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Environmental Science & Technology Mar 2024The mechanism and kinetics of reactive oxygen species (ROS) formation when atmospheric secondary organic aerosol (SOA) is exposed to solar radiation are poorly...
The mechanism and kinetics of reactive oxygen species (ROS) formation when atmospheric secondary organic aerosol (SOA) is exposed to solar radiation are poorly understood. In this study, we combined an in situ UV-vis irradiation system with electron paramagnetic resonance (EPR) spectroscopy to characterize the photolytic formation of ROS in aqueous extracts of SOA formed by the oxidation of isoprene, α-pinene, α-terpineol, and toluene. We observed substantial formation of free radicals, including OH, superoxide (HO), and organic radicals (R/RO) upon irradiation. Compared to dark conditions, the radical yield was enhanced by a factor of ∼30 for OH and by a factor of 2-10 for superoxide radicals, and we observed the emergence of organic radicals. Total peroxide measurements showed substantial decreases of peroxide contents after photoirradiation, indicating that organic peroxides can be an important source of the observed radicals. A liquid chromatography interfaced with high-resolution mass spectrometry was used to detect a number of organic radicals in the form of adducts with a spin trap, BMPO. The types of detected radicals and aqueous photolysis of model compounds indicated that photolysis of carbonyls by Norrish type I mechanisms plays an important role in the organic radical formation. The photolytic ROS formation serves as the driving force for cloud and fog processing of SOA.
Topics: Peroxides; Reactive Oxygen Species; Photolysis; Superoxides; Aerosols; Air Pollutants
PubMed: 38412378
DOI: 10.1021/acs.est.3c08662 -
Chemosphere Sep 2023In this study, the removal efficiency of chemicals of emerging concerns (CECs) was evaluated under exposure to various doses of UV/HO-based oxidation processes in...
In this study, the removal efficiency of chemicals of emerging concerns (CECs) was evaluated under exposure to various doses of UV/HO-based oxidation processes in combination with membrane filtration for three cleaning cycles. Polyethersulphone (PES) and polyvinylidene fluoride (PVDF) materials based membranes were used for this study. The chemical cleaning of the membranes was performed by immersion of the membranes into 1 N HCl followed by adding 3000 mg.L NaOCl for 1hr. Degradation and filtration performance was evaluated using Liquid Chromatography with tandem mass spectrometry (LC-MS/MS) and total organic carbon (TOC) analysis. Membrane fouling analysis for assessing the comparative performance of PES and PVDF membranes was determined by specific fouling and fouling indices evaluation. Membrane characterization results show that the alkynes and carbonyl group formation are due to dehydrofluorination and oxidation of PVDF and PES membranes under the attack of foulants and cleaning chemicals, which resulted in a reduction of fluoride percentage and an increase in sulfur percentage in the PVDF and PES membranes. A decrease in the hydrophilicity of the membranes in underexposed conditions was observed and is consistent with an increase in dose. Degradation results of CECs follow with the highest removal efficiency of chlortetracycline (CTC) followed by atenolol (ATL), acetaminophen (ACT), and caffeine (CAF) degradation due to attack on the aromatic ring and the carbonyl group of CECs by OH exposure. Membrane exposed at 3 mg.L-1 dose of UV/HO-based CECs shows minimum alteration with higher filtration efficiency and lower fouling, particularly in PES membranes.
Topics: Water; Chromatography, Liquid; Hydrogen Peroxide; Membranes, Artificial; Tandem Mass Spectrometry
PubMed: 37295688
DOI: 10.1016/j.chemosphere.2023.139096 -
Journal of Environmental Management Jul 2024The redesigned engineering building of nanocomposite (NCP) depends on metal oxides of palladium oxide (PdO) nanoparticles (NPs) conjugate with the n-type semiconductor...
Removal of pollutants through photocatalysis, adsorption, and electrochemical sensing by a unique plasmonic structure of palladium and strontium oxide nanoparticles sandwiched between 2D nanolayers.
The redesigned engineering building of nanocomposite (NCP) depends on metal oxides of palladium oxide (PdO) nanoparticles (NPs) conjugate with the n-type semiconductor of strontium oxide (SrO) NPs on the electron carrier surface of graphene oxide (GO) and reduce graphene oxide (rGO) nanosheet is the main target of the current work. The low efficiency of PdO (n-type) and SrO (p-type) gave an overview of the increasing generation electron efficiency via building the ohmic area on the GO and rGO surface using the Z-scheme mechanism. The efficiency of the NCP surface for destroying organic pollutants such as mixed dyes of Rhodamine B and methylene blue (RhB/MB), as against insecticides like imidacloprid, and the removal of heavy metals such as chromium ions was studied. The production of clean water against pollutants materials was investigated through adsorption and photocatalytic processes, electrochemical, and spectroscopy methods to detect the activity of NCP. The rate constant of the adsorption pollutants is 0.1776 min (MB), 0.3489 min (RhB), 0.3627 min (imidacloprid), and 0.5729 min (Cr). The photocatalytic rate recorded at 0.01218 min (MB), 0.0096 min (RhB), appeared degradation rate at 0.0086 min (imidacloprid), 0.0019 min (Cr), and 0.0471 min (Cr). The adsorption and photocatalytic efficiency of nanocatalyst (NCP) was calculated at 91% (RhB), 93% (MB), 73% (imidacloprid), 63% (Cr), while the photocatalytic efficiency is 63% (RhB), 94% (MB), 86% (imidacloprid), 33% (Cr). The recyclability of NCP was tested for five cycles, and the efficiency was discovered at 55% after the fifth cycle. The cytotoxicity of NCP was studied to detect the safety of the fabricated materials. The study validates that the fabricated nanocomposite exhibits great potential as an innovative material for producing clean water.
Topics: Palladium; Adsorption; Catalysis; Graphite; Strontium; Water Pollutants, Chemical; Oxides; Rhodamines; Nanoparticles; Electrochemical Techniques
PubMed: 38850913
DOI: 10.1016/j.jenvman.2024.121257 -
The Science of the Total Environment Mar 2024Papermaking wastewater contained various of toxic and hazardous pollutants that pose significant threats to both the ecosystem and human health. Despite these risks,...
Papermaking wastewater contained various of toxic and hazardous pollutants that pose significant threats to both the ecosystem and human health. Despite these risks, limited research has addressed the detoxification efficiency and mechanism involved in the typical process treatment of papermaking wastewater. In this study, the acute toxicity of papermaking wastewater after different treatment processes was assessed using luminousbacteria, zebrafish and Daphnia magna (D. magna). Meanwhile, the pollution parament of the corresponding wastewater were measured, and the transformation of organic pollutant in the wastewater was identified by three-dimensional fluorescence and other techniques. Finally, the possible mechanism of toxicity variation in different treatment processes were explored in combination with correlation analyses. The results showed that raw papermaking wastewater displayed high acute toxicity to luminousbacteria, and exhibited slight acute toxicity and acute toxicity effect to zebrafish and D. magna, respectively. After physical and biochemical processes, not only the toxicity of the wastewater to zebrafish and D. magna was completely eliminated, but also the inhibitory effect on luminousbacteria was significantly reduced (TU value decreased from 11.07 to 1.66). Among them, the order of detoxification efficiency on luminousbacteria was air flotation > hydrolysis acidification > IC > aerobic process. Correlation analyses revealed a direct link between the reduced of Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD) and the detoxification efficiency of the different processes on the wastewater. In particular, the removal of benzene-containing aromatic pollutant correlated positively with decreased toxicity. However, the Fenton process, despite lowering TOC and COD, increased of the acute toxicity of the luminousbacteria (TU value increased from 1.66 to 2.33). This may result from the transformation generation of organic pollutant and oxidant residues during the Fenton process. Hence, oxidation technologies such as the Fenton process, as a deep treatment process, should be more concerned about the ecological risks that may be caused while focusing on their effectiveness in removing pollutant.
Topics: Animals; Humans; Wastewater; Zebrafish; Environmental Pollutants; Ecosystem; Water Pollutants, Chemical; Oxidation-Reduction; Waste Disposal, Fluid; Hydrogen Peroxide
PubMed: 38199367
DOI: 10.1016/j.scitotenv.2024.169937 -
Journal of Environmental Management Oct 2023In recent times, emerging contaminants (ECs) like pharmaceuticals and personal care products (PPCPs) in water and wastewater have become a major concern in the...
In recent times, emerging contaminants (ECs) like pharmaceuticals and personal care products (PPCPs) in water and wastewater have become a major concern in the environment. Electrochemical treatment technologies proved to be more efficient to degrade or remove PPCPs present in the wastewater. Electrochemical treatment technologies have been the subject of intense research for the past few years. Attention has been given to electro-oxidation and electro-coagulation by industries and researchers, indicating their potential to remediate PPCPs and mineralization of organic and inorganic contaminants present in wastewater. However, difficulties arise in the successful operation of scaled-up systems. Hence, researchers have identified the need to integrate electrochemical technology with other treatment technologies, particularly advanced oxidation processes (AOPs). Integration of technologies addresses the limitation of indiviual technologies. The major drawbacks like formation of undesired or toxic intermediates, s, energy expenses, and process efficacy influenced by the type of wastewater etc., can be reduced in the combined processes. The review discusses the integration of electrochemical technology with various AOPs, like photo-Fenton, ozonation, UV/HO, O/UV/HO, etc., as an efficient way to generate powerful radicals and augment the degradation of organic and inorganic pollutants. The processes are targeted for PPCPs such as ibuprofen, paracetamol, polyparaben and carbamezapine. The discussion concerns itself with the various advantages/disadvantages, reaction mechanisms, factors involved, and cost estimation of the individual and integrated technologies. The synergistic effect of the integrated technology is discussed in detail and remarks concerning the prospects subject to the investigation are also stated.
Topics: Wastewater; Hydrogen Peroxide; Water Pollutants, Chemical; Oxidation-Reduction; Cosmetics; Pharmaceutical Preparations; Water Purification
PubMed: 37392690
DOI: 10.1016/j.jenvman.2023.118385 -
Journal of Environmental Management Oct 2023The objective of this study was to enrich the nutrient content of compost and to investigate the passivation and solubilization of plant micronutrients (Fe, Al, Cu, Ni,...
The objective of this study was to enrich the nutrient content of compost and to investigate the passivation and solubilization of plant micronutrients (Fe, Al, Cu, Ni, Zn, Na, Mn), macroelements (P, K, Mg, Ca), and heavy metals (Cr, Cd, Pb) during sewage sludge composting with nutrient-rich biomass ash additives. T0: 0%, T1: 3.5%, T2: 7.0%, and T3: 14.0% dry weight (DW), weight/weight (w/w) biomass ash was added to the sewage sludge + sawdust mixture (volume, 1:1) to obtain the final NPK content and monitored over a 45-day period. Sawdust was used as auxiliary material. The sequential extraction method was used to determine the elemental species. Cr, Cd and Pb showed higher affinity to the residual fraction and occluded in the oxide fraction, which decreased the bioavailability factor (BF) (<1% BF-Cr, 21% BF-Cd and 9% BF-Pb) compared to the control treatment (46% BF-Cr, 47% BF-Cd and 80% BF-Pb). As the amount of biomass ash increased (T1-T3), the percentages of residual Cr (Res-Cr) (10-65%), exchangeable Cd (Exc-Cd) and organically bound Cd (Org-Cd) (14% and 21%), and oxides-Pb (Oxi-Pb) (20-61%) increased. In all composts, Fe, Al, and Cu were associated with organically bound and oxides-entrapped fractions. More than 50% of total Mn and Mg were concentrated mainly in exchangeable fractions, suggesting high mobility and bioavailability (42% BF-Mn and 98% BF-Mg). Ni, Zn, and Na tended to be present in oxide-bound, organically bound, and residual fractions, while K and P were associated with exchangeable and organically bound fractions. The overall results suggest that composting sewage sludge with biomass ash may be the best strategy and technique to overcome soil application bottlenecks because it passivates heavy metals and improves the bioavailability of plant nutrients.
Topics: Sewage; Composting; Biomass; Cadmium; Lead; Metals, Heavy; Soil; Oxides
PubMed: 37327636
DOI: 10.1016/j.jenvman.2023.118330 -
Chemosphere Dec 2023This study aims to explore the reusability of wastewater treatment by-product for photo-Fenton process to treat an organic pollutant model. The optimal condition,...
This study aims to explore the reusability of wastewater treatment by-product for photo-Fenton process to treat an organic pollutant model. The optimal condition, reactive oxygen species (ROS), and kinetic approach in photo-Fenton process was discussed. The Metal oxide crystal pellets from are a by-product of the Fluidized-Bed Crystallization (FBC) process and can be used as a catalyst in the Photo-Fenton process. Electroplating wastewater containing iron and copper was treated via the FBC process using granulated Al(OH) as carrier seeds. The binary oxide of FeOOH and CuO on the Al(OH) surface (FeCu@Al(OH)) was identified as the FBC by-product after characterization using FTIR and XPS analysis. In the photo-Fenton process, visible light from a fluorescence lamp with a wavelength of 400-610 nm was chosen as an irradiation source. Oxalic acid was added as chelating agent to form photosensitive iron oxalate species and hydrogen peroxide was applied as oxidant to generate active radical to decolorize and mineralize RB5 synthesized solution (100 mg/L). The operating conditions including the oxalic acid to pollutant ratio ([OA]/[RB5]) of 4.5-13.0, reaction pH (pHr) of 3-7 and initial to theoretical hydrogen peroxide molar ratio [HO]/[ HO] of 35%-120% were optimized. Under the optimal conditions, pH = 5.0; [HO]/[RB5] at 75% stoichiometric and [OA]/[RB5] = 9, the RB5 is almost completely decolorized after 210 min of operation and the mineralization efficiency is 58%. The contribution of •OH, O, and O to the Photo-Fenton system was determined using ESR analysis with the addition of DMPO and TEMP as spin trap agents. The kinetic analysis reveals the observed rate constants k, k and k from fitting are 0.0120, 0.0054 and 0.0001 Ms, respectively.
Topics: Hydrogen Peroxide; Copper; Azo Compounds; Kinetics; Light; Oxides; Environmental Pollutants; Oxalic Acid; Oxidation-Reduction
PubMed: 37758073
DOI: 10.1016/j.chemosphere.2023.140268 -
Environmental Science & Technology Dec 2023The use of household bleach cleaning products results in emissions of highly oxidative gaseous species, such as hypochlorous acid (HOCl) and chlorine (Cl). These species...
Gas-Phase and Surface-Initiated Reactions of Household Bleach and Terpene-Containing Cleaning Products Yield Chlorination and Oxidation Products Adsorbed onto Indoor Relevant Surfaces.
The use of household bleach cleaning products results in emissions of highly oxidative gaseous species, such as hypochlorous acid (HOCl) and chlorine (Cl). These species readily react with volatile organic compounds (VOCs), such as limonene, one of the most abundant compounds found in indoor enviroments. In this study, reactions of HOCl/Cl with limonene in the gas phase and on indoor relevant surfaces were investigated. Using an environmental Teflon chamber, we show that silica (SiO), a proxy for window glass, and rutile (TiO), a component of paint and self-cleaning surfaces, act as a reservoir for adsorption of gas-phase products formed between HOCl/Cl and limonene. Furthermore, high-resolution mass spectrometry (HRMS) shows that the gas-phase reaction products of HOCl/Cl and limonene readily adsorb on both SiO and TiO. Surface-mediated reactions can also occur, leading to the formation of new chlorine- and oxygen-containing products. Transmission Fourier-transform infrared (FTIR) spectroscopy of adsorption and desorption of bleach and terpene oxidation products indicates that these chlorine- and oxygen-containing products strongly adsorb on both SiO and TiO surfaces for days, providing potential sources of human exposure and sinks for additional heterogeneous reactions.
Topics: Humans; Hypochlorous Acid; Limonene; Chlorine; Halogenation; Silicon Dioxide; Terpenes; Gases; Oxygen; Air Pollution, Indoor
PubMed: 38010858
DOI: 10.1021/acs.est.3c06656 -
The Science of the Total Environment Oct 2023Sanitary landfills are widely accepted and promoted as the environmentally friendly way to properly dispose of solid waste. However, a harmful aspect is the leachate...
Sanitary landfills are widely accepted and promoted as the environmentally friendly way to properly dispose of solid waste. However, a harmful aspect is the leachate generation and management, which are currently recognized as one of the greatest challenges in the environmental engineering field. Due to the high leachate recalcitrance, Fenton treatment has been accepted as a viable and efficient treatment process, which significantly reduces the organic matter: 91 % of COD; 72 % of BOD5; and 74 % of DOC. However, the acute toxicity of leachate must be assessed, mainly after the Fenton process, with the view of performing a low-cost biological post-treatment of the effluent. Despite the high redox potential, degrading 185 organic chemicals compounds identified in raw leachate, the present work reports a removal efficiency of almost 84 %, counting 156 organic compounds removed, and almost 16 % of persistent compounds. After Fenton treatment, 109 organic compounds were identified, beyond the persistent fraction of almost 27 %, wherein 29 organic compounds remained unchanged after Fenton treatment, counting 80 new short chain and lower complexity organic compounds formed. Despite the biogas production ratio increase (3-6 times), and significant enhancement of the biodegradable fraction susceptible to oxidation in respirometric test, a higher reduction in the oxygen uptake rate (OUR) was identified after Fenton treatment due to persistent compounds and their bioaccumulation. Additionally, the D. magna bioindicator parameter indicated that treated leachate is three times more toxic than raw leachate.
Topics: Water Pollutants, Chemical; Hydrogen Peroxide; Solid Waste; Oxidation-Reduction; Organic Chemicals
PubMed: 37329909
DOI: 10.1016/j.scitotenv.2023.164870 -
Journal of Colloid and Interface Science Sep 2023Targeted tumor therapy through tumor microenvironment (TME)-responsive nanoplatforms is an emerging treatment strategy used to enhance tumor-specificity to selectively...
Targeted tumor therapy through tumor microenvironment (TME)-responsive nanoplatforms is an emerging treatment strategy used to enhance tumor-specificity to selectively kill cancer cells. Here, we introduce a nanosized zeolitic imidazolate framework-8 (ZIF-8) that simultaneously contains natural glucose oxidase (GOx) and Prussian blue nanoparticles (PBNPs) to construct multi-component metal-organic framework nanocomposites (denoted as ZIF@GOx@PBNPs), which possess cascade catalytic activity selectively within the TME. Once reaching a tumor site, GOx and PBNPs inside the nanocomposites are sequentially released and participate in the cascade catalytic reaction. In weak acidic TME, GOx, which effectively catalyzes the oxidation of intratumoral glucose to hydrogen peroxide (HO) and gluconic acid, not only initiates starvation therapy by cutting off the nutrition source for cancer cells but also produces the reactant for sequential Fenton reaction for chemodynamic therapy. Meanwhile, PBNPs, which are released from the ZIF-8 framework dissociated by acidified pH due to the produced gluconic acid, convert the generated HO into harmful radicals to melanomas. In this way, the cascade catalytic reactions of ZIF@GOx@PBNPs enhance reactive oxygen species production and cause oxidative damage to DNA in cancer cells, resulting in remarkable inhibition of tumor growth. The tumor specificity is endowed by using the biomolecules overexpressed in TME as a "switch" to initiate the first catalytic reaction by GOx. Given the significant antitumor efficiency both in vitro and in vivo, ZIF@GOx@PBNPs could be applied as a promising therapeutic platform enabling starvation/chemodynamic synergism, high therapeutic efficiency, and minimal side effects.
Topics: Humans; Metal-Organic Frameworks; Hydrogen Peroxide; Glucose Oxidase; Neoplasms; Nanocomposites; Cell Line, Tumor; Nanoparticles; Tumor Microenvironment
PubMed: 37167915
DOI: 10.1016/j.jcis.2023.04.161