Oxidation of emerging organic contaminants by in-situ H_(2)O_(2) fenton system

The existence and risk of emerging organic contaminants(EOCs)have been under consideration and paid much effort to degrade these pollutants.Fenton system is one of the most widely used technologies to solve this problem.The original Fenton system relies on the hydroxyl radicals produced by Fe(Ⅱ)/H_(2)O_(2) to oxidize the organic contaminants.However,the application of the Fenton system is limited by its low iron cycling efficiency and the high risks of hydrogen peroxide transportation and storage.The introduction of external energy(including light and electricity etc.)can effectively promote the Fe(Ⅲ)/Fe(Ⅱ)cycle and the reduction of oxygen to produce hydrogen peroxide in situ.This review introduces three in-situ Fenton systems,which are electro-Fenton,Photo-Fenton,and chemical reaction.The mechanism,influencing factors,and catalysts of these three in-situ Fenton systems in degrading EOCs are discussed systematically.This review strengthens the understanding of Fenton and in-situ Fenton systems in degradation,offering further insight into the real application of the in-situ Fenton system in the removal of EOCs.

Microbial Degradation of Organic Contaminants in Streambed/Floodplain Sediments in Passaic River—New Jersey Area

This paper is intended to explore soil organic matter and carbon isotope fractionation at three locations of the Passaic River to determine if microbial degradation of organic contaminants in soil is correlated to the surrounding physical environment. Microbial degradation of organic contaminants is important for the detoxification of toxic substances thereby minimizing stagnation in the environment and accumulating in the food chain. Since organic contaminants are not easily dissolved in water, they will penetrate sediment and end up enriching the adjacent soil. The hypothesis that we are testing is microbial activity and carbon isotope fractionation will be greater in preserved soils than urban soils. The reason why this is expected to be the case is the expectation of higher microbial activity in preserved environments due to less exposure to pollutants, better soil structure, higher organic matter content, and more favorable conditions for microbial growth. This is contrasted with urban soils, which are impacted by pollutants and disturbances, potentially inhibiting microbial activity. We wish to collect soil samples adjacent to the Passaic River at a pristine location, Great Swamp Wildlife Refuge, a suburban location, Goffle Brook Park, Hawthorne NJ, and an urban location, Paterson NJ. These soil samples will be weighed for soil organic matter (SOM) and weighed for isotope ratio mass spectrometry (IRMS) to test organic carbon isotopes. High SOM and δ13C depletion activity indicate microbial growth based on the characteristics of the soil horizon rather than the location of the soil sample which results in degradation of organic compounds.

Emerging Organic Contaminants in Chinese Surface Water:Identification of Priority Pollutants

The occurrence and impacts of emerging organic contaminants(EOCs)in the aquatic environment have gained widespread attention over the past two decades.Due to large number of potential contaminants,monitoring campaigns,treatment plants,and proposed regulations should preferentially focus on specific pollutants with the highest potential for ecological and human health effects.In the present study,a multi-criteria screening approach based on hazard and exposure potentials was developed for prioritization of 405 unregulated EOCs already present in Chinese surface water.Hazard potential,exposure potential,and risk quotients for ecological and human health effects were quantitatively analyzed and used to screen contaminants.The hazard potential was defined by contaminant persistence,bioaccumulation,ecotoxicity,and human health effects;similarly,the exposure potential was a function of contaminant concentration and detection frequency.In total,123 compounds passed the preselection process,which involved a priority index equal to the normalized hazard potential multiplied by the normalized exposure potential.Based on the prioritization scheme,11 compounds were identified as top-priority,and 37 chemicals were defined as high-priority.The results obtained by the priority index were compared with four other prioritization schemes based on exposure potential,hazard potential,or risk quotients for ecological effects or human health.The priority index effectively captured and integrated the results from the more simplistic prioritization schemes.Based on identified data gaps,four uncertainty categories were classified to recommend:①regular monitoring,derivation of environmental quality standards,and development of control strategies;②increased monitoring;③fortified hazard assessment;and④increased efforts to collect occurrence and toxicity data.Overall,20 pollutants were recommended as priority EOCs.The prioritized list of contaminants provides the necessary information for authoritative regulations to monitor,control,evaluate,and manage the risks of environmentally-relevant EOCs in Chinese surface water.

Analysis of diffusion-adsorption equivalency of landfill liner systems for organic contaminants

The equivalence between multilayered barriers regarding diffusion and adsorption was studied. The bottom boundary of the liner system is defined by assuming concentration continuous and flux continuous conditions of the contaminant between the bottom liner layer and the underlying soil. Five different liner systems were compared in terms of solute breakthrough time. The results of the analysis showed that breakthrough time of the hydrophobic organic compounds for a 2-meter-thick compacted clay liner （CCL） could be 3-4 orders of magnitude is greater than the breakthrough time for a geosynthetic clay liner （GCL） composite liner. The GM/GCL and GM/CCL composite liner systems provide a better diffusion barrier for the hydrophilic organic compounds than that for the hydrophobic compounds due to their different Henry＇s coefficient. The calculated breakthrough times of the organic contaminants for the Chinese standard liner systems were found to be generally greater than those for the GCL alternatives, for the specific conditions examined. If the distribution coefficient increases to 2.8 for the hydrophobic compounds or 1.0 for the hydrophilic compounds, the thickness of the attenuation layer needed to achieve the same breakthrough time as the standard liner systems can be reduced by a factor of about 1.9-2.4. As far as diffusive and adsorption contaminant transport are concerned, GM or GCL is less effective than CCL.

Construction of MoFs-based nanocomposite membranes for emerging organic contaminants abatement in water

Presence of emerging organic contaminants(EOCs)in water is one of the major threats to water safety.In recent decades,an increasing number of studies have investigated new approaches for their effective removal.Among them,metal-organic frameworks(MOFs)have_attracted increasing attention since their first development thanks to their tunable metal nodes and versatile,functional linkers.However,whether or not MOFs have a promising future for practical application in emerging contaminants-containing wastewater is debatabie.This review summarizes recent studies about the removal of EOCs using MOFs-related material.The synthesis strategies of both MOF particles and composites,including thin-film nanocomposite and mixed matrix membranes,are criticaily reviewed,as well as various characterization technologies.The application of the MOF-based composite membranes in adsorption,separation(nanofiltration and ultrafiltration),and catalytic degradation are discussed.Overall,literature survey shows that MOFs-based composite could play a crucial role in eliminating EOCs in the future.In particular,modified membranes that realize separation and degradation might be the most promising materials for such application.

Engineering carbon nanocatalysts towards efficient degradation of emerging organic contaminants via persulfate activation:A review

The engineering of carbon nanocatalysts for the persulfate activated elimination of emerging organic contaminants(EOCs)demonstrates promising potential compared with metal-based counterparts due to their unique advantage of high stability and low toxicity.The early reviews introduced the theoretical background of persulfate activation together with a detailed summary of different mechanisms responsible for degradation of EOCs.To further unify the state of knowledge,identify the research gaps,and prompt new research in this area,we present a thorough review on current trends in research on metal-free carbon nanocatalysts(e.g.,0D nanodiamond,1D carbon nanotubes and carbon nanofibers,2D graphene and graphitic carbon nitride,and 3D carbon nanocatalysts),with emphasis on their applications in persulfate activation and EOCs decontamination.We also discuss the current challenges and future perspectives in practically relevant applications.Last,we highlight that the development of sustainable carbon nanocatalysts/persulfate systems lies at the interface of multiple disciplines,which calls for future in-depth interdisciplinary collaborations.

Biochar-based materials and their applications in removal of organic contaminants from wastewater:state-of-the-art review

As a class of famous carbon materials,biochars(BCs)and their derivative materials with excellent physicochemical properties and diversified functionalities present great potential in wastewater treatment fields.This review focuses on the latest development in reported biochar-based materials as superior adsorbents or catalysts for removing harmful organic contaminants from wastewater.The construction and properties of biochar-based materials are briefly introduced at the beginning.As one of the major factors affecting the properties of BCs,the wide diversity of feedstocks,such as agricultural and forest residues,industrial by-products as well as municipal wastes,endows BCs different chemical compositions and structures.Woody and herbaceous BCs usually have higher carbon contents,larger surface areas and strong aromaticity,which is in favor of the organic contaminant removal.Driven by the desire of more cost-effective materials,several types of biochar-based hybrid materials,such as magnetic BC composites(MBC),nanometal/nanometallic oxides/hydroxide BC composites and layered nanomaterial-coated BCs,as well as physically/chemically activated BCs,have also been developed.With the help of foreign materials,these types of hybrid BCs have excellent capacities to remove a wide range of organic contaminants,including organic dyestuff,phenols and chemical intermediates,as well as pharmaceutically active compounds,from aquatic solutions.Depending on the different types of biochar-based materials,organic contaminants can be removed by different mechanisms,such as physical adsorption,electrostatic interaction,π-πinteraction and Fenton process,as well as photocatalytic degradation.In summary,the low cost,tunable surface chemistry and excellent physical-chemical properties of BCs allow it to be a potential material in organic contaminant removal.The combination of BCs with foreign materials endows BCs more functionalities and broader development opportunities.Considering the urgent demand of practical wastewater treatment,we hope more researches will focus on the applications and commercialization of biochar-based materials.

Sustainable wood-based nanotechnologies for photocatalytic degradation of organic contaminants in aquatic environment

Wood-based nanotechnologies have received much attention in the area of photocatalytic degradation of organic contaminants in aquatic environment in recent years,because of the high abundance and renewability of wood as well as the high reaction activity and unique structural features of these materials.Herein,we present a comprehensive review of the current research activities centering on the development of wood-based nanocatalysts for photodegradation of organic pollutants.This review begins with a brief introduction of the development of photocatalysts and hierarchical structure of wood.The review then focuses on strategies of designing novel photocatalysts based on wood or its recombinants(such as 1D fiber,2D films and 3D porous gels)using advanced nanotechnology including sol-gel method,hydrothermal method,magnetron sputtering method,dipping method and so on.Next,we highlight typical approaches that improve the photocatalytic property,including metal element doping,morphology control and semiconductor coupling.Also,the structure-activity relationship of photocatalysts is emphasized.Finally,a brief summary and prospect of wood-derived photocatalysts is provided.

Complex interplay between formation routes and natural organic matter modification controls capabilities of C_(60)nanoparticles(nC_(60)) to accumulate organic contaminants

Accumulation of organic contaminants on fullerene nanoparticles（nC（60）） may significantly affect the risks of C（60） in the environment.The objective of this study was to further understand how the interplay of nC（60） formation routes and humic acid modification affects contaminant adsorption of nC（60）.Specifically,adsorption of 1,2,4,5-tetrachlorobenzene（a model nonionic,hydrophobic organic contaminant） on nC（60） was greatly affected by nC（60）formation route- the formation route significantly affected the aggregation properties of nC（60）,thus affecting the available surface area and the extent of adsorption via the pore-filling mechanism.Depending on whether nC（60） was formed via the ＂top-down＂ route（i.e.,sonicating C（60） powder in aqueous solution） or ＂bottom-up＂ route（i.e.,phase transfer from an organic solvent） and the type of solvent involved（toluene versus tetrahydrofuran）,modification of nC（60） with Suwannee River humic acid（SRHA） could either enhance or inhibit the adsorption affinity of nC（60）.The net effect depended on the specific way in which SRHA interacted with C（60） monomers and/or C（60） aggregates of different sizes and morphology,which determined the relative importance of enhanced adsorption from SRHA modification via preventing C（60） aggregation and inhibited adsorption through blocking available adsorption sites.The findings further demonstrate the complex mechanisms controlling interactions between nC（60） and organic contaminants,and may have significant implications for the life-cycle analysis and risk assessment of C（60）.

Efficient elimination of organic contaminants with novel and stable zeolite@MOF layer adsorbents

Many metal-organic frameworks(MOFs)trapped in water exhibit instability and small-particle agglomeration issues,which unquestionably constrain their potential applications,such as the capture of organic contaminants(OCs).In this study,four types of micron-sized MOFs(Zn/Cu-BTC,MOF-5,ZIF-8,and UiO-66)were grown within a zeolite-13X support to form millimeter-sized zeolite-13X@MOF composites for the elimination of benzothiophene,methyl orange,and tetracycline from the liquid phase by dynamic adsorption in a column.We observed that the 13X@Zn/Cu-BTC exhibited extraordinarily high OC capture capacities as a result of the Zn^(2+) and Cu^(2+) combinative effects of the acid-base interaction.Remarkably,the 13X@UiO-66 preserved its structural integrity when immersed in water for 15 days,in contact with boiling water for 12 h,and in both strong acidic and basic aqueous media.Moreover,the OC capture abilities of the 13X@UiO-66 only underwent a slight change after the fifth round.This work provides new method for the design of desirable millimeter-sized zeolite@MOFs,thereby advancing their practical application for OC capture.

Peroxymonosulfate enhanced photoelectrocatalytic oxidation of organic contaminants and simultaneously cathodic recycling of silver

Degradation of organic contaminants with simultaneous recycling of Ag+from silvercontaining organic wastewater such as photographic effluents is desired. Although photoelectrocatalysis(PEC) technology is a good candidate for this type of wastewater, its reaction kinetics still needs to be improved. Herein, peroxymonosulfate(PMS) was employed to enhance the PEC kinetics for oxidation of phenol(PhOH) at the anode and reduction of Ag^(+) at the cathode. The degradation efficiency of phenol(PhOH, 0.1 mmol/L) was increased from 42.8% to 96.9% by adding 5 mmol/L PMS at a potential of 0.25 V. Meanwhile, the Ag(by wt%)deposited on the cathode was 28.1%(Ag_(2)O) in PEC process, while that of Ag(by wt%) was 69.7%(Ag^(0)) by adding PMS. According to the electrochemistry analysis, PMS, as photoelectrons acceptor, enhances the separation efficiency of charges and the direct hoxidation of Ph OH at the photoanode. Meantime, the increasing cathode potential avoided Hevolution and strongly alkaline at the surface of cathode, thus enabling the deposition of Ag+in the form of metallic silver with the help of PMS. In addition, PMS combined with PEC process was effective in treating photographic effluents.

Enhanced utilization efficiency of peroxymonosulfate via water vortex-driven piezo-activation for removing organic contaminants from water

The efficient activation and utilization of peroxymonosulfate(PMS)in PMS-based advanced oxidation processes is a high-priority target for the removal of organic contaminants.This work introduces a water vortex-driven piezoelectric effect from few-odd-layered MoS_(2)into the PMS activation to remove benzotriazole(BTR)and other organic contaminants from the water.Approximately 91.1%of BTR can be removed by the MoS_(2)piezo-activated PMS process with a reaction rate constant of 0.428 min
1,which is 2.09 times faster than the sum of the individual MoS_(2),water vortex,and piezocatalysis rates.Meanwhile,the PMS utilization efficiency reached 0.0147 in the water vortex-driven piezo-activation system,which is 3.97 times that of the sum from the vortex/PMS and MoS_(2)/PMS systems.These results demonstrate that the presence of MoS_(2)under a water vortex can trigger a piezoelectric potential and generate abundant free electrons to activate PMS to generate various active species for degradation of organic contaminants.

Hierarchical porous metal-organic frameworks/polymer microparticles for enhanced catalytic degradation of organic contaminants

This work reports on a simple microfluidic strategy to controllably fabricate uniform polymeric microparticles containing hierarchical porous structures integrated with highly accessible catalytic metal organic frameworks for efficient degradation of organic contaminants.Monodisperse(W1/O)/W2 emulsion droplets generated from microfluidics are used as templates for the microparticle synthesis.The emulsion droplets contain tiny water microdroplets from homogenization and water nanodroplets from diffusion-induced swollen micelles as the dual pore-forming templates,and Fe-based metal-organic framework nanorods as the nanocatalysts.The obtained microparticles possess interconnected hierarchical porous structures decorated with highly accessible Fe-based metal-organic framework nanorods for enhanced degradation of organic contaminants via a heterogeneous Fenton-like reaction.Such a degradation performance is highlighted by using these microparticles for efficient degradation of rhodamine B in hydrogen peroxide solution.This work provides a simple and general strategy to flexibly combine hierarchical porous structures and catalytic metal-organic frameworks to engineer advanced microparticles for water decontamination.

Anaerobic degradation of xenobiotic organic contaminants(XOCs):The role of electron flow and potential enhancing strategies

In groundwater,deep soil layer,sediment,the widespread of xenobiotic organic contaminants(XOCs)have been leading to the concern of human health and eco-environment safety,which calls for a better understanding on the fate and remediation of XOCs in anoxic matrices.In the absence of oxygen,bacteria utilize various oxidized substances,e.g.nitrate,sulphate,metallic(hydr)oxides,humic substance,as terminal electron acceptors(TEAs)to fuel anaerobic XOCs degradation.Although there have been increasing anaerobic biodegradation studies focusing on species identification,degrading pathways,community dynamics,systematic reviews on the underlying mechanism of anaerobic contaminants removal from the perspective of electron flow are limited.In this review,we provide the insight on anaerobic biodegradation from electrons aspect-electron production,transport,and consumption.The mechanism of the coupling between TEAs reduction and pollutants degradation is deconstructed in the level of community,pure culture,and cellular biochemistry.Hereby,relevant strategies to promote anaerobic biodegradation are proposed for guiding to an efficient XOCs bioremediation.

Environmental Properties of Minerals and Contaminants Purified by the Mineralogical Method

The investigation of the environmental properties of minerals, i.e., environmental mineralogy, is a branch of science dealing with interactions between natural minerals and spheres of the Earth surface as well as a reflection of global change, prevention of ecological destruction, participation in biomineralogy, and remediation of environmental pollution. Pollutant treatment by natural minerals is based on the natural law and reflects natural self-purification functions in the inorganic world, similar to that of the organic world - a biological treatment. A series of case studies related to natural self-purification, which were mostly completed by our group, are discussed in this paper. In natural cryptomelane there is a larger pseudotetragonal tunnel than that formed by [MnO6] octahedral double chains, with an aperture of 0.462-0.466 nm2, filled with K cations. Cryptomelane might be a real naturally-occurring mineral of the active octahedral molecular sieve (OMS-2). CrⅥ-bearing wastewater can be treated by natural pyrrhotite, which is used as a reductant to reduce CrⅥ and as a precipitant to precipitate CrⅢ simultaneously. Batch experiments were conducted using the CTMAB-Montmorillonite as an adsorbent for aromatic contaminants (phenol, aniline, benzene, toluene and xylenes), which are detected frequently in the leaching water from municipal waste deposits around China. The CTMAB modification has proved very effective to enhance the adsorption capacity of the sorbent. Expansion of vermiculite develops loose interior structures, such as pores or cracks, inside briquettes, and thus brings enough oxygen for combustion and the sulfation reaction. Effective combustion of the original carbon reduces the amount of dust in the fly ash.

Human Health Risk Assessment Model of Organic Pollution in Groundwater:Shijiazhuang Industrial Zone

In this study, a risk-based management model is developed and applied to an industrial zone. The models proposed by the United States Environmental Protection Agency and Han Bing have been improved by adding a residual ratio of volatile organic compounds （VOC） after boiling and deleting the related parameters in half-life. Using this improved model, an integrated process was used to assess human health risk level in the study area. Compared with water quality analysis, the results highlight the importance of applying an integrated approach for decision making on risk levels and water protection. The results of this study demonstrated that： （1） Compared with these permissible level standards in China （GB 3838-2002） and National Primary Drinking Water Regulations of the United States, the residents＇ daily life had not been affected by the groundwater in this area （except for relative bad water quality of HB3-4 and HB3-6）; （2） The typical detected organic contaminants of all groundwater samples were chloroform, carbon tetrachloride, trichloroethylene and tetrachloroethene, and the pollution sources were mainly industrial sources by preliminary investigations; （3） As for groundwater, the non-carcinogenic risk values of all samples do not exceed the permissible level of 1.0 and the carcinogenic risk values are relatively lower than the permissible level of 1.00E-06 to 1.00E-04; （4） Drinking water pathway of trichloroethylene and tetrachloroethylene mainly contribute to increasing the health risk of residents＇ in study areas; （5） In terms of non-carcinogenic risk and carcinogenic risk, the health risk order for drinking water pathway and dermal contact pathway was： drinking water pathway 〉 dermal contact pathway.

Organic contamination in the Great Wall bay,Antarctica in austral summer

During 1992/1993 austral summer,oil, BHCs,DDTs,PCBs etc.were determined in the sea water, sediments and organisms samples of the Great Wall bay,Antarctica.In surface sea water,the mean concentrations of oil were 0. 26-0. 93 μg/L.DDTs were all lower than the DL of the method,that was<0.04ng/L. BHCs mean concentrations were<0.69-<1.94 ng/L. In other samples,oil,BHCs,DDTs,and PCBs were all relatively higher in patella than that in sediments and seaweed. PAHs could not be detected in all samples. By comparison,the concentrations level of organic contaminants in the Great Wall bay was low yet.

Potential risks of organic contaminated soil after persulfate remediation:Harmful gaseous sulfur release

Persulfate is considered a convenient and efficient remediation agent for organic contaminated soil.However,the potential risk of sulfur into the soil remediation by persulfate remains ignored.In this study,glass bottles with different persulfate dosages and groundwater tables were set up to simulate persulfate remediation of organic pollutants(aniline).The results found sulfate to be the main end-product(83.0%–99.5%)of persulfate remediation after10 days.Moreover,H_(2)S accounted for 93.4%–99.4%of sulfur reduction end-products,suggesting that H_(2)S was the final fate of sulfur.H_(2)S was released rapidly after one to three days at a maximum concentration of 33.0 ppm,which is sufficient to make a person uncomfortable.According to the fitted curve results,H_(2)S concentration decreased to a safe concentration(0.15 ppm)after 20–85 days.Meanwhile,the maximum concentration of methanethiol reached 0.6 ppm.These results indicated that secondary pollution from persulfate remediation could release harmful gases over a long time.Therefore,persulfate should be used more carefully as a remediation agent for soil contamination.

The mechanism study of low-pressure air plasma cleaning on large-aperture optical surface unraveled by experiment and reactive molecular dynamics simulation

Low-pressure air plasma cleaning is an effective method for removing organic contaminants on large-aperture optical components in situ in the inertial confinement fusion facility.Chemical reactions play a significant role in plasma cleaning,which is a complex process involving abundant bond cleavage and species generation.In this work,experiments and reactive molecular dynamics simulations were carried out to unravel the reaction mechanism between the benchmark organic contaminants of dibutyl phthalate and air plasma.The optical emission spectroscopy was used to study the overall evolution behaviors of excited molecular species and radical signals from air plasma as a reference to simulations.Detailed reaction pathways were revealed and characterized,and specific intermediate radicals and products were analyzed during experiments and simulation.The reactive species in the air plasma,such as O,HO_(2)and O_(3)radicals,played a crucial role in cleaving organic molecular structures.Together,our findings provide an atomic-level understanding of complex reaction processes of low-pressure air plasma cleaning mechanisms and are essential for its application in industrial plasma cleaning.

Influence of dissolved organic carbon on multimedia distribution and toxicity of fipronil and its transformation products in lotic waterways

Environmental fate and ecological impacts of fipronil and its transformation products(FIPs)in aquatic environment have caused worldwide attention,however,the influence of dissolved organic carbon(DOC)on multimedia distribution,bioavailability,and toxicity of FIPs in field waterways was largely unknown.Here,we collected 11 companion water and sediment samples along a lotic stream in Guangzhou,South China.FIPs were ubiquitous with total water concentrations ranging from 1.22 to 43.2 ng/L(14.8±12.9 ng/L)and fipronil sulfone was predominant in both water and sediment.More than 70%of FIPs in aqueous phase were bound to DOC and the KDOC values of FIPs were approximately 1–2 orders of magnitude higher than K_(d-s)/K_(OC),emphasizing the significance of DOC in phase partitioning and transport of FIPs in aquatic environment.Water and sediment samples were more toxic to Chironomus dilutus than Hyallela azteca,and FIPs(especially fipronil sulfone)pronouncedly contributed toxicity to C.dilutus.Toxic units(TU)based on freely dissolved concentrations in water determined by solid phase microextraction significantly improved toxicity estimation of FIPs to the invertebrates compared to TUs based on aqueous concentrations.The present study highlights the significance of DOC association on fate and ecological risk of hydrophobic insecticides in lotic ecosystem.