Organic Contaminants In Water Research Articles

Enhanced photo-Fenton degradation of fluoroquinolones in water assisted by a 3D composite sponge complexed with a S-scheme MoS2/Bi2S3/BiVO4 ternary photocatalyst

A constructed MoS2/Bi2S3/BiVO4 ternary photocatalyst(MBB) mainly with a S-scheme heterostructure was loaded on a 3D lignosulfonate modified poly(vinyl formal) sponge to obtain a novel composite sponge(PLS-MBB) with an enhanced performance in synergistic adsorption and photo-Fenton degradation of various fluoroquinolones(FQs) in water. The synergistic adsorption and photocatalysis of PLS-MBB notably improved the applicable pH from 2.0 to 9.0 and reduced the dosage of Fe2+ to 0.014 mmol/L in Fenton reaction, which could achieve the degradation efficiency of 92.8 % for FQs within 60.0 min at pH 6.0. The photo-generated electrons by MBB and the redox transformation of Mo(IV)/Mo(VI) and Bi(III)/Bi(V) accelerated the conversion of Fe3+ to Fe2+; besides, the efficient adsorption of FQs on the sponge carrier promoted the surface degradation in solution, thereby causing an enhanced photo-Fenton reaction. This work provided a novel strategy to improve photo-Fenton reaction and accordingly fabricated a talented material for effective removal of organic contaminants in water.

Preparation of ultra-thin porous carbon nitride and its photocatalytic H2O2 production and photodegradation of RhB

The degradation of organic contaminants in water is a pressing issue that must be addressed·H2O2 has a strong oxidation ability and is frequently used in environmental remediation as a reactive oxygen species in advanced oxidation technology. In this study, using supramolecular self-assembly method we synthesized carbon nitride (CN) with an ultra-thin porous structure. The optimally modified CN (CN-MCA-U-2.5), had excellent H2O2 production activity under LED white light, with a rate of 377.06 μmol/(g × h), which was 12.09 times greater than that of CN. Furthermore, after 5 h under visible light irradiation, the H2O2 yield of CN-MCA-U-2.5 was 1256.80 μmol/g. Furthermore, CN-MCA-U-2.5 also had excellent Rhodamin B (RhB) degrading activity. The degradation degree reached 88.50% in 30 min under the excitation of LED white light. The reaction pathway of H2O2 for CN-MCA-U-2.5 was found to be a two-step single-electron O2 reduction reaction, according to the mechanism analysis. O2 and HO2 were the major variables in the degradation process.

Effect-Directed Analysis Based on the Reduced Human Transcriptome (RHT) to Identify Organic Contaminants in Source and Tap Waters along the Yangtze River.

Since a large number of contaminants are detected in source waters (SWs) and tap waters (TWs), it is important to perform a comprehensive effect evaluation and key contributor identification. A reduced human transcriptome (RHT)-based effect-directed analysis, which consisted of a concentration-dependent RHT to reveal the comprehensive effects and noteworthy pathways and systematic identification of key contributors based on the interactions between compounds and pathway effects, was developed and applied to typical SWs and TWs along the Yangtze River. By RHT, 42% more differentially expressed genes and 33% more pathways were identified in the middle and lower reaches, indicating heavier pollution. Hormone and immune pathways were prioritized based on the detection frequency, sensitivity, and removal efficiency, among which the estrogen receptor pathway was the most noteworthy. Consistent with RHT, estrogenic effects were widespread along the Yangtze River based on in vitro evaluations. Furthermore, 38 of 100 targets, 39 pathway-related suspects, and 16 estrogenic nontargets were systematically identified. Among them, diethylstilbestrol was the dominant contributor, with the estradiol equivalent (EEQ) significantly correlated with EEQwater. In addition, zearalenone and niclosamide explained up to 54% of the EEQwater. The RHT-based EDA method could support the effect evaluation, contributor identification, and risk management of micropolluted waters.

Passive sampling hydrophilic and hydrophobic bisphenol analogues using hydrophilic-lipophilic balance sorbent-embedded cellulose acetate membrane in surface waters

Bisphenol analogues (BPs) are ubiquitous emerging contaminants in water environments and have wide polarity ranges (1.65 < log Kow < 7.2). Integrated passive sampling strategy rarely contains hydrophilic and hydrophobic organics simultaneously, while the method has good application perspective in monitoring organic contaminants. This work evaluated passive sampling performance for fifteen BPs in a newly developed passive sampler, i.e., hydrophilic-lipophilic balance sorbent-embedded cellulose acetate membrane (HECAM). In the dynamic accumulation experiments, both hydrophilic and hydrophobic BPs (including moderately hydrophilic BPs) well followed first-order kinetic uptake in the HECAMs. The estimated uptake rate constants, elimination rate constants, and equilibrium partition coefficients for BPs ranged from 4.4 L g−1 d−1 to 14.7 L g−1 d−1, 0.22 d−1 to 0.72 d−1, and 3.99 to 4.64, respectively. The kinetic parameters for BPs in HECAM show limited correlations to log Kow values, which the rule differs from traditional passive sampler. In the study of elimination kinetics, three deuterium labeled compounds showed incomplete elimination in HECAM and did not follow first-order isotropic exchange kinetics. Dual sorption mechanisms including both adsorption and partition were found for chemicals in HECAM, which the partitioned part could release to water and the adsorbed part could not easily release to water from HECAM. As a result, performance reference compounds (PRCs) calibration may be inapplicable to HLB sorbent-based passive sampler. The field deployment of HECAM in coastal waters of Guangdong, China resulted in the detection of eleven BPs, which indicated that the waters have been polluted by various BPs. Finally, monitoring strategy of simultaneous passive sampling hydrophobic and hydrophilic organic contaminants in surface waters was recommended.

Treatment of water contaminated with petroleum hydrocarbons using a biochar derived from seagrass biomass as low-cost adsorbent: isotherm, kinetics and reusability studies

ABSTRACT Petroleum hydrocarbons, including alkanes ranging from C10 to C32, have been recognized as priority organic water contaminants with a toxic impact on ecosystems. Therefore, the removal of these contaminants is of utmost importance to protect humans, plants and animals. In this work, biochar derived from the dead leaves of the widely-distributed seagrass Halodule uninervis (SGC) was prepared through biomass pyrolysis at 800°C and characterized using SEM, FTIR, TGA and surface area analysis. The prepared SGC was investigated for adsorptive removal of total petroleum hydrocarbons (TPHs) and individual alkane hydrocarbons (C10 to C32) from water contaminated with crude oil. The SGC displayed good removal efficiency, adsorption capacity and recyclability toward these hydrocarbons. Using the SGC, 98.8% of the TPHs were removed within 300 minutes with an adsorption capacity of 23.5 mg/g. The adsorption results were tested with the most commonly used isotherm and kinetics models. The hydrocarbon adsorption data for the SGC fit the Langmuir and Freundlich isotherms, which indicates non-uniformity of the adsorbent and a predominance of multilayer adsorption of the hydrocarbons onto the prepared SGC adsorbent. The performance and reusability of the prepared SGC adsorbent were promising, losing only 22% of its hydrocarbon removal efficiency after the 3rd cycle.

Comparison of in-situ and ex-situ methods for synthesis of iron magnetic nanoparticles-doped graphene oxide: Characterization, adsorption capacity, and Fenton catalytic efficiency

In this research, iron magnetic nanoparticles-doped graphene oxide (Fe3O4/GO or FG) materials were synthesized via the in-situ (FGI) and ex-situ (FGE) methods, with several mass ratios of precursors. The FG2I and FG2E samples with the mass ratio of Fe3O4:GO = 3:7 exhibit effective removal of methylene blue (MB) in water by utilizing the adsorption and Fenton catalyst methods. Characterizations of the materials were investigated by modern analysis methods. The results showed that FGI material possesses a larger specific surface area and Fe3O4 nanoparticles are more evenly dispersed on the GO surface than that of FG2E. The examination of MB removal also demonstrated the predominance of FGI over FGE material in both adsorption and Fenton catalyst evaluations. The MB adsorption process of FGI is consistent with the apparent second-order kinetics equation and the Langmuir isotherm model. The highest removal by Fenton reaction of MB (over 99 %) using FG2I was achieved with 1 mL of H2O2 and 50 mg/L of MB at a temperature of 50 °C for 180 min. Thus, the efficiency of the material via adsorption and Fenton catalytic experiments reached 69.21 and 91.23 %, respectively, after five consecutive runs. Therefore, the use of FGI is cost-saving and relatively effective for eliminating organic contaminants in water, which shows its high potential in future applications.

Novel 3D Printed Vortex-like Flexible Roller-Compacted Triboelectric Nanogenerator for Self-Powered Electrochemical Degradation of Organic Contaminants.

It is an ideal way to use triboelectric nanogenerators (TENGs) to capture energy from the environment for the degradation of organic contaminants in water as a zero-carbon pathway. However, there is an urgent need to further develop TENGs with a simple structure and high output power. Herein, a novel TENG with a vortex-like flexible self-recovery blades of inner stator (denoted as VFR-TENG) is designed and manufactured with the assistance of a fused deposition modeling 3D printing technology. With the rotation of the outer rotor, a facile rotating contact-separation mode is achieved by the alternating arrangement of the flexible self-recovery blades. The contact tightness of the friction layer, a key factor for the transfer of charge density, can be easily adjusted by the thickness and arrangement style of the flexible self-recovery blades. The regulation of material elasticity and rotational frequency on the output characteristics is further investigated based on the special flexible structure. The VFR-TENG exhibits an instantaneous short-circuit current of 350 μA, an open-circuit voltage of 650 V, a transferred charge of 1.1 μC, and an optimum output power density of 4.4 W·m-2. This high-performance VFR-TENG is used for electrochemical degradation systems, which achieves excellent degradation efficiencies of 88.9, 91.7, and 94.1% for methylene blue, methyl orange, and malachite green within 150 min, respectively. This work provides a new idea for the design of flexible self-recovery contact-separation TENGs, which is of great inspiration for the exploitation of TENGs with both the high peak current and high-frequency characteristics for efficient water treatment.

Graphitic biochar with in situ confined magnetic iron oxides via synchronous pyrolysis of lignin as an effective H2O2 activator for fast degradation of organic pollutants.

Magnetic iron oxide confined in carbon capsules/biochar composite (FeOx@g-BC) was created using in-situ synchronous pyrolysis of alkali lignin as a low-cost carbon source. Characterization results indicated the FeOx was confined in carbon nanotubes and carbon capsules, inhibiting growing of nanoparticles and deactivation. The composite catalyst demonstrated significant activity in activating H2O2 for the degradation of persistent organic pollutants in water over a wide pH range. Particularly, tetracycline (TC) could be completely degraded within 25min, even at a high pH of 6.8, which performed much better than previously reported Fenton-like catalysts. Moreover, the excellent magnetism of FeOx@g-BC aided in its recovery and reuse. The stability of FeOx@g-BC recycling was also measured by continuous cycles of reactions. According to ESR analysis and free radical quenching studies, OH and 1O2 were discovered as the dominant active species governing the degradation of TC, and two pathways of TC degradation were proposed. This study developed a novel heterogeneous catalyst for catalytic degradation of persistent organic contaminants in water by the value-added usage of lignin.

Halides and oxyhalides-based photocatalysts for abatement of organic water contaminants – An overview

Recently, halides (silver halides, AgX; perosvkite halides, ABX3) and oxyhalides (bismuth oxyhalides, BiOX) based nanomaterials are noticeable photocatalysts in the degradation of organic water pollutants. Therefore, we review the recent reports to explore improvement strategies adopted in AgX, ABX3 and BiOX (X = Cl, Br and I)-based photocatalysts in water pollution remediation. Herein, the photocatalytic degradation performances of each type of these photocatalysts were discussed. Strategies such as tailoring the morphology, crystallographic facet exposure, surface area, band structure, and creation of surface defects to improve photocatalytic activities of pure halides and BiOCl photocatalysts are emphasized. Other strategies like metal ion and/or non-metal doping and construction of composites, adopted in these photocatalysts were also reviewed. Furthermore, the way of production of active radicals by these photocatalysts under ultraviolet/visible light source is highlighted. The deciding factors such as structure of pollutant, light sources and other parameters on the photocatalytic performances of these materials were also explored. Based on this literature survey, the need of further research on AgX, ABX3 and BiOX-based photocatalysts were suggested. This review might be beneficial for researchers who are working in halides and oxyhalides-based photocatalysis for water treatment.

CuO with (0 0 1)-plane exposure efficiently induces peroxymonosulfate to form ≡Cu-OOSO3-intermediates directly oxidizing organic contaminants in water

Copper (Cu)/peroxymonosulfate (PMS) is a complex coupling system due to its multiple activation pathways with the formation of diverse radical and nonradical species. However, the effects of CuO with different plane exposures on the properties of the coupling system are not clear. In this research, Cu atom-terminated (001) plane-exposed CuO (CuO-10) is synthesized by a facile hydrothermal method using NH3·H2O as the structure directing agent for the first time. CuO-10 has the excellent property of inducing PMS to degrade bisphenol A (BPA) in water, and its reaction rate constant (k) reaches 14 times higher than that of commercial CuO with exposed (010) plane terminated by O atoms (CuO-C). Meanwhile, CuO-10 exhibits a wide pHinitial adaptability, and its BPA degradation exceeds 87% in the pH range of 3–9. Furthermore, compared with CuO-C/PMS, less radical and 1O2 are found in CuO-10/PMS oxidation system. Compared to the UV/PMS system, organic contaminants in CuO/PMS systems are easier to oxidize via an oxygen-atom-transfer mechanism. Therefore, the ≡Cu(II)-OOSO3- metastable intermediate is speculated to play an important role in the CuO/PMS activation process, which oxidizes organic contaminants directly through oxygen-atom-transfer and single-electron-transfer pathways. Furthermore, the CuO-10/PMS system is more likely to degrade organic pollutants through the oxygen-atom-transfer pathway than the CuO-C/PMS system. This study not only explores the influence of CuO crystal planes in efficiently inducing PMS activation but also provides new insights into the PMS activation process in the CuO/PMS oxidation system.

Charge separation effect in the nanocomposites of Co3O4-QDs: visible light photocatalytic dye degradation in aqueous solutions.

Photo-treatment of water is a promising environmentally friendly process that provides clean water and makes wastewater reusable in industry. Thus, efforts toward finding highly efficient photocatalysts have gained a huge attention to remove the organic contaminants in water. Quantum dots (QDs) are extensively utilized for photocatalytic remediation regarding their prominent optical, electrical, and chemical properties. Herein, we report the highly efficient and environmentally friendly synthesis of Co3O4-QDs-based graphene quantum dots (GQDs) and infinite coordination polymer comprising Zn nodes (Zn-ICP) nanocomposites as active and robust photocatalysts for photo-assisted water treatment. The pristine Co3O4-QDs, GQDs, and Zn-ICP showed lower activity under visible light. However, after functionalization of GQDs and Zn-ICP with Co3O4-QDs, the activity increased, and more photocatalytic efficiency was achieved. For instance, Zn-ICP, GQDs, Co3O4-QDs, Co3O4-QDs/Zn-ICP, and Co3O4-QDs/GQD degraded 21, 19, 52, 73, and 83% of rhodamine B (RhB) and 34, 46, 50, 73, and 76% of methylene blue (MB) after 60min. The high photocatalytic efficiency was ascribed to the conjugation of Co3O4-QDs with GQDs and Zn-ICP which causes efficient absorption of visible light. The existence of Co3O4-QDs was found to be essential not only for effective charge separation but also widening the region of light absorption followed by increase in photocatalytic performances. Charge separation in photocatalytic reactions, energy levels of nanocomposites, and mechanism of the photocatalytic process were investigated by photoluminescence spectra (PL), Mott-Schottky, electrochemical impedance (EIS), and diffuse reflectance UV-Vis spectroscopy (DRS).

Bisulfite activated permanganate for oxidative water decontamination

Recently, bisulfite-activated permanganate (MnO4−; Mn(VII)) process has attracted considerable attention as a novel class of advanced oxidation technology for destruction of organic contaminants in water. However, disputes over the underlying activation mechanism as well as reactive species generated in the Mn(VII)/bisulfite system remain for a long period due to the fairly complex chemistry involved in this system. This article aims to present a critical review on scientific development of the Mn(VII)/bisulfite system, with particular focus on the generation and contribution of various reactive intermediates. Both reactive manganese species (RMnS) (i.e., soluble Mn(III), Mn(V), and Mn(VI)) and radical species (primarily SO4•−) are identified as the oxidizing components responsible for enhanced degradation of organic contaminants by the Mn(VII)/bisulfite system. Bisulfite plays a dual role of being an activating agent for reactive intermediates generation and acting as a complexing agent to stabilize RMnS. Solution chemistry (e.g., the [Mn(VII)]/[bisulfite] molar ratio, solution pH, the type of contaminants, ligands, and water matrix components) greatly impacts the generation and consumption of RMnS and radicals, thus influencing the degradation kinetics and pathways of organics. Particularly, dissolved oxygen (DO) is a vital factor for driving the oxidation of organics since the absence of DO can block the generation of SO4•− and meantime causes the consumption of RMnS by excess SO3•− as a strong reductant. Interestingly, ferrate (FeO42−, Fe(VI)) and hexavalent chromium (CrO42−/HCrO4−, Cr(VI)) that are high-valent metal oxyanions analogous to Mn(VII) can be activated by bisulfite via a similar pathway (i.e. both high-valent metal-oxo intermediates and reactive radicals are involved). Furthermore, key knowledge gaps are identified and future research needs are proposed to address the potential challenges encountered in practical application of the Mn(VII)/bisulfite oxidation technology.

Synthesis of heterogeneous photo-Fenton catalyst from iron rust and its application to degradation of Acid Red 97 in aqueous medium

In this work, magnetic nanoparticles were synthesized from iron rust waste and used as a catalyst for photo-Fenton degradation of Acid red 97 (AR97). The morphology and size of Fe3O4 nanoparticles could be controlled by adding an appropriate amount of water as co-solvent in solvothermal treatment. For a comparative study, α-FeOOH and α-Fe2O3 with nanorod shape were also prepared from iron rust and employed as photo-Fenton catalyst. The photo-Fenton degradation results showed that the prepared Fe3O4 nanoparticles with spherical-like shape possessed higher catalytic activity than octahedral-shaped Fe3O4, α-FeOOH, and α-Fe2O3. It was demonstrated that the synergetic effect between H2O2 and oxalic acid (OA) led to an improvement in the catalytic efficiency of the photo-Fenton system towards AR97 degradation in awide pH range. At 180 min, about 81% of total organic carbon (TOC) was removed. Thus, the mineralization of organic matter is strongly involved during the photo-Fenton process. The quenching experiments showed that •OH radical played a crucial role in the degradation of AR97 by Fe3O4/H2O2/OA/UV system. Benefiting from the high catalytic activity and easy magnetic separation, the prepared Fe3O4 nanoparticles revealed good stability and reusability even after five consecutive cycles. This work offers a sustainable and effective way to recycle iron rust waste into an efficient catalyst for the degradation of organic contaminants in water.

Novel assembly of BiVO4@N-Biochar nanocomposite for efficient detoxification of triclosan

The wide spread of antibacterial and antifungal agents demands in growing multifunctional materials to completely eliminate these organic contaminants in water. BiVO4 (Bismuth vanadate) is a superior catalyst under visible light but suffers with high photoelectron-hole pair recombination rate and poor adsorption capacity which limits its efficiency. Addition of N-doped Biochar (N-Biochar) to BiVO4 with large specific surface area and high conductivity are anticipated to overcome the problem and promote the catalytic performance. Thus, the present study developed a simple hydrothermal method to prepare BiVO4@N-Biochar catalyst for efficient detoxification of Triclosan (TCS). The morphological analysis results suggested that BiVO4 particles were evenly distributed on carbon surface amongst the N-Biochar matrix. Within 60 min of visible light irradiation, nearly 94.6% TCS degradation efficiency was attained by BiVO4@N-Biochar (k = 0.02154 min−1) while only 56.7% was attained with pure BiVO4 (k = 0.00637 min−1). In addition, LC-MS/MS technique was utilized to determine the TCS degradation products generation in the photodegradation process and pathway was proposed. Furthermore, the E. coli (Escherichia coli) colony forming unit assay was used to determine the biotoxicity of the degradation products in which 72.3 ± 2.6% of detoxification efficiency was achieved and suggested a substantial reduction in biotoxicity during the photodegradation.

New insight into environmental photochemistry of PAHs induced by dissolved organic matters: A model of naphthalene in seawater

The photochemical behavior of a model PAH, naphthalene, was investigated under simulated sunlight irradiation with different dissolved organic matter (DOM) in seawater. The results revealed that naphthalene was prone to direct photolysis (Φd = 1.34 × 10-3) and could be degraded by 3DOM*/1O2-induced reactions with fulvic acid (FA) and humic acid (HA) at low concentrations. However, the DOM at a high level dramatically decreased the kobs due to the higher light attenuation and radical competition effect. The presence of FA resulted in lower 3DOM*/1O2 generation and quantum yield compared with HA, but it achieved higher degradation kinetics due to the higher reactivity between 3FA* and naphthalene and their lower binding effect. The naphthalene degradation in natural water with different depths and DOM were modeled based on the experimental results, which revealed the important role of indirect photolysis initiated by inorganic constituents. Moreover, several degradation intermediates were identified by GC-MS and three possible pathways were proposed. The Quantitative Structure Activity Relationships (QSAR) evaluation revealed that some intermediates are more toxic than original naphthalene. This study offers further insights into the photochemical behavior of PAHs, which will facilitate our understanding of the persistence and ecological risks of organic contaminants in natural waters.

Heterogeneous Photocatalytic Activation of Persulfate for the Removal of Organic Contaminants in Water: A Critical Review

Heterogeneous Photocatalytic Activation of Persulfate for the Removal of Organic Contaminants in Water: A Critical Review

Photodegradation and in‐Situ SERS Monitoring Properties of Ag@AgCl Anchored on Sea Urchin‐shaped Fe3O4@C/1D PANI Nanoparticles**

AbstractHere, sea urchin‐shaped nanoparticles were first fabricated by growing one dimensional polyaniline (1D PANI) nanowire array on carbon layer encapsulated Fe3O4 nanoparticles, and then Ag@AgCl photocatalyst were tightly anchored on the surface of PANI nanowire to form Fe3O4@C/1D PANI/Ag@AgCl bifunctional material as recyclable adsorption‐photocatalysts and surface enhanced Raman scattering (SERS) substrate to monitor photocatalytic degradation of dye molecules. Compared with Fe3O4@C/1D PANI, Ag@AgCl and Fe3O4@C/PANI/Ag@AgCl catalysts, the fast electron transfer characteristics of conductive 1D PANI nanowire array and the synergistic effect between the surface plasmon resonance of Ag and the photosensitive characteristic of AgCl, enabled the prepared Fe3O4@C/1D PANI/Ag@AgCl excellent adsorption‐photocatalytic efficiency for the degradation of RhB under visible‐light irradiation. PL spectra and a series of photoelectrochemical measurements were carried out to investigate the reasons for such enhanced photocatalytic activity and the possible improved photocatalytic degradation mechanism was proposed. Meanwhile, the detection of the presence of RhB and its degradation process were achieved with real‐time SERS technology employing the prepared Fe3O4@C/1D PANI/Ag@AgCl photocatalyst itself as the substrate. All the results made it great promise for simultaneously monitoring and removal of organic contaminants in water.

Photo-Fenton Degradation of Methyl Orange with Dunino Halloysite as a Source of Iron

The Fenton reaction is one of the most important processes for water and soil remediation, although this process has some drawbacks such as the use of H2O2 in large amounts, the formation of sludge due to the use of iron salts, and the need for acid pH values. Here we present the use of a natural clay, modified by acid treatment, as a heterogeneous catalyst to replace soluble iron salts and to avoid the use of water peroxide, resulting in a considerable increase in the attractiveness of the process. Halloysite (HT) clay from the Dunino mine consists of alumina and silica layers with the presence of iron species acting as a source of Fe ions. The etching of alumina layers using hydrochloric acid induces the release of iron species (mainly ions) in the solution, giving rise to the photodegradation activity of organic contaminants in water (i.e., Methyl Orange, MO) under UV irradiation without the need for hydrogen peroxide and avoiding the formation of sludges. MO adsorption properties and MO photodegradation ability were investigated for untreated and acid treated samples, respectively, to achieve the optimal process conditions. MO was not adsorbed on the clay’s surface due to electrostatic repulsion, but a complete degradation was observed after three hours under UV irradiation. The kinetics of photodegradation and the values of the half-life time are presented as a measure of the degradation rate. The proposed process shows a new route for effective remediation of water containing biologically active organic substances dissolved in it.

Differential Organic Contaminant Ionization Source Detection and Identification in Environmental Waters by Nontargeted Analysis.

The development of nontargeted analysis (NTA) methods to assess environmental contaminants of emerging concern, which are not commonly monitored, is paramount, especially when no previous knowledge on the identity of the pollution source is available. We compared complementary ionization techniques, namely electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), in the detection and identification of organic contaminants in tap and surface waters from South Florida. Furthermore, the performance of a simple rationalized NTA method was assessed by analyzing 10 complex mixtures as part of the US Environmental Protection Agency's Non-targeted Analysis Collaborative Trial interlaboratory study, where limitations of the NTA approach have been identified (e.g., number of employed databases, false positives). Different water bodies displayed unique chemical features that can be used as chemical fingerprints for source tracking and discrimination. The APCI technique detected at least threefold as many chemical features as ESI in environmental water samples, corroborating the fact that APCI is more energetic and can ionize certain classes of compounds that are traditionally difficult to ionize by liquid chromatography-mass spectrometry. Kendrick mass defect plots and Van Krevelen diagrams were applied to elucidate unique patterns and theoretical chemical space regions of anthropogenic organic compounds belonging to homologous series or similar classes covered by ESI and APCI. Overall, APCI and ESI were established as complementary, expanding the detected NTA chemical space which would otherwise be underestimated by a single ionization source operated in a single polarity setting. Environ Toxicol Chem 2022;41:1154-1164. © 2021 SETAC.

The ozone-activated peroxymonosulfate process (O3/PMS) for removal of trace organic contaminants in natural and wastewater: Effect of the (in)organic matrix composition

• PMS addition improves TrOC removal during ozonation of natural waters. • Higher loads of (in)organic matter in effluent reduces the added value of O 3 /PMS. • Increase in IOD after PMS addition is a good indicator of radical production. • ● OH is the dominant species for TrOC removal by O 3 /PMS in real (waste)water. • Chloride ions are most likely responsible for conversion of SO 4 ●- into ● OH. The ozone-activated peroxymonosulfate process (O 3 /PMS) is an emerging advanced oxidation process for the removal of trace organic contaminants (TrOCs) in water, because it produces both hydroxyl and sulfate radicals. Its potential has been shown in distilled water, but limited research has been performed in real (waste)waters. Therefore, this work focuses on the added value of PMS in ozonation and on fundamental aspects of the process in three different types of water, i.e. secondary effluent, surface water and groundwater. The instantaneous ozone demand (IOD) of the different waters, representing the ozone decomposition by highly ozone reactive species, increased by adding PMS. This effect is more pronounced in surface water and groundwater than in secondary effluent, which indicates more reaction between O 3 and PMS and thus a higher potential for radical production in less loaded matrices. This is also reflected in the (increased) removal of atrazine (ATZ) and chloramphenicol (CHLOR) when applying the O 3 /PMS process. Compared to ozonation, the removal efficiency obtained with O 3 /PMS was 12% higher in secondary effluent, while this was up to 35% and 43% higher in respectively surface water and groundwater. Scavenging experiments and removal of p-nitrobenzoic acid (pNBA), an ● OH probe, showed that hydroxyl radicals rather than sulfate radicals are the main species contributing for > 60% to O 3 /PMS induced TrOC removal in natural and wastewaters. Next to the bulk organic matter, chloride proved to be a crucial matrix constituent that might be responsible for the conversion of sulfate into hydroxyl radicals.