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• 近年来，由于经济的迅速发展，频发的原油泄漏事故以及工业含油废水的不断排放对人们生存环境造成的严重污染引起了人们的广泛关注。由于传统油/水分离方法如围栏吸附法^[1]、聚结剂^[2]、离心法^[3]和化学破乳法^[4]等能耗高、效率低，且二次污染严重，所以寻找一种廉价高效、绿色环保以及实际应用范围广的方法来治理含油废水是环保领域面临的重要挑战。

  随着“Lotus Effect(荷叶效应)”的提出，特殊润湿性表面的应用范围越来越广泛，尤其是在油/水分离领域。同时，纤维素作为可再生的天然聚合物，具有无污染、化学惰性、高亲水表面和高比表面积等优点^[5-7]。因此人们对纤维素基材料的改性及其在油/水分离领域的应用做了大量的研究。

  本文主要综述了纤维素基超润湿性材料的发展现状及应用，指出了目前存在的问题，展望了这类材料在油/水分离领域的发展前景。

  1.   纤维素基超润湿性油/水分离材料

  根据润湿性的差异可将油/水分离材料分为以下3种：超亲水/水下超疏油的“水移除”型油/水分离材料^[8-9]；智能响应型油/水分离材料^[10-12]；超疏水/超亲油的“油移除”型油/水分离材料^[13-14]。

  1.1   超亲水/水下超疏油的油/水分离材料

  分离材料表现出超亲水/水下超疏油性能通常是由高表面能物质和微纳米结构的组合而引起的。当材料预先被水润湿时表面会形成一层致密的水合层，此时材料再接触到含油污水时，水会透过材料，而油则会被阻隔在材料表面，从而达到油/水分离的效果。“水移除”型油/水分离材料仅允许水的流通，避免了油对材料的污染。而且材料的亲水性越强，其表面的水合层就越致密，对油的阻隔效果越好，抗污染效果就越好^[15-18]。

  简单的制备工艺使得膜材料在含油废水方面得到广泛应用。Zhou等^[19]将碱性的纤维素溶液稀释，然后通过冷冻萃取方法制备出纤维素纳米片，之后再利用层层组装的方法将纤维素纳米片沉积到醋酸纤维素上，最终合成一种新型超薄纤维素纳米膜，如图 1(a)所示。该膜具有86~200 nm范围内的可控厚度，其中112 nm厚的膜其水通量可达到0.01620 L/(m²·h·Pa)，几乎是商业膜的2倍。应用该分离膜也可以实现水包油型乳化液的油/水分离，但其制备工艺相对复杂。Gao等^[20]则是在商业多孔硝化纤维素(NC)膜的基底上，利用一种简单的射孔方法，制备了具有水下超疏油性质的双尺度穿孔膜并将其用于油/水分离操作。通过控制针刺深度获得了不同孔径的p-NC膜，而且刺穿得到的“舌形”孔既提供了表面粗糙度，还有利于承受较高的油压，该材料对于原油、汽油以及多种有机溶剂的分离效率均达到99.8%，具有良好的应用前景。

  图 1

  

  图 1.  (a) 纤维素纳米薄膜的制备流程^[19]和(b)纤维素海绵的制备工艺^[23]

  Figure 1.  (a)Preparation process of cellulose nanofilm^[19] and (b)preparation process of cellulose sponge^[23]

  下载: 全尺寸图片 幻灯片

  与二维材料相比，气凝胶、海绵等三维材料具有网状空隙充足、密度小、质量轻等特点，可以提供足够的吸附空间，是作为油/水分离材料较为优异的选择。譬如，Zhang等^[21]制备了一种可高效油/水分离的耐盐超疏油型气凝胶。采用冷冻干燥法将纳米纤维素(NFC)结合到壳聚糖(CS)基质中，将壳聚糖固有的亲水性与气凝胶的粗糙微观结构相结合，使其具有优异的水下超疏油性质。该气凝胶在经过40次油/水分离循环后仍具有出色的可回收性，且分离效率＞99%。在高盐度海水中浸泡30天后，水下油的接触角依然＞150°。优异的性能与简便的制造工艺使其有望应用于海洋环境中油/水分离操作。Sun等^[22]采用高碘酸钠氧化法和连续亚硫酸钠磺化法制备了超亲水/水下超疏油的纳米纤维素气凝胶。先用高碘酸钠将纤维素上的羟基氧化成醛基，然后用亚硫酸钠磺化处理之后冷冻干燥得到气凝胶。该方法引入了带负电荷的磺酸基(—SO₃^-)，电荷密度从-39.8 mmol/kg增加至-325 mmol/kg，减少了氢键的自聚集，增加了极性，从而增大了亲水性。具有优异的可回收性和稳定的润湿强度，在含油废水净化处理中有广阔的前景。

  Wang等^[23]则是利用冷冻-干燥法制备了一种超亲水/水下超疏油的双孔径纤维素海绵用于油/水分离。如图 1(b)所示，纤维素海绵上层为＜1 μm的纳米孔，是油/水分离的选择层，可阻止大孔径油滴的渗透；下层为＞3 μm的微米孔，是油/水分离的支撑层，能保持水形成致密的水合层。经接触角测试，氯仿、正己烷等有机试剂以及大豆油、原油等其水下油的接触角皆＞150°，且该材料具有良好的抗污染性和耐酸碱性，在没有化学改性的情况下，仅依靠构建微纳米结构即可达到油/水分离的效果，且分离效率高达99.94%，但其循环性以及机械性能一般，实用性差。

  纤维素基超亲水/水下超疏油材料由于致密水合层对油滴的阻隔作用避免了孔道被油污染甚至堵塞孔道的问题，这也赋予了材料优异的自清洁性能, 为开发可持续和高效的分离材料提供了依据。

  1.2   智能响应型油/水分离材料

  智能响应型油/水分离材料通常是利用外界条件的改变来调控其表面润湿性的。通常智能响应型分离材料分为pH响应、温度响应、紫外光照射响应等类型^[24-27]。这些材料适用于多类型的油/水污染处理应用，具有可观的研究价值和应用前景。其中，本课题组在先前的工作中对智能响应型油/水分离材料的制备也有较深入的研究^[28-29]。

  Dang等^[28]以聚甲基丙烯酸十二烷基酯(PDMA)、3-(三甲氧基甲硅烷基)丙基甲基丙烯酸酯(PTMSPMA)和甲基丙烯酸二甲氨乙酯(PDMAEMA)为原料通过自由基聚合的方式制备出具有原位和非原位pH响应的无规共聚物油/水分离材料。然后利用浸涂法将纳米粒子共混，涂到棉布、海绵等二维或三维基底上，得到具有pH响应性的二维薄膜或三维海绵油/水分离材料。该材料在酸性条件下可以由最初的超疏水状态转变为超亲水状态，碱性条件下可再恢复超疏水性质，且该材料适用于三相油/水混合物的分离，以及油包水型乳液、水包油型乳液和酸性水包油型乳液的分离，对各种油相均可吸附，为进一步解决含油污水问题提供了可能。此外，Fang等^[29]还报道了一种低成本的方法来制造由超支化聚氨酯(HBPU)和氟改性二氧化硅(F-SiO₂)组成的，具有可调润湿性的静电纺丝膜。通过等离子体处理，HBPU/F-SiO₂复合膜可由超疏水性转变为超亲水性，可分别有效分离表面活性剂稳定的油包水型乳液和水包油型乳液。

  智能响应型生物基油/水分离材料由于其具有可选择性和可生物降解性已经成为环境修复和废水处理的新生力量。Chen等^[30]就是将纤维素与热敏性分子相结合，通过Ge引发自由基单体聚合反应，将N-异丙基丙烯酰胺单体(PNIPAAm)接枝到蔗渣浆纤维素上，制备了一种热敏性纤维素基材料。该材料具有临界的热敏温度，当温度达到临界温度以上时，呈疏水性; 在该温度以下时，则为亲水性。主要是由PNIPAAm链中响应温度的CO和N—H基团之间的分子间/分子内氢键的竞争作用导致的。低温下，水分子间氢键作用强使链呈松散构象从而材料亲水；高温时，链中CO和N—H基团形成分子内氢键导致链呈致密折叠构象，难与水分子作用，从而疏水。通过调节温度，该材料可连续去除纸中的吸附油，实现材料的重复利用。Zhan等^[31]制备了一种UV诱导的自清洁TiO₂/纳米纤维素膜用于油/水乳化液分离。TiO₂纳米粒子具有独特的光诱导超亲水性，他们利用这一特性制备了一种紫外光照射响应型油/水分离材料。将纤维素分散液与TiOSO₄·H₂SO₄·H₂O粉末混合，通过TiOSO₄的水解，使TiO₂纳米粒子原位聚合到纳米纤维素上，合成TiO₂/TCNC膜。紫外线诱导下可以提高水通量和水下疏油性，还可快速降解石油酸，实现膜的自清洁和重复利用。

  利用质子化和去质子化的原理可制得pH响应的油/水分离材料。Cheng等^[32]是将丙烯酸(AA)和丙烯酰胺(AM)分别接枝于纸浆纤维素上，得到具有pH可控润湿性的超疏水纸。而Fan等^[33]制备的超疏水/超亲油开关式智能可逆润湿性的纤维素膜则是以NaOH /尿素和ZnCl₂水溶液为原料，通过在纤维素表面沉积ZnO，再接枝月桂酸得到的。而且，水润湿性的可逆转变在经历10个循环后仍没有明显的响应性损失。这种简便、高效的方法为稳定性好、可回收性好的智能响应型油/水分离材料的制备奠定了基础。

  智能响应性能为材料的功能化应用拓宽了路径。智能响应型材料可通过外部条件刺激实现润湿性改变，制备一种材料就可以兼具超疏水/超亲油和超亲水/水下超疏油两种材料才有的润湿性能和分离功能。这极大地拓宽了特殊润湿性油/水分离材料的适用范围，使特殊润湿性材料在工业生产中得到实际应用又向前迈进了一步。

  1.3   超疏水/超亲油的油/水分离材料

  制备超疏水/超亲油材料一般需要满足两个条件：提供低表面能的物质和粗糙微纳米结构^[34-35]。通常会用有机硅氧烷等低表面能的有机单体或者长碳链材料来构建低表面能表面，采用原位生长法、刻蚀法、粒子装饰法等来构建粗糙度^[36-38]。在这里，纤维素本身具有亲水性，所以在制备超疏水材料的过程中只需要用低表面能的氟或有机硅材料改性即可。目前，研究人员已通过溶胶-凝胶法^[39]、气相沉积法^[40]、冷冻干燥法^[41]等制备了纤维素基超疏水/超亲油的油/水分离材料。

  2018年，Lv等^[42]通过对棉花的改性处理制备了一种具备超疏水/超亲油性质的油吸附性棉，见图 2(a)。他们将棉花去蜡处理之后采用溶胶-凝胶法将SiO₂ 颗粒附着到棉纤维表面，再接枝十八烷基三氯硅烷，制得超疏水超亲油吸附剂。该材料制备工艺简单、运行成本低、重复利用性优异，测试结果表明，其对温度、盐度、pH值均有良好的耐性，为大规模清理海洋溢油提供了一种绿色友好的方法。

  图 2

  

  图 2.  (a) 改性棉纤维的原理图^[42]，(b)超疏水PA-Mⁿ⁺@PDMS涂层织物的制备示意图^[43]，(c)弹簧层状超亲油性木质海绵的制备原理图^[44]

  Figure 2.  (a)Schematic diagram of modified cotton fibers^[42], (b)schematic diagram of the preparation of a superhydrophobic PA-Mⁿ⁺@PDMS coated fabric^[43], and (c)schematic diagram of preparation of spring layered super-lipophilic wood sponge^[44]

  下载: 全尺寸图片 幻灯片

  Zhou等^[42]利用植酸(PA)能与某些金属离子结合形成不溶性的配位复合物，制备出一种用于油/水分离的超疏水织物，如图 2(b)。将亲水性棉布浸入PA溶液，然后再浸入金属离子溶液，如此反复多周期组装，从而使棉织物上产生适当的颗粒度，清洗干燥之后再用聚二甲基硅氧烷(PDMS)浸泡固化做疏水改性处理。然后将制得的超疏水/超亲油棉布包裹到海绵上制成“集油包”与泵和收集器连接来吸附海洋原油。

  Guan等^[44]以天然巴尔沙木为原料通过气相沉积法(CVD)制备了一种弹簧片状的高度可压缩的超亲油木质海绵(图 2(c)所示)。在化学处理脱除天然原木中的木质素和半纤维素之后，得到由纤维素骨架构成的木海绵，然后用甲基三甲氧基硅烷通过CVD工艺对其润湿性进行调节。他们对木海绵的润湿性和机械压缩性进行了测试，表明经过10次压缩-吸收循环后，油吸附容量仅从24.5 g/g下降至23.0 g/g，当压缩至40%应变时，100次循环压缩后材料还可以恢复93%，这表明弹簧状片状结构使海绵具有足够的机械压缩性和弹性，为大范围处理含油污水提供依据。

  Zhou等^[45]报道了一种简单、环保的纳米纤维素气凝胶液相改性方法。将块状微纤维素气凝胶浸入乙醇/甲基三乙氧基硅烷溶液中，真空干燥得到超低密度(≤5.08 mg/cm³)，优异孔隙率(≥99.68%)以及高机械稳定性的超疏水纳米纤维素气凝胶。Mi等^[46]先采用双向冷冻干燥法制备出各向异性的纤维素/石墨烯气凝胶，然后通过化学气相沉积接枝长碳链改性得到超疏水性纤维素/石墨烯气凝胶。柔性纤维素、刚性石墨烯和特殊双向排列的多孔结构的协同效应使气凝胶具有出色的压缩和可恢复性能。

  目前制备油吸附性分离材料的方法虽然多样化，但是大部分超亲油材料存在的共有弊端是其孔道容易被油污染导致循环利用性差，此外，对粘度大的原油等吸附回收性差，在海洋防污的实际应用上还需进一步的优化提高。

  综上所述，当前应用于油/水分离的纤维素基超润湿材料主要有超亲水/水下超疏油的“水移除”型油/水分离材料、智能响应型油/水分离材料以及超疏水/超亲油的“油移除”型油/水分离材料等3种类型的分离材料，不同类型的润湿性材料在油/水分离过程中有不同的优缺点, 表 1对以上3种不同类型的纤维素基超润湿性油/水分离材料进行了进一步的对比分析与总结。

  表 1

  

  表 1  3种纤维素基超润湿材料的对比分析总结

  Table 1.  Comparative analysis of three kinds of cellulose-based superwetting materials

  下载: 导出CSV

  Type of Separation Material	Resolve Resolution	Principle of Separation	Material Properties	Reference
  Superhydrophilic/superoleophobic material	Gel-coated retina method, SiO2 mineral deposition adhesion method, Surface grafted zwitterionic method, Dip coating adhesion hydrophilic polymer method, etc.	When the oily sewage contacts the material, the hydrophilic surface is quickly wetted by the water and forms a dense hydration layer, and the oil is blocked on the surface of the material to achieve the oil-water separation effect.	Excellent resistance to oil and self-cleaning, low cost, freon-free, and effective control of secondary pollution.	[47-50]
  Smart response separation material	Free radical polymerization	By adjusting the pH, temperature, ultraviolet light and other factors to achieving the purpose of oil-water separation, because of the hydrophilicity of the material changes	Changing the external conditions can regulate the wettability, and the applications widely; the preparation cost is high, and the synthesis process is complicated and unable to industrialized product	[28, 30]
  Superhydrophobic/superoleophibic material	Chemical deposition, Sol-gel method, Phase separation Template method, Etching method, Electrospinning method, etc.	The membrane has a strong affinity for oil. When the oil-water mixture contacts the membrane, the membrane surface is rapidly wetted by the oil, so that the oil passes through the membrane at a high speed, and the water is blocked on the membrane.	High oil absorbency, suitable for large-scale marine oil spill recovery; poor anti-pollution ability, easy to block the pore size and cause oil waste.	[42-46]

  2.   纤维素基超润湿性材料的应用

  随着分离材料制备技术和性能的不断进步，纤维素基超润湿材料不仅可以在油/水分离应用领域中发挥作用，而且在净水、抗菌、压敏导电^[51-52]等方面也有很好的发展。

  例如，在油/水分离中可以做涂层应用，Huang等^[53]就是以纤维素为基底制备了一种超疏水的涂层，制备机理如图 3所示。将纳米纤维素(CNC)作为骨架在碱性条件下将SiO₂原位生长在纤维素上，然后将得到的“珍珠项链”状的CNC/SiO₂棒接枝上十三氟辛基三乙氧基硅烷进行疏水处理，制得疏水性CNC/SiO₂。测试了将涂层喷涂到不同基底的接触角测试，结果显示水接触角皆＞150°，而且，表面在经过磨损之后依然具有超疏水性。

  图 3

  

  图 3.  CNC/SiO₂超疏水涂层的制作示意图^[51]

  Figure 3.  Schematic diagram of CNC/SiO₂ superhydrophobic coating^[51]

  下载: 全尺寸图片 幻灯片

  而Avijit等^[54]则是在水介质中制备了一种氟烷基功能化防水纸。通过向超声预处理的纤维素悬浮液中加入一定比例的十三氟辛基三乙氧基硅烷(FS)和N-(2-氨乙基)-3-氨丙基三甲氧基硅烷(AS)，室温搅拌6~7 h，最后将悬浊液喷涂到不同基底上或者制成超疏水的纸。实验结果表明，超润湿性纤维素材料不仅可以用来分离含油废水，而且在耐菌方面也有优异的性能。

  Xiong等^[55]将丝素蛋白与纳米纤维素利用模板定向组装构建了特殊的“ shish kebab”层次结构。形成的滤膜不仅具有比商用滤膜高2~3个数量级的极高透水性，而且由于丝素蛋白的存在使得材料能有效地吸收和回收重金属离子，起到良好的净水效果。

  Li等^[56]制备了一种不仅可以用于油/水分离同时还具有压敏导电性能的多功能碳气凝胶。将活化后的纤维分散在乙醇溶液中，然后悬浮液过滤得到潮湿状态下的凝胶，干燥之后于1000 ℃ N₂气氛围下热解4 h最终得到碳化气凝胶。该气凝胶不仅具有优异的油吸附性，而且还可以通过控制压缩力度来调控LED灯的亮度。

  除上述应用之外，纤维素基超润湿性材料在防潮包装、防火、脱盐以及耐腐蚀方面也有很好的发展前景。表 2综述了近年来纤维素基超润湿性材料在油/水分离之外的应用。

  表 2

  

  表 2  纤维素基超润湿性材料应用简述

  Table 2.  Brief introduction of cellulose-based superwetting materials

  下载: 导出CSV

  Application Type	Raw Material	Resolve Resolution	Preparation Process	Material properties	Reference
  Damp-proof Packing	A:Polydiallyldimethylammonium chloride B:Silica nanoparticles C:Perfluorooctyltriethoxysilane	Multilayer self- assembly deposition chemical vapor deposition	The raw materials A and B were deposited on a filter paper, and the filter paper was subjected to perfluorination treatment by a vapor deposition method using C.	It still has high tensile strength when the relative humidity is high, and it can be used for damp-proof Packing It is resistant to bacterial contamination.	[57]
  Anti-fire function	A:Perfluorooctyltriethoxysilane B:Dimethyloctadecyl[3-(trimethoxysilyl)propyl] ammonium chloride C:P, P-diphenyl-N-(3- (trimethoxysilyl)propyl) phosphinamide	Sol-gel method	The three-component polymer is disposed in a certain proportion, and then the cotton fabric is dip coated, and the cotton fabric is dried and solidified by a rolling-bake-bake production process.	The fluorine-containing hydrocarbon group reduces the surface energy of the cotton fiber, impart super-amphiphobic properties to the material. The functional groups containing phosphorus and nitrogen provide excellent fire resistance of cotton fibers.	[58]
  Desalination	A:Poly(vinylidene fluoride-co-hexafluoropropylene) B:Cellulose	Electrospinning Physical accumulation	The raw material A was formed into a film by electrospinning, and then the cell-PVDF-HFP film material was prepared by soaking the cellulose solution, and superimposed with the original A material to obtain a superhydrophobic double-layer film.	Superhydrophobic; in the 1×10-3 oil-containing brine feed separation experiment, the fresh water flux of the two-layer membrane is as high as 12.8 kg/(m·h), which can be used for desalination of oily wastewater.	[59]
  corrosion resistance	A: Tetraethyl silicate B: Trimethylethoxysilane	Coating method	A SiO2 sol was obtained by using two raw materials, and a super-hydrophobic paper was obtained by a coating method.	Super hydrophobic; good cycle; excellent acid and alkali resistance	[60]

  3.   总结与展望

  近年来，纤维素基超润湿材料的研究已经取得了丰硕的成果，理论体系也越来越完善，但仍需要深入钻研与改进。比如，棉布以及纸张在进行超疏水改性时，容易受到酸碱、高温、紫外等影响，而出现结构不稳定现象，影响其长期使用，所以进一步对其稳定性进行深入研究较有意义。另外，纤维素虽然是自然界含量最多的天然可再生资源，但它既不溶于水，又不溶于一般的有机溶剂，而且目前报道的纤维素基超润湿性材料基本都是在分散体系中进行的，所以纤维素的溶解与反应体系也是当前亟待解决的问题之一。除此之外，认为纤维素基超润湿材料的研究方向应主要聚集在以下3个方面：1)在实验室条件下进行的油/水分离实验虽然达到了理想的效果，但在极端条件下对于大量的油/水混合物处理，还需要进一步的研究探索；2)采用生物基材料与纳米颗粒相结合制备具有超疏水性能的涂层，是目前纤维素功能化研究的重点，但混合物之间的界面效应是目前需要克服的一个难点；3)深入润湿性材料在抗菌净水吸附重金属离子等方面的研究，扩大纤维素基超润湿材料在醇/水分离以及离子液体/水等分离方面的应用范围。

  
  
• 1. [1]

     Gao J F, Song X, Huang X W. Facile Preparation of Polymer Microspheres and Fibers with a Hollow Core and Porous Shell for Oil Adsorption and Oil/Water Separation[J]. Appl Surf Sci, 2018, 439:  394-404. doi: 10.1016/j.apsusc.2018.01.013

  2. [2]

     Fard A K, Rhadfi T, Mckay G. Enhancing Oil Removal from Water Using Ferric Oxide Nanoparticles Doped Carbon Nanotubes Adsorbents[J]. Chem Eng J, 2016, 293:  90-101. doi: 10.1016/j.cej.2016.02.040

  3. [3]

     Zouboulis A I, Avranas A. Treatment of Oil-in-Water Emulsions by Coagulation and Dissolved-Air Flotation[J]. Colloids Surf A, 2000, 172(1/3):  153-161.

  4. [4]

     Nikkhah M, Tohidian T, Rahimpour M R. Efficient Demulsification of Water-in-Oil Emulsion by a Novel Nano-Titania Modified Chemical Demulsifier[J]. Chem Eng Res Des, 2015, 94:  164-172. doi: 10.1016/j.cherd.2014.07.021

  5. [5]

     Tashiro K, Kobayashi M. Theoretical Evaluation of Three-Dimensional Elastic Constants of Native and Regenerated Celluloses:Role of Hydrogen Bonds[J]. Polymer, 1991, 32(8):  1516-1526. doi: 10.1016/0032-3861(91)90435-L

  6. [6]

     Šturcová A, R Davies G, J Eichhorn S. Elastic Modulus and Stress-Transfer Properties of Tunicate Cellulose Whiskers[J]. Biomacromolecules, 2005, 6(2):  1055-1061. doi: 10.1021/bm049291k

  7. [7]

     Mansouri J, Harrisson S, Chen V. Strategies for Controlling Biofouling in Membrane Filtration Systems:Challenges and Opportunities[J]. J Mater Chem, 2010, 20(22):  4567-4586. doi: 10.1039/b926440j

  8. [8]

     Liu R C, Dangwal S, Shaik I. Hydrophilicity-Controlled MFI-Type Zeolite-Coated Mesh for Oil/Water Separation[J]. Sep Purif Technol, 2018, 195:  163-169. doi: 10.1016/j.seppur.2017.11.064

  9. [9]

     Xue Z X, Cao Y Z, Liu N. Special Wettable Materials for Oil/Water Separation[J]. J Mater Chem A, 2014, 2(8):  2445-2460. doi: 10.1039/C3TA13397D

  10. [10]

      Cheng Z J, Li C, Lai H. A pH-Responsive Superwetting Nanostructured Copper Mesh Film for Separating both Water-in-Oil and Oil-in-Water Emulsions[J]. RSC Adv, 2016, 6(76):  72317-72325. doi: 10.1039/C6RA14454C

  11. [11]

      Guo J H, Wang J K, Gao Y H. pH-Responsive Sponges Fabricated by Ag-S Ligands Possess Smart Double-Transformed Superhydrophilic Superhydrophobic Superhydrophilic Wettability for Oil-Water Separation[J]. ACS Sustainable Chem Eng, 2017, 5(11):  10772-10782. doi: 10.1021/acssuschemeng.7b02734

  12. [12]

      Fu Y C, Jin B Y, Zhang Q H. pH-Induced Switchable Superwettability of Efficient Antibacterial Fabrics for Durable Selective Oil/Water Separation[J]. ACS Appl Mater Interfaces, 2017, 9(35):  30161-30170. doi: 10.1021/acsami.7b09159

  13. [13]

      Pham V H, Dickerson J H. Superhydrophobic Silanized Melamine Sponges as High Efficiency Oil Absorbent Materials[J]. ACS Appl Mater Interfaces, 2014, 6(16):  14181-14188. doi: 10.1021/am503503m

  14. [14]

      Ge J, Ye Y D, Yao H B. Pumping Through Porous Hydrophobic/Oleophilic Materials:An Alternative Technology for Oil Spill Remediation[J]. Angew Chem Int Ed, 2014, 53(14):  3612-3616. doi: 10.1002/anie.201310151

  15. [15]

      Jang S H, Jeong Y G, Min B G. Preparation and Lead Ion Removal Property of Hydroxyapatite/Polyacrylamide Composite Hydrogels[J]. J Hazard Mater, 2008, 159(2/3):  294-299.

  16. [16]

      Laus R, de Fávere V T. Competitive Adsorption of Cu(Ⅱ) and Cd(Ⅱ) Ions by Chitosan Crosslinked with Epichlorohydrin-Triphosphate[J]. Bioresour Technol, 2011, 102(19):  8769-8776. doi: 10.1016/j.biortech.2011.07.057

  17. [17]

      Zhao L, Mitomo H. Adsorption of Heavy Metal Ions from Aqueous Solution onto Chitosan Entrapped CM-Cellulose Hydrogels Synthesized by Irradiation[J]. J Appl Polym Sci, 2008, 110(3):  1388-1395.

  18. [18]

      孟凡宁, 宋菁, 张新妙. 超润湿性油水分离膜的研究进展[J]. 化工环保, 20191-9. MENG Fanning, SONG Jing, ZHANG Xinmiao. Research Progress of Membranes with Special Wettability for Oil-Water Separation[J]. Environ Prot Chem Ind, 2019, :  1-9.

  19. [19]

      Zhou K, Zhang Q G, Li H M. Ultrathin Cellulose Nanosheet Membranes for Superfast Separation of Oil-in-Water Nanoemulsions[J]. Nanoscale, 2014, 6(17):  10363-10369. doi: 10.1039/C4NR03227F

  20. [20]

      Gao X F, Xu L P, Xue Z X. Dual-Scaled Porous Nitrocellulose Membranes with Underwater Superoleophobicity for Highly Efficient Oil/Water Separation[J]. Adv Mater, 2014, 26(11):  1771-1775. doi: 10.1002/adma.201304487

  21. [21]

      Zhang H, Li Y Q, Shi R H. A Robust Salt-Tolerant Superoleophobic Chitosan/Nanofibrillated Cellulose Aerogel for Highly Efficient Oil/Water Separation[J]. Carbohydr Polym, 2018, 200:  611-615. doi: 10.1016/j.carbpol.2018.07.071

  22. [22]

      Sun F F, Liu W, Dong Z X. Underwater Superoleophobicity Cellulose Nanofibril Aerogel Through Regioselective Sulfonation for Oil/Water Separation[J]. Chem Eng J, 2017, 330:  774-782. doi: 10.1016/j.cej.2017.07.142

  23. [23]

      Wang G, He Y, Wang H. A Cellulose Sponge with Robust Superhydrophilicity and Underwater Superoleophobicity for Highly Effective Oil/Water Separation[J]. Green Chem, 2015, 17(5):  3093-3099. doi: 10.1039/C5GC00025D

  24. [24]

      Chen W J, Su Y L, Peng J M. Engineering a Robust, Versatile Amphiphilic Membrane Surface Through Forced Surface Segregation for Ultralow Flux-Decline[J]. Adv Funct Mater, 2011, 21(1):  191-198. doi: 10.1002/adfm.201001384

  25. [25]

      Chen W J, Su Y L, Zhang L. In Situ Generated Silica Nanoparticles as Pore-Forming Agent for Enhanced Permeability of Cellulose Acetate Membranes[J]. J Membr Sci, 2010, 348(1/2):  75-83.

  26. [26]

      Xue Z X, Liu M J, Jiang L. Recent Developments in Polymeric Superoleophobic Surfaces[J]. J Polym Sci Pol Phys, 2012, 50(17):  1209-1224. doi: 10.1002/polb.23115

  27. [27]

      Cao Y Z, Chen Y N, Liu N. Mussel-Inspired Chemistry and Stöber Method for Highly Stabilized Water-in-Oil Emulsions Separation[J]. J Mater Chem A, 2014, 2(48):  20439-20443. doi: 10.1039/C4TA05075D

  28. [28]

      Dang Z, Liu L B, Li Y. In Situ and Ex Situ pH-Responsive Coatings with Switchable Wettability for Controllable Oil/Water Separation[J]. ACS Appl Mater Interfaces, 2016, 8(45):  31281-31288. doi: 10.1021/acsami.6b09381

  29. [29]

      Fang W Y, Liu L B, Guo G L. Tunable Wettability of Electrospun Polyurethane/Silica Composite Membranes for Effective Separation of Water-in-Oil and Oil-in-Water Emulsions[J]. Chem-Eur J, 2017, 23(47):  11253-11260. doi: 10.1002/chem.201701409

  30. [30]

      Chen W, He H, Zhu H. Thermo-responsive Cellulose-Based Material with Switchable Wettability for Controllable Oil/Water Separation[J]. Polymers, 2018, 10(6):  592. doi: 10.3390/polym10060592

  31. [31]

      Zhan H, Peng N, Lei X. UV-Induced Self-Cleanable TiO₂/Nanocellulose Membrane for Selective Separation of Oil/Water Emulsion[J]. Carbohydr Polym, 2018, 201:  464-470. doi: 10.1016/j.carbpol.2018.08.093

  32. [32]

      Cheng M X, He H, Zhu H X. Preparation and Properties of pH-Responsive Reversible-Wettability Biomass Cellulose-Based Material for Controllable Oil/Water Separation[J]. Carbohydr Polym, 2019, 203:  246-255. doi: 10.1016/j.carbpol.2018.09.051

  33. [33]

      Fan T, Qian Q H, Hou Z H. Preparation of Smart and Reversible Wettability Cellulose Fabrics for Oil/Water Separation Using a Facile and Economical Method[J]. Carbohydr Polym, 2018, 200:  63-71. doi: 10.1016/j.carbpol.2018.07.040

  34. [34]

      Nosonovsky M, Bhushan B. Biomimetic Superhydrophobic Surfaces:Multiscale Approach[J]. Nano Lett, 2007, 7(9):  2633-2637. doi: 10.1021/nl071023f

  35. [35]

      Patankar N A. Mimicking the Lotus Effect:Influence of Double Roughness Structures and Slender Pillars[J]. Langmuir, 2004, 20(19):  8209-8213. doi: 10.1021/la048629t

  36. [36]

      Peng H I, Wang H, Wu J N. Preparation of Superhydrophobic Magnetic Cellulose Sponge for Removing Oil from Water[J]. Ind Eng Chem Res, 2016, 55(3):  832-838. doi: 10.1021/acs.iecr.5b03862

  37. [37]

      Matin A, Baig U, Gondal M A. Facile Fabrication of Superhydrophobic/Superoleophilic Microporous Membranes by Spray-Coating Ytterbium Oxide Particles for Efficient Oil-Water Separation[J]. J Membr Sci, 2018, 548:  390-397. doi: 10.1016/j.memsci.2017.11.045

  38. [38]

      Guo D Y, Chen J H, Hou K. A Facile Preparation of Superhydrophobic Halloysite-Based Meshes for Efficient Oil-Water Separation[J]. Appl Clay Sci, 2018, 156:  195-201. doi: 10.1016/j.clay.2018.01.034

  39. [39]

      徐耀. 溶胶-凝胶化学的发展和应用[J]. 科技导报, 2017,35,(4): 96. XU Yao. Development and Application of Sol-Gel Chemistry[J]. Sci Technol Rev, 2017, 35(4):  96.

  40. [40]

      刘晓红, 陈志勇, 邓山江. 气相沉积技术的现状与发展[J]. 北华航天工业学院学报, 2006(3): 26-28. LIU Xiaohong, CHEN Zhiyong, DENG Shanjiang. Current Situation and Development Trend of Vapor Deposition Tachnology[J]. J North China Inst Aerospace Eng, 2006, (3):  26-28.

  41. [41]

      马珊珊, 张美云, 杨斌. 冷冻干燥法制备纤维素基多孔材料的研究[J]. 中国造纸, 2017,36,(11): 29-36. MA Shanshan, ZHANG Meiyun, YANG Bin. Study on the Preparation of Cellulose-Based Porous Material by Freeze-Drying Process[J]. China Pulp Paper, 2017, 36(11):  29-36.

  42. [42]

      Lv N, Wang X L, Peng S T. Superhydrophobic/Superoleophilic Cotton-Oil Absorbent:Preparation and Its Application in Oil/Water Separation[J]. RSC Adv, 2018, 8(53):  30257-30264. doi: 10.1039/C8RA05420G

  43. [43]

      Zhou C L, Chen Z D, Yang H. A Nature-Inspired Strategy Toward Superhydrophobic Fabrics for Versatile Oil/Water Separation[J]. ACS Appl Mater Interfaces, 2017, 9(10):  9184-9194. doi: 10.1021/acsami.7b00412

  44. [44]

      Guan H, Cheng Z Y, Wang X Q. Highly Compressible Wood Sponges with a Spring-Like Lamellar Structure as Effective and Reusable Oil Absorbents[J]. ACS Nano, 2018, 12(10):  10365-10373. doi: 10.1021/acsnano.8b05763

  45. [45]

      Zhou S K, Liu P P, Wang M. Sustainable, Reusable, and Superhydrophobic Aerogels from Microfibrillated Cellulose for Highly Effective Oil/Water Separation[J]. ACS Sustainable Chem Eng, 2016, 4(12):  6409-6416. doi: 10.1021/acssuschemeng.6b01075

  46. [46]

      Mi H Y, Jing X, Politowicz A L. Highly Compressible Ultra-Light Anisotropic Cellulose/Graphene Aerogel Fabricated by Bidirectional Freeze Drying for Selective Oil Absorption[J]. Carbon, 2018, 132:  199-209. doi: 10.1016/j.carbon.2018.02.033

  47. [47]

      Yuan T, Meng J Q, Hao T Y. A Scalable Method Toward Superhydrophilic and Underwater Superoleophobic PVDF Membranes for Effective Oil/Water Emulsion Separation[J]. ACS Appl Mater Interfaces, 2015, 7(27):  4896-14904.

  48. [48]

      He K, Duan H R, Chen G Y. Cleaning of Oil Fouling with Water Enabled by Zwitterionic Polyelectrolyte Coatings:Overcoming the Imperative Challenge of Oil-Water Separation Membranes[J]. ACS Nano, 2015, 9:  9188-9198. doi: 10.1021/acsnano.5b03791

  49. [49]

      Zhang S Y, Lu F, Tao L. Bio-inspired Anti-Oil-Fouling Chitosan-Coated Mesh for Oil/Water Separation Suitable for Broad pH Range and Hyper-saline Environments[J]. ACS Appl Mater Interfaces, 2013, 5(22):  11971-11976. doi: 10.1021/am403203q

  50. [50]

      Chen P C, Xu Z K. Mineral-Coated Polymer Membranes with Superhydrophilicity and Underwater Superoleophobicity for Effective Oil/Water Separation[J]. Sci Rep, 2013, 3(1):  2776. doi: 10.1038/srep02776

  51. [51]

      Bethke K, Palant ken S, Andrei V. Functionalized Cellulose for Water Purification, Antimicrobial Applications and Sensors[J]. Adv Funct Mater, 2018, 28(23):  1800409. doi: 10.1002/adfm.201800409

  52. [52]

      Voisin H, Bergstr m L, Liu P. Nanocellulose-Based Materials for Water Purification[J]. Nanomaterials, 2017, 7(3):  57. doi: 10.3390/nano7030057

  53. [53]

      Huang J D, Lyu S Y, Chen Z L. A Facile Method for Fabricating Robust Cellulose Nanocrystal/SiO₂ Superhydrophobic Coatings[J]. J Colloid Interface Sci, 2019, 536:  349-362. doi: 10.1016/j.jcis.2018.10.045

  54. [54]

      Baidya A, Ganayee M A, Jakka Ravindran S. Organic Solvent-Free Fabrication of Durable and Multifunctional Superhydrophobic Paper from Waterborne Fluorinated Cellulose Nanofiber Building Blocks[J]. ACS Nano, 2017, 11(11):  11091-11099. doi: 10.1021/acsnano.7b05170

  55. [55]

      Xiong R, Kim H S, Zhang S D. Template-Guided Assembly of Silk Fibroin on Cellulose Nanofibers for Robust Nanostructures with Ultrafast Water Transport[J]. ACS Nano, 2016, 11(12):  12008-12019.

  56. [56]

      Li L X, Hu T, Sun H X. Pressure-Sensitive and Conductive Carbon Aerogels from Poplars Catkins for Selective Oil Absorption and Oil/Water Separation[J]. ACS Appl Mater Interfaces, 2017, 9(21):  18001-18007. doi: 10.1021/acsami.7b04687

  57. [57]

      Yang H T, Deng Y L. Preparation and Physical Properties of Superhydrophobic Papers[J]. J Colloid Interface Sci, 2008, 325(2):  588-593. doi: 10.1016/j.jcis.2008.06.034

  58. [58]

      Vasiljević J, Tomšič B, Jerman I. Novel Multifunctional Water- and Oil-Repellent, Antibacterial, and Flame-Retardant Cellulose Fibres Created by the Sol-Gel Process[J]. Cellulose, 2014, 21(4):  2611-2623. doi: 10.1007/s10570-014-0293-4

  59. [59]

      Makanjuola O, Ahmed F, Janajreh I. Development of a Dual-Layered PVDF-HFP/Cellulose Membrane with Dual Wettability for Desalination of Oily Wastewater[J]. J Membr Sci, 2019, 570/571:  418-426. doi: 10.1016/j.memsci.2018.10.028

  60. [60]

      Wang N, Xiong D S, Pan S. Superhydrophobic Paper with Superior Stability Against Deformations and Humidity[J]. Appl Surf Sci, 2016, 389:  354-360. doi: 10.1016/j.apsusc.2016.07.110

• 

  图 1  (a) 纤维素纳米薄膜的制备流程^[19]和(b)纤维素海绵的制备工艺^[23]

  Figure 1  (a)Preparation process of cellulose nanofilm^[19] and (b)preparation process of cellulose sponge^[23]

  下载: 全尺寸图片 幻灯片
  

  图 2  (a) 改性棉纤维的原理图^[42]，(b)超疏水PA-Mⁿ⁺@PDMS涂层织物的制备示意图^[43]，(c)弹簧层状超亲油性木质海绵的制备原理图^[44]

  Figure 2  (a)Schematic diagram of modified cotton fibers^[42], (b)schematic diagram of the preparation of a superhydrophobic PA-Mⁿ⁺@PDMS coated fabric^[43], and (c)schematic diagram of preparation of spring layered super-lipophilic wood sponge^[44]

  下载: 全尺寸图片 幻灯片
  

  图 3  CNC/SiO₂超疏水涂层的制作示意图^[51]

  Figure 3  Schematic diagram of CNC/SiO₂ superhydrophobic coating^[51]

  下载: 全尺寸图片 幻灯片

  表 1  3种纤维素基超润湿材料的对比分析总结

  Table 1.  Comparative analysis of three kinds of cellulose-based superwetting materials

  Type of Separation Material	Resolve Resolution	Principle of Separation	Material Properties	Reference
  Superhydrophilic/superoleophobic material	Gel-coated retina method, SiO2 mineral deposition adhesion method, Surface grafted zwitterionic method, Dip coating adhesion hydrophilic polymer method, etc.	When the oily sewage contacts the material, the hydrophilic surface is quickly wetted by the water and forms a dense hydration layer, and the oil is blocked on the surface of the material to achieve the oil-water separation effect.	Excellent resistance to oil and self-cleaning, low cost, freon-free, and effective control of secondary pollution.	[47-50]
  Smart response separation material	Free radical polymerization	By adjusting the pH, temperature, ultraviolet light and other factors to achieving the purpose of oil-water separation, because of the hydrophilicity of the material changes	Changing the external conditions can regulate the wettability, and the applications widely; the preparation cost is high, and the synthesis process is complicated and unable to industrialized product	[28, 30]
  Superhydrophobic/superoleophibic material	Chemical deposition, Sol-gel method, Phase separation Template method, Etching method, Electrospinning method, etc.	The membrane has a strong affinity for oil. When the oil-water mixture contacts the membrane, the membrane surface is rapidly wetted by the oil, so that the oil passes through the membrane at a high speed, and the water is blocked on the membrane.	High oil absorbency, suitable for large-scale marine oil spill recovery; poor anti-pollution ability, easy to block the pore size and cause oil waste.	[42-46]

  下载: 导出CSV

  表 2  纤维素基超润湿性材料应用简述

  Table 2.  Brief introduction of cellulose-based superwetting materials

  Application Type	Raw Material	Resolve Resolution	Preparation Process	Material properties	Reference
  Damp-proof Packing	A:Polydiallyldimethylammonium chloride B:Silica nanoparticles C:Perfluorooctyltriethoxysilane	Multilayer self- assembly deposition chemical vapor deposition	The raw materials A and B were deposited on a filter paper, and the filter paper was subjected to perfluorination treatment by a vapor deposition method using C.	It still has high tensile strength when the relative humidity is high, and it can be used for damp-proof Packing It is resistant to bacterial contamination.	[57]
  Anti-fire function	A:Perfluorooctyltriethoxysilane B:Dimethyloctadecyl[3-(trimethoxysilyl)propyl] ammonium chloride C:P, P-diphenyl-N-(3- (trimethoxysilyl)propyl) phosphinamide	Sol-gel method	The three-component polymer is disposed in a certain proportion, and then the cotton fabric is dip coated, and the cotton fabric is dried and solidified by a rolling-bake-bake production process.	The fluorine-containing hydrocarbon group reduces the surface energy of the cotton fiber, impart super-amphiphobic properties to the material. The functional groups containing phosphorus and nitrogen provide excellent fire resistance of cotton fibers.	[58]
  Desalination	A:Poly(vinylidene fluoride-co-hexafluoropropylene) B:Cellulose	Electrospinning Physical accumulation	The raw material A was formed into a film by electrospinning, and then the cell-PVDF-HFP film material was prepared by soaking the cellulose solution, and superimposed with the original A material to obtain a superhydrophobic double-layer film.	Superhydrophobic; in the 1×10-3 oil-containing brine feed separation experiment, the fresh water flux of the two-layer membrane is as high as 12.8 kg/(m·h), which can be used for desalination of oily wastewater.	[59]
  corrosion resistance	A: Tetraethyl silicate B: Trimethylethoxysilane	Coating method	A SiO2 sol was obtained by using two raw materials, and a super-hydrophobic paper was obtained by a coating method.	Super hydrophobic; good cycle; excellent acid and alkali resistance	[60]

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