superoleophilicity. Water contact angle on the superhydrophobic corn straw powders is 158.6° and the sliding angle of water droplet is about 4°, but the oil droplets can spread out completely on the corn straw powders due to the superoleophilicity. Synergy effects between surface morphology and surface chemical composition are known as the crucial factors to realize the opposite wettability to oil and water. The surface morphology and surface chemical composition of the obtained corn straw powders with superhydrophobicity and superoleophilicity were characterized by scanning electron microscopy(SEM) and X-ray photoelectron spectrum(XPS), respectively, and the wettability were measured with an optical contact angle meter at ambient temperature. The research indicates that both the dip-coating ZnO sol and surface modification with OTS play an important role for the performance of superhydrophobicity and superoleophilicity of corn straw powders. Because water and many oils are intrinsically immiscible, and the corn straw powders with extremely different affinities towards oils and water can be employed to separate oil-water mixtures by ways of filtration, and the separation efficiency towards water and oil is up to 99.6% and 98.0%. In addition, the spilled oil on water can also be removed by adsorption. Compared with the adsorption capacity of the pristine corn straw powder to spilled oil, the adsorption capacity of superhydrophobic corn straw powder is much high, and the corresponding adsorption capacity is 2.1 and 3.8 g/g, respectively. Moreover, the corn straw and spilled oil adsorbed by superhydrophobic corn straw can be reused and recovered by treatment of high speed centrifugation. When the adsorption time increased from 1 to 10, the water contact angle on the recovered corn straw powders is still about 156°±1°, and the corresponding sliding angle of water is about 8°, and the average percentage of recovery of superhydrophobic corn straw to hexadecane is above 70%. The design and fabrication of oil sorbent of superhydrophobic-superoleophilic corn straw made by dip-coating ZnO sol and modifying with OTS are expected to provide a new idea for the processing and utilization of corn straw as well as preparation of oil sorbents.
引文
1 Xiao L J,Deng M,Zeng W G,et al.Novel robust superhydrophobic coating with self-cleaning properties in air and oil based on rare earth metal oxide.Ind Eng Chem Res,2017,56:12354-12361
2 Xiang T F,Han Y,Guo Z Q,et al.Fabrication of inherent anti-corrosion superhydrophobic surfaces on metals.ACS Sust Chem Eng,2018,6:5598-5606
3 Ellinas K,Kefallinou D,Stamatakis K,et al.Is there a threshold in the antibacterial action of superhydrophobic surfaces?ACS Appl Mater Interfaces,2017,9:39781-39789
4 Baidya A,Ganayee M A,Ravindran S J,et al.Organic solvent-free fabrication of durable and multifunctional superhydrophobic paper from waterborne fluorinated cellulose nanofiber building blocks.ACS Nano,2017,11:11091-11099
5 Li C X,Wu L,Yu C L,et al.Peristome-mimetic curved surface for spontaneous and directional separation of micro water-in-oil drop.Angew Chem Int Ed,2017,56:13623-13628
6 Zhou W T,Li S,Liu Y,et al.A dual superlyophobic copper foam with good durability and recyclability for high-flux,high-efficiency and continuous oil-water separation.ACS Appl Mater Interfaces,2018,10:9841-9848
7 Cui Y,Li D W,Bai H.Bioinspired smart materials for directional liquid transport.Ind Eng Chem Res,2017,56:4887-4897
8 Wang R,Hashimoto K,Fujishima A,et al.Photogeneration of highly amphiphilic TiO2 surfaces.Adv Mater,1998,10:135-138
9?ner D,McCarthy T J.Ultrahydrophobic surfaces effects of topography length scales on wettability.Langmuir,2000,16:7777-7782
10 Feng L,Li S,Li Y,et al.Super-hydrophobic surfaces:From natural to artificial.Adv Mater,2002,14:1857-1860
11 Wang Y S,Shi Y L,Feng X J,et al.Investigation of superhydrophobicity on water boatman’s hind wings(in Chinese).Chin Sci Bull(Chin Ver),2012,57:1227-1230[王永生,石彦龙,冯晓娟,等.划蝽后翅翅面的超疏水性.科学通报,2012,57:1227-1230]
12 Gao X F,Jiang L.Water-repellent legs of water striders.Nature,2004,432:36
13 Shi Y L,Feng X J,Yang W,et al.Large yellow spot mosquitos favor humid conditions and display superhydrophobic properties on their wings and legs(in Chinese).Chin Sci Bull(Chin Ver),2011,56:1241-1245[石彦龙,冯晓娟,杨武,等.黄斑大蚊的喜湿性及其翅膀、腿表面的超疏水性.科学通报,2011,56:1241-1245]
14 Wang S T,Liu K S,Yao X,et al.Bioinspired surfaces with superwettability:New insight on theory,design,and applications.Chem Rev,2015,115:8230-8293
15 Feng L,Zhang Z Y,Mai Z H,et al.A super-hydrophobic and super-oleophilic coating mesh film for the separation of oil and water.Angew Chem Int Ed,2004,43:2012-2014
16 Wang C F,Tzeng F S,Chen H G,et al.Ultraviolet-durable superhydrophobic zinc oxide-coated mesh films for surface and underwateroil capture and transportation.Langmuir,2012,28:10015-10019
17 Yang J,Zhang Z Z,Xu X H,et al.Superhydrophilic-superoleophobic coatings.J Mater Chem,2012,22:2834-2837
18 Zhu Q,Pan Q M.Mussel-inspired direct immobilization of nanoparticles and application for oil-water separation.ACS Nano,2014,8:1402-1409
19 Zhou X Y,Zhang Z Z,Xu X H,et al.Robust and durable superhydrophobic cotton fabrics for oil/water separation.ACS Appl Mater Interfaces,2013,5:7208-7214
20 Chen Y,Bai Y K,Chen S B,et al.Stimuli-responsive composite particles as solid-stabilizers for effective oil harvesting.ACS Appl Mater Interfaces,2014,6:13334-13338
21 Dong Y,Li J,Shi L,et al.Underwater superoleophobic graphene oxide coated meshes for the separation of oil and water.Chem Commun,2014,50:5586-5589
22 Zand D L,Zhang M,Liu F,et al.Superhydrophobic/superoleophilic corn straw fibers as effective oil sorbents for the recovery of spilled oil.J Chem Technol Biotechnol,2015,91:2449-2456
23 Xu Y,Yang H Y,Zang D L,et al.Preparation of a new superhydrophobic/superoleophilic corn straw fiber used as an oil absorbent for selective absorption of oil from water.Biores Bioproc,2018,doi.org/10.1186/s40643-018-0194-8
24 Spanhel L,Anderson M A.Semiconductor clusters in the sol-gel process:Quantized aggregation,gelation,and crystal growth in concentrated zinc oxide colloids.J Am Chem Soc,1991,113:2826-2833
25 Li D,Zhu F Z,Li J Y,et al.Preparation and characterization of cellulose fibers from corn straw as natural oil sorbents.Ind Eng Chem Res,2013,52:516-524
26 Chen K L,Zhao W H,Yuan X Y.Chemical modification of silica:Method,mechanism,and application(in Chinese).Prog Chem,2013,25:95-104[陈凯玲,赵蕴慧,袁晓燕.二氧化硅粒子的表面化学修饰-方法、原理及应用.化学进展,2013,25:95-104]
27 Tsibouklis J,Stone M,Adrian A T,et al.Surface energy characteristics of polymer film structures:A further insight into the molecular design requirements.Langmuir,1999,15:7076-7079
28 Cassie A B D,Baxter S T.Wettability of porous surfaces.Faraday Soc,1944,40:546-551
29 Gao L C,Thomas J M.Contact angle hysteresis explained.Langmuir,2006,22:6234-6237
30 Yuan X,Long M C,Song F,et al.Biomineralized cotton/CaCO3 composite for selective oil absorption(in Chinese).Acta Polym Sin,2018,(4):524-531[袁雪,龙曼成,宋飞,等.疏水矿化棉纤维的制备及其油水分离性能.高分子学报,2018,(4):524-531]
2 Xiang T F,Han Y,Guo Z Q,et al.Fabrication of inherent anti-corrosion superhydrophobic surfaces on metals.ACS Sust Chem Eng,2018,6:5598-5606
3 Ellinas K,Kefallinou D,Stamatakis K,et al.Is there a threshold in the antibacterial action of superhydrophobic surfaces?ACS Appl Mater Interfaces,2017,9:39781-39789
4 Baidya A,Ganayee M A,Ravindran S J,et al.Organic solvent-free fabrication of durable and multifunctional superhydrophobic paper from waterborne fluorinated cellulose nanofiber building blocks.ACS Nano,2017,11:11091-11099
5 Li C X,Wu L,Yu C L,et al.Peristome-mimetic curved surface for spontaneous and directional separation of micro water-in-oil drop.Angew Chem Int Ed,2017,56:13623-13628
6 Zhou W T,Li S,Liu Y,et al.A dual superlyophobic copper foam with good durability and recyclability for high-flux,high-efficiency and continuous oil-water separation.ACS Appl Mater Interfaces,2018,10:9841-9848
7 Cui Y,Li D W,Bai H.Bioinspired smart materials for directional liquid transport.Ind Eng Chem Res,2017,56:4887-4897
8 Wang R,Hashimoto K,Fujishima A,et al.Photogeneration of highly amphiphilic TiO2 surfaces.Adv Mater,1998,10:135-138
9?ner D,McCarthy T J.Ultrahydrophobic surfaces effects of topography length scales on wettability.Langmuir,2000,16:7777-7782
10 Feng L,Li S,Li Y,et al.Super-hydrophobic surfaces:From natural to artificial.Adv Mater,2002,14:1857-1860
11 Wang Y S,Shi Y L,Feng X J,et al.Investigation of superhydrophobicity on water boatman’s hind wings(in Chinese).Chin Sci Bull(Chin Ver),2012,57:1227-1230[王永生,石彦龙,冯晓娟,等.划蝽后翅翅面的超疏水性.科学通报,2012,57:1227-1230]
12 Gao X F,Jiang L.Water-repellent legs of water striders.Nature,2004,432:36
13 Shi Y L,Feng X J,Yang W,et al.Large yellow spot mosquitos favor humid conditions and display superhydrophobic properties on their wings and legs(in Chinese).Chin Sci Bull(Chin Ver),2011,56:1241-1245[石彦龙,冯晓娟,杨武,等.黄斑大蚊的喜湿性及其翅膀、腿表面的超疏水性.科学通报,2011,56:1241-1245]
14 Wang S T,Liu K S,Yao X,et al.Bioinspired surfaces with superwettability:New insight on theory,design,and applications.Chem Rev,2015,115:8230-8293
15 Feng L,Zhang Z Y,Mai Z H,et al.A super-hydrophobic and super-oleophilic coating mesh film for the separation of oil and water.Angew Chem Int Ed,2004,43:2012-2014
16 Wang C F,Tzeng F S,Chen H G,et al.Ultraviolet-durable superhydrophobic zinc oxide-coated mesh films for surface and underwateroil capture and transportation.Langmuir,2012,28:10015-10019
17 Yang J,Zhang Z Z,Xu X H,et al.Superhydrophilic-superoleophobic coatings.J Mater Chem,2012,22:2834-2837
18 Zhu Q,Pan Q M.Mussel-inspired direct immobilization of nanoparticles and application for oil-water separation.ACS Nano,2014,8:1402-1409
19 Zhou X Y,Zhang Z Z,Xu X H,et al.Robust and durable superhydrophobic cotton fabrics for oil/water separation.ACS Appl Mater Interfaces,2013,5:7208-7214
20 Chen Y,Bai Y K,Chen S B,et al.Stimuli-responsive composite particles as solid-stabilizers for effective oil harvesting.ACS Appl Mater Interfaces,2014,6:13334-13338
21 Dong Y,Li J,Shi L,et al.Underwater superoleophobic graphene oxide coated meshes for the separation of oil and water.Chem Commun,2014,50:5586-5589
22 Zand D L,Zhang M,Liu F,et al.Superhydrophobic/superoleophilic corn straw fibers as effective oil sorbents for the recovery of spilled oil.J Chem Technol Biotechnol,2015,91:2449-2456
23 Xu Y,Yang H Y,Zang D L,et al.Preparation of a new superhydrophobic/superoleophilic corn straw fiber used as an oil absorbent for selective absorption of oil from water.Biores Bioproc,2018,doi.org/10.1186/s40643-018-0194-8
24 Spanhel L,Anderson M A.Semiconductor clusters in the sol-gel process:Quantized aggregation,gelation,and crystal growth in concentrated zinc oxide colloids.J Am Chem Soc,1991,113:2826-2833
25 Li D,Zhu F Z,Li J Y,et al.Preparation and characterization of cellulose fibers from corn straw as natural oil sorbents.Ind Eng Chem Res,2013,52:516-524
26 Chen K L,Zhao W H,Yuan X Y.Chemical modification of silica:Method,mechanism,and application(in Chinese).Prog Chem,2013,25:95-104[陈凯玲,赵蕴慧,袁晓燕.二氧化硅粒子的表面化学修饰-方法、原理及应用.化学进展,2013,25:95-104]
27 Tsibouklis J,Stone M,Adrian A T,et al.Surface energy characteristics of polymer film structures:A further insight into the molecular design requirements.Langmuir,1999,15:7076-7079
28 Cassie A B D,Baxter S T.Wettability of porous surfaces.Faraday Soc,1944,40:546-551
29 Gao L C,Thomas J M.Contact angle hysteresis explained.Langmuir,2006,22:6234-6237
30 Yuan X,Long M C,Song F,et al.Biomineralized cotton/CaCO3 composite for selective oil absorption(in Chinese).Acta Polym Sin,2018,(4):524-531[袁雪,龙曼成,宋飞,等.疏水矿化棉纤维的制备及其油水分离性能.高分子学报,2018,(4):524-531]