Nanomaterials for environmental burden reduction, waste treatment, and nonpoint source pollution control: a review

Nanomaterials are applicable in the areas of reduction of environmental burden, reduction/treatment of industrial and agricultural wastes, and nonpoint source (NPS) pollution control. First, environmental burden reduction involves green process and engineering, emissions control, desulfurization/denitrification of nonrenewable energy sources, and improvement of agriculture and food systems. Second, reduction/treatment of industrial and agricultural wastes involves converting wastes into products, groundwater remediation, adsorption, delaying photocatalysis, and nanomembranes. Third, NPS pollution control involves controlling water pollution. Nanomaterials alter physical properties on a nanoscale due to their high specific surface area to volume ratio. They are used as catalysts, adsorbents, membranes, and additives to increase activity and capability due to their high specific surface areas and nano-sized effects. Thus, nanomaterials are more effective at treating environmental wastes because they reduce the amount of material needed.     

Applications of nanomaterials in water treatment and environmental remediation

Nanotechnology has revolutionized plethora of scientific and technological fields; environmental safety is no exception. One of the most promising and well- developed environmental applications of nanotechnology has been in water remediation and treatment where different nanomaterials can help purify water through different mechanisms including adsorption of heavy metals and other pollutants, removal and inactivation of patho- gens and transformation of toxic materials into less toxic compounds. For this purpose, nanomaterials have been produced in different shapes, integrated into various composites and functionalized with active components. Nanomaterials have also been incorporated in nanostructured catalytic membranes which can in turn help enhance water treatment. In this article, we have provided a succinct review of the most common and popular nanomaterials （titania, carbon nanotubes （CNTs）, zero-valent iron, dendrimers and silver nanomaterials） which are currently used in environmental remediation and particularly in water purification. The catalytic properties and functionalities of the mentioned materials have also been discussed.     

Nanomaterials for water pollution monitoring and remediation

Water shortage and pollution are serious challenges for many countries. Nanomaterials are promising new tools for water quality management due to unique physicochemical properties, high economic benefit, high removal efficiency and environmental friendliness. Here we describe four types of nanomaterials used for water treatment: nanofiltration membranes, photocatalytic nanomaterials, adsorption nanomaterials and reducing nanomaterials. We discuss their properties, applications and mechanisms for pollutant removal. We also review nanomaterials used for water quality monitoring, notably nanomaterials used for the detection of trace pollutants and pathogens. These nanomaterials include carbon nanotubes, magnetic nanoparticles, noble metal nanomaterials and quantum dots.     

Nanosized magnetite in low cost materials for remediation of water polluted with toxic metals,azo- and antraquinonic dyes

Nanosized magnetite has emerged as an adsorbent of pollutants in water remediation. Nanoadsorbents include magnetic iron oxide and its modifiers/stabilizers, such as carbon, silica, clay, organic moieties (polymers, aminoacids, and fatty acids) and other inorganic oxides. This review is focused on the recent developments on the synthesis and use of magnetic nanoparticles and nanocomposites in the treatment of contaminated water. The emphasis is on the influence of the iron oxide modifiers on some properties of interest such as size, BET area, and magnetization. The characteristics of these nanomaterials are related to their ability to eliminate heavy metal ions and dyes from wastewater. Comparative analysis of the actual literature was performed aiming to present the magnetic material, its preparation methodology and performance in the elimination of the selected pollutants. Vast information has been properly summarized according to the materials, their properties and preferential affinity for selected contaminants. The mechanisms governing nanomaterial’s formation as well as the interactions with heavy metals and dyes have been carefully analyzed and associated to their efficiency.     

Auswirkungen nanotechnologischer Entwicklungen auf die Umwelt

Background

Nanotechnology is about discovering, developing and using materials consisting in their primary stage at a size within the low nanometer range. These ultrafine particles offer new properties and opportunities. Even if the synthesis of nanoparticles has been discovered not until during the last decades, the exposure of humans to ultrafine particles occurred long before, due to the generation of ultrafine particles in ambient air during combustion processing.

Aim

Within this review, only engineered nanoparticles are considered, because these technical products are associated with many hopes for new applications, while only little information is available about their potential adverse effects. At workpiaces, during manufacturing, in technical applications or in drugs, nanoparticles will always have ‘side effects’ which have carefully to be weighed against their advantages, before they can be released in the environment. Therefore, information about their safety and potential hazards is urgently needed.

Results and Discussion

Along with the technical development of nanoparticles, a public discussion has started, leading to extensive investigations on possible negative ‘side effects’ on human health. Research activities have been strengthened in departments for environmental toxicology, hygiene institutes and other academic facilities to identify hazard and risks during handling and use of these new materials. On the other hand, nanotechnology offers the promise to prematurely identify environmental problems through improved detection and monitoring capabilities, and significantly reduced environmental effects from cleaner manufacturing and synthesis approaches, which results in a reduction or elimination of wastes as well as reduced energy use, and unique remediation solutions as well as pollution strategies.

Conclusions

However, the potential impact of manufactured nanomaterials used in various applications also needs to be evaluated in the context of human health with regard to potential toxicology and routes of exposure, environmental effects, including fate, transport, transformation, bio-availability, and bio-accumulation, and an analysis of product-life cycle.     

石墨烯纳米材料对哺乳动物的毒性及其作用机制

石墨烯是一种应用广泛的新兴非金属纳米材料，具有独特的电学机械性能、超大的比表面积以及潜在的生物相容性，在材料、电子、能源、光学以及生物医学等领域得到广泛应用。与此同时，石墨烯的环境行为和生物毒性也随之引起日益广泛的关注。本文通过对石墨烯纳米材料的动物毒性、细胞毒性、毒性影响因素和毒性机制等相关研究进展进行总结。石墨烯纳米材料可通过气管滴注、吸入、静脉注射、腹腔注射以及口服等方式进入体内，通过机械屏障、血脑屏障和血液胎盘屏障等积累在肺、肝、脾等部位引起急性或者慢性损伤；目前有关石墨烯毒性机制的研究主要集中于线粒体损伤、DNA损伤、炎性反应、凋亡等终点及氧化应激参与的复杂信号通路，不同石墨烯纳米材料的浓度、尺寸、表面结构和官能团等对石墨烯的生物毒性影响不同。鉴于当前该领域研究的局限性，对石墨烯纳米材料生物毒性研究的发展方向进行了展望，进而为石墨烯材料的安全应用提供理论借鉴和实践参考。     

Nanomaterials for water cleaning and desalination,energy production,disinfection, agriculture and green chemistry

Nanomaterials may help to solve issues such as water availability, clean energy generation, control of drug-resistant microorganisms and food safety. Here we review innovative approaches to solve these issues using nanotechnology. The major topics discussed are wastewater treatment using carbon-based, metal-based and polymeric nanoadsorbents for removing organic and metal contaminants; nanophotocatalysis for microbial control; desalination of seawater using nanomembranes; energy conversion and storage using solar cells and hydrogen-sorbents nanostructures; antimicrobial properties of nanomaterials; smart delivery systems; biocompatible nanomaterials such as nanolignocellulosis and starches-based materials, and methods to decrease the toxicity of nanomaterials. Significantly, here it is reviewed two ways to palliate nanomaterials toxicity: (a) controlling physicochemical factors affecting this toxicity in order to dispose of more safe nanomaterials, and (b) harnessing greener synthesis of them to bring down the environmental impact of toxic reagents, wastes and byproducts. All these current challenges are reviewed at the present article in an effort to evaluate environmental implications of nanomaterials technology by means of a complete, reliable and critical vision.     

Recent advances in antimony removal using carbon-based nanomaterials: A review

• The synthesis and physicochemical properties of various CNMs are reviewed. • Sb removal using carbon-based nano-adsorbents and membranes are summarized. • Details on adsorption behavior and mechanisms of Sb uptake by CNMs are discussed. • Challenges and future prospects for rational design of advanced CNMs are provided. Recently, special attention has been deserved to environmental risks of antimony (Sb) element that is of highly physiologic toxicity to human. Conventional coagulation and ion exchange methods for Sb removal are faced with challenges of low efficiency, high cost and secondary pollution. Adsorption based on carbon nanomaterials (CNMs; e.g., carbon nanotubes, graphene, graphene oxide, reduced graphene oxide and their derivatives) may provide effective alternative because the CNMs have high surface area, rich surface chemistry and high stability. In particular, good conductivity makes it possible to create linkage between adsorption and electrochemistry, thereby the synergistic interaction will be expected for enhanced Sb removal. This review article summarizes the state of art on Sb removal using CNMs with the form of nano-adsorbents and/or filtration membranes. In details, procedures of synthesis and functionalization of different forms of CNMs were reviewed. Next, adsorption behavior and the underlying mechanisms toward Sb removal using various CNMs were presented as resulting from a retrospective analysis of literatures. Last, we prospect the needs for mass production and regeneration of CNMs adsorbents using more affordable precursors and objective assessment of environmental impacts in future studies.     

Nanomaterials for agriculture,food and environment: applications,toxicity and regulation

Nanotechnology is expected to have a beneficial influence on agriculture, food and environment, due to the unique properties of nanomaterials. However, little is known about their safety and potential toxicity. Here we review metal nanoparticles, nanometal oxides, carbon nanotubes, liposomes and dendrimers. We present the application of these nanomaterials in agriculture, food and environment for plant protection; disease treatment; packing materials; development of new tastes, textures and sensations; pathogen detection; and delivery systems. We discuss risk assessment of nanomaterials and toxicological impacts of nanomaterials on agriculture, food and environment. We then provide regulatory guidelines for the safer use of nanomaterials.     

纳米零价铁的生态毒性效应研究进展

纳米零价铁(n ZVI)由于其比表面积大、表面反应活性高以及强还原性,可以作为一种高效的环境修复材料,广泛运用于污染地下水及土壤修复。大量的n ZVI颗粒直接注射到污染位点会增加生态系统的暴露可能性,并且由于n ZVI粒径特别小,能穿过细胞膜和生物体的各类天然屏障,对环境及生态系统存在潜在风险,因此科学家们开始更多地关注n ZVI的生物安全性研究。鉴于n ZVI在环境修复应用中的巨大潜力和可能的毒性效应,对n ZVI环境风险的研究也显得尤为重要。综述了近几年国内外关于n ZVI生态毒性的研究成果,n ZVI对病毒、细菌、微生物群落、以及动植物等都能导致一定的负面效应,尽管其毒性机制尚不明确,但普遍认为n ZVI暴露后铁离子的释放和氧化损伤确实可以引起生物效应,部分研究还分析了环境因素和表面改性对其毒性的影响。文章对其未来的发展方向进行了展望,以期为今后纳米零价铁的研究提供参考。     

Review on design and evaluation of environmental photocatalysts

Heterogeneous photocatalysis has long been considered to be one of the most promising approaches to tackling the myriad environmental issues. However, there are still many challenges for designing efficient and cost-effective photocatalysts and photocatalytic degradation systems for application in practical environmental remediation. In this review, we first systematically introduced the fundamental principles on the photocatalytic pollutant degradation. Then, the important considerations in the design of photocatalytic degradation systems are carefully addressed, including charge carrier dynamics, catalytic selectivity, photocatalyst stability, pollutant adsorption and photodegradation kinetics. Especially, the underlying mechanisms are thoroughly reviewed, including investigation of oxygen reduction properties and identification of reactive oxygen species and key intermediates. This review in environmental photocatalysis may inspire exciting new directions and methods for designing, fabricating and evaluating photocatalytic degradation systems for better environmental remediation and possibly other relevant fields, such as photocatalytic disinfection, water oxidation, and selective organic transformations.

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金属和非金属纳米材料对四膜虫生物毒性研究

纳米材料是"21世纪最有前途的材料",以其优良的性能广泛应用于许多领域,随之以多种形式释放到环境中。目前,关于纳米材料的安全性还没有明确的论断。本文介绍了四膜虫在纳米材料生物效应研究中的优势,重点论述了金属纳米材料、非金属纳米材料对四膜虫的生物效应以及毒性机制的研究状况,并对今后纳米材料生物毒性效应研究提供了建设性的方法及意见。     

Visible light photocatalytic degradation of microplastic residues with zinc oxide nanorods

Microplastics have recently become a major environmental issue due to their ubiquitous distribution, uncontrolled environmental occurrences, small sizes and long lifetimes. Actual remediation methods include filtration, incineration and advanced oxidation processes such as ozonation, but those methods require high energy or generate unwanted by-products. Here we tested the degradation of fragmented, low-density polyethylene (LDPE) microplastic residues, by visible light-induced heterogeneous photocatalysis activated by zinc oxide nanorods. The reaction was monitored using Fourier-transform infrared spectroscopy, dynamic mechanical analyser and optical imaging. Results show a 30% increase of the carbonyl index of residues, and an increase of brittleness accompanied by a large number of wrinkles, cracks and cavities on the surface. The degree of oxidation was directly proportional to the catalyst surface area. A mechanism for polyethylene degradation is proposed.

     

Strategies to design modified activated carbon fibers for the decontamination of water and air

The rapid industrialization has induced the entry of organic and inorganic contaminants into the environment at a rate greater than environmental cleaning. As a consequence, pollutants have accumulated in environmental media, thus posing health risk for living organisms. Here, we present surface treatment strategies that modify physicochemical properties of activated carbon fibers for environmental remediation. In particular, we review metals, metal oxides and various advanced materials used for modifying activated carbon fibers. We discuss the utilization of modified activated carbon fibers for adsorption of organic pollutants and inorganic pollutants, and for the degradation of organic pollutants by photocatalysis, electrocatalysis, Fenton process and dielectric barrier discharge. We also discuss air pollutant removal, capacitive deionization, removal of inorganic ions and microbial decontamination by modified activated carbon fibers.     

An exploratory study of chemical elements in drinking water and non-Hodgkin's lymphoma

Nanomaterials are widely used in the field of engineering and in modern society. Although the unique characteristics of nanoparticles also enable them to provide environmental solutions to reduce the formation and emissions of pollutants, adverse effects on human health may occur from the exposure to nanomaterials during the manufacturing processes and when nanomaterials are released and they contaminate the environment. It is essential to understand the factors affecting the accumulation, aggregation, deposition, translocation, and distribution of nanomaterials (natural or engineered) in the ecosystem. This study presents an extensive review of the environmental effects of nanomaterials, including classification, adverse impacts on human health and the environment, transport pathways, monitoring methods, and the current regulations regarding nanomaterials. The review indicates that the diversity of nanoparticles and their properties make the identification and characterization of nanomaterials a difficult task, and an improvement in sensitivity and selectivity of analytical methods for detecting nanoparticles in the environment is required. Besides, few regulations have been established for the management of nanoparticles released into the environment. In order to expedite the environmental management of nanomaterials, this study proposes a risk assessment framework based on the findings in the review as a practice alternative for the environmental assessment and effective management of nanomaterials. Development of practical innovative risk-based management measures may help us to find answers to the concerns such as safety of engineering and applying nanomaterials and effective control of nanoparticle contamination in the environment.     

Regulating non-precious transition metal nitrides bifunctional electrocatalysts through surface/interface nanoengineering for air-cathodes of Zn-air batteries

Zn-air batteries (ZABs), especially the secondary batteries, have engrossed a great interest because of its high specific energy, economical and high safety. However, due to the insufficient activity and stability of bifunctional electrocatalysts for air-cathode oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) processes, the practical application of rechargeable ZABs is seriously hindered. In the effort of developing high active, stable and cost-effective electrocatalysts, transition metal nitrides (TMNs) have been regarded as the candidates due to their high conductivity, strong corrosion-resistance, and bifunctional catalytic performance. In this paper, the research progress in TMNs-based material as ORR and OER electrocatalysts for ZABs is discussed with respect to their synthesis, chemical/physical characterization, and performance validation/optimization. The surface/interface nanoengineering strategies such as defect engineering, support binding, heteroatom introduction, crystal plane orientation, interface construction and small size effect, the physical and chemical properties of TMNs-based electrocatalysts are emphasized with respect to their structures/morphologies, composition, electrical conductivity, specific surface area, chemical stability and corrosion resistance. The challenges of TMNs-based materials as bifunctional air-cathode electrocatalysts in practical application are evaluated, and numerous research guidelines to solve these problems are put forward for facilitating further research and development.     

包装材料及食品中纳米材料的检测与表征技术

随着纳米技术的发展,纳米材料在包装行业及食品工业中得到了广泛的应用。然而,纳米材料的安全应用高度依赖于对其生物及环境效应的了解。有研究表明,纳米材料对人类健康及生态环境存在着潜在危害,这使得纳米材料的安全性成为毒理学领域的热点研究课题。同时纳米材料的安全性问题也成为纳米复合包装材料及纳米食品研究和开发的新瓶颈。在对纳米材料没有充分认识的情况下,为了消费者和生态环境的安全,必须控制包装材料及食品中纳米颗粒的种类、来源、含量及可能的释放,这就需要可靠的方法对纳米颗粒的性质和结构进行检测及表征。首先,综述了目前纳米材料在复合包装材料及食品加工中的应用,然后总结了包装材料及食品中纳米材料的检测技术及表征方法,例如显微技术、色谱分离技术、光谱与质谱技术等。由于纳米材料的理化性质参数众多,应用多种分析手段来检测和表征纳米材料成为必然。最后对目前检测技术及表征方法的不足和今后发展方向进行了探讨。     

Natural and synthesised iron-rich amendments for As and Pb immobilisation in agricultural soil

The immobilisation of heavy metals in contaminated soils is a promising alternative to conventional remediation techniques. Very few studies have focused on the use of iron-rich nanomaterials and natural materials for the adsorption of toxic metals in soils. Synthesised iron-rich nanomaterials (Fe and Zr–Fe oxides) and natural iron-rich materials (natural red earth; NRE) were used to immobilise As and Pb in contaminated agricultural soil. Total concentrations of As and Pb in the initial soil (as control) were 170.76 and 1945.11 mg kg^?1, respectively. Amendments were applied into the soil at 1, 2.5 and 5% (w/w) in triplicate and incubated for 150 days. Except for the NRE-amended soil, soil pH decreased from 5.6 to 4.9 with increasing application rates of Fe and Zr–Fe oxides. With addition of Fe and Zr–Fe oxides at 5%, the ammonium acetate (NHO₄Ac)-extractable Pb was greatly decreased by 83 and 65% compared with NRE addition (43%). All subjected amendments also led to a decrease in NHO₄Ac-extractable As in the soils, indicating the high capacity of As immobilisation. Soil amended with NRE showed a lower ratio of cy19:0 to 18:1ω7c, indicating decreased microbial stress. The toxicity characteristic leaching procedure produced results similar to the NHO₄Ac extraction for As and Pb. The NRE addition is recommended for immobilising heavy metals and maintaining biological soil properties.     

Perspectives and applications of nanotechnology in water treatment

Industrialization and excessive use of pesticides for boosting agricultural production have adversely affected the ecosystem, polluting natural water reserves. Remediation of contaminated water has been an area of concern with numerous techniques being applied to improve the quality of naturally available water to the level suitable for human consumption. Most of these methods, however, generate by-products that are sometimes toxic. Heterogenous photocatalysis using metal oxide nanostructures for water purification is an attractive option because no harmful by-products are created. A discussion on possible methods to engineer metal oxides for visible light photocatalysis is included to highlight the use of solar energy for water purification. Multifunctional photocatalytic membranes are considered advantageous over freely suspended nanoparticles due to the ease of its removal from the purified water. An overview of water remediation techniques is presented, highlighting innovations through nanotechnology for possible addressing of problems associated with current techniques.     

农田重金属污染原位钝化修复研究进展

污染土壤重金属原位钝化修复是通过向土壤中施加一些活性钝化修复材料,通过溶解沉淀、离子交换吸附、氧化还原、有机络合等反应来改变重金属在土壤中的赋存状态,降低土壤中重金属的有效浓度、迁移性和生物有效性。这种方法成本较低、操作简单、见效快且适合大面积推广,在重金属污染土壤修复中有着不可替代的作用。尤其对主要由污水灌溉、大气沉降等造成的农田土壤面源污染,一些具有吸附固定土壤中重金属离子特性的天然物质和工业副产品都可运用在实地的钝化修复中,且不同类型的钝化修复剂对重金属污染土壤的钝化修复效果各不相同。采用实验室评价和实地应用评价,一方面可以评估钝化修复材料对污染土壤中重金属离子的固定效率;另一方面可以评估钝化修复材料对土壤理化性状、养分状况和生物活性的影响。对重金属污染土壤原位钝化修复中不同来源的钝化剂进行了分类,目前广泛使用的钝化修复剂主要包括硅钙物质、含磷材料、有机物料、黏土矿物、金属及金属氧化物、生物碳及新型材料等,概述了它们各自对重金属污染土壤的钝化修复效果。从研究方法、评价指标、环境影响因子、钝化机制以及环境风险评价等方面分析了该领域的研究现状以及存在的主要问题,今后应重点关注钝化修复剂对土壤-作物系统的潜在环境风险以及钝化材料修复效果的田间长期稳定性评价。