高铁酸盐:一种绿色的多功能水处理剂

多种新型污染物和微生物污染等问题的出现,导致地表水水质复杂多变,传统的水处理药剂和处理方式已无法满足人们对饮用水处理的需求。 高铁酸盐作为一种新型水处理试剂,同时具备优良的氧化性和混凝性,而且不会引起二次污染,是一种可大力开发的绿色试剂。 本文综述了高铁酸盐净水剂的制备与表征分析方法,及其用于水处理对重金属、新型污染物和微生物等去除的作用机制。 目前,有关高铁酸盐用于有机污染物去除的混凝和氧化去除协同作用的研究尚不多见,高铁酸盐的氧化-混凝协同特性尚未被充分开发。 本文以此为重点进行了讨论,并对高铁酸盐净水剂的应用进行了展望。     

Ionic liquid modification of zeolite and its removal of chromate from water

This study focused on using imidazolium of different chain lengths to modify the negatively charged zeolite. The modification involves a cation exchange process of the organic cations of ionic liquids (ILs) for the alkali and alkaline earth elements on zeolite surfaces. X-ray diffraction analyses revealed that the uptake of ILs was on the external surfaces. Fourier transform infrared analyses showed that different mechanisms were attributed to IL uptake on zeolite at below and above the external cation exchange capacity. After modification, the zeolite reversed its surface charge to positive, thus enhancing adsorptive removal of anionic contaminants such as chromate from water. At the same time, the modified zeolite increased their total organic carbon content, and thus could promote better adsorptive removal of hydrophobic organic contaminants from water, too. These features enable IL-modified zeolite to be used as inexpensive sorbents for the removal of multi-types of contaminants from water simultaneously.     

Removal of Multiple Contaminants from Water by Polyoxometalate Supported Ionic Liquid Phases (POM‐SILPs)

The simultaneous removal of organic, inorganic, and microbial contaminants from water by one material offers significant advantages when fast, facile, and robust water purification is required. Herein, we present a supported ionic liquid phase (SILP) composite where each component targets a specific type of water contaminant: a polyoxometalate‐ionic liquid (POM‐IL) is immobilized on porous silica, giving the heterogeneous SILP. The water‐insoluble POM‐IL is composed of antimicrobial alkylammonium cations and lacunary polyoxometalate anions with heavy‐metal binding sites. The lipophilicity of the POM‐IL enables adsorption of organic contaminants. The silica support can bind radionuclides. Using the POM‐SILP in filtration columns enables one‐step multi‐contaminant water purification. The results show how multi‐functional POM‐SILPs can be designed for advanced purification applications.     

Synthesis and surface engineering of magnetic nanoparticles for environmental cleanup and pesticide residue analysis: A review

In recent years, water pollution and pesticide accumulation in the food chain have become a serious environmental and health hazard problem. Direct determination of these contaminants is a difficult task due to their low concentration level and the matrix interferences. Therefore, an efficient separation and preconcentration procedure is often required prior to the analysis. With the advancement in nanotechnology, various types of magnetic core–shell nanoparticles have successfully been synthesized and received considerable attention as sorbents for decontamination of diverse matrices. Magnetic core–shell nanoparticles with surface modifications have the advantages of large surface‐area‐to‐volume ratio, high number of surface active sites, no secondary pollutant, and high magnetic properties. Due to their physicochemical properties, surface‐modified magnetic core–shell nanoparticles exhibit high adsorption efficiency, high rate of removal of contaminants, and easy as well as rapid separation of adsorbent from solution via external magnetic field. Such facile separation is essential to improve the operation efficiency. In addition, reuse of nanoparticles would substantially reduce the treatment cost. In this review article, we have attempted to summarize recent studies that address the preconcentration methods of pesticide residue analysis and removal of toxic contaminants from aquatic systems using magnetic core–shell nanoparticles as adsorbents.     

Photooxidation of aqueous trichloroethylene using a buoyant photocatalyst with reaction progress monitored via micro-headspace GC/MS

Although photooxidation has previously been shown to be successful in removing organic contaminants from water, methods combining the rapid photooxidation of the desired contaminant with easy catalyst manipulation and removal are few and far between. In the absence of an easy means of catalyst removal, the photooxidation process becomes more costly and time consuming, and photocatalysis cannot be employed as an in situ method for the remediation of aqueous organic contaminants. In this study, the photocatalyst was added to an aqueous trichloroethylene (TCE) solution in the form of TiO₂-coated buoyant microspheres. The solution, placed in a flow-cell photoreactor along with the buoyant catalyst, was irradiated with a UV-filtered Xenon light source. Limited sample sizes necessitated the development of a low-cost headspace GC/MS analysis method, utilizing a standard direct-injection autosampler. This analytical technique aptly monitored reaction progress and indicated that aqueous TCE concentration decreases by nearly 90% in the first hour of irradiation. Subsequent solvent extraction GC/MS analysis indicated that the TCE is initially sorbed by the photocatalyst spheres, but as irradiation continued, TCE is removed from the catalyst spheres surfaces. During the course of irradiation, the expected TCE mineralization product hydrochloric acid appeared, as indicated by a decrease in pH and ion chromatography analysis. The microsphere-born catalyst was easily removed from the treated solution by filtration. Thus, it is possible that a method for effective, low-cost in situ photooxidation of aqueous organic contaminants will be realized in the near future.     

Ion Exchange in Hydrometallurgical Processing: An Overview and Selected Applications

Ion exchange has traditionally been employed for the purification of water and the removal of metal contaminants from dilute waste streams. More recently, its use in removing trace metallic impurities from hydrometallurgical process streams (with typical background metal concentrations of 50–100 g/L) has increased substantially. It is also used as a primary recovery and concentration unit operation for certain commodities, where both technical and cost advantages become apparent for complex flow sheets. This overview discusses selected modern applications of ion exchange in hydrometallurgical processes for uranium, precious metals, copper, cobalt, nickel and zinc, and identifies some opportunities for the future.     

Improved MEUF removal of naphthenic acids from produced water

Naphthenic acids are naturally occurring organics in produced waters from oil recovery operations. In principle, these contaminants can be removed using micellar-enhanced ultrafiltration (MEUF), which is an effective technique for the removal of organic contaminants from water streams. In this work, we show that the amphiphilic nature of the naphthenic acids contributed to decreasing the critical micelle concentration (CMC) of cetylpyridinium chloride (CPC), a widely used surfactant in MEUF. This reduction in CMC allowed a decrease in the CPC dosage required to attain certain removal of the organics, and hence, improved the performance of traditional MEUF as a result of reducing back contamination and potential fouling of the membrane. The effect of CPC feed concentration, and the concentration and carbon number of the naphthenic acids on permeate flux, recovery ratio and percent rejection of CPC and naphthenic acids were explored over a range of trans-membrane pressure. The MEUF setup employed hydrophilic polyacrylonitrile (PAN) hollow fiber membrane with 13 kDa MWCO, since it allowed for high permeate flux and contaminant rejection.     

Transition metal modified and partially calcined inorganic-organic pillared clays for the adsorption of salicylic acid, clofibric acid, carbamazepine, and caffeine from water

Pharmaceutical and Personal Care Products (PPCPs) are considered emerging contaminants, and their efficient removal from water is going to be a challenging endeavor. Microporous adsorbent materials, including pillared clays, could offer a potential solution if tailored properly. Although pillared clays have been employed previously for the removal of organics, the effective removal of PPCPs will only be possible if their surface and textural properties are manipulated from the bottom-up. This work presents the use of modified inorganic-organic pillared clays (IOCs) for the adsorption of salicylic acid, clofibric acid, carbamazepine, and caffeine. The IOCs have been modified with Co(2+), Cu(2+), or Ni(2+) to induce complexation-like adsorbate-adsorbent interactions at ambient conditions, in an attempt to provide an efficient and yet reversible driving force in the sub-ppm concentration range. Furthermore, the IOCs were partially calcined to increase effective surface area by an order of magnitude while preserving some hydrophobicity. In general, the Ni(2+) IOCs exhibited the greatest interaction with salicylic and clofibric acids, respectively, while the Co(2+) adsorbents excelled at adsorbing caffeine at low concentrations. All of the metal-modified IOCs showed comparable adsorption capacities for the case of carbamazepine, probably due to the lack of availability of particular functional groups in this adsorbate.     

The trapping of indoor air contaminants

The removal of indoor air contaminants by reactivity with air filters coated with reagents has been found to be effective for aldehydes, acidic and basic vapours as well as isocyanates Coatings of polymeric amines were used for formaldehyde trapping as well as for the removal of acidic vapours and for the removal of isocyanates. The addition of glycerol as a plasticizer for the coating can also be an effective reagent.     

Influence of operating conditions on performance of ceramic membrane used for water treatment

The removal of natural organic matter (NOM) is a critical aspect of potable water treatment because NOM compounds are precursors of harmful disinfection by-products, hence should be removed from water intended for human consumption. Ultrafiltration using ceramic membranes can be a suitable process for removal of natural substances. Previously reported experiments were dedicated to evaluating the suitability of ultrafiltration through ceramic membrane for water treatment with a focus on the separation of natural organic matter. The effects of the membrane operating time and linear flow velocity on transport and separation properties were also examined. The experiments, using a 7-channel 300 kDa MWCO ceramic membrane, were carried out with model solutions and surface water at trans-membrane pressure of 0.2–0.5 MPa. The results revealed that a loose UF ceramic membrane can successfully eliminate natural organic matter from water. The permeability of the membrane was strongly affected by the composition of the feed stream, i.e. the permeate flux decreased with an increase in the NOM concentration. The permeate flux also decreased over the period of the operation, while this parameter did not influence the effectiveness of separation, i.e. the removal of NOM. It was observed that the increased cross-flow velocity resulted in the decrease in the membrane-fouling intensity and slightly improved the retention of contaminants.     

Accurate mass screening and identification of emerging contaminants in environmental samples by liquid chromatography-hybrid linear ion trap Orbitrap mass spectrometry

The European Reach legislation will possibly drive producers to develop newly designed chemicals that will be less persistent, bioaccumulative or toxic. If this innovation leads to an increased use of more hydrophilic chemicals it may result in higher mobilities of chemicals in the aqueous environment. As a result, the drinking water companies may face stronger demands on removal processes as the hydrophilic compounds inherently are more difficult to remove. Monitoring efforts will also experience a shift in focus to more water-soluble compounds. Screening source waters on the presence of (emerging) contaminants is an essential step in the control of the water cycle from source to tap water. In this article, some of our experiences are presented with the hybrid linear ion trap (LTQ) FT Orbitrap mass spectrometer, in the area of chemical water analysis. A two-pronged strategy in mass spectrometric research was employed: (i) exploring effluent, surface, ground- and drinking-water samples searching for accurate masses corresponding to target compounds (and their product ions) known from, e.g. priority lists or the scientific literature and (ii) full-scan screening of water samples in search of 'unknown' or unexpected masses, followed by MS(n) experiments to elucidate the structure of the unknowns. Applications of both approaches to emerging water contaminants are presented and discussed. Results are presented for target analysis search for pharmaceuticals, benzotriazoles, illicit drugs and for the identification of unknown compounds in a groundwater sample and in a polar extract of a landfill soil sample (a toxicity identification evaluation bioassay sample). The applications of accurate mass screening and identification described in this article demonstrate that the LC-LTQ FT Orbitrap MS is well equipped to meet the challenges posed by newly emerging polar contaminants.     

Development of the performance reference compound approach for the calibration of “polar organic chemical integrative sampler” (POCIS)

The purpose of the Water Framework Directive is to ensure the quality of the natural water across Europe. In this context, passive samplers have shown interesting capacities for the monitoring of contaminants in aqueous ecosystems. They allow the measurement of time-weighted average concentrations, overcoming many drawbacks of the spot-sampling techniques known to be expensive and time consuming. However, application of passive samplers such as polar organic chemical integrative samplers (POCIS) for the monitoring of hydrophilic contaminants requires calibration to define compound sampling rates; key parameters to deduce the pollutant water concentrations from the amounts of pollutants accumulated by the device. Unfortunately, sampling rates are influenced by a range of environmental factors; in that respect, a question remains: is it not evident to know to what extent the sampling rates obtained in laboratory experiments can be used in field conditions? The problem can be solved for hydrophobic samplers by using performance reference compounds (PRCs), and an ongoing challenge for POCIS is focused on the improvement of the quantitative aspect of this family of samplers. In this study, potential PRCs have been selected during a specific experiment and their performance was tested in the laboratory under two hydrodynamic conditions. Results revealed a good proportionality between elimination rates of PRCs and sampling rates of chemicals. Afterwards, the application of the approach under environmental conditions was assessed by deploying POCIS in the Arcachon Bay (France) where POCIS–PRC-derived water concentrations appear to be close to the simultaneous grab-sampling results.

The removal of pharmaceutical pollutants from aqueous solution by Agro-waste

Pharmaceuticals are a unique class of emerging contaminants owing to their intrinsic ability to induce physiological effects on man and animals at low concentrations. Pharmaceuticals are released into the environment via diverse routes; human and animal wastes are the major sources. The persistence and mode of action of pharmaceuticals in the environment make them a major concern. Among methods available for wastewater treatment, the adsorption technique is found to be effective and easy to operate. The expensive nature of commercial activated carbons, however, created a limitation to the adsorption technique; hence the exploration for low-cost and sustainable adsorbents for the removal of different categories of water contaminants. Agricultural wastes offer such advantages as low-cost, abundance and eco-friendly materials in adsorbent preparation. Herein presented are the category and classes of pharmaceuticals cum the risks associated with pharmaceuticals released into the environment. The chemistry of activated carbon/agro wastes viz-a-viz suitability and potency in adsorption of different pharmaceutical waste removal were reviewed; the benefits associated with agricultural wastes usage in pharmaceutical removal have also been presented. Various challenges, gaps cum research prospects in the current field of discussion are herein presented. This work will serve as a tool for public education and enlightenment, help environmentalists make plans for envisaged threats and serve as a guide for policy makers.     

Current Trends in the Application of Nanomaterials for the Removal of Pollutants from Industrial Wastewater Treatment—A Review

In the recent decades, development of new and innovative technology resulted in a very high amount of effluents. Industrial wastewaters originating from various industries contribute as a major source of water pollution. The pollutants in the wastewater include organic and inorganic pollutants, heavy metals, and non-disintegrating materials. This pollutant poses a severe threat to the environment. Therefore, novel and innovative methods and technologies need to adapt for their removal. Recent years saw nanomaterials as a potential candidate for pollutants removal. Nowadays, a range of cost-effective nanomaterials are available with unique properties. In this context, nano-absorbents are excellent materials. Heavy metal contamination is widespread in underground and surface waters. Recently, various studies focused on the removal of heavy metals. The presented review article here focused on removal of contaminants originated from industrial wastewater utilizing nanomaterials.     

Surfactant-enhanced remediation of organic contaminated soil and water

Surfactant based remediation technologies for organic contaminated soil and water (groundwater or surface water) is of increasing importance recently. Surfactants are used to dramatically expedite the process, which in turn, may reduce the treatment time of a site compared to use of water alone. In fact, among the various available remediation technologies for organic contaminated sites, surfactant based process is one of the most innovative technologies. To enhance the application of surfactant based technologies for remediation of organic contaminated sites, it is very important to have a better understanding of the mechanisms involved in this process. This paper will provide an overview of the recent developments in the area of surfactant enhanced soil and groundwater remediation processes, focusing on (i) surfactant adsorption on soil, (ii) micellar solubilization of organic hydrocarbons, (iii) supersolubilization, (iv) density modified displacement, (v) degradation of organic hydrocarbon in presence surfactants, (vi) partitioning of surfactants onto soil and liquid organic phase, (vii) partitioning of contaminants onto soil, and (viii) removal of organics from soil in presence of surfactants. Surfactant adsorption on soil and/or sediment is an important step in this process as it results in surfactant loss reduced the availability of the surfactants for solubilization. At the same time, adsorbed surfactants will retained in the soil matrix, and may create other environmental problem. The biosurfactants are become promising in this application due to their environmentally friendly nature, nontoxic, low adsorption on to soil, and good solubilization efficiency. Effects of different parameters like the effect of electrolyte, pH, soil mineral and organic content, soil composition etc. on surfactant adsorption are discussed here. Micellar solubilization is also an important step for removal of organic contaminants from the soil matrix, especially for low aqueous solubility organic contaminants. Influences of different parameters such as single and mixed surfactant system, hydrophilic and hydrophobic chain length, HLB value, temperature, electrolyte, surfactant type that are very important in micellar solubilization are reviewed here. Microemulsion systems show higher capacity of organic hydrocarbons solubilization than the normal micellar system. In the case of biodegradation of organic hydrocarbons, the rate is very slow due to low water solubility and dissolution rate but the presence of surfactants may increase the bioavailability of hydrophobic compounds by solubilization and hence increases the degradation rate. In some cases the presence of it also reduces the rate. In addition to fundamental studies, some laboratory and field studies on removal of organics from contaminated soil are also reviewed to show the applicability of this technology.     

Observation of microcontaminants on pure chromium surface by AFM and their removal by UV light illumination

Microcontaminants on a pure chromium surface were observed and confirmed by atomic force microscope (AFM). On the basis of surface observation, X‐ray photoelectron spectroscopy (XPS) analysis and wettability measurement, the removal of microcontaminants by ultraviolet (UV) light illumination was investigated. Particle‐ and film‐like microcontaminants on the specimen surface were observed. With an increase in air exposure time, particle‐like contaminants increased in size, and then film‐like contaminants almost covered the entire surface. Most organic substance in the contaminants was removed by UV light illumination in a sealed chamber, except water in the contaminants. The re‐adhesion of contaminants on the UV‐light‐illuminated surface seemed slower after compared to before UV light illumination. Copyright © 2008 John Wiley & Sons, Ltd.     

A review of cyanobacteria and cyanotoxins removal/inactivation in drinking water treatment

This review focuses on the efficiency of different water treatment processes for the removal of cyanotoxins from potable water. Although several investigators have studied full-scale drinking water processes to determine the efficiency of cyanotoxin inactivation, many of the studies were based on ancillary practice. In this context, “ancillary practice” refers to the removal or inactivation of cyanotoxins by standard daily operational procedures and without a contingency operational plan utilizing specific treatment barriers. In this review, “auxiliary practice” refers to the implementation of inactivation/removal treatment barriers or operational changes explicitly designed to minimize risk from toxin-forming algae and their toxins to make potable water. Furthermore, the best drinking water treatment practices are based on extension of the multibarrier approach to remove cyanotoxins from water. Cyanotoxins are considered natural contaminants that occur worldwide and specific classes of cyanotoxins have shown regional prevalence. For example, freshwaters in the Americas often show high concentrations of microcystin, anatoxin-a, and cylindrospermopsin, whereas Australian water sources often show high concentrations of microcystin, cylindrospermopsin, and saxitoxins. Other less frequently reported cyanotoxins include lyngbyatoxin A, debromoaplysiatoxin, and β-N-methylamino-l-alanine. This review focuses on the commonly used unit processes and treatment trains to reduce the toxicity of four classes of cyanotoxins: the microcystins, cylindrospermopsin, anatoxin-a, and saxitoxins. The goal of this review is to inform the reader of how each unit process participates in a treatment train and how an auxiliary multibarrier approach to water treatment can provide safer water for the consumer.     

Surface preparation of glassy carbon electrodes

Recent work on glassy carbon electrodes for various applications is reviewed. Activation of glassy carbon electrodes by different types of polishing, heat treatment, and electrochemical methods yields enhanced rates of electron transfer. Characterization of different glassy carbon surfaces by x-ray photoelectron spectroscopy shows that polished and electrochemically pretreated surfaces contain more oxygen on the surface than do unactivated surfaces; much of this oxygen is associated with phenolic groups. Causes of activation, characterization of glassy carbon by spectroscopic methods, and the role of surface cleanliness are summarized. For simple electron-transfer reactions, removal of contaminants from the electrode surface is important. For proton-coupled electrode reactions, specific interactions of reactants with catalytic groups created on the surface during polishing tend to play an important role in electrode activation     

Highly Efficient Nano-Structured Polymer-Based Membrane/Sorbent for Oil Adsorption from O/W Emulsion Conducted of Petroleum Wastewater

Wastewater disposal has been an important issue from an environmental perspective in terms of the serious damages and harms its contaminants may cause. Treatment of the wastewater, through the pollutants removal, either before disposal or for the reuse in certain industrial or agricultural purposes, is an essential process. In response to this environmental claim, a novel nano-structured, macro-porous, polymer-based membrane/sorbent was prepared, in terms of its highly open and porous structure with nano-structured sorbent interconnecting walls and based on high internal phase emulsion polymerization. This sorbent was used to remove the oil from polluted wastewater in a laboratory-scale through the application of a new method called flotation–nano-filtration. In order to avoid the water flux decline and simultaneously enhance the oil removal efficiency from the wastewater, the polymeric material, after being prepared and used in sheet form (membrane), was ultimately introduced to the wastewater system as small pieces, as with the intention of physically increasing the area of surface for the oil removal. The material performance studies applied several variables, namely, the physical sectioning of the material surface area, sorbent concentration, mixing speed, and mixing time. An efficiency of 99.75% for the oil removal from the polluted water was successfully achieved at 75 minutes mixing time, a sorbent concentration of 0.158 g/200 mL (each piece with dimensions of 2 mm × 3 mm × 1 mm), and 300 rpm mixing speed. The sorbent structure before and after the oil removal process was examined using scanning electron microscope and x-ray diffraction analysis.     

Simultaneous Removal of Antibiotics and Heavy Metals with Poly(Aspartic Acid)-Based Fenton Micromotors

The discharge of diverse pollutants has led to a complex water environment and posed a huge health threat to humans and animals. Self-propelled micromotors have recently attracted considerable attention for efficient water remediation due to their strong localized mass transfer effect. However, a single functionalized component is difficult to tackle with multiple contaminants and requires to combine different decontamination effects together. Here, we introduced a multifunctional micromotor to implement the adsorption and degradation roles simultaneously by integrating the poly(aspartic acid) (PASP) adsorbent with a MnO₂-based catalyst. The as-prepared micromotors are well propelled in contaminated waters by MnO₂ catalyzing hydrogen peroxide. In addition, the catalytic ramsdellite MnO₂(R-MnO₂) inner layer is decorated with Fe₂O₃ nanoparticles to improve their catalytic performance, contributing to an excellent degradation ability with 90% tetracycline (TC) removal in 50 minutes by enhanced Fenton-like reactions. Combining the attractive adsorption capability of poly (aspartic acid) (PASP), the composite micromotors offer an efficient removal of heavy metal ions in short time. Moreover, the designed micromotors are able to simultaneously remove antibiotic and heavy metals in mixed contaminants circumstance just in single treatment. This multifunctional micromotor with distinctive decontamination ability exhibits a promising prospective in treating multiple pollutants in the future.