A review on catalytic reduction/degradation of organic pollution through silver-based hydrogels

Various challenging pollutants are produced in the environment by organic materials of diverse industries including leather, paint, and textile. Nowadays, it is vital to develop efficient manners regarding the fundamental issues and removing pollutants. Such pollutants can be effectively removed from the environment through heterogeneous catalysts. Recently, a huge deal of interest has been attracted by hydrogel-based metal catalysts as heterogeneous and efficient catalysts. In this regard, silver with its unique features is suitable for environmental remediation. Hence, the present review deals with summarizing the present advances in the synthesis of silver-based hydrogel catalysts, as well as their applications for environmental remediation. Some advantages have been proposed using silver-based hydrogel catalysts suggested including high catalytic ability, reusability, easy work-up, and simple synthesis.     

Piezocatalytic Techniques in Environmental Remediation

As a consequence of rapid industrialization throughout the world, various environmental pollutants have begun to accumulate in water, air, and soil. This endangers the ecological environment of the earth, and environmental remediation has become an immediate priority. Among various environmental remediation techniques, piezocatalytic techniques, which uniquely take advantage of the piezoelectric effect, have attracted much attention. Piezoelectric effects allow pollutant degradation directly, while also enhancing photocatalysis by reducing the recombination of photogenerated carriers. In this Review, we provide a comprehensive summary of recent developments in piezocatalytic techniques for environmental remediation. The origin of the piezoelectric effect as well as classification of piezoelectric materials and their application in environmental remediation are systematically summarized. We also analyze the potential underlying mechanisms. Finally, urgent problems and the future development of piezocatalytic techniques are discussed.     

土壤中多环芳烃修复技术的研究进展

近年来我国的土壤污染问题日益严重,严重危害着人类的生活环境与身体健康,其中主要的有机污染物之一为多环芳烃(PAHs)。PAHs作为一种持久性有机污染物在全球范围内广泛存在,其主要污染来源于人为因素。由于PAHs复杂的杂环芳环结构、较强的疏水性和较高的热稳定性等,使其在土壤中不易自然降解因而具有较高的持久性。本文综述PAHs的主要污染来源、暴露途径及其对人体的危害,并从物理、化学和生物三个方面简要介绍土壤中PAHs的修复方法,并分析每种方法的优势以及面临的挑战。新兴的修复技术结合三种修复技术的优点,具有更好的修复效果和应用前景,但仍存在着一些亟待解决的问题。期望本文能为土壤中PAHs的修复提供借鉴,并为今后的研究方向提供新的思路。     

微塑料介导重金属在陆生植物中迁移及生物效应的影响

随着地膜在现代化农业中的广泛应用,微塑料在土壤中的残留问题日益严重。环境中释放的微塑料可能会与先前存在的重金属相互作用,导致生物效应(生物积累/毒性),并对人类健康和农产品安全构成威胁。目前,大多数研究集中于单一影响因素在土壤系统中的暴露和转化分析,有关微塑料和共存金属对环境联合影响的相当有限。本文综述了微塑料与重金属来源、相互作用机理与影响因素的研究现状,阐述了陆生植物对二者联合污染的生理响应。此外,未来的研究还应重点探讨微塑料与重金属共同在植物上暴露的具体分子机制、通过食物链对人类健康的影响、与其他混合污染物联合作用及微塑料老化过程对重金属迁移动态变化过程的影响。     

Sample preparation and analytical methods for polycyclic aromatic hydrocarbons in sediment

Polycyclic aromatic hydrocarbons (PAHs) are a large category of ubiquitous persistent environmental pollutants, some of them have strong carcinogenicity to human and animals. These pollutants can easily enter the river through multiple ways including rainfall, dry deposition and water washout, and deposit in the sediment. However, it is easy for them to re-enter the river water and pollute water sources, as well as aquatic animals and plants, bringing potential harm to human health. Therefore, it is requisite to accurately analyze the PAHs in sediment. In this review, the analytical methods of PAHs in sediment, focused on the methods of sample extraction, purification, concentration and determination, are summarized.     

Photocatalytic remediation of persistent organic pollutants (POPs): A review

The release of persistent organic pollutants (POPs) into the environment is an issue of global concern, as the chemicals are stable over a prolonged period resulting in their accumulation in many animals and plants. Although POPs are banned in several countries, many chemicals have been proposed as POP candidates to be added to the existing compounds as defined by the United Nations Stockholm Convention committee. To address the safe disposal and clean-up of such chemicals, new, and especially cost-effective, remediation technologies for POPs are urgently required. This review focuses on existing POPs and the types of remediation processes available for their removal. Particular attention is paid towards photocatalysis using nanocatalysts in this review, due to their effectiveness towards POP degradation, technological feasibility, and energy and cost-efficiency. The underlying principles and the key mechanisms of the photocatalysts based on TiO₂ based materials, metal oxides, light-assisted Fenton systems, framework materials e.g. metal-organic frameworks and polyoxometalates, including metal-free and hybrid photocatalysts for POPs cleanup are described for advance applications in solving the POPs contamination in the environment. The improvements of photocatalytic performance especially the POPs removal mechanism using the conventional and modified process, the design and optimization of photoreactors, and the integration technology are the critical challenges for the emerging pollutants and require intensive research for the forthcoming future.     

Mechanistic implications of plastic degradation

Plastics have become an indispensable ingredient of human life. Their enormous use is a matter of great environmental and economic concern, which has motivated the researchers and the technologists to induce different degrees of degradations in the plastic. These degradations can be induced in a better way if their mechanistic implications are properly understood. A better understanding of the mechanism for these degradations is also advocated in order to facilitate the proper use of the alternative waste disposal strategies. In view of the facts concerning the plastic degradation, in this review article, we have discussed various types of polymeric degradations along with their mechanisms, which include photo-oxidative degradation, thermal degradation, ozone-induced degradation, mechanochemical degradation, catalytic degradation and biodegradation. This article also discusses the different methods used to study these degradations and the factors that affect these degradations.     

Applications of electrokinetic phenomena in materials science

The discovery of electrokinetic phenomena by Reuss in 1808 and further investigations that gave rise to the concept of the electrical double layer have played an important role in the understanding of colloidal stability. Electrokinetic phenomena are a family of effects in which a liquid moves tangentially to a charged surface. Well-known phenomena of this kind are electrophoresis, electro-osmosis, streaming potential, and sedimentation potential. A review of parameters involved in the electrochemistry of suspensions is made. The practical applications of these phenomena have become widespread in a broad range of research fields such as biomaterials, biofilms, electrokinetic waste remediation, membranes, nuclear and fossil-fired power plants, adhesive and sealant science, and concrete science. The purpose of this paper is to provide an overview of electrokinetic phenomena and their application to surface modification and characterization in a large number of research fields such as corrosion and protection processes, environmental remediation (soil and sediments, transport processes, inorganic pollutants, solid particle surfaces, filter membranes, and biosorption phenomena), cement-based systems, and biological systems.     

Iron-based nanoparticles in wastewater treatment: A review on synthesis methods,applications, and removal mechanisms

Nanomaterial is an emerging material with potential technological impacts in various applications. It imposes great opportunities in various disciplines including wastewater remediation. Industrial wastewater is generated with anthropogenic activities and is the most environmental threat that needs remediation to overcome the environmental damages, thereby reducing human risks. Currently, several wastewater treatment techniques are applied and the utilization of nanomaterials for pollutant removal is an emerging technology. This is evident that the publication trends in the field of iron-based wastewater have been drastically increased. In this work, the overview of the preparation of iron-based nanoparticles, such as different polymorphs of iron-oxides, oxyhydroxides, iron hydroxide, and zero-valent iron nanoparticles are reviewed. In addition to the detailed discussion on the preparation of iron-based nanoparticles, their application on waste water treatment, removal mechanisms, advantages, and limitations are also assessed and discussed. Moreover, the iron-based nanoparticles' removal efficiency for specific pollutants and perspective in environmental remediation are also analyzed. Additionally, the advancements and future perspectives of iron-based nanoparticles are highlighted.     

Recent advances in BiOBr-based photocatalysts for environmental remediation

The efficient utilization of solar energy through photocatalysis is ideal for solving environmental issues and the development sustainable future. BiOBr-based semiconductors possess unique narrowed bandgaps and layered structures, thereby widely studied as photocatalysts for environmental remediation. However, a little has been focused on the comprehensive reviewing of BiOBr despite its extensive and promising applications. In this review, the state-of-the-art developments of BiOBr-based photocatalysts for environmental remediation are summarized. Particular focus is paid to the synthetic strategies for the control of the resulting morphologies, as well as efficient modification strategies for improving the photocatalytic activities. These include boosting the bulk phase by charge separation, enhancing the spatial charge separation, and engineering the surface states. The environmental uses of BiOBr-based photocatalysts are also reviewed in terms of purification of pollutants and CO₂ reduction. Finally, future challenges and opportunities of BiOBr-based materials in photocatalysis are discussed. Overall, this review provides a good basis for future exploration of high-efficiency solar-driven photocatalysts for environmental sustainability.     

Pure and modified TiO2 photocatalysts and their environmental applications

Semiconductor photocatalysis is a process that harnesses light energy in chemical conversions. In particular, its applications to environmental remediation have been intensively investigated. The characteristics of TiO₂, the most popular photocatalyst, is briefly described and selected studies on the degradation/conversion of various recalcitrant pollutants using pure and modified TiO₂ photocatalysts, which were carried out in this group, are reviewed. Photocatalytic reactions are multi-phasic and take place at interfaces of not only water/TiO₂ and air/TiO₂ but also solid/TiO₂. Examples of photocatalytic reactions of various organic and inorganic substrates that are converted through the photocatalytic oxidation or reduction are introduced. TiO₂ has been modified in various ways to improve its photocatalytic activity. Surface modifications of TiO₂ that include surface platinization, surface fluorination, and surface charge alteration are discussed and their applications to pollutants degradation are also described in detail.     

铅污染土壤的修复技术

综述了铅对土壤的污染及其修复技术。目前应用于污染土壤的修复技术可分为物理化学修复技术和生物修复技术。物理化学修复技术又可分为隔离包埋技术,固化稳定技术,Pyrometalluryical separation,化学稳定技术,电动修复技术等;生物修复技术可分为微生物修复技术和植物修复技术等。以期进一步推动铅污染土壤的治理和修复工作。     

A Comprehensive Review for Groundwater Contamination and Remediation: Occurrence,Migration and Adsorption Modelling

The provision of safe water for people is a human right; historically, a major number of people depend on groundwater as a source of water for their needs, such as agricultural, industrial or human activities. Water resources have recently been affected by organic and/or inorganic contaminants as a result of population growth and increased anthropogenic activity, soil leaching and pollution. Water resource remediation has become a serious environmental concern, since it has a direct impact on many aspects of people’s lives. For decades, the pump-and-treat method has been considered the predominant treatment process for the remediation of contaminated groundwater with organic and inorganic contaminants. On the other side, this technique missed sustainability and the new concept of using renewable energy. Permeable reactive barriers (PRBs) have been implemented as an alternative to conventional pump-and-treat systems for remediating polluted groundwater because of their effectiveness and ease of implementation. In this paper, a review of the importance of groundwater, contamination and biological, physical as well as chemical remediation techniques have been discussed. In this review, the principles of the permeable reactive barrier’s use as a remediation technique have been introduced along with commonly used reactive materials and the recent applications of the permeable reactive barrier in the remediation of different contaminants, such as heavy metals, chlorinated solvents and pesticides. This paper also discusses the characteristics of reactive media and contaminants’ uptake mechanisms. Finally, remediation isotherms, the breakthrough curves and kinetic sorption models are also being presented. It has been found that groundwater could be contaminated by different pollutants and must be remediated to fit human, agricultural and industrial needs. The PRB technique is an efficient treatment process that is an inexpensive alternative for the pump-and-treat procedure and represents a promising technique to treat groundwater pollution.     

可用于环境修复的半导体光催化剂及其改性策略研究进展

多相光催化技术作为一种直接利用太阳光降解多种污染物的先进氧化工艺在环境修复领域的研究中引起了广泛关注.在多相光催化过程中,半导体材料在太阳光的激发下,其强大的氧化/还原能力可快速高效降解各种污染物.研究者通常根据环境中污染物的状态和种类选择合适的半导体材料及修饰策略,构建高效多相光催化体系,探究光催化材料在环境修复中的...     

Flow of non‐newtonian fluids in porous media

The study of flow of non‐Newtonian fluids in porous media is very important and serves a wide variety of practical applications in processes such as enhanced oil recovery from underground reservoirs, filtration of polymer solutions and soil remediation through the removal of liquid pollutants. These fluids occur in diverse natural and synthetic forms and can be regarded as the rule rather than the exception. They show very complex strain and time dependent behavior and may have initial yield‐stress. Their common feature is that they do not obey the simple Newtonian relation of proportionality between stress and rate of deformation. Non‐Newtonian fluids are generally classified into three main categories: time‐independent whose strain rate solely depends on the instantaneous stress, time‐dependent whose strain rate is a function of both magnitude and duration of the applied stress and viscoelastic which shows partial elastic recovery on removal of the deforming stress and usually demonstrates both time and strain dependency. In this article, the key aspects of these fluids are reviewed with particular emphasis on single‐phase flow through porous media. The four main approaches for describing the flow in porous media are examined and assessed. These are: continuum models, bundle of tubes models, numerical methods and pore‐scale network modeling. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Mutual solubilities of hydrocarbons and water with the CPA EoS

The knowledge of hydrocarbon/water phase equilibria is important in the design and operation of equipment for petroleum transport and refining and petrochemical plants. The presence of water in a hydrocarbon mixture can affect the product quality and damage the operation equipment due to corrosion and formation of gas hydrates. Tracing the concentration of hydrocarbons in aqueous media is also important for technical purposes like preventing oil spills and for ecological concerns such as predicting the fate of these organic pollutants in the environment.     

Localized hydrogels based on cellulose nanofibers and wood pulp for rapid removal of methylene blue

Access to clean water has become increasingly difficult, motivating the need for materials that can efficiently remove pollutants. Hydrogels have been explored for remediation, but they often require long times to reach high levels of adsorption. To overcome this limitation, we developed a rapid, locally formed hydrogel that adsorbs dye during gelation. These hydrogels are derived from cellulose—a renewable, nontoxic, and biodegradable resource. More specifically, we found that sulfated cellulose nanofibers or sulfated wood pulps, when mixed with a water-soluble, cationic cellulose derivative, efficiently remove methylene blue (a cationic dye) within seconds. The maximum adsorption capacity was found to be 340 ± 40 mg methylene blue/g cellulose. As such, these localized hydrogels (and structural analogues) may be useful for remediating other pollutants.     

Nanoparticle-based strategies for detection and remediation of environmental pollutants

Sensitive detection and efficient removal of an increasing number of persistent and emerging environmental pollutants are major challenges in our industrialized world. Now these challenges can be better answered by utilizing the advantages of nanotechnology in addition to traditional methods. Due to unique features of nanomaterials, such as size, surface area, adsorptivity, photoelectronic, and photocatalytic properties, they have emerged to be important materials in the analytical detection and remediation of environmental pollutants.     

Radiation processing techniques in remediation of pollutants,and the role of the IAEA in supporting capacity building in developing countries

Radiation treatment, or a combination of radiation with conventional biological–chemical–physical processes, can help in the remediation of contaminated surfaces and in combating industrial chemical effluents and air pollution. The use of ionizing radiation as a powerful tool for inactivation of microbes is a valuable option to address likely threats from biohazard contamination that could be introduced either deliberately or inadvertently into areas where the public are exposed to, as well as for treatment of volatile organic compounds and similar hazardous chemical agents is an emerging development in tackling harmful pollutants. The role of the IAEA has been crucial both in supporting the development of local capabilities as well as in fostering international cooperation due to the multidisciplinary expertise required for achieving sustainable benefits. The IAEA is implementing Coordinated Research Projects, (CRP) thematic topical reviews of issues and challenges involved, and Technical Cooperation (TC) assistance in establishing and maintaining infrastructure in the MS. This paper will give an insight into the above mentioned IAEA activities, with examples of successes achieved through CRPs, as well as challenges on the road for broader dissemination of radiation processing technology for environmental remediation.     

Electrochemical technologies combined with membrane filtration

The aim of this article is to review the recent progress in the coupling of membrane separation and electrochemical technologies for water treatment. Process integration strategies have been classified in three groups. The first group deals with electrocoagulation and electrooxidation as pretreatment of membrane separation, in most cases aimed at reducing membrane fouling and decay of permeate flux of porous ultrafiltration membranes. The second group is dedicated to electrooxidation as remediation treatment for nanofiltration and reverse osmosis concentrates, which accumulate priority pollutants and emerging contaminants. Finally, the article evaluates the optimal integration of technologies using process systems engineering tools, for producing a single purified water stream, considering not only the minimization of the energy consumption but also of the total costs. Overall, it is concluded that the preconcentration strategy provides a remarkable enhancement of electrooxidation performance to degrade persistent pollutants.