Nitrite leads to the formation of N-nitrosodimethylamine during sulfate radical oxidation of dimethylamine compounds.

Sulfate radical (SO) advanced oxidation processes (SR-AOPs) are efficient for degrading a broad spectrum of contaminants. This study demonstrates that the existence of environmentally relevant concentrations of nitrite (NO) can lead to the formation of N-nitrosodimethylamine (NDMA), a probable human carcinogen, when heat activated peroxydisulfate (heat/PDS) is applied to address contaminants with dimethylamine moieties, such as tetracyclines. NO effectively competes with tetracyclines for SO at a high second-order reaction rate constant of 8.

Revealing the Overlooked Catalytic Ability of γ-AlO: Efficient Activation of Peroxymonosulfate for Enhanced Water Treatment.

Activated alumina (γ-AlO) is one of the few nanomaterials manufactured at a ton-scale and successfully implemented in large-scale water treatment. Yet its role in advanced oxidation processes (AOPs) has primarily been limited to functioning as an inert carrier due to its inherently nonredox nature. This study, for the first time, presents the highly efficient capability of γ-AlO to activate peroxymonosulfate (PMS) for selectively eliminating electron-rich organic pollutants in the presence of Cl.

Nitrite facilitated transformation of halophenols in ice.

This study investigated the expediated transformation of halophenols in the presence of nitrite (NO) under slightly acidic conditions in ice, whereas such transformation was negligible in liquid water at 4 °C. We proposed that this phenomenon was attributed to the freeze-concentration effect, incurring a pH drop and the aggregation of NO and halophenols within the liquid-like grain boundary layer amid ice crystals. Within this micro-environment, NO underwent protonation to generate reactive nitrous acid (HNO) and nitrosonium ions (NO) that facilitate the nitration and oxidation of halophenols.

Photochemical degradation of bisphenol S and its tetrahalogenated derivatives in water.

Bisphenol S (BPS), a widely used plasticizer, is known to have potential endocrine disrupting effects to organisms. Its tetrahalogenated derivatives, tetrachlorobisphenol S (TCBPS) and tetrabromobisphenol S (TBBPS), are flame retardants exhibiting high neurodevelopmental toxicity and cytotoxicity. Halogen substitution has been shown to significantly affect the optical and photochemical properties of organic compounds.

Aqueous photolysis of naproxen exposed to UV and natural sunlight: Formation of excited triplet and photosensitizing product.

Photochemical transformation is an important attenuation process for the non-steroidal anti-inflammatory drug naproxen (NPX) in both engineered and natural waters. Herein, we investigated the photolysis of NPX in aqueous solution exposed to both ultraviolet (UV, 254 nm) and natural sunlight irradiation. Results show that N purging significantly promoted NPX photolysis under UV irradiation, suggesting the formation of excited triplet state (NPX*) as a critical transient.

Photo-transformation of isoproturon under UV-A irradiation: The synergy of nitrite and natural organic matter.

Isoproturon (IPU), a widely utilized phenylurea herbicide, is recognized as an emerging contaminant. Previous studies have predominantly attributed the degradation of IPU in natural waters to indirect photolysis by natural organic matter (NOM). Here, we demonstrate that nitrite (NO) also serves as an important photosensitizer that induces the photo-degradation of IPU.

Formation of brominated and nitrated byproducts during unactivated peroxymonosulfate oxidation of phenol.

Brominated and nitrated byproducts generated from bromide (Br) and nitrite (NO), respectively, by sulfate radical (SO) oxidation have raised increasing concern. However, little is known about the concurrent generation of brominated and nitrated byproducts in the unactivated peroxymonosulfate (PMS) oxidation process. This study revealed that Br can facilitate the transformation of NO to nitrated byproducts during unactivated PMS oxidation of phenol.

Formation of nitrated naphthalene in the sulfate radical oxidation process in the presence of nitrite.

Polycyclic aromatic hydrocarbons (PAHs) have become a global environmental concern due to their potential hazardous implication for human health. In this study, we found that sulfate radical (SO) could effectively degrade naphthalene (NAP), a representative PAH in groundwaters, generating 1-naphthol. This intermediate underwent further degradation, yielding ring-opening products including phthalic acid and salicylic acid.

Ketoprofen products induced photosensitization of sulfonamide antibiotics: The cocktail effects of pharmaceutical mixtures on their photodegradation.

Indirect photolysis induced by naturally occurring sensitizers constitutes an important pathway accounting for the transformation and fate of many recalcitrant micropollutants in sunlit surface waters. However, the photochemical transformation of micropollutants by photosensitizing pharmaceuticals has been less investigated. In this study, we demonstrated that the non-steroidal anti-inflammatory drug ketoprofen (KTF) and its photoproducts, 3-acetylbenzophenone (AcBP) and 3-ethylbenzophenone (EtBP), could sensitize the photodegradation of coexisting sulfonamide antibiotics, e.

Oxidation of emerging contaminants by S(IV) activated ferrate: Identification of reactive species.

Studies on the Fe(VI)/S(IV) process have focused on improving the efficiency of emerging contaminants (ECs) degradation under alkaline conditions. However, the performance and mechanisms under varying pH levels remain insufficiently investigated. This tudy delved into the efficiency and mechanism of Fe(VI)/S(IV) process using sulfamethoxazole (SMX) and ibuprofen (IBU) as model contaminants.

Formation of halogenated chloroxylenols through chlorination and their photochemical activity.

Trace organic contaminants usually go through multiple treatment units in a modern water treatment train. Structural modification triggered by pretreatment (e.g.

Photo-transformation of acetaminophen sensitized by fluoroquinolones in the presence of bromide.

Fluoroquinolones (FQs) are a class of antibiotics with emerging concern. This study investigated the photochemical properties of two representative FQs, i.e.

Degradation of tetracyclines by peracetic acid and UV/peracetic acid: Reactive species and theoretical computations.

As an environment-friendly oxidant and disinfectant, peracetic acid (PAA) and PAA based-advanced oxidation processes (AOPs) for the treatment of emerging micropollutants have raised increasing interest, owing to their ease of activation and less generation of harmful disinfection byproducts. Tetracyclines (TCs) antibiotics as a group of wide-spectrum antibiotics are frequently detected in sewage effluents, while the knowledge of PAA-based advanced oxidation reactions to remove the substrates is quite limited. In this work, we systematically investigated the kinetics and underlying transformation mechanisms of three TCs including tetracycline (TTC), oxytetracycline (OTC), and chlortetracycline (CTC) in the UV-activated PAA oxidation process.

New Insights into the Role of Nitrite in the Degradation of Tetrabromobisphenol S by Sulfate Radical Oxidation.

Tetrabromobisphenol S (TBBPS) is a brominated flame retardant and a contaminant of emerging concern. Several studies found that sulfate radical (SO) oxidation is effective to degrade TBBPS. Here, we demonstrate that the presence of nitrite (NO) at environmentally relevant levels causes dramatic changes in the kinetics and pathways of TBBPS degradation by SO.

Amorphous zirconium oxide activates peroxymonosulfate for selective degradation of organic compounds: Performance, mechanisms and structure-activity relationship.

Application of heterogeneous advanced oxidation processes (AOPs) for wastewater treatment suffers from the low oxidant utilization efficiency, slow catalytic cycling and severe matrix interference. Herein, we report that amorphous zirconium dioxide (aZrO), a redox-inert metal oxide, can efficiently activate peroxymonosulfate (PMS) to degrade organic micropollutants under very low oxidant doses and complex coexisting matrices. Distinct from conventional AOPs where radicals are formed, the surface Zr(IV)-PMS* complex was identified as the principal reactive species, and primarily conducted oxygen-atom-transfer route with selected molecules.

Photodegradation of phenylurea herbicides sensitized by norfloxacin and the influence of natural organic matter.

The photochemical activity of fluoroquinolone antibiotics (FQs) has gained attention due to the discovery of their phototoxicity and photocarcinogenicity in clinics. This study reveals that norfloxacin (NOR) can sensitize the photodegradation of phenylurea (PU) herbicides. This is attributed to the formation of an excited triplet of norfloxacin (NOR*) by UV-A irradiation of its quinolone chromophore, which can further react with O to form singlet oxygen (O).

Aquatic photolysis of the pharmaceutical ambroxol: The role of 2,4-dibromoaniline chromophore and heavy atom effect of bromine.

As one of the most effective expectorant class drugs, ambroxol (AMB) has been frequently used to treat acute and chronic bronchitis. Extensive use and human excretion result in the widespread occurrence of AMB in wastewater. Herein, we reported the photolysis of AMB in aqueous solution upon 254 nm ultraviolet radiation (UV).

Degradation of Tetrabromobisphenol S by thermo-activated Persulphate Oxidation: reaction Kinetics, transformation Mechanisms, and brominated By-products.

Brominated flame retardants (BFRs) are a group of contaminants of emerging environmental concern. In this study, systematic exploration was carried out to investigate the degradation of tetrabromobisphenol S (TBBPS), a typical emerging BFRs, by thermally activated persulfate (PDS) oxidation. The removal of 5.

Electrochemical Reduction and Oxidation of Chlorinated Aromatic Compounds Enhanced by the Fe-ZSM-5 Catalyst: Kinetics and Mechanisms.

Devising cost-effective electrochemical catalyst system for the efficient degradation of chlorinated aromatic compounds is urgently needed for environmental pollution control. Herein, a Fe-ZSM-5 zeolite was used as a suspended catalyst to facilitate the degradation of lindane as a model chlorinated pesticide in an electrochemical system consisting of the commercial DSA (Ti/RuO-IrO) anode and graphite cathode. It was found that the Fe-ZSM-5 zeolite greatly accelerated the degradation of lindane, with the degradation rate constant more than 8 times higher than that without Fe-ZSM-5.

Formation of chlorate and perchlorate during electrochemical oxidation by Magnéli phase TiO anode: inhibitory effects of coexisting constituents.

Formation of chlorate (ClO) and perchlorate (ClO) as by-products in electrooxidation process has raised concern. In the present study, the formation of ClO and ClO in the presence of 1.0 mM Cl on boron doped diamond (BDD) and Magneli phase titanium suboxide (TiO) anodes were evaluated.

Nitrophenolic byproducts formation during sulfate radical oxidation and their fate in simulated drinking water treatment processes.

Nitrite can be transformed to nitrophenolic byproducts in sulfate radical oxidation processes (SR-AOPs). These nitrophenols are highly mobile in subsurface and can potentially contaminate drinking water sources. However, their fate in a drinking water treatment remains ambiguous.

Differentiation of Pathways of Nitrated Byproduct Formation from Ammonium and Nitrite During Sulfate Radical Oxidation.

Recent studies found that both nitrite (NO) and ammonium (NH) lead to nitrophenolic byproducts in SO oxidation processes, during which NO generated through the oxidation of the inorganic nitrogen by SO is the key nitrating agent. This study demonstrates that the formation of phenoxy radicals to which NO can be incorporated immediately is another governing factor. Two types of sites having distinct reactivities in natural organic matter (NOM) molecules can be transformed to phenoxy radicals upon SO oxidation.

Experimental and theoretical study on Fe(VI) oxidative degradation of dichlorophen in water: Kinetics and reaction mechanisms.

Dichlorophenol (DCP), a commonly used fungicide and insecticide, is widely found in waters and wastewaters. Herein, the degradation of DCP by Ferrate (Fe(VI)) in different matrices was comprehensively investigated. In pure water, a complete removal of DCP was achieved in 300 s at [Fe(VI)]:[DCP] molar ratio of 2:1.

Formation of brominated by-products during the degradation of tetrabromobisphenol S by Co/peroxymonosulfate oxidation.

Tetrabromobisphenol S (TBBPS), an emerging brominated flame retardant, can cause neurotoxic and cytotoxic effects to human physiology. In this study, the degradation of TBBPS in Co activated peroxymonosulfate (PMS) oxidation process was explored. In particular, brominated by-products formed during the degradation of the TBBPS were examined.

Transformation of amino acids and formation of nitrophenolic byproducts in sulfate radical oxidation processes.

In this study, the transformation of five amino acids (AAs), i.e., glycine (GLY), alanine (ALA), serine (SER), aspartic acid (ASP), and methionine (MET), in a heat activated peroxydisulfate (PDS) oxidation process was investigated.