Presence Of Inorganic Anions Research Articles

Photochemical treatment of tyrosol, a model phenolic compound present in olive mill wastewater, by hydroxyl and sulfate radical-based advanced oxidation processes (AOPs).

The photochemical degradation and mineralization of tyrosol (TSL), a model phenolic compound present in olive mill wastewater, were studied by UV-254 nm irradiated peroxymonosulfate (PMS), hydrogen peroxide (H2O2) and persulfate (PS). Effects of initial TSL concentration, UV fluence, pH, phosphate buffer and presence of inorganic anions (i.e., Cl-, SO42- and NO3-) were also investigated. Sulfate and hydroxyl radicals were demonstrated to be responsible for TSL degradation and mineralization. Regardless of the treatment conditions, pseudo-first-order kinetics could be obtained, with the efficiencies following UV/PS > UV/H2O2 > UV/PMS. The better removal of TSL by UV/PS correlated with the quantum yield and concentration of sulfate radical in the system. Albeit acidic condition slightly enhanced the performance of the AOPs, complete oxidation of TSL was achieved at pH 6.8 by both UV/PS and UV/H2O2. Though, inorganic anions or different concentrations of phosphate buffer did not affect TSL degradation kinetics, presence of inorganic ions decreased significantly the TOC removal for both UV/PMS and UV/H2O2 processes. Meanwhile, UV/PS process was the least influenced by inorganic ions and showed the highest TOC removal of ∼35%. Overall, UV/PS process was the most effective for TSL degradation and mineralization in the presence or absence of common water constituents.

Radiation-induced degradation of sulfamethoxazole in the presence of various inorganic anions

The effect of common inorganic anions (chloride, bicarbonate, carbonate, nitrate, sulfate and phosphate) on the radiation-induced degradation of sulfamethoxazole (SMX) was investigated. In the absence of anions, the removal efficiency of SMX reached 99.6% at dose of 1 kGy. However, the presence of inorganic anions had obvious influence on SMX degradation, which was dependent on their initial concentrations. Nitrate ions had inhibitive effect, which increased with increase of its initial concentration. Chloride ions showed no obvious inhibition at low concentration, while they had significant inhibition at higher concentration. For bicarbonate, carbonate and phosphate ions, they presented inhibition at low concentration, while they had enhancing effect at higher concentration. The promotion of SMX removal efficiency was observed when the initial concentration of bicarbonate, carbonate and phosphate was 50, 20 and 50 mM, respectively. Quenching experiments proved that hydroxyl radicals made a major contribution to SMX degradation in the absence of anions. However, in the presence of 50 mM of carbonate or phosphate ions, carbonate and phosphate radicals played a key role in SMX degradation. In addition, carbonate and phosphate radicals preferentially attacked the amino group and resulted in the formation of different intermediate products compared to hydroxyl radicals. The results suggested that the effect of inorganic anions on the radiation-induced degradation of sulfonamides antibiotics should be considered when radiation technology is used for the treatment of industrial wastewater.

Photo-Fenton degradation of a herbicide (2,4-D) in groundwater for conditions of natural pH and presence of inorganic anions.

The effects of four inorganic anions (Cl-, SO42-, HCO3-, NO3-) usually present in groundwater were investigated on the photo-Fenton degradation of 2,4-dichlorophenoxyacetic acid (2,4-D). A kinetic model derived from a reaction sequence is proposed using the ferrioxalate complex as iron source at pH close to natural conditions (pH = 5). It was demonstrated that oxalate not only maintained iron in solution for the natural groundwater system, but also increased the photochemical activation of the process. Results showed that the minimum conversion of 2,4-D for the simulated groundwater after 180 min was 63.80%. This value was only 14.1% lower than the conversion achieved without anions. However, with all anions together, the consumption of hydrogen peroxide (HP) per mole of herbicide showed an increase with respect to the test without anions. Only one kinetic parameter was estimated for each anion applying a nonlinear regression method. Subsequently, these optimized kinetic constants were used to simulate the system behaviour, considering the influence of all the studied anions together. A good agreement between kinetic model predictions and experimental data was observed, with the following errors: RMSE2,4-D = 3.98 × 10-3 mM, RMSEHP = 1.83 × 10-1 mM, RMSEOX = 1.39 × 10-2 mM, and RMSE2,4-DCP = 5.59 × 10-3 mM.

Mobility and retention of phenolic acids through a goethite-coated quartz sand column

In the present work, a natural mineral, such as quartz sand (NQS), was modified with a small amount of goethite to yield a goethite-coated quartz sand (GCQS) adsorbent that was used for depolluting water contaminated with a series of phenolic acids that have various numbers and positions of hydroxyl groups in the benzene ring. Thus, the transport and retention of gallic acid and its derivatives from water onto GCQS column were carried out at ambient temperature. Prior to the column adsorption experiments, the GCQS adsorbent was characterized with various methods such as X-ray diffraction, X-ray fluorescence, and scanning electron microscopy (SEM) coupled with X-ray microanalysis and zeta potential. The amount of adsorbed phenolic acid at the GCQS-water interface was found to be controlled by hydrogen bonding and electrostatic interactions, and it was tuned by varying parameters such as the aqueous phase pH, the ionic strength and the nature of inorganic ions. In addition, the effect of the number and the positions of hydroxyl groups (OH) on the benzoic acid mobility was also examined. The data indicate that adding no more than 2.5 wt% of goethite to NQS shifts the solid Isoelectrical Point from 2.5 for pure NQS to 5.7 for GCQS and leads to a 16-fold increase in the maximum adsorbed amount of gallic acid. Moreover, the adsorbed amount of gallic acid was also found to decrease in the presence of inorganic anions in the order Cl− > NO3− > SO42− > H2PO4−, and to decrease as the ionic strength of the aqueous phase increases. This study brings new insight to the role of colloid and interface science for mineral processing and the environment.

Fe(III)-Doped g-C3N4 Mediated Peroxymonosulfate Activation for Selective Degradation of Phenolic Compounds via High-Valent Iron-Oxo Species.

Herein, we proposed a new peroxymonosulfate (PMS) activation system employing the Fe(III) doped g-C3N4 (CNF) as catalyst. Quite different from traditional sulfate radical-based advanced oxidation processes (SR-AOPs), the PMS/CNF system was capable of selectively degrading phenolic compounds (e.g., p-chlorophenol, 4-CP) in a wide pH range (3-9) via nonradical pathway. The generated singlet oxygen (1O2) in the PMS/CNF3 (3.46 wt % Fe) system played negligible role in removing 4-CP, and high-valent iron-oxo species fixated in the nitrogen pots of g-C3N4 (≡FeV═O) was proposed as the dominant reactive species by using dimethyl sulfoxide as a probe compound. The mechanism was hypothesized that PMS was first bound to the Fe(III)-N moieties to generate ≡FeV═O, which effectively reacted with 4-CP via electron transfer. GC-MS analysis indicated that 4-chlorocatechol and 1,4-benzoquinone were the major intermediates, which could be further degraded to carboxylates. The kinetic results suggested that the formation of ≡FeV═O was proportional to the dosages of PMS and CNF3 under the experimental conditions. Also, the PMS/CNF3 system exhibited satisfactory removal of 4-CP in the presence of inorganic anions and natural organic matters. We believe that this study will provide a new routine for effective PMS activation by heterogeneous iron-complexed catalysts to efficiently degrade organic contaminants via nonradical pathway.

The role of hydrophobic properties in ion exchange removal of organic compounds from water

The removal of organic compounds by ion exchange resins is a complex process due to the involvement of several interacting phenomena during the course of removal. The objective of this research is to clarify the contribution of these interactions to the removal of different organic compounds under various solution conditions. This study investigates the sorption of three ionizable organic compounds, which are identical in terms of ionic charges and different in their non‐polar moieties, in order to better evaluate the contribution of solute‐solvent interactions to the affinity of these compounds for ion exchange. The higher uptake of hydrophobic compounds and lower competition effect from inorganic anions on the removal of these compounds provide evidence for the importance of the hydrophobic effect. The hydrophobic characteristics of organic compounds and the favourable entropy change that they impose during de‐solvation contribute greatly to the ion exchange selectivity of these compounds. Furthermore, increasing the ionic strength of solution by adding high charge density anions, such as sulphate, to the water diminishes the contribution of electrostatic interaction, and hence the potential physical adsorption between resin and organic molecule predominates the removal mechanism. No change in removal mechanism is observed in the presence of inorganic anions with low charge density such as nitrate.

Degradation of diclofenac by UV-activated persulfate process: Kinetic studies, degradation pathways and toxicity assessments

Diclofenac (DCF) is the frequently detected non-steroidal pharmaceuticals in the aquatic environment. In this study, the degradation of DCF was evaluated by UV-254nm activated persulfate (UV/PS). The degradation of DCF followed the pseudo first-order kinetics pattern. The degradation rate constant (kobs) was accelerated by UV/PS compared to UV alone and PS alone. Increasing the initial PS dosage or solution pH significantly enhanced the degradation efficiency. Presence of various natural water constituents had different effects on DCF degradation, with an enhancement or inhibition in the presence of inorganic anions (HCO3− or Cl−) and a significant inhibition in the presence of NOM. In addition, preliminary degradation mechanisms and major products were elucidated using LC-MS/MS. Hydroxylation, decarbonylation, ring-opening and cyclation reaction involving the attack of SO4•− or other substances, were the main degradation mechanism. TOC analyzer and Microtox bioassay were employed to evaluate the mineralization and cytotoxicity of solutions treated by UV/PS at different times, respectively. Limited elimination of TOC (32%) was observed during the mineralization of DCF. More toxic degradation products and their related intermediate species were formed, and the UV/PS process was suitable for removing the toxicity. Of note, longer degradation time may be considered for the final toxicity removal.

One-step selective electrokinetic removal of inorganic anions from small volumes and its application as sample clean-up for mass spectrometric techniques

The presence of inorganic anions in a sample interferes with mass spectrometric (MS) analysis. Here, a simple method to remove these ions from a liquid sample in one-step is described. The inorganic anions present in a 50μL sample were extracted into a low pH solution inside a 200μm i.d.×33cm long capillary by the use of an electric field. The selective removal of unwanted anions and retention of target analytes was accomplished by control of the apparent electrophoretic velocities of anions and analytes at a boundary that separated the sample and extraction solution. No physical barrier (e.g., membrane) was required and with the boundary situated at the tip of the capillary, efficient removal of inorganic anions (e.g., >80% removal) and good recovery of target analytes (e.g., >80% recovery) were achieved. The time required for removal of the inorganic anions was found to depend on their initial concentrations. The removal process was investigated using different concentrations of bromide and nitrate (as potassium salts) and negatively chargeable drugs as target analytes. This micro-sample clean-up technique used no organic solvents and little consumables and was studied to the determination of 0.6μg/L arsenic and 8.3μg/L vanadium in 500mg/L sodium chloride using inductively coupled plasma MS and 50μM angiotensin I in 1000mg/L sodium chloride using electrospray ionisation MS. Micro-sample clean-up was performed for 45min at 3kV in both demonstrations. The calculated recoveries for the metals at trace levels were 110–130%, and for the peptide was 103.8%.

Combination of photocatalysis with hydrodynamic cavitation for degradation of tetracycline

Hydrodynamic cavitation is a promising technology for wastewater treatment. In this study, TiO2 (P25) photocatalytic degradation of tetracycline, an antibiotic compound extensively used and environmentally hazardous, was conducted with hydrodynamic cavitation employed simultaneously. Many factors, such as initial tetracycline concentration, solution pH and presence of inorganic anions, were explored. Kinetics were investigated at varied contaminant concentrations, and the pseudo-first-order rate constant for tetracycline photocatalysis coupled with hydrodynamic cavitation was 1.5–3.7 times of the sum of those for the individual processes. These results indicated that a synergistic effect occurred in the combined method. Tetracycline degradation was pH-dependent and favored at alkaline pH. The presence of HCO3− in the medium induces promotive effect on the photocatalytic degradation of tetracycline in the presence of hydrodynamic cavitation, while sulfate and chloride exhibit only minor effect. UV/Vis spectra, Fourier transform infrared (FTIR) adsorption spectra and liquid chromatography–mass spectra (LC–MS) were used to evaluate the degradation mechanism. Scanning electron microscopic (SEM) images of TiO2 confirmed that hydrodynamic cavitation can prevent photocatalytic particles from agglomeration.

Assessing the potential of inorganic anions (Cl−, NO3−, SO42− and PO43−) to increase the bioaccessibility of emitted palladium in the environment: Experimental studies with soils and a Pd model substance

Palladium (Pd) emitted from vehicles equipped with exhaust catalytic converters has been accumulating at a greater rate relative to other platinum group elements (PGE) in the last 10–20 years. Little is known, however, regarding the various environmental factors and conditions which are likely to modulate the chemical behavior and bioaccessibility of this element post-emission. To meet data needs, soils and a Pd model substance were treated with solutions containing common anions (Cl−, NO3−, SO42− und PO43−) to shed light on the geochemical behavior of emitted Pd under ambient conditions. As part of this, the particle surface chemistry of treated residues (insoluble phase) and solutions (soluble phase) was examined using XPS to assess the chemical transformation of Pd in the presence of inorganic anions. The results show that Pd is the most soluble in the presence of anionic species, followed by rhodium (Rh) and platinum (Pt). Pd in field-collected samples was found to be considerably more soluble than the metallic Pd in the model substance, Pd black, when treated with anionic species. The results also demonstrate that the solubility of Pd black is strongly dependent on solution pH, concentration and the duration of reaction. The outer 3–4 atomic layers of metallic Pd was determined via XPS to be partially oxidized when treated with anion solutions, with the degree being dependent on anion type. The concentration of dissolved O2 in solution was found to have little impact on the transformation of metallic Pd. Given the ubiquitous nature of the anions examined, we can expect that Pd will become more bioaccessible post-emission.

Authenticity screening of seized whiskey samples using electrophoresis microchips coupled with contactless conductivity detection.

This report describes for the first time the use of microchip electrophoresis (ME) devices integrated with capacitively coupled contactless conductivity detection (C4 D) to investigate the authenticity of seized whiskey samples, which were probably adulterated by simple dilution with tap water. The proposed microfluidic platform was explored for the monitoring of anionic species (Cl- and F- ) in both original and tampered samples. The best separations were achieved within 70 s using a running buffer composed of lactic acid and histidine (pH = 5.9). ME-C4 D devices were used to analyze samples from three different brands (five samples each). Based on the presence of inorganic anions like Cl- , F- , SO42- and NO2- in different amounts, the authenticity of seized whiskeys was compared to original samples. According to the reported data, the proposed microfluidic platform can be useful to help regulatory authorities in the investigation and monitoring of authenticity of commercialized whiskey beverages.

Kinetics and Mechanistic Investigation of the Photocatalytic Degradation of Clothianidin

Clothianidin was selected as a model compound for kinetics and mechanistic investigation of the photocatalytic degradation of nicotine insecticides. We assessed the feasibility of the degradation process, and systematically explored the effects of catalyst amount, reaction temperature, substrate concentration, initial solution pH value, and the presence of inorganic anions and cations on the reaction. The results revealed a Langmuir-Hinshelwood interaction of pseudo-first-order kinetics, showing a rate constant of 0.0506 min-1. The photocatalytic degradation rate was the highest when the amount of catalyst (TiO2) was 3 g·L-1. It was observed that an increase of reaction temperature or lowering of substrate concentration was beneficial to clothianidin degradation. Additionally, the initial pH value of the solution had an obvious effect on the degradation process. Strong acid and alkali were not conducive and the degradation rate constant was the largest at pH=5. Furthermore, most of the inorganic anions and cations significantly hindered the degradation of clothianidin. Finally, the degradation intermediates were identified by GC/MS, and the reaction pathways at the initial stage of the photocatalytic process were proposed:hydroxylation of parent compound, cleavage of N-N bond in the nitroguanidine group, and cleavage of the C-N bond connected to the nitroguanidine and thiazole rings.

Kinetic and mechanistic investigation of azathioprine degradation in water by UV, UV/H2O2 and UV/persulfate

This study investigated the removal of azathioprine (AZA), an immunosuppressant xenobiotic found in hospital effluent, using direct UV-254nm photolysis, UV/H2O2 and UV/persulfate (UV/PS). AZA cannot be effectively degraded by direct UV photolysis, while the photodegradation efficiency of AZA significantly increases with addition of H2O2 or PS, due to the generation of HO and SO4−, respectively. Compared with AZA removal of 10% by direct UV photolysis at UV dose of 510mJcm−2, UV/H2O2 and UV/PS can remove 68% and 87% of AZA, respectively, at an oxidant dose of 100μM. The second-order rate constants of AZA with HO and SO4− are 1.86×109M−1s−1 and 2.16×109M−1s−1, respectively. There is a proportional increase of AZA degradation efficiency with the increasing oxidant dose in the range of 10–100μM, beyond which radical scavenging effect can negate the radical generation process. The effects of water quality, including pH, NOM and inorganic anions, were also investigated. The removal efficiency of AZA in the UV/H2O2 and UV/PS processes constantly decreases with the increasing pH. NOM significantly reduces the degradation efficiency of AZA through radical scavenging and UV absorption. The inhibition of AZA photodegradation is also affected by the presence of inorganic anions, following the order of HCO3−>Cl−>NO3−≈SO42−. Real water samples of treated water from a water treatment plant and secondary effluent from a wastewater treatment plant were used for the assessment of the UV treatment performances. Various AZA transformation by-products were identified to investigate the degradation mechanism of AZA in the UV-AOP systems. The addition of 100μM oxidant significantly decreases the treatment cost from 0.844 (for UV photolysis) to 0.078 (for UV/H2O2) and 0.067US$m−3order−1 (for UV/PS), respectively, indicating that UV/PS is the most cost-effective process for AZA degradation.

Sulfate radicals from Fe3+/persulfate system for Rhodamine B degradation

The Fe3+/persulfate system for Rhodamine B (RhB) oxidative degradation has been investigated. The catalytic mechanism in the Fe3+/persulfate system was proposed as follows: Fe3+ was restored to Fe2+ by the generated intermediate products during the degradation process. The influence parameters were examined in batch experiments, including Fe3+ and persulfate concentration and initial pH. The results indicated that the Fe3+/persulfate system exhibited good performance for RhB degradation and followed first-order kinetics. 95.91% of the RhB was removed within 30 min under the following conditions: [Fe3+]0 = 1 mM, [persulfate]0 = 1mM and pH 3.0. The RhB degradation efficiencies increased as the Fe3+ and persulfate concentrations increased. In addition, the RhB degradation was inhibited in the presence of inorganic anions, which was primarily due to a complex reaction between Fe3+ and various anions except for NO3-.

Modification of nanosized natural montmorillonite for ultrasound-enhanced adsorption of Acid Red 17

This work aims to modify montmorillonite (MMT) via dodecyltrimethylammonium bromide (DTMA) and investigate its ability in ultrasound (US) assisted decolorization of a polluted solution. BET surface area of MMT was increased from 19.76 to 42.57m2/g and basal spacing of MMT structural layers was increased from 1.13 to 1.69nm by DTMA modification. The application of DTMA–modified MMT (DTMA–MMT) and US for the decolorization of Acid Red 17 (AR17) showed that US could improve the ability of DTMA–MMT on decolorization of AR17 solution due to simultaneous adsorption and sonocatalysis. The ability of US assisted DTMA–MMT was slightly decreased with pH, the initial dye concentration and the presence of inorganic anions.

Solar CPC Pilot Plant Photocatalytic Degradation of Indigo Carmine Dye in Waters and Wastewaters Using Supported-TiO2: Influence of Photodegradation Parameters

The photocatalytic degradation of indigo carmine (IC) dye in the presence of titanium dioxide under different conditions was reported. Several factors which interfere with the photodegradation efficiency as catalyst concentration, pH, initial concentration of dye, presence of inorganic anions, temperature, and the addition of hydrogen peroxide were studied under artificial irradiation with a 125 W mercury vapor lamp. Additionally, the catalyst supported on glass spheres was used for the photocatalytic degradation of the dye present in several types of waters in a CPC solar pilot plant. The photocatalytic products, carboxylic acids, andSO42-andNH4+were followed during IC mineralization. Formate, acetate, and oxalate were detected in real MWWTP secondary effluent. The mineralization efficiency was of 42 and 21% using in suspension and supported TiO2, respectively. In order to evaluate biological effects,Eisenia andreiearthworms were used as a model organism. No significant difference (P>0.05) of weight was observed in the earthworm submitted to different concentrations of IC and its photoproducts. The photocatalytic degradation of IC on TiO2supported on glass spheres suffered strong influence of the water matrix; nevertheless the method has the enormous advantage that it eliminates the need for the final catalyst removal step, reducing therefore the cost of treatment.

UV/S2O82− process for degrading polyvinyl alcohol in aqueous solutions

This investigation evaluates the effectiveness of the UV/S2O82− process in the degradation of polyvinyl alcohol (PVA) in aqueous solutions without adjusting their pH. The effects of UV wavelength and Na2S2O8 dosage on the efficiency of degradation of PVA were examined. The efficiency of degradation of PVA under UV-254nm exceeded that under UV-365nm. A larger Na2S2O8 dosage was associated with a higher efficiency of degradation of PVA under UV-254nm irradiation. However, an excessive Na2S2O8 dosage inhibited the degradation of PVA by the UV-365nm/S2O82− process. Both UV-254nm/S2O82− and UV-365nm/S2O82− processes exhibited pseudo-first-order kinetics. SO4− was detected by performing quenching studies using specific alcohols, revealing that SO4− was found to be the predominant radical in the UV-254nm/S2O82− process. Additionally, the presence of inorganic anions with various effects inhibited the degradation of PVA by the UV-254nm/S2O82− process. Complete degradation of PVA (20mg/L) was achieved within 5min under UV-254nm using an Na2S2O8 dosage of 0.12g/L in the absence of inorganic anions, indicating that UV irradiation to activate S2O82− promotes the degradation of PVA in aqueous solutions without adjusting their pH.

Reprint of "How do components of real cloud water affect aqueous pyruvate oxidation?"

Chemical oxidation of dissolved volatile or semi-volatile organic compounds within fog and cloud droplets in the atmosphere could be a major pathway for secondary organic aerosol (SOA) formation. This proposed pathway consists of: (1) dissolution of organic chemicals from the gas phase into a droplet; (2) reaction with an aqueous phase oxidant to yield low volatility products; and (3) formation of particle phase organic matter as the droplet evaporates. The common approach to simulating aqueous SOA (aqSOA) reactions is photo-oxidation of laboratory standards in pure water. Reactions leading to aqSOA formation should be studied within real cloud and fog water to determine whether additional competing processes might alter apparent rates of reaction as indicated by rates of reactant loss or product formation. To evaluate and identify the origin of any cloud water matrix effects on one example of observed aqSOA production, pyruvate oxidation experiments simulating aqSOA formation were monitored within pure water, real cloud water samples, and an aqueous solution of inorganic salts. Two analysis methods were used: online electrospray ionization high-resolution time-of-flight mass spectrometry (ESI-HR-ToF-MS), and offline anion exchange chromatography (IC) with quantitative conductivity and qualitative ESI-HR-ToF-MS detection. The apparent rate of oxidation of pyruvate was slowed in cloud water matrices: overall measured degradation rates of pyruvate were lower than in pure water. This can be at least partially accounted for by the observed formation of pyruvate from reactions of other cloud water components. Organic constituents of cloud water also compete for oxidants and/or UV light, contributing to the observed slowed degradation rates of pyruvate. The oxidation of pyruvate was not significantly affected by the presence of inorganic anions (nitrate and sulfate) at cloud-relevant concentrations. Future bulk studies of aqSOA formation reactions using simplified simulated cloud solutions and model estimates of generated aqSOA mass should take into account possible generation of, or competition for, oxidant molecules by organic components found in the complex matrices typically associated with real atmospheric water droplets. Additionally, it is likely that some components of real atmospheric waters have not yet been identified as aqSOA precursors, but could be distinguished through further simplified bulk oxidations of known atmospheric water components.

How do components of real cloud water affect aqueous pyruvate oxidation?

Chemical oxidation of dissolved volatile or semi-volatile organic compounds within fog and cloud droplets in the atmosphere could be a major pathway for secondary organic aerosol (SOA) formation. This proposed pathway consists of: (1) dissolution of organic chemicals from the gas phase into a droplet; (2) reaction with an aqueous phase oxidant to yield low volatility products; and (3) formation of particle phase organic matter as the droplet evaporates. The common approach to simulating aqueous SOA (aqSOA) reactions is photo-oxidation of laboratory standards in pure water. Reactions leading to aqSOA formation should be studied within real cloud and fog water to determine whether additional competing processes might alter apparent rates of reaction as indicated by rates of reactant loss or product formation. To evaluate and identify the origin of any cloud water matrix effects on one example of observed aqSOA production, pyruvate oxidation experiments simulating aqSOA formation were monitored within pure water, real cloud water samples, and an aqueous solution of inorganic salts. Two analysis methods were used: online electrospray ionization high-resolution time-of-flight mass spectrometry (ESI-HR-ToF-MS), and offline anion exchange chromatography (IC) with quantitative conductivity and qualitative ESI-HR-ToF-MS detection. The apparent rate of oxidation of pyruvate was slowed in cloud water matrices: overall measured degradation rates of pyruvate were lower than in pure water. This can be at least partially accounted for by the observed formation of pyruvate from reactions of other cloud water components. Organic constituents of cloud water also compete for oxidants and/or UV light, contributing to the observed slowed degradation rates of pyruvate. The oxidation of pyruvate was not significantly affected by the presence of inorganic anions (nitrate and sulfate) at cloud-relevant concentrations. Future bulk studies of aqSOA formation reactions using simplified simulated cloud solutions and model estimates of generated aqSOA mass should take into account possible generation of, or competition for, oxidant molecules by organic components found in the complex matrices typically associated with real atmospheric water droplets. Additionally, it is likely that some components of real atmospheric waters have not yet been identified as aqSOA precursors, but could be distinguished through further simplified bulk oxidations of known atmospheric water components.

Advanced treatment of refractory sebacic acid wastewater

Advanced treatment of refractory sebacic acid (SA) present in wastewater discharges from SA manufacturing industry (SAWW) is reported. Ion exchange (IE), electrochemical oxidation (EO), EO coupled with electrocoagulation (EO–EC), wet air oxidation (WAO), and catalytic wet air oxidation (CWAO) experiments were conducted. It is found that SA can be efficiently removed from aqueous solutions using a strong base anion-exchange resin (Amberlite IR 400), which showed a breakthrough capacity of 49.0 mg SA/mL resin (0.485 meq/mL). However, presence of inorganic anions (SO42-, PO42-, Cl–, and NO3-) is detrimental. Regeneration and reuse of spent resin, the effect of inorganic anions and morphology (SEM) of spent resin were also investigated. In addition, batch EO experiments conducted using Ti/RuO2-Pt anode and stainless steel (SS) cathode showed poor mineralization efficiency (8.4%). Pd2+-catalyzed WAO experiments performed in a high pressure reactor (473 K, 0.689 MPa, 2 h) provided more efficient mineralization of SA (42.2%) compared with EO. The results constitute an important outcome which may be useful to SA manufacturing industry.