稻壳基材料应用于水污染治理领域的研究进展

随着工业的快速发展,电镀设备、采矿、纺织等行业排放的废水含有大量的重金属离子和有机污染物,这些污染物严重危害人类的身体健康.因此,如何快速有效地处理水体中的重金属离子和有机污染物是环境修复领域中亟待解决的问题.稻壳因具有来源广泛、可再生、环境友好等特点而被广泛应用于吸附材料和光催化材料领域.大量研究表明,稻壳能够去除污染水体中重金属离子和有机物的种类很多,但是对大多数污染物的去除能力不强,难以在实际应用中得到进一步推广.以稻壳为基体材料制备有高效去除能力的功能性材料,是近几年环境修复领域的研究热点.目前,研究者尝试以炭化、化学修饰等方式对稻壳改性,从而增大比表面积、孔隙率或者增加含氧官能团的数量,吸附性能也能随之改善,但是以上改性后的稻壳材料存在吸附能力弱和容易产生二次污染等问题.研究发现,负载Fe3 O4制备的磁性稻壳生物炭复合材料,不仅吸附性能强,且具有易分离、稳定性强、不会对环境造成二次污染等优点,这为稻壳基材料在实际应用的推广奠定了基础.另外,有研究报道,将稻壳中的SiO2作为半导体光催化剂(如TiO2、Ni2 O3)的载体可提高其光催化性能、回收利用率,使其在光学领域具有良好的使用性能.本文综述了稻壳材料本身的特性和改性稻壳制备稻壳基吸附剂的方法,讨论了稻壳基及其复合材料在水污染治理领域中作为吸附剂和光催化剂的应用.从不同类型的污染物角度出发,论述了稻壳基材料针对重金属离子、有机污染物处理过程中稻壳掺杂材料功能及体系作用机理的影响,还分析了影响污染物吸附的重要因素,最后对目前稻壳基材料在水治理领域应用进行了总结和对今后的研究方向做了展望.     

金属-有机框架材料对废水中污染物的吸附研究进展

可用的清洁水资源缩减已成为全球面临的重要危机.引起该危机的主要原因是各种污染物因生产、生活或事故排入水体导致水体污染.因此,解决水资源危机的关键在于对污水处理和再生.多种污水处理和再生方法应运而生,其中吸附法因处理效率高、操作简便、成本低而被广泛应用到污水处理中.吸附法的关键在于吸附剂的选择和应用.应用于水处理的传统吸附剂,如活性炭、沸石、天然粘土、活性氧化铝等,在面对复杂水体环境和各种性质迥异的污染物时已不能符合水污染处理的更高标准.因此,新型吸附剂的开发与应用成为吸附领域研究热点.金属有机框架(Metal-organic frame,MOF)材料,一类金属离子或金属簇与有机配体之间自组装配位形成的化合物,具有高比表面积、高孔隙率和可控的孔结构,已成为吸附领域冉冉升起的新星.目前MOF材料作为水处理吸附剂的研究主要集中在:(1)各种MOF材料对不同污染物的吸附性能研究,以揭示相关吸附规律;(2)MOF材料自身功能化或MOF复合材料的制备,以改善自身稳定性,提高其吸附性能或实现选择性吸附;(3)MOF衍生碳吸附材料的研究,以应对恶劣水体环境或极端水处理条件.本文对单一MOF材料、功能化MOF材料、MOF衍生碳材料吸附去除水体中有机染料、其他有机污染物、重金属离子的相关研究进行了综述.概述了多种MOF材料对不同污染物的吸附性能,总结了针对吸附应用的多种MOF功能化方式及其吸附效果的改进,归纳了多种MOF衍生碳材料作为吸附剂在水处理中的应用,指出了目前MOF吸附材料在水处理中存在的主要问题,并提出了解决这些问题的思路.     

柠檬酸交联环糊精金属有机框架材料的制备及对结晶紫的吸附

环糊精金属有机框架材料(CD-MOFs)是一种绿色环保的新型金属有机框架材料，但由于其水稳定性差，在实际应用中受到了限制。通过交联CD-MOFs和柠檬酸(CA)来提高环糊精基MOFs的水溶液稳定性。研究制备了CA改性的CA-γ-CD-MOF复合材料，并作为吸附剂从水溶液中去除阳离子染料结晶紫。在15mg CA-γ-CD-MOF用量、20℃、pH 6和60mg/L初始结晶紫浓度下，CA-γ-CD-MOF对结晶紫的平衡吸附能力为79.86mg/g,相应的清除率达到99.83%。此外，CA-γ-CD-MOF在经过3次吸附解吸循环，吸附率仍达第一次的98%以上，表现出良好的再生能力。动力学和吸附等温线研究表明，吸附遵循拟二阶动力学，CA-γ-CD-MOF吸附结晶紫是一种自发的单层吸热过程。因此，CA-γ-CD-MOF是一种高效、绿色、可循环利用的吸附剂。     

碳纳米管的吸附性能及对水中污染物的吸附:综述

碳纳米管是一种新型吸附剂,其对各种无机和有机污染物均表现出优异的吸附能力,因而引起了广泛关注。本文综述了碳纳米管的性质及其从水溶液中吸附各种有机和无机污染物的有关性质,介绍了碳纳米管作为吸附剂对水溶液中的各种污染物的预富集和固定化方面的应用,并展望了碳纳米管在吸附去除污染物领域的下一步研究趋势和动向。     

碳基纳米复合材料吸附剂的制备及应用进展

近年来，碳基纳米复合材料的制备与应用备受关注，尤其是碳基纳米复合材料作为吸附剂的研究取得了一系列重要进展。综述了碳基纳米复合材料在制备中起到的关键影响因素。重点介绍了碳基纳米复合材料所具备的高比表面积、强机械性能、热稳定性等独特性能，及其在重金属废水、大气污染物吸附领域中的功能化应用。最后阐述了碳基纳米复合材料研究的不足和未来的发展方向，提出了对碳基纳米复合材料进行更进一步多功能化的研究，深度挖掘其在吸附领域的发展潜力等建议。     

改性吸附剂脱除工业废气中AsH3研究进展

非常规大气污染物砷化氢(AsH₃)主要来源于有色金属矿冶炼、磷化工、煤化工、石油加工炼制等行业,其特有的毒性对人体健康和生态安全造成严重的威胁。20世纪初,国内外一直鲜有关于砷化氢去除的研究,近几十年来,由于人类工业化进程的加快,越来越多的学者对砷化氢的毒性性状、迁移转化和去除机制开展了研究。由于砷化氢具有较强的还原性,早期的去除方法主要为氧化性溶液吸收法,目前国内仍采用此方法,后来又相继出现直接燃烧法和催化分解法。然而,这几种方法都存在能耗大、工艺复杂等缺陷。 研究者们致力于寻找一种更合理的砷化氢去除方法。对比一些结构不规则、比表面积小的传统吸附剂,改性吸附剂具有三大优势:(1)通过化学吸附、催化氧化等多种途径去除砷化氢,效率高、成本低;(2)对目标污染物具有选择性吸附能力;(3)砷化氢的反应产物能被稳定吸附在改性吸附剂上,不会造成二次污染。 在较高效率的改性吸附剂中已获得成功应用的载体材料包括活性炭、介孔氧化铝和各类分子筛等。其中铜基改性活性炭吸附剂的研究应用最早;钯基改性介孔氧化铝是目前抗毒稳定性最强的改性吸附剂;公认的21世纪“革命性材料”——石墨烯也被改性并应用于砷化氢的去除研究。近几年的研究工作将负载双金属协同作用、载体优化等手段引入改性吸附剂的制备中,实现了改性吸附剂的晶体结构规整化和表面化学活性优化,为砷化氢去除效率的再次突破性提高提供了可能。此外,除研究改性吸附剂的作用机理和去除性能外,研究者们主要在选择合适的活性组分和载体材料组合制备工艺方面进行了不断尝试,并取得了丰硕的成果,在充分发挥改性吸附剂高效去除能力优势的同时大幅提升了工业适应性。目前,已有几种改性吸附剂应用于工业排放废气中砷化氢的净化处理。 本文总结了砷化氢的主要工业来源和排放后的迁移转化过程,综述了吸附法脱除工业废气中砷化氢研究进展及其在工业上的应用现状;指出虽然改性吸附剂去除砷化氢技术可行,可为工业上高效去除砷化氢废气提供新思路,但是依然存在吸附剂工业推广方面的经验较为欠缺、相关研究较少等问题。随着国家对砷化氢污染造成的环境问题越来越重视,一些更高效、经济和环保的改性吸附剂将会成为研究热点,具有广阔的工业应用前景。     

蔗渣基吸附剂在污水处理中的应用及研究进展

为了去除环境中特别是水中污染物，十分需要高效、低成本，且不会对环境产生二次污染的方法。蔗渣基吸附剂用于水中污染物的去除，不仅实现了蔗渣的二次利用，也可以有效去除水中污染物。蔗渣基吸附剂的改性方式是实现污染物去除的关键。旨在综述蔗渣基吸附剂去除水中污染物的研究进展，并对蔗渣基吸附剂今后的研究进行了展望。     

金属有机骨架材料吸附去除水体中重金属研究进展

金属有机骨架(metal-organic frameworks,MOFs)是一类新型的有机-无机杂化多孔材料,由于其具有比表面积大、孔隙率高、孔径可调、结构多样、开放的金属位点和化学可修饰性等诸多优点在污染物吸附去除领域受到广泛的关注。通过总结近几年MOFs、MOFs复合材料和MOFs后修饰材料在水体中重金属离子的吸附去除方面的研究进展,并对其应用前景做出展望。     

石墨炔：一种用于合成水污染物有效吸附剂的新型炭材料（英文）

石墨炔(GDY)是一种新生的二维材料,其在去除水溶液中污染物的研究方面引起了广泛关注。GDY是sp和sp²杂化碳原子的框架,其在二维对称网络中存在苯环和二乙基键,因此具有优异的共轭性、独特的可调谐电子性能、以及优异的化学和热稳定性。GDY的分子中有C≡C键,且具有均匀分布的三角形孔,可提供更多的反应位点和多种反应路径。因而,GDY具有吸附性,其作为吸附剂时在去除污染水中的油、有机污染物、染料和金属方面表现优异。在已发表的文献中,GDY被用作吸附剂的报道十分有限。本文综述了GDY的合成方法、GDY作为吸附剂的应用以及GDY基吸附剂的表征,并展望了GDY在污染物修复中的应用前景。     

氧化石墨烯复合材料吸附铀的研究进展

氧化石墨烯由于具有超大的比表面积、高强度和化学稳定性好等优点,其在环保领域作为含铀废水吸附材料的应用潜能备受关注。本文综述了近年来石墨烯基复合材料吸附水溶液中铀的研究现状及进展,介绍了石墨烯基复合材料对铀的吸附性能,分析了溶液pH值、温度、离子强度、接触时间和吸附剂用量等因素对吸附效果影响的原理,阐述了通过表面络合模型,光谱分析和理论计算等方法探讨氧化石墨烯复合材料的微观形貌结构与铀吸附效果之间的内在联系,最后研究了氧化石墨烯复合材料吸附铀研究中面临的挑战,对石墨烯材料与轴的相互作用机理及其在环保方面的开发应用进行了展望。     

Environmental-benign utilisation of fly ash as low-cost adsorbents

Fly ash is a waste substance from thermal power plants, steel mills, etc. that is found in abundance in the world. In recent years, utilisation of fly ash has gained much attention in public and industry, which will help reduce the environmental burden and enhance economic benefit. In this paper, the technical feasibility of utilisation of fly ash as a low-cost adsorbent for various adsorption processes for removal of pollutants in air and water systems has been reviewed. Instead of using commercial activated carbon or zeolites, a lot of researches have been conducted using fly ash for adsorption of NO(x), SO(x), organic compounds, and mercury in air, and cations, anions, dyes and other organic matters in waters. It is recognised that fly ash is a promising adsorbent for removal of various pollutants. Chemical treatment of fly ash will make conversion of fly ash into a more efficient adsorbent for gas and water cleaning. Investigations also revealed that unburned carbon component in fly ash plays an important role in adsorption capacity. Directions for future research are also discussed.     

Surface modification of low-cost bentonite adsorbents—A review

The growth of science and technology over the world has led to the establishment of various industries which has helped the industrial, technological, and agricultural development of many nations. Environmental pollution from a variety of toxic derivatives, particularly heavy metals and minerals, aromatic molecules and dyes in wastewater posed a great danger to human, plants, and aquatic creatures. Adsorption appears to be the most widely used method among other techniques for the removal of toxic compounds from wastewater. The use of different adsorbents for heavy metal removal has become a subject of great interest, and there have been continuous efforts to develop new, low-cost, and efficient adsorbent materials. Bentonite, in natural and modified forms, has been applied in the removal of different water contaminants. This paper provides a review on recent progress of surface modifications of bentonite and their applications in the removal of organic and inorganic water pollutants. A comparison on the physicochemical characteristics and removal performance was presented. The adsorption mechanisms in relation to the bentonite properties were briefly discussed to offer readers some insight on the usefulness of this clay mineral in wastewater treatment. The challenges encountered and remarks on future prospects were highlighted.     

金属基吸附剂及其复合材料吸附除氟研究进展

化工、冶炼、电池等行业所排放的氟废水引发的氟中毒现象备受关注,分析了沉淀、膜处理、离子交换、吸附等技术的优缺点,吸附法由于操作简单、经济高效被认为是极具前景的水体除氟方法。本文对铝基、铁基、稀土基、金属有机骨架吸附剂及其改性材料在含氟废水中的除氟性能进行了总结和评价,分析了其制备过程、脱氟机制以及外界影响因素。发现材料晶型可以决定吸附过程的吸附能,大的比表面积可以在吸附过程中提供更多的活性位点,良好的孔结构可以降低吸附传质阻力,提高吸附性能;材料表面官能团的强化、不同金属材料的复合协同作用可以提高吸附剂的脱氟效率,可为今后制备新型高效除氟材料提供参考。提出了目前吸附除氟领域亟待解决的问题并对金属基吸附剂在除氟领域的发展作出展望。     

Removal of mercury(II) from wastewater using camel bone charcoal

Camel bone charcoal is used as an adsorbent for the removal of Hg(II) from wastewater effluents. The equilibrium data are fitted to Langmiur isotherm rather than linear and Freundlich isotherms. The adsorption capacity Qo is 28.24 mg of Hg(II)/g of the adsorbent. The optimum removal conditions are pH 2, contact time 30 min and temperature 25 degrees C. A comparison of the adsorption capacity (Qo) of camel bone charcoal with different adsorbents previously used for Hg(II) removal from wastewater effluents reveals its remarkable efficiency over many other treated and untreated natural and synthetic adsorbents. X-ray fluorescence and infrared spectrometry of camel bone charcoal after contact with mercury solutions confirm surface adsorption of Hg(II) ions. Electron microscopy reveals the formation of a spongy like structure on the adsorbent surface due to Hg(II) adsorption. Quantitative removal of mercury from hazardous effluents is demonstrated.     

PET纤维固载β-环糊精聚合物的合成与吸附性能研究

环糊精的疏水性空腔可以包络尺寸大小适宜的有机物分子,其外侧亲水性的羟基对高价金属离子具有螯合作用,因而具有一定的立体选择和识别性能。在各种吸附领域得到了广泛的应用。PET纤维具有机械强度好、化学性质稳定、比表面积大、来源丰富、种类齐全等的特点,纤维本身经过改性也可以作为良好的吸附材料。若能将其与环糊精独特的包合性能结合起来,在开发新型纺织材料和吸附分离材料方面,具有良好的研究和开发前景。本文将β-环糊精固栽到PET纤维上,考察了PET纤维固载β-环糊精聚合物的固载率、离子交换容量和对碱性品红的吸附,为环糊精化学在水处理领域中的实际应用提供参考。     

Removal of lead(II) by adsorption using treated granular activated carbon: batch and column studies

In the present study, a deeper understanding of adsorption behavior of Pb(II) from aqueous systems onto activated carbon and treated activated carbon has been attempted via static and column mode studies under various conditions. It probes mainly two adsorbents that is, activated carbon (AC) and modified activated carbon (AC-S). Characterization of both the adsorbents was one of the key focal areas of the present study. This has shown a clear change or demarcation in the various physical and chemical properties of the modified adsorbent from its precursor activated carbon. Both the adsorbents are subjected to static mode adsorption studies and then after a comparison based on isotherm analysis; more efficient adsorbent is screened for column mode adsorption studies. The lead removal increased for sample of treated carbon. The extent of Pb(II) removal was found to be higher in the treated activated carbon. The aim of carrying out the continuous-flow studies was to assess the effect of various process variables, viz., of bed height, hydraulic loading rate and initial feed concentration on breakthrough time and adsorption capacity. This has helped in ascertaining the practical applicability of the adsorbent. Breakthrough curves were plotted for the adsorption of lead on the adsorbent using continuous-flow column operation by varying different operating parameters like hydraulic loading rate (3.0-10.5 m3/(hm2)), bed height (0.3-0.5 m) and feed concentrations (2.0-6.0 mg/l). At the end, an attempt has also been made to model the data generated from column studies using the empirical relationship based on Bohart-Adams model. This model has provided an objective framework to the subjective interpretation of the adsorption system and the model constant obtained here can be used to achieve the ultimate objective of our study that is, up scaling and designing of adsorption process at the pilot plant scale level. AC-S column regeneration using 0.5 and 1.0M concentration of HNO3 has been investigated. It has shown a regeneration efficiency of 52.0% with 0.5 M HNO3.     

The role of sawdust in the removal of unwanted materials from water

Sawdust, a relatively abundant and inexpensive material is currently being investigated as an adsorbent to remove contaminants from water. Chemical substances including dyes, oil, toxic salts and heavy metals can be removed very effectively with the organic material. This article presents a brief review on the role of sawdust in the removal of contaminants. Studies on the adsorption of various pollutants by different sawdust materials are reviewed and the adsorption mechanism, influencing factors, favorable conditions, etc. discussed in this paper. Some valuable guidelines can be drawn for either scientific research or industrial design.     

MXene-based nanomaterials as adsorbents for wastewater treatment: a review on recent trends

The wastewater treatment is a challenging research area to reduce the increasing pressure on limited fresh water resources. Amongst several techniques adopted and practiced, adsorption is one of the most effective and sustainable eco-friendly processes. In recent years, MXene nanomaterials, a new family of transition metal carbides, have gained increasing attention as the potential adsorbent for pollutants due to their unique features such as large surface area with abundant active sites and hydrophilicity. A wide range of pollutants viz. heavy metal ions, organic dyes, radionuclides, and toxic gas molecules have been sensed by 2D MXenes. An inclusive understanding on the adsorptive behavior of MXene-based materials is needed to explain the removal mechanism and effects of different adsorption parameters. This review gives a general overview on recent research progress on MXene materials with special reference to their applications for the adsorptive removal of different pollutants. The general trends in the synthesis of MXenes, their stability and different factors affecting the adsorption process along with the main challenges in understanding the full potential of MXenes for environmental applications are discussed.     

Magnetic nanocomposites for environmental remediation

This article provides an overview of current research activities on the synthesis and applications of magnetic nanocomposites, especially highlights their potential environmental remediations such as heavy metal (Cr, As, Pd, Hg) removal. After a brief introduction of the emergency situation of heavy metal pollution all over the world and current techniques designed to deal with these situations, different synthetic methods to fabricate various types of magnetic nanocomposites will be reviewed. The focus is to reveal the advantages of magnetic nanocomposites as an efficient adsorbent which is able to reduce the heavy metal concentrations well below the EPA requirement. At the same time, the conventional process can be redesigned to be an economic and energetic one without using extra energy to recycle the adsorbent, which is desired for future. This review mainly deals with the heavy metal removal using magnetic nanocomposites, the adsorption behaviors of heavy metal ions on the surface of novel adsorbents are well investigated including the concentration effect of both contaminants and adsorbents, adsorption kinetics, solution pH effect with regards to real application.     

Amphiphilically Modified Porous Polymeric Nanosandwich-Based Membranes for Rapid and Efficient Water Treatment

Low removal efficiency, long treatment time, and high energy consumption hinder advanced and eco-friendly use of traditional adsorbents and separation membranes. Here, a class of amphiphilically modified 2D porous polymeric nanosandwich is designed and is subsequently assembled into adsorptive membranes. The 2D nanosandwich is gifted with high porosity and excellent pore accessibility, demonstrating rapid adsorption kinetics. The as-assembled membrane integrates unimpeded interlayer channels and well-developed, amphiphilic, and highly accessible intralayer nanopores, leading to ultrafast water permeation (1.2 × 10⁴ L m⁻² h⁻¹ bar⁻¹), high removal efficiency, and easy regeneration. The family of the membrane can be expanded by changing amphiphilic functional groups, further providing treatment of a wide-spectrum of pollutants, including aromatic compounds, pesticide, and pharmaceuticals. It is believed that the novel amphiphilically modified adsorptive membrane offers a distinct water treatment strategy with ultrahigh water permeation and efficient pollutants removal performances, and provides a multiple-in-one solution to the detection and elimination of pollutants.