石偉群, 王祥科

無機(jī)環(huán)境材料及其對(duì)環(huán)境污染物的去除

石偉群1, 王祥科2

(1. 中國(guó)科學(xué)院 高能物理研究所, 北京 100049; 2. 華北電力大學(xué) 環(huán)境科學(xué)與工程學(xué)院, 北京 102206)

隨著人類現(xiàn)代化進(jìn)程的加快和社會(huì)經(jīng)濟(jì)的飛速發(fā)展, 傳統(tǒng)能源消耗不斷加快, 氣候變化問題日益凸顯。現(xiàn)代工業(yè)特別是化學(xué)工業(yè)的發(fā)展在給人們帶來便利的同時(shí), 也給與人類生活息息相關(guān)的生態(tài)環(huán)境帶來了前所未有的改變, 導(dǎo)致環(huán)境問題成為當(dāng)今世界面臨的巨大挑戰(zhàn)。為了更好地應(yīng)對(duì)挑戰(zhàn), 保護(hù)我們賴以生存的家園, 廣大科研工作者不斷尋求和探索綠色環(huán)保并能高效利用的新材料與新技術(shù), 著力解決日益嚴(yán)峻的環(huán)境污染問題。在這種形勢(shì)下, 新型環(huán)境材料與技術(shù)受到了廣泛重視并得到迅猛發(fā)展。

環(huán)境材料, 顧名思義, 是針對(duì)環(huán)境問題而設(shè)計(jì)發(fā)展的材料。環(huán)境問題的核心是環(huán)境污染, 當(dāng)前人們密切關(guān)注的環(huán)境污染物包括氣體污染物、持久性有機(jī)污染物和重金屬污染物等。近年來隨著核工業(yè)的崛起和發(fā)展, 放射性污染物也日益受到重視。通過不同手段對(duì)環(huán)境中的這些污染物進(jìn)行分離去除是環(huán)境污染治理的主要方法。在過去幾十年間, 研究人員不斷開發(fā)出去除特定污染物的新材料。這些材料種類繁多, 結(jié)構(gòu)多樣, 性能各異。研究較多的包括傳統(tǒng)的分子篩[1], 礦物材料[2], 以石墨烯、碳納米管為代表的碳材料[3], 樹脂等高分子材料[4], 以及近年來頗受學(xué)者重視的金屬有機(jī)框架材料(MOFs)[5]和共價(jià)有機(jī)框架材料(COFs)等[6]。在這些材料當(dāng)中, 無機(jī)材料以其穩(wěn)定性好、廉價(jià)易得和對(duì)環(huán)境友好等特點(diǎn), 在環(huán)境污染物的去除分離領(lǐng)域具有廣闊的應(yīng)用前景, 尤其是無機(jī)納米多孔材料近年來備受青睞。納米尺寸使得材料不僅具有量子尺寸效應(yīng), 而且比其它普通材料具有更大的比表面和較多的表面原子, 表現(xiàn)出吸附能力強(qiáng)、在水中分散性好等不同于一般材料的獨(dú)特性質(zhì)。多孔性在大幅度提高材料的比表面積、增加材料與污染物接觸面的同時(shí), 還可加快污染物在材料內(nèi)部的擴(kuò)散和傳輸, 使得這類材料在吸附應(yīng)用中更具潛力和優(yōu)勢(shì)。金屬納米材料、金屬氧化物納米材料、礦物材料等都是無機(jī)納米材料家族的典型代表。

從已有文獻(xiàn)來看, 提高污染物去除的效率和選擇性一直是無機(jī)環(huán)境材料領(lǐng)域的研究熱點(diǎn)和努力方向。與有機(jī)材料相比, 無機(jī)材料雖然具有更高的穩(wěn)定性, 但是通常對(duì)污染物去除效率偏低和選擇性不佳, 這主要是因?yàn)闊o機(jī)材料表面缺少活性功能基團(tuán)。為了克服這一缺點(diǎn), 常規(guī)做法是對(duì)無機(jī)材料進(jìn)行功能化修飾。將對(duì)目標(biāo)污染物具有強(qiáng)結(jié)合能力的功能基團(tuán)通過物理或化學(xué)手段修飾在材料表面[7], 以提高其對(duì)污染物的去除能力。在提高選擇性方面, 除了在材料表面修飾特異性識(shí)別基團(tuán)[8]外, 調(diào)節(jié)材料的孔道結(jié)構(gòu), 利用尺寸效應(yīng)物理篩分污染物[9]也是常用和有效方法?；蛘咄ㄟ^分子印跡、復(fù)合等手段將尺寸效應(yīng)、鍵合作用以及靜電作用等有機(jī)結(jié)合起來以提高對(duì)目標(biāo)污染物的選擇性[10]。此外, 除了改善分離效率和選擇性, 發(fā)展在高酸、高堿、高溫等苛刻條件下應(yīng)用的無機(jī)環(huán)境材料近年來也逐漸成為研究熱點(diǎn)[11]。

總而言之, 經(jīng)過幾十年的發(fā)展, 無機(jī)環(huán)境材料研究已經(jīng)取得了顯著進(jìn)展, 但為了更好地解決日益嚴(yán)峻的環(huán)境問題, 仍然需要廣大材料研究者們攻堅(jiān)克難, 不懈努力。

With the fast advancement of human modernization and rapid development of social economy, traditional energy consumption has been enormously increased and climate change has therefore become a very challenging issue for the human being. The development of modern industry, especially the chemical industry, has brought not only convenience to people, but also unprecedented destruction to the ecological environment closely related to human life. Energy and environmental issues have become a global challenge for us today. In order to better deal with the challenges and protect our living homeland, the majority of researchers are constantly seeking and exploring new materials and technologies which are environmentally friendly and can be used efficiently, aiming to solve increasingly serious environmental problems. In current stage, environmental materials and technologies have received ever-increasing attention and are developing rapidly.

Environmental materials, as the name implies, are materials designed and developed for environmental issues. The key issue of environmental problems is environmental pollution. At present, the widely concerned pollutants include gas pollutants, persistent organic pollutants (POPs), and heavy metals. At the same time, with drastic development of nuclear energy industry in the past two decades in China, radioactive pollutants have also received increasing attention. Separation and removal of these pollutants from environment by certain means is an effective and common method for environmental pollution control. Therefore, the key for solving environmental problems is to develop materials and technologies that can effectively remove environmental pollutants. Plenty of versatile materials for specific contaminant removals have been reported over the past few decades. These materials come in a wide variety of functions, with varying structures and performance. Most concerned materials include traditional molecular sieves[1], mineral materials[2], carbon materials such as graphene and carbon nanotubes[3], polymer based materials such as resins[4], metal organic frameworks (MOFs)[5]and covalent organic frameworks (COFs)[6]. Among these materials, inorganic materials have broad application prospects in the removal and separation of environmental pollutants due to their stability, low cost and environmental friendliness. In particular, inorganic nanoporous materials have become favorable in recent years. The nanometer size makes nanomaterials not only have quantum size effect, but also possess larger specific surface area and more surface atoms compared to other common materials, thus exhibiting stronger adsorption ability and better dispersibility in aqueous solution. In addition, the porosity of materials greatly enhances the specific surface area and correspondingly increases the contact opportunity between the material and contaminant. Meanwhile, it also improves the diffusion and transportation of contaminants inside the material, elevating the adsorption kinetics. Metal nanomaterials, metal oxide nanomaterials, mineral materials,are typical representatives of inorganic nanomaterial family.

Based on the published works, many efforts in the field of inorganic environmental materials focused on improving the removal efficiency and selectivity toward one or more target pollutants. Inorganic materials have higher stability than organic materials, but possess low removal capacity and poor selectivity, due to lacking of active functional groups on the surface. Functionalization of inorganic materials should be a reasonable approach to overcome this drawback. It is well known that functional groups with strong binding or coordination ability to the target contaminant decorated on the surface of material by physical or chemical means can greatly improve the adsorption performance of inorganic materials[7]. Moreover, besides modifying the specific recognition group on the surface of the material[8], adjusting the pore structure of material and physically screening contaminants by the size effect[9]are always common and effective. It is also promising to combine size effects, bonding and electrostatic interactions by means of molecular imprinting or composition[10]. Besides, developing inorganic environmental materials used under harsh conditions[11], such as high acid, high alkali, and high temperature, is becoming a research hot topic in recent years.

In all, after decades of development, researches on inorganic environmental materials have made significant progress, whereas most of materials are still not satisfactory for industrial applications. In order to better solve the increasingly serious environmental problems, it is still necessary for the material researchers to overcome difficulties and make continuous efforts.

[1] SHI W M, FU Y W, JIANG W,. Enhanced phosphate removal by zeolite loaded with Mg-Al-La ternary (hydr)oxides from aqueous solutions: performance and mechanism.,2019, 357: 33–44.

[2] ALSHAMERI A, HE H P, ZHU J X,Adsorption of ammonium by different natural clay minerals: characterization, kinetics and adsorption isotherms., 2018, 159: 83–93.

[3] SHAO D D, JIANG Z Q, WANG X K,Plasma induced grafting carboxymethyl cellulose on multiwalled carbon nanotubes for the removal of UO22+from aqueous solution., 2009, 113(4): 860–864.

[4] NAUSHAD M, ALOTHMAN Z A, AWUAL M R,. Adsorption of rose Bengal dye from aqueous solution by amberlite Ira-938 resin: kinetics, isotherms, and thermodynamic studies..,2016, 57(29): 13527–13533.

[5] LI J, WANG X X, ZHAO G X,. Metal-organic framework-based materials: superior adsorbents for the capture of toxic and radioactive metal ions., 2018, 47(7): 2322–2356.

[6] YU J, YUAN L, WANG S,Phosphonate-decorated covalent organic frameworks for actinide extraction: a breakthrough under highly acidic conditions.,2019, 1(3): 286–295.

[7] YUAN L Y, LIU Y L, SHI W Q,A novel mesoporous material for uranium extraction, dihydroimidazole functionalized SBA-15.,2012, 22(33): 17019–17026.

[8] YUAN L Y, ZHU L, XIAO C L,. Large-Pore 3D cubic mes-oporous (KIT-6) hybrid bearing a hard-soft donor combined ligand for enhancing U(VI) capture: an experimental and theoretical inv-estigation.,2017, 9(4): 3774–3784.

[9] CUI X L, CHEN K J, XING H B,Pore chemistry and size control in hybrid porous materials for acetylene capture from ethylene.,2016, 353(6295): 141–144.

[10] WANG L, SONG H, YUAN L Y,Effective removal of anionic Re(VII) by surface-modified Ti2CTMXene nanocomposites: implications for Tc(VII) sequestration.,2019, 53(7): 3739–3747.

[11] WU Z Y, LI C, LIANG H W,. Carbon nanofiber aerogels for emergent cleanup of oil spillage and chemical leakage under harsh conditions.,2014, 4: 4079.

石偉群, 研究員, 2019年獲國(guó)家杰出青年科學(xué)基金資助。現(xiàn)為中國(guó)化學(xué)會(huì)核化學(xué)與放射化學(xué)分會(huì)及中國(guó)核學(xué)會(huì)錒系物理與化學(xué)分會(huì)常務(wù)理事、中國(guó)有色金屬學(xué)會(huì)熔鹽化學(xué)與技術(shù)專業(yè)委員會(huì)副主任委員, 并擔(dān)任Journal of Nuclear Science and Technology的國(guó)際顧問編委。長(zhǎng)期從事核燃料循環(huán)化學(xué)與錒系元素化學(xué)相關(guān)基礎(chǔ)研究。E-mail: shiwq@ihep.ac.cn

王祥科, 教授, 2003年入選中科院百人計(jì)劃“引進(jìn)海外杰出人才”, 2012年獲國(guó)家杰出青年科學(xué)基金資助, 2015年被評(píng)為教育部長(zhǎng)江學(xué)者特聘教授, 2017年入選中組部萬人計(jì)劃領(lǐng)軍人才。主要從事三廢治理、納米材料在廢水處理、等離子體技術(shù)應(yīng)用、環(huán)境污染檢測(cè)和治理中的應(yīng)用等方面的研究工作。E-mail: xkwang@ncepu.edu.cn

Inorganic Environmental Materials and Their Applications in Pollutant Removal

SHI Weiqun1, WANG Xiangke2

(1. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; 2. College of Enviromental Science and Engineering, North China Electric Power University, Beijing 102206, China)

1000-324X(2020)03-0257-03

10.15541/jim20190900