用于从水中进行超快速、选择性油吸附的 具有双峰孔结构的可回收3D石墨烯气凝胶外文翻译资料

 2022-01-17 09:01

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Recyclable 3D graphene aerogel with bimodal pore structure for ultrafast and selective oil sorption from water

用于从水中进行超快速、选择性油吸附的

具有双峰孔结构的可回收3D石墨烯气凝胶

Abstract: Development of next-generation porous sorbents to overcome the challenges, such as low uptake capacity, slow sorption rate, and non-recyclability, associated with conventional sorbents is of utmost importance. Herein, we report the synthesis of a highly porous graphene aerogel (GA) with a unique three-dimensional hierarchical bimodal porous network of macro and meso-pores via a facile hydrothermal technique; this aerogel has sorption capacity that is more than 5 times that of conventional commercial sorbents. Fluoroalkyl silane functionalization of the GA surface results in a significant reduction in its water sorption from 20 g*g-1 to 5 g*g-1 due to the GA surface becoming more hydrophobic, which renders it useful in practical application to selectively remove oil from seawater. Moreover, the sorption rate of the GA for oils and organic solvents has been found to be extremely fast, and saturation of the GA is completed in a few seconds. This is attributed to its unique meso–macro bimodal porous structure with large pore channels called macro-pores or voids of various sizes ranging from 300 nm to over 10 mm, which facilitate mass transport into its inner mesopores of 14–18 nm at high rate. Finally, the GA is shown to be a highly recyclable material due to its good mechanical strength, where the oil- and organic solvent-sorbed GA can be efficiently recovered using thermal or chemical methods for several sorption–desorption cycles without significant loss in its capacity, which also makes the process cost effective and environmentally friendly.

摘要：开发下一代多孔吸附剂以克服与常规吸附剂相关的诸如低吸收容量，低吸附速率和不可再循环性的挑战是至关重要的。在本文中，我们通过简单的水热技术合成了高孔隙率石墨烯气凝胶，这种气凝胶具有独特的三维分层双峰多孔（包含大孔和中孔）网状结构，其吸附容量是传统商业吸附剂的5倍以上。氟硅烷对石墨烯气凝胶表面的修饰使其表面变得更加疏水，导致其吸水量从20g*g-1显著减少到5g*g-1，这使得在实际应用中气凝胶可以选择性地从海水中除油。此外，我们发现石墨烯气凝胶对油和有机溶剂的吸附速率非常快，并且石墨烯气凝胶的饱和在几秒钟内完成。这一点归因于其独特的双峰多孔结构，该结构具有被称为大孔或尺寸范围在300nm到超过10mm的空隙，有利于传质高速运输到尺寸在14~ 18nm的内孔中。最后，由于其良好的力学强度，石墨烯气凝胶被证明是一种高度可回收的材料。吸附了油和有机溶剂的石墨烯气凝胶可以使用加热或化学方法有效回收，并且在数次吸附/脱附循环后其容量没有明显损失，这使得工艺环保且成本低廉。

  1. 引言

Marine oil spills occur frequently as a result of anthropogenic activities, such as oil rig drilling and oil tanker accidents, which may cause irreparable ecological impacts and devastating long-term environmental disasters. Various strategies, such as in situ burning, are being used for oil spill remediation; however, the gaseous products and particulates emitted through oil combustion pollute the atmosphere. The deployment of booms and skimmers confine the oil to a specific location for collection, but this method is inefficient in turbulent wavy surfaces, time-consuming, laborious and requires a large number of equipment. Porous sorbent materials have recently attracted great attention owing to their ability to remove all traces of oil from spill sites. However, there are several challenges with these porous sorbents, including low uptake capacity and low sorption rate, which are yet to be overcome.

由于诸如石油钻井和油船事故等人类活动，海上石油泄漏事件经常发生，其可能造成无法挽回的生态影响以及长期的破坏性的环境灾害。人们正利用各种策略比如就地燃烧来解决石油泄漏问题。然而，石油燃烧排放的气态产物和颗粒会污染大气。布置拦油索和撇油器可将油控制在特定的位置以便收集，但在湍流波状表面上这种方法不仅效率低、费时费力，还需要大量的设备。多孔吸附剂材料最近引起了极大的关注，因为它们能够从溢油部位除掉所有油迹。然而，这些多孔吸附剂还存在许多问题，包括低吸附容量和低吸附速率，这些问题尚未被解决。

Graphene, due to its extraordinary properties, has been used for numerous applications such as lithium ion batteries, super-capacitors, flexible electronics, sensors and composite materials. It is also a promising material for sorption applications due to its high surface area. However, the dispersion of pristine graphene in water is difficult which precludes its application in aqueous media. Therefore, graphene oxide (GO) is an alternative material to graphene that has facile aqueous solution processability due to the abundance of polar functional groups on its surface. For applications, especially those requiring high porosity such as contaminant removal from aqueous solution via sorption processes, the assembly of graphene oxide sheets into a three dimensional structure can be advantageous to form a material with a high surface area, enhanced porosity and high strength at very low density. This structure has been realized recently via the one step hydrothermal reduction of graphene oxide under controlled conditions which has been used for lithium ion batteries and photocatalysis. Unlike activated carbons and zeolites with micro- and/or mesoporous structures and high surface areas, aerogel sponges are mainly characterized by their high porosity and large macropores in addition to mesopores. Therefore, although activated carbons and zeolites employ electrostatic interaction or  interactions to adsorb specific components, such as phenols and dyes, graphene aerogels are well-tailored for the absorption of nonpolar substances, such as hydrocarbons and oils. The great potential of graphene aerogels in oil sorption not only stems from their hydrophobicity, but also their large pore sizes which lead to facile oil diffusion into the bulk of the sorbent at high rates.

由于具备优异的性能，石墨烯被用于多种领域，比如锂离子电池、超级电容器、柔性电子元件、传感器和复合材料等。此外，由于具有高的比表面积，石墨烯也是一种很有前景的吸附材料。然而，原始石墨烯在水中的分散性不佳，这阻碍了其在水介质中的应用。因此，氧化石墨烯是石墨烯的替代材料，由于表面上存在大量极性官能团，其具有易于溶于水的特性。在要求高孔隙率的应用场景下（例如通过吸附作用从水溶液中除掉污染物），将氧化石墨烯片组装成三维结构有利于形成高表面积，高孔隙率和低密度高强度的材料。依靠在受控条件下的一步水热还原法，氧化石墨烯的这种结构最近已被实现，并且已被用于锂离子电池和光催化。与具有微孔或中孔结构以及高表面积的活性炭和沸石不同，海绵状气凝胶的主要特征在于它们的高孔隙率、大量的大孔和中孔。因此，尽管活性炭和沸石采用静电相互作用或pi;-pi;相互作用来吸附特殊成分（例如酚类和染料），但石墨烯气凝胶非常适合吸收非极性物质，例如烃类和油类。石墨烯气凝胶在油吸附中的巨大潜力不仅源于它们的疏水性，而且还源于它们的大孔径，这可让易燃油高速进入吸附剂主体。

Some oil sorption studies using graphene based materials have been reported. For example, Bi et al. (2012) reported the synthesis of spongy graphene via a 24 hour hydrothermal reaction of a GO a

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