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.

Acute airway emergency caused by an organic foreign body located in the laryngeal mucosa

INTRODUCTION Organic material(e.g.nuts in children and bones or food in adults)is the most common foreign body inhaled by patients.Just one tenth of all foreign bodies in the airway are located in the larynx.^([1])Laryngeal foreign bodies among adults are rarely seen but can be a life threatening

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.

Mottness,phase string,and high-T_(c)superconductivity

It is a great discovery in physics of the twentieth century that the elementary particles in nature are dictated by gauge forces,characterized by a nonintegrable phase factor that an elementary particle of charge q acquires from A to B points:P exp(iq/hc∫A^(B)A_(μ)dxμ),where Aμis the gauge potential and P stands for path ordering.In a many-body system of strongly correlated electrons,if the so-called Mott gap is opened up by interaction,the corresponding Hilbert space will be fundamentally changed.A novel nonintegrable phase factor known as phase-string will appear and replace the conventional Fermi statistics to dictate the low-lying physics.Protected by the Mott gap,which is clearly identified in the high-Tc cuprate with a magnitude>1.5 e V,such a singular phase factor can enforce a fractionalization of the electrons,leading to a dual world of exotic elementary particles with a topological gauge structure.A non-Fermi-liquid“parent”state will emerge,in which the gapless Landau quasiparticle is only partially robust around the so-called Fermi arc regions,while the main dynamics are dominated by two types of gapped spinons.Antiferromagnetism,superconductivity,and a Fermi liquid with full Fermi surface can be regarded as the low-temperature instabilities of this new parent state.Both numerics and experiments provide direct evidence for such an emergent physics of the Mottness,which lies in the core of a high-Tc superconducting mechanism.

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.

Insights into the enzymatic degradation of DNA expedited by typical perfluoroalkyl acids

Perfluoroalkyl acids(PFAAs)are considered forever chemicals,gaining increasing attention for their hazardous impacts.However,the ecological effects of PFAAs remain unclear.Environmental DNA(eDNA),as the environmental gene pool,is often collected for evaluating the ecotoxicological effects of pollutants.In this study,we found that all PFAAs investigated,including perfluorohexanoic acid,perfluorooctanoic acid,perfluorononanoic acid,and perfluorooctane sulfonate,even at low concentrations(0.02 and 0.05 mg/L),expedited the enzymatic degradation of DNA in a nonlinear dose–effect relationship,with DNA degradation fragment sizes being lower than 1,000 bp and 200 bp after 15 and 30 min of degradation,respectively.This phenomenon was attributed to the binding interaction between PFAAs and AT bases in DNA via groove binding.van der Waals force(especially dispersion force)and hydrogen bonding are the main binding forces.DNA binding with PFAAs led to decreased base stacking and right-handed helicity,resulting in loose DNA structure exposing more digestion sites for degrading enzymes,and accelerating the enzymatic degradation of DNA.The global ecological risk evaluation results indicated that PFAA contamination could cause medium and high molecular ecological risk in 497 samples from 11 contamination-hot countries(such as the USA,Canada,and China).The findings of this study show new insights into the influence of PFAAs on the environmental fates of biomacromolecules and reveal the hidden molecular ecological effects of PFAAs in the environment.

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.

Activation of peracetic acid by metal-organic frameworks(ZIF-67)for efficient degradation of sulfachloropyridazine

Peracetic acid(PAA)-based system is becoming an emerging advanced oxidation process(AOP)for effective removal of organic contaminants from water.Various approaches have been tested to activate PAA,while no previous researches reported the application of metal-organic frameworks(MOFs)materials for PAA activation.In this study,zeolitic imidazole framework(ZIF)-67,a representative MOFs,was facile synthesized via direct-mixing method at room temperature,and tested for PAA activation and sulfachloropyridazine(SCP)degradation.The as-synthesized ZIF-67 exhibited excellent performance for PAA activation and SCP degradation with 100%of SCP degraded within 3 min,owing to the specific MOFs structure and abundant Co^(2+) sites.The pseudo-first-order kinetic model was applied to fit the kinetic data,with rate constant k_(1) of ZIF-67 activated PAA system 34.2 and 156.5 times higher than those of conventional Co_(3)O_(4)activated PAA and direct oxidation by PAA.Radical quenching experiments and electron paramagnetic resonance(EPR)analysis indicated that CH_(3)C(O)OO^(·)played a major role in this PAA activation system.Then,the Fukui index based on density functional theory(DFT)calculation was used to predict the possible reaction sites of SCP for electrophilic attack by CH_(3)C(O)OO^(·).In addition,the degradation pathway of SCP was proposed based on Fukui index values and intermediates detection,which mainly included the S-N bond cleavage and SO_(2)extrusion and followed by further oxidation,dechlorination,and hydroxylation.Therefore,ZIF-67 activated PAA is a novel strategy and holds strong potential for the removal of emerging organic contaminants(EOCs)from water.

Highly efficient degradation of emerging contaminants by magnetic CuO@Fe_(x)O_(y) derived from natural mackinawite(FeS) in the presence of peroxymonosulfate

In this study,natural mackinawite (Fe S),a chalcophilic mineral,was utilized to prepare iron/copper bimetallic oxides (Cu^(O)@Fe_(x)O_(y)) by displacement plating and calcination process.Various characterization methods prove that Cu;is successfully coated on the surface of Fe S,which were further oxidized to Cu^(O),Fe_(3)O_(4)and/or Fe_(2)O_(3)during calcination process,respectively.Cu^(O)@Fe_(x)O_(y)performed highly efficient capacity to activate PMS for the degradation of various emerging pollutants including sulfamethoxazole(SMX),carbamazepine (CBZ),bisphenol A (BPA),2,4-dichlorophenol (2,4-DCP) and diclofenac (DCF) in aqueous solution.Complete removal of the above pollutants was observed after 8 min of Cu^(O)@Fe_(x)O_(y)/PMS treatment.Taking SMX as an example,the key parameters including Cu^(O)@Fe_(x)O_(y)dosage,PMS dosage and initial p H were optimized.The results show that the catalytic system can be worked in a wide p H range (3.0-9.0).The quenching experiments and electron spin resonance (ESR) test demonstrated that the main reactive oxygen species in Cu^(O)@Fe_(x)O_(y)/PMS system were hydroxyl radicals (^(·)OH) and sulfate radicals(SO_(4)^(·ˉ)),and SO_(4)^(·ˉ)was the primary reactive species.Besides,the influence of coexisting anions (i.e.,Cl^(ˉ),NO_(3)^(ˉ),HCO_(3)^(ˉ)and H_(2)PO_(4)^(ˉ)) for the degradation of SMX was explored.Cu^(O)@Fe_(x)O_(y)/PMS system can maintain good catalytic activity and reusability in different water bodies and long-term running.This work provided a green strategy to fabricate the efficient catalyst in PMS-based advanced oxidation processes.

Remediation of preservative ethylparaben in water using natural sphalerite:Kinetics and mechanisms

As a typical class of emerging organic contaminants(EOCs), the environmental transformation and abatement of preservative parabens have raised certain environmental concerns. However, the remediation of parabens-contaminated water using natural matrixes(such as, naturally abundant minerals) is not reported extensively in literature. In this study, the transformation kinetics and the mechanism of ethylparaben using natural sphalerite(NS) were investigated. The results show that around 63% of ethylparaben could be absorbed onto NS within 38 hr, whereas the maximum adsorption capacity was 0.45 mg/g under room temperature. High temperature could improve the adsorption performance of ethylparaben using NS. In particular, for the temperature of 313 K, the adsorption turned spontaneous. The well-fitted adsorption kinetics indicated that both the surface adsorption and intra-particle diffusion contribute to the overall adsorption process. The monolayer adsorption on the surface of NS was primarily responsible for the elimination of ethylparaben. The adsorption mechanism showed that hydrophobic partitioning into organic matter could largely govern the adsorption process, rather than the Zn S that was the main component of NS. Furthermore, the ethylparaben adsorbed on the surface of NS was stable, as only less than 2% was desorbed and photochemically degraded under irradiation of simulated sunlight for 5 days. This study revealed that NS might serve as a potential natural remediation agent for some hydrophobic EOCs including parabens, and emphasized the significant role of naturally abundant minerals on the remediation of EOCs-contaminated water bodies.

Predicting the effect of dissolved humic acid on sorption of benzotriazole to biochar

Dissolved organic matter plays a critical role in affecting sorption properties of biochar for organic contaminants.In this study,dissolved humic acid(DHA)as a representative of dissolved organic matter and oak sawdust-derived biochar as a sorbent were prepared and characterized.Roles of DHA in sorption of benzotriazole(BTA),an emerging organic contaminant,to biochar in different electrolyte solutions were investigated.The results revealed the dual roles of DHA in BTA sorption to biochar.On the one hand,DHA can compete for sites and/or block pores available for BTA to inhibit the adsorption of BTA to biochar.On the other hand,the sorbed DHA on biochar can serve as additional partitioning phase to promote the partition of BTA.The finding was in accordance with the site energy distribution analysis of BTA sorption that the site energy of the highest occurring frequency in the DHA-BTA system was lower than that in the DHA-free system(3.41-10.4 versus 13.1-20.1 kJ mol^(−1)).The variation in apparent BTA sorption to biochar affected by DHA was thus a combination of changes in both its partition and adsorption properties.A modified Dual-mode model including the aqueous concentration of DHA was proposed to predict the effect of DHA on BTA sorption to biochar in different electrolyte solutions,which showed good prediction performance with most BTA sorption coefficient(K_(d),L g^(−1))deviations within 0.1 log unit.