Measuring the Surface Tension of Atmospheric Particles and Relevant Mixtures to Better Understand Key Atmospheric Processes.

Aerosol and aqueous particles are ubiquitous in Earth's atmosphere and play key roles in geochemical processes such as natural chemical cycles, cloud and fog formation, air pollution, visibility, climate forcing, etc. The surface tension of atmospheric particles can affect their size distribution, condensational growth, evaporation, and exchange of chemicals with the atmosphere, which, in turn, are important in the above-mentioned geochemical processes. However, because measuring this quantity is challenging, its role in atmospheric processes was dismissed for decades.

Comparative removal of pharmaceuticals in aqueous phase by agricultural waste-based biochars.

The intensification of pharmaceutical use globally has led to an increase in the number of water bodies contaminated by drugs, and an effective strategy must be developed to address this issue. In this work, several biochars produced from Miscanthus straw pellets (MSP550, MSP700) and wheat straw pellets (WSP550, WSP700) at 550 and 700°C, respectively, were selected as adsorbents for removing various pharmaceuticals, such as pemetrexed (PEME), sulfaclozine (SCL), and terbutaline (TBL), from the aqueous phase. The biochar characterizations (physicochemical properties, textural properties, morphological structures, and zeta potentials) and adsorptive conditions (contact times, temperatures, and pH effect) were investigated.

Salting out, non-ideality and synergism enhance surfactant efficiency in atmospheric aerosols.

In Earth's atmosphere, the surface tension of sub-micron aerosol particles is suspected to affect their efficiency in becoming cloud droplets. But this quantity cannot be measured directly and is inferred from the chemical compounds present in aerosols. Amphiphilic surfactants have been evidenced in aerosols but experimental information on the surface properties of their mixtures with other aerosol components is lacking.

Surface tension models for binary aqueous solutions: a review and intercomparison.

The liquid-air surface tension of aqueous solutions is a fundamental quantity in multi-phase thermodynamics and fluid dynamics and thus relevant in many scientific and engineering fields. Various models have been proposed for its quantitative description. This Perspective gives an overview of the most popular models and their ability to reproduce experimental data of ten binary aqueous solutions of electrolytes and organic molecules chosen to be representative of different solute types.

Detailed Speciation of Non-Methane Volatile Organic Compounds in Exhaust Emissions from Diesel and Gasoline Euro 5 Vehicles Using Online and Offline Measurements.

The characterization of vehicle exhaust emissions of volatile organic compounds (VOCs) is essential to estimate their impact on the formation of secondary organic aerosol (SOA) and, more generally, air quality. This paper revises and updates non-methane volatile organic compounds (NMVOCs) tailpipe emissions of three Euro 5 vehicles during Artemis cold urban (CU) and motorway (MW) cycles. Positive matrix factorization (PMF) analysis is carried out for the first time on proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS) datasets of vehicular emission.

New insights into clopyralid degradation by sulfate radical: Pyridine ring cleavage pathways.

Contamination by herbicides such as clopyralid (CLP) poses a significant threat to human health and ecological systems. In the present study, efficient removal of CLP was achieved by thermo activated persulfate, among which sulfate radical was identified as the predominant oxidizing species responsible for the decontamination. Based on high resolution LC-MS, derivatization method and density functional theory (DFT) computation, the detailed oxidation pathways and mechanisms were proposed.

Concentrations and Adsorption Isotherms for Amphiphilic Surfactants in PM Aerosols from Different Regions of Europe.

Predicting the activation of submicrometer particles into cloud droplets in the atmosphere remains a challenge. The importance of surface tension, σ (mN m), in these processes has been evidenced by several works, but information on the "surfactants" lowering σ in actual atmospheric particles remains scarce. In this work, PM aerosols from urban, coastal, and remote regions of Europe (Lyon, France, Rogoznica, Croatia, and Pallas, Finland, respectively) were investigated and found to contain amphiphilic surfactants in concentrations up to 2.

Contrasting photoreactivity of β2-adrenoceptor agonists Salbutamol and Terbutaline in the presence of humic substances.

The photodegradation reactions of two typical β2-adrenoceptor agonists, salbutamol (SAL) and terbutaline (TBL), alone, and in the presence of Aldrich humic acid (AHA) or Suwannee River fulvic acid (SRFA) were investigated by steady-state photolysis experiments, laser flash photolysis (LFP), kinetic modeling and quantum calculation. AHA and SRFA (2-20 mgC L) accelerated the phototransformation of both SAL and TBL. For SAL, an inhibiting effect of oxygen on the photodegradation was observed that is fully consistent with the main involvement of excited triplet states of HS (HS*).

Non-activated peroxymonosulfate oxidation of sulfonamide antibiotics in water: Kinetics, mechanisms, and implications for water treatment.

Despite that sulfate radical-based activated peroxymonosulfate (PMS) oxidation processes (e.g., UV/PMS, Co/PMS, etc.

Rethinking sulfate radical-based oxidation of nitrophenols: Formation of toxic polynitrophenols, nitrated biphenyls and diphenyl ethers.

Sulfate radical (SO)-based oxidation of nitrophenols (NPs) have been widely studied; however, formation of potentially more toxic polynitroaromatic intermediates has been overlooked. In this contribution, we systematically investigated the degradation of four NPs by a SO-based oxidation process. Degradation efficiency of NPs followed the order: 2-nitrophenol (2-NP) > 4-nitrophenol (4-NP) > 2,4-dinitrophenol (2,4-DNP) > 2,6-dinitrophenol (2,6-DNP).

Transformation of antimicrobial agent sulfamethazine by peroxymonosulfate: Radical vs. nonradical mechanisms.

Peroxymonosulfate (PMS) is increasingly used as an oxidant for in situ remediation of organic contaminants in soil and groundwater. In this study we demonstrated that sulfamethazine (SMZ) could be transformed by PMS in the absence of any activators. Such transformation was ascribed to the oxidation by PMS per se, rather than free radicals (SO or HO), superoxide (O), or singlet oxygen (O).

Sulfate radical induced degradation of β2-adrenoceptor agonists salbutamol and terbutaline: Phenoxyl radical dependent mechanisms.

The present study investigated the reactivity and oxidation mechanisms of salbutamol (SAL) and terbutaline (TBL), two typical β2-adrenoceptor agonists, towards sulfate radical (SO) by using photo-activated persulfate (PS). The reaction pathways and mechanisms were proposed based on products identification using high resolution HPLC-ESI-MS, laser flash photolysis (LFP) and molecular orbital calculations. The results indicated that SO was the dominant reactive species in the UV/PS process.

Ferrous-activated peroxymonosulfate oxidation of antimicrobial agent sulfaquinoxaline and structurally related compounds in aqueous solution: kinetics, products, and transformation pathways.

Sulfaquinoxaline (SQX) is a coccidiostatic drug widely used in poultry and swine production and has been frequently detected in various environmental compartments such as surface water, groundwater, soils, and sediments. In the present study, degradation of SQX by ferrous ion-activated peroxymonosulfate oxidation process (Fe(II)/PMS), a promising in situ chemical oxidation (ISCO) technique, was systematically investigated. Experimental results showed that Fe(II)/PMS process appeared to be more efficient for SQX removal relative to Fe(II)/persulfate process (Fe(II)/PS).

The role of nitrite in sulfate radical-based degradation of phenolic compounds: An unexpected nitration process relevant to groundwater remediation by in-situ chemical oxidation (ISCO).

As promising in-situ chemical oxidation (ISCO) technologies, sulfate radical-based advanced oxidation processes (SR-AOPs) are applied in wastewater treatment and groundwater remediation in recent years. In this contribution, we report for the first time that, thermally activated persulfate oxidation of phenol in the presence of nitrite (NO), an anion widely present in natural waters, could lead to the formation of nitrated by-products including 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), 2,4-dinitrophenol (2,4-DNP), and 2,6-dinitrophenol (2,6-DNP). Nitrogen dioxide radical (NO), arising from SO scavenging by NO, was proposed to be involved in the formation of nitrophenols as a nitrating agent.

Extraction and Characterization of Surfactants from Atmospheric Aerosols.

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in the Earth's atmosphere, a central process in meteorology, hydrology, and for the climate system. But because specific extraction and characterization of these compounds have been lacking for decades, very little is known on their identity, properties, mode of action and origins, thus preventing the full understanding of cloud formation and its potential links with the Earth's ecosystems. In this paper we present recently developed methods for 1) the targeted extraction of all the surfactants from atmospheric aerosol samples and for the determination of 2) their absolute concentrations in the aerosol phase and 3) their static surface tension curves in water, including their Critical Micelle Concentration (CMC).

Sulfate radical-based oxidation of antibiotics sulfamethazine, sulfapyridine, sulfadiazine, sulfadimethoxine, and sulfachloropyridazine: Formation of SO extrusion products and effects of natural organic matter.

The widespread occurrence of sulfonamide antibiotics in the environment has raised great concerns about their potential to proliferate antibacterial resistance. Sulfate radical (SO) based advanced oxidation processes (SR-AOPs) are promising in-situ chemical oxidation (ISCO) technologies for remediation of soil and groundwater contaminated by antibiotics. The present study reported that thermally activated persulfate oxidation of sulfonamides (SAs) bearing six-membered heterocyclic rings, e.

Photochemical behavior of carbon nanotubes in natural waters: reactive oxygen species production and effects on •OH generation by Suwannee River fulvic acid, nitrate, and Fe (III).

The photochemical activities of three kinds of carbon nanotubes (CNTs) were investigated in the present study. Efficient procedures of dispersing the three kinds of carbon nanotubes in water were established, and the quantitative analysis methods were also developed by TOC-absorbance method. High pH value or low ionic strength of the colloidal solutions facilitated the dispersion of CNTs.

Degradation of ciprofloxacin and sulfamethoxazole by ferrous-activated persulfate: implications for remediation of groundwater contaminated by antibiotics.

The wide occurrence of antibiotics in groundwater raised great scientific interest as well as public awareness in recent years due to their potential ability to spread antibiotic resistant gene and pose risk to humans. The present study investigated the ferrous ion (Fe(II)) activated decomposition of persulfate (S2O8(2-)), as a potential in situ chemical oxidation (ISCO) approach, for remediation of groundwater contaminated by antibiotics. Fe(II)-persulfate mediated ciprofloxacin (CIP) degradation was found to be more efficient than sulfamethoxazole (SMX) at near neutral pH (pH6.

Photochemical degradation of sunscreen agent 2-phenylbenzimidazole-5-sulfonic acid in different water matrices.

The occurrence of sunscreen agents in natural environment is of scientific concern recently due to their potential risk to ecology system and human beings as endocrine disrupting chemicals (EDCs). In this work the photodegradation mechanism and pathways of sunscreen agent 2-phenylbenzimidazole-5-sulfonic acid (PBSA) were investigated under artificial solar irradiation with the goal of assessing the potential of photolysis as a transformation mechanism in aquatic environments. The quantum yield of PBSA direct photolysis in pH 6.

Nitrate-induced photodegradation of atenolol in aqueous solution: kinetics, toxicity and degradation pathways.

The extensive utilization of β-blockers worldwide led to frequent detection in natural water. In this study the photolysis behavior of atenolol (ATL) and toxicity of its photodegradation products were investigated in the presence of nitrate ions. The results showed that ATL photodegradation followed pseudo-first-order kinetics upon simulated solar irradiation.

The remediation of wastewater containing 4-chlorophenol using integrated photocatalytic and biological treatment.

In this work, the performance of integrated photocatalytic and biological treatment was studied for the degradation of 4-chlorophenol (MCP) present in wastewaters. Photocatalysis was used as a pre-treatment to biological degradation. Pollutant removal efficiency was quantified using MCP removal and total organic carbon (TOC) removal.

Photocatalytic removal of pesticide dichlorvos from indoor air: a study of reaction parameters, intermediates and mineralization.

This paper presents for the first time the investigation of TiO2 photocatalysis for the removal of pesticides in gas phase. Dichlorvos was used as a model pesticide, and experiments were carried out using both static and dynamic reaction systems to explore the different aspects of the process. Thus, adsorption, reaction kinetics, and the influence of several operational parameters such as relative humidity (RH), inlet concentration, flow rate, and association of TiO2 with activated carbon (AC) were all examined in detail.