Experimental and theoretical insight into carbamazepine degradation by chlorine-based advanced oxidation processes: Efficiency, energy consumption, mechanism and DBPs formation.

Chlorine has been widely used in different advanced oxidation processes (AOPs) for micropollutants removal. In this study, different chlorine-based AOPs, namely medium pressure (MP) UV/chlorine, low pressure (LP) UV/chlorine, and in-situ chlorination, were compared for carbamazepine (CBZ) removal efficiency, energy consumption, and disinfection by-products (DBPs) formation. All three processes could achieve nearly 100% CBZ removal, while the reaction time needed by in-situ chlorination was double the time required by UV/chlorine processes. The energy consumed per magnitude of CBZ removed (EE/O) of MP UV/chlorine was 13 times higher than that of LP UV/chlorine, and relative to that of in-situ chlorination process. Accordingly, MP and LP UV/chlorine processes generated one to two orders of magnitude more hydroxyl radicals (•OH) and reactive chlorine species (RCS) than in-situ chlorination. Besides, RCS were the dominant reactive species, contributing to 78.3%, 75.6%, and 71.6% of CBZ removal in MP, LP UV/chlorine, and in-situ chlorination, respectively. According to the Gibbs free energy barriers between CBZ and RCS/•OH calculated based on density functional theory (DFT), RCS had more reaction routes with CBZ and showed lower energy barrier in the main CBZ degradation pathways like epoxidation and formation of iminostilbene. When applied to secondary wastewater effluent, UV/chlorine and in-situ chlorination produced overall DBPs ranging from 104.77 to 135.41 µg/L. However, the production of chlorate during UV/chlorine processes was 15 times higher than that during in-situ chlorination.

Z-scheme plasmonic Ag decorated Bi2WO6/NiO hybrids for enhanced photocatalytic treatment of naphthenic acids in real oil sands process water under simulated solar irradiation.

A novel photocatalyst, Bi2WO6/NiO/Ag, with hierarchical flower-like Z-scheme heterojunction, which exhibited excellent stability and photocatalytic activity over a wide light spectrum, was firstly synthesized and used in the remediation of real oil sands process water (OSPW) and achieved complete removal of aromatics, classical naphthenic acids (NAs), and heteroatomic NAs after 6 h of photocatalytic treatment. The acute toxicity of OSPW was completely eliminated after only 2 h of treatment. h+ and ∙OH were found to be the major oxidative species in the photocatalytic system. The enhanced photocatalytic efficiency is the result of the unique Z-scheme electron transfer among electron mediators Ag, NiO, and Bi2WO6, which was supported by the in-situ irradiated XPS. The study benefits the design of engineered passive treatment approach for OSPW remediation through solar light-driven catalyst.

Can short-term data accurately model long-term environmental exposures? Investigating the multigenerational adaptation potential of Daphnia magna to environmental concentrations of organic ultraviolet filters.

Organic ultraviolet filters (UVFs) are contaminants of concern, ubiquitously found in many aquatic environments due to their use in personal care products to protect against ultraviolet radiation. Research regarding the toxicity of UVFs such as avobenzone, octocrylene and oxybenzone indicate that these chemicals may pose a threat to invertebrate species; however, minimal long-term studies have been conducted to determine how these UVFs may affect continuously exposed populations. The present study modeled the effects of a 5-generation exposure of Daphnia magna to these UVFs at environmental concentrations. Avobenzone and octocrylene resulted in minor, transient decreases in reproduction and wet mass. Oxybenzone exposure resulted in > 40% mortality, 46% decreased reproduction, and 4-fold greater reproductive failure over the F0 and F1 generations; however, normal function was largely regained by the F2 generation. These results indicate that Daphnia are able to acclimate over long-term exposures to concentrations of 6.59 µg/L avobenzone, ∼0.6 µg/L octocrylene or 16.5 µg/L oxybenzone. This suggests that short-term studies indicating high toxicity may not accurately represent long-term outcomes in wild populations, adding additional complexity to risk assessment practices at a time when many regions are considering or implementing UVF bans in order to protect these most sensitive invertebrate species.

Transformation and toxicity studies of UV filter diethylamino hydroxybenzoyl hexyl benzoate in the swimming pools.

Diethylamino hydroxybenzoyl hexyl benzoate (DHHB), an ultraviolet (UV) filter, can be found in sunscreens and other personal care products and thus can be introduced into swimming pools through the swimmers. In outdoor pools, DHHB will inevitably interact with free chlorine and sunlight. Therefore, the mechanism of solar­chlorine chemical transformation of DHHB, as well as the environmental risk, were investigated in this work. In chlorinated with solar (Cl + solar) process, free chlorine was the dominant contributor to 85% of the DHHB degradation, while hydroxyl radicals and reactive chlorine species contributed only 15% because of low free radical generation and fast DHHB and free chlorine reaction rates. Scavenging matrices, such as Cl-, NH4+, and dissolved organic matter (DOM), inhibited the degradation of DHHB in the Cl + solar process, while Br-, HCO3-, NO3-, and urea promoted DHHB degradation. DHHB degradation was inhibited in tap water swimming pool samples, while it was enhanced in seawater pool samples by the Cl + solar process. Seven transformation by-products (TBPs) including mono-, dichlorinated, dealkylate, and monochloro-hydroxylated TBPs were identified. Three degradation pathways, chlorine substitution, chlorine and hydroxyl substitution, and dealkylation were proposed for DHHB transformation in the Cl + solar process. Both Quantitative structure-activity relationship and Aliivibrio fischeri toxicity tests demonstrated increased toxicity for the chlorinated TBPs. A risk assessment of the DHHB and its TBPs suggested that both DHHB and its chlorinated TBPs pose a significant health risk.

New insights into the biological roles of immune cells in neural stem cells in post-traumatic injury of the central nervous system.

Traumatic injuries in the central nervous system, such as traumatic brain injury and spinal cord injury, are associated with tissue inflammation and the infiltration of immune cells, which simultaneously affect the self-renewal and differentiation of neural stem cells. However, the tissue repair process instigated by endogenous neural stem cells is incapable of restoring central nervous system injuries without external intervention. Recently, resident/peripheral immune cells have been demonstrated to exert significant effects on neural stem cells. Thus, the restoration of traumatic injuries in the central nervous system by the immune intervention in neural stem cells represents a potential therapeutic method. In this review, we discuss the roles and possible mechanisms of immune cells on the self-renewal and differentiation of neural stem cells along with the prognosis of central nervous system injuries based on immune intervention. Finally, we discuss remaining research challenges that need to be considered in the future. Further elucidation of these challenges will facilitate the successful application of neural stem cells in central nervous system injuries.

Using immune cell-based bioactivity assays to compare the inflammatory activities of oil sands process-affected waters from a pilot scale demonstration pit lake.

In this study, we provide evidence that oil sands process-affected waters (OSPW) contain factors that activate the antimicrobial and proinflammatory responses of immune cells. Specifically, using the murine macrophage RAW 264.7 cell line, we establish the bioactivity of two different OSPW samples and their isolated fractions. Here, we directly compared the bioactivity of two pilot scale demonstration pit lake (DPL) water samples, which included expressed water from treated tailings (termed the before water capping sample; BWC) as well as an after water capping (AWC) sample consisting of a mixture of expressed water, precipitation, upland runoff, coagulated OSPW and added freshwater. Significant inflammatory (i.e. macrophage activating) bioactivity was associated with the AWC sample and its organic fraction (OF), whereas the BWC sample had reduced bioactivity that was primarily associated with its inorganic fraction (IF). Overall, these results indicate that at non-toxic exposure doses, the RAW 264.7 cell line serves as an acute, sensitive and reliable biosensor for the screening of inflammatory constituents within and among discrete OSPW samples.

Interface Design Enabling Stable Polymer/Thiophosphate Electrolyte Separators for Dendrite-Free Lithium Metal Batteries.

Organic/inorganic interfaces greatly affect Li+ transport in composite solid electrolytes (SEs), while SE/electrode interfacial stability plays a critical role in the cycling performance of solid-state batteries (SSBs). However, incomplete understanding of interfacial (in)stability hinders the practical application of composite SEs in SSBs. Herein, chemical degradation between Li6 PS5 Cl (LPSCl) and poly(ethylene glycol) (PEG) is revealed. The high polarity of PEG changes the electronic state and structural bonding of the PS4 3- tetrahedra, thus triggering a series of side reactions. A substituted terminal group of PEG not only stabilizes the inner interfaces but also extends the electrochemical window of the composite SE. Moreover, a LiF-rich layer can effectively prevent side reactions at the Li/SE interface. The results provide insights into the chemical stability of polymer/sulfide composites and demonstrate an interface design to achieve dendrite-free lithium metal batteries.

Effects of Fe3O4 nanoparticles on anaerobic digestion enzymes and microbial community of sludge.

Fe3O4 nanoparticles (NPs) have potential effects on the anaerobic digestion of excess sludge. The effects of different concentrations of Fe3O4 NPs (0, 100, 200, 400 and 600 mg/L) on enzymes and microorganisms in anaerobic digestion were studied to explore the mechanism of the effect of Fe3O4 NPs on anaerobic digestion. The results showed that 100, 200 and 400 mg/L Fe3O4 NPs could promote anaerobic digestion, and 200 mg/L Fe3O4 NPs had the most obvious promoting effect. The activities of protease, cellulase, dehydrogenase, acetic kinase and coenzyme F420 in the 200 mg/L Fe3O4 NPs group reached 120 U/mg VS, 71.75 U/g VS, 135 U/mL, 94 mol/L, 1.37 umol/g VSS, respectively, which were 3.8, 1.5, 1.2, 1.2 and 1.6 times of the blank group, respectively. However, when the concentration of Fe3O4 NPs reached 600 mg/L, the activities of cellulase, dehydrogenase and acetic kinase were lower than those of the blank group, and anaerobic digestion was inhibited. The above conclusions can also be confirmed by high-throughput sequencing. The abundance of longilinea and ornatilina in the 200 mg/L Fe3O4 NPs group was 8.8% and 4.1% respectively, and methanthrix abundance was 69%, which was more conducive to decomposition acetic acid into CH4.Highlights To explore the effects of Fe3O4 NPS on enzyme activity and microorganisms.200mg/L Fe3O4 NPs could significantly promote the activity of enzyme.200mg/L Fe3O4 NPs could promote the diversity of bacterial and archaeal communities.600mg/L Fe3O4 NPs could inhibit some enzyme activities and microbial community diversity.

Aerobic degradation of anionic polyacrylamide in oil sands tailings: Impact factor, degradation effect, and mechanism.

An investigation was carried out to study the degradation of anionic polyacrylamide (A-PAM) under different temperature and microorganism conditions as well as to assess its effects on water chemistry and toxicity in oil sands tailings. The maximum removal efficiency of A-PAM was 41.0 % in tailings water with augmented microorganisms at 20 °C. No acrylamide (AMD) monomer was released during the A-PAM degradation, while residual AMD, from the manufacturing process to make A-PAM, was completely removed within 4 weeks. Both temperature and microorganisms showed significant effects (p < 0.05) on the degradation of A-PAM and residual AMD. Gel permeation chromatography (GPC) and Fourier transform infrared (FT-IR) analyses showed that biodegradation could be the active pathway for A-PAM degradation in oil sands tailings. These analyses also indicated that macromolecular A-PAM was degraded into lower molecular weight organic compounds. No remarkable changes of the total concentration of naphthenic acids (NAs) were observed in A-PAM treated tailings water. However, low concentrations of fatty acids (<2.5 mg/L), which fit the NAs formula, were detected in pure polymer solution, indicating that A-PAM degradation would not affect the total concentration of NAs in tailings water but affect their distribution. Our results also showed that total organic carbon (TOC) and chemical oxygen demand (COD) could be used as indicators of A-PAM degradation in tailings water due to their strong linear correlations (R2 > 0.90). Only slight increases in zeta potential and pH were found during A-PAM degradation. Limited effect on acute toxicity and no genotoxicity were found in A-PAM treated tailings water. Furthermore, the results suggest that A-PAM undergoes hydrolysis of amide groups by amidase enzymes, releasing ammonia and smaller molecules like organic acids. This research provides valuable information regarding the stability and impacts of A-PAM and thus will be beneficial for the management of oil sands tailings in long period of time.

Impact of the Chlorination of Lithium Argyrodites on the Electrolyte/Cathode Interface in Solid-State Batteries.

Lithium argyrodite-type electrolytes are regarded as promising electrolytes due to their high ionic conductivity and good processability. Chemical modifications to increase ionic conductivity have already been demonstrated, but the influence of these modifications on interfacial stability remains so far unknown. In this work, we study Li6 PS5 Cl and Li5.5 PS4.5 Cl1.5 to investigate the influence of halogenation on the electrochemical decomposition of the solid electrolyte and the chemical degradation mechanism at the cathode interface in depth. Electrochemical measurements, gas analysis and time-of-flight secondary ion mass spectrometry indicate that the Li5.5 PS4.5 Cl1.5 shows pronounced electrochemical decomposition at lower potentials. The chemical reaction at higher voltages leads to more gaseous degradation products, but a lower fraction of solid oxygenated phosphorous and sulfur species. This in turn leads to a decreased interfacial resistance and thus a higher cell performance.

Potential promotion of activated carbon supported nano zero-valent iron on anaerobic digestion of waste activated sludge.

A large amount of waste activated sludge (WAS) harms the ecological environment, and anaerobic digestion (AD) is an effective method for WAS treatment. In this study, activated carbon (AC)/ nano zero-valent iron (NZVI) was synthesized by a liquid-phase reduction method, and was used to boost methane production. The associated mechanisms and effects of additives on AD during the addition and removal stage were investigated systematically. Compared to the blank group, the cumulative methane production was increased by 14.3%, 26.3% and 34.1% in the groups of AC, NZVI and AC/NZVI, respectively. The addition of AC/NZVI significantly increased the concentration of VFAs and promoted the hydrolysis and acidification of WAS. After the AD of the additives addition stage was finished, the additives were removed and the sludge was replenished in all groups, the methanogenesis performance of the experimental groups was significantly inhibited. The cumulative methane production in the AC and AC/NZVI groups was 21.7% and 13.5% lower than the blank group, respectively. The experimental results have a good correlation with curve fitting by the modified Gompertz model. The modified Gompertz model found that AC, NZVI and AC/NZVI increased the methanogenic potential and maximum methane production rate of WAS, but also prolonged the lag-phase time. AC/NZVI might play a role in coupling effects. It could not only maintain the original characteristics of NZVI and increase its stability, but also develop the advantages of AC promoting direct interspecies electron transfer. Microbial community analysis indicated that the abundance of hydrogenotrophic methanogens was enriched by AC/NZVI.

Fully-automated SPE coupled to UHPLC-MS/MS method for multiresidue analysis of 26 trace antibiotics in environmental waters: SPE optimization and method validation.

Achieving simultaneous determination of antibiotic multiresidues in environmental waters by solid phase extraction (SPE) coupled with ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) with detection limits ≤ ng L-1 is still a huge challenge. Moreover, the offline SPE procedure was performed manually, costly, and time-consuming, while the online SPE required precision pretreatment instruments that require highly-skilled personnel. In this paper, a fully automated SPE coupled with UHPLC-MS/MS method was developed for analysis of antibiotics (sulfonamides, quinolones, and macrolides) in water matrices. Sample preparation optimization included SPE materials and configuration (HLB disks), sample volume (500-1000 mL), and pH (pH = 3) with a flow rate at 2~5 mL min-1, and an elution procedure with 2 × 6 mL methanol, and 2 × 6 mL acetone. Meanwhile, the parameters for UHPLC-MS/S detection of analytes were optimized, including LC retention time, and MS parameters. The instrumental limits of detection (LOD) and quantification (LOQ) of analytes ranged from 0.01-0.72 µg L-1 and 0.05-2.39 µg L-1, respectively, with satisfactory linear calibration (R2 > 0.995) and precision (< 9.9%). Recoveries in spike samples ranged between 77.5-104.9% in pure water, 59.4-97.8% in surface water (SW), and 58.2-108.6% in wastewater effluent (WWE) with relative standard deviations ≤ 12.8%. The matrix effects observed for most analytes were suppression (0-28.1%) except for five analytes having presented enhancement (0-14.6 %) in SW or WWE. This method can basically meet the needs of trace antibiotic residues detection in waters, with examples of concentrations of detected antibiotics being lower than LOQ (LLQ) -94.47 ng L-1 in WWEs and LLQ-15.47 ng L-1 in SW in the lower reaches of the Yangtze River Basin.

Effect of Fe3O4 nanoparticles on the performance of anaerobic digestion through electrochemical analysis.

In view of the high cost and complex operation of the traditional chemical method for the determination of the anaerobic digestion (AD) process, this study investigated the feasibility of using electrochemistry analysis to determine the effect of Fe3O4 nanoparticles (NPs) on the AD process. The quantity of electric charge of Fe3O4 NPs modified graphite electrode in sodium acetate electrolyte was higher than that of graphite electrode. The addition of Fe3O4 NPs was beneficial to improve the electrochemical activity of the electrode. On this basis, enzymes and microorganisms were extracted from anaerobic reactors containing different concentrations of Fe3O4 NPs to make electrodes respectively to further investigate the effects of Fe3O4 NPs on enzyme and microbial activities in AD. The electrochemical analysis results of the enzyme electrodes and microbial electrodes showed that the quantity of electric charge produced by the group of 200 mg/L Fe3O4 NPs was the highest. The cumulative biogas production of 200 mg/L Fe3O4 NPs was 809 mL/g VS, and better than other groups. These results showed that 200 mg/L Fe3O4 NPs was the best dosage, and the electrochemical analysis has higher sensitivity in the AD detection.Highlight Electrochemistry was used to investigate the activities of enzymes and microorganisms in anaerobic digestion.The effects of Fe3O4 nanoparticles on different stages of anaerobic digestion were analyzed by electrochemical method.The feasibility of electrochemical analysis was verified from the perspective of microbiology.

A mechanistic investigation of the Li10GeP2S12|LiNi1-x-yCoxMnyO2 interface stability in all-solid-state lithium batteries.

All-solid-state batteries are intensively investigated, although their performance is not yet satisfactory for large-scale applications. In this context, the combination of Li10GeP2S12 solid electrolyte and LiNi1-x-yCoxMnyO2 positive electrode active materials is considered promising despite the yet unsatisfactory battery performance induced by the thermodynamically unstable electrode|electrolyte interface. Here, we report electrochemical and spectrometric studies to monitor the interface evolution during cycling and understand the reactivity and degradation kinetics. We found that the Wagner-type model for diffusion-controlled reactions describes the degradation kinetics very well, suggesting that electronic transport limits the growth of the degradation layer formed at the electrode|electrolyte interface. Furthermore, we demonstrate that the rate of interfacial degradation increases with the state of charge and the presence of two oxidation mechanisms at medium (3.7 V vs. Li+/Li < E < 4.2 V vs. Li+/Li) and high (E ≥ 4.2 V vs. Li+/Li) potentials. A high state of charge (>80%) triggers the structural instability and oxygen release at the positive electrode and leads to more severe degradation.

Influences of integrated coagulation-ozonation pretreatment on the characteristics of dissolved organic pollutants (DOPs) of heavy oil electric desalting wastewaters.

The quality of heavy oil electric desalting wastewaters (HO-EDWs) affects the effectiveness of refinery wastewater treatment plants. In this study, an integrated coagulation-ozonation (ICO) process was used to pretreat HO-EDWs and the influences on the characteristics of dissolved organic pollutants (DOPs) were investigated. Coagulation using aluminum sulfate removed 39% of soluble chemical oxygen demand (SCOD), 21% of dissolved organic carbon (DOC), 57% of petroleum hydrocarbons and 38% of polar oils from Liaohe HO-EDWs and the biodegradability was greatly improved. Ozonation removed 33% of SCOD and 88% of polar oils from the coagulated HO-EDWs. Most species of aromatic compounds, phenols, aliphatic acids, anilines and naphthenic acids with high C numbers and ring numbers were degraded and the unsaturation degrees of DOPs significantly decreased under ozonation. As a result, the biodegradability was further improved and the acute toxicity towards Vibrio fischeri was substantially reduced. Some OxS1 species and organic nitrogen compounds in HO-EDWs were penetrated through ozonation and caused the residual biotoxicity. The results demonstrate the potential of ICO pretreatment for improving the quality of refractory HO-EDWs.

Enhanced primary treatment during wet weather flow using ferrate as a coagulant, coagulant aid and disinfectant.

This study evaluated the dual-function of ferrate as a coagulant and disinfectant for chemically-enhanced primary treatment during wet weather flow (WWF). For the first time, ferrate was thoroughly examined as a coagulant aid with aluminum sulfate (alum) to minimize the organic and inorganic contents along with microbial level during WWF. Ferrate as a coagulant was evaluated based on a two-level factorial design. At an optimized condition, a ferrate dose of 0.5 mg/L Fe with a cationic polymer (1.25 mg/L) removed 83% of turbidity, 87% of total suspended solids (TSS), 70% of chemical oxygen demand (COD), and 23% of ortho-phosphate (OP). Linear models were developed and used to adequately predict the removals. Ferrate as a coagulant aid added with alum showed better removal of TSS while no improvement was observed in the removals of turbidity and COD. The disinfection capacity of ferrate was evaluated at different dosing points when it was used as a coagulant, coagulant aid and as post dosed as a disinfectant. In particular, ferrate dose of 8 mg/L Fe removed only 2 logs of E. coli when it was used as a coagulant compared to more than 3-log removal of E. coli when ferrate was used as a coagulant aid and as a disinfectant. At optimal ferrate dose of 10 mg/L Fe as a coagulant aid with 6 mg/L Al achieved the target levels of turbidity (<8 NTU), TSS (<25 mg/L), and ferrate-induced iron particles (<0.6 mg/L) along with 5-log removal of E. coli within 31 min. This study suggested that using ferrate as a coagulant aid/disinfectant might be considered an effective approach for treating the wastewater during WWF.

Solar photocatalytic treatment of model and real oil sands process water naphthenic acids by bismuth tungstate: Effect of catalyst morphology and cations on the degradation kinetics and pathways.

Bitumen extraction from oil sands produces large quantities of oil sands process water (OSPW), which contains recalcitrant naphthenic acids (NAs). In this study, three different morphologies of bismuth tungstate (Bi2WO6) photocatalysts were prepared by hydrothermal method. The prepared catalyst was characterized to obtain its structural, textural and chemical properties and tested for the degradation of model NAs and real OSPW under simulated solar irradiation. Nanoplate, flower-like and swirl-like Bi2WO6 were prepared and the results showed that the flower-like structure exhibited the highest specific surface area and total pore volume. The highest photocatalytic activity for the degradation of NAs was also demonstrated by the flower-like Bi2WO6, achieving complete degradation of cyclohexanoic acid (CHA) at fluence-based rate constant of 0.0929 cm2/J. Superoxide radicals (O2•-) and holes were identified as the major reactive species generated during the photocatalytic process. The effect of metallic ions on the degradation rates of S-containing and N-containing NAs differed and the heteroatom was found to be the main reactive site. The by-products of heteroatomic NAs were identified and degradation pathways were reported for the first time. The concentration changes of each byproduct were further estimated by mass balance. This research provides valuable information for the treatment of NAs by engineered passive solar-based approaches.

Advancing the treatment of primary influent and effluent wastewater during wet weather flow by single versus powdered activated carbon-catalyzed ozonation for the removal of trace organic compounds.

For the first time, single and PAC-catalyzed ozonation were explored for the wastewater treatment during wet weather flow in a prompt and efficient process. The effect of varying the ozone (O3) specific dose on the removal of micropollutants (MPs) was first investigated with a mixture of pharmaceuticals, herbicides and perfluorinated compounds in clean water. Most MPs showed higher affinity towards catalytic ozonation. Carbamazepine and Atrazine were found to be good surrogates for fast and slow reacting compounds, respectively. Applying single or PAC-catalyzed ozonation for 1 min only after coagulation was more efficient than applying them simultaneously. PAC-catalyzed ozonation was more efficient for the removal of organics and O3-resistant MPs. Both single and PAC-catalyzed ozonation achieved 4 log removal of E. coli, reduced the acute and genetic toxicity, and estrogenic activity of the wastewater. A detailed cost analysis revealed that applying single ozonation after coagulation costs between 0.06 and 0.32 $/m3 while applying PAC-catalyzed ozonation costs between 0.32 and 0.63 $/m3 for a flow rate between 100 and 600 MLD. Through a comprehensive performance assessment, PAC-catalyzed ozonation was deemed superior with one drawback related to the disposal of PAC.

Characterization of raw and ozonated oil sands process water utilizing atmospheric pressure gas chromatography time-of-flight mass spectrometry combined with solid phase microextractionun.

This work describes a novel application of atmospheric pressure gas chromatography time-of-flight mass spectrometry (APGC-TOF-MS) combined with solid-phase microextraction (SPME) for the simultaneous analysis of hydrocarbons and naphthenic acids (NAs) species in raw and ozone-treated oil sands process water (OSPW). SPME method using polydimethylsiloxane (PDMS)-coated fibers was validated using gas chromatography with flame ionization detector (GC-FID) to ensure the SPME extractions were operated appropriately. The ionization pathways of the hydrocarbon species in OSPW in the APGC source were verified by analyzing a mixture of eight polyaromatic hydrocarbons which were ionized primarily via charge transfer to produce [M+] while NAs in OSPW were found to be ionized through protonation to generate [MH+] in the wet APGC source. SPME/APGC-TOF-MS analysis demonstrated a different composition profile in OSPW #1, with 74.5% of hydrocarbon species, 23.4% of O2-NAs, and 2.1% of the oxidized NA species at extraction pH 2.0 compared with that obtained by UPLC-TOF-MS analysis (36.9% of O2-NAs, 26.8% of O3-NAs, 24.9% of O4-NAs, 9.1% of O5-NAs, 2.3% of O6-NAs). Moreover, the peak areas of the total NAs and the total peak areas of NAs + hydrocarbons measured by SPME/APGC-TOF-MS correlated excellently with the total NA concentration determined by UPLC-TOF-MS (R2 = 0.90) and the concentrations of the total acid-extractable organics determined by SPME/GC-FID (R2 = 0.98), respectively. APGC-TOF-MS integrated with the SPME techniques could extend the range of target compounds and be a promising alternative to evaluate and characterize NAs and hydrocarbon in different water types.

Influences of coagulation pretreatment on the characteristics of crude oil electric desalting wastewaters.

Highly polluted crude oil electric desalting wastewaters (EDWs) severely affect the efficiency of refinery wastewater treatment plants (WWTPs). Coagulation is an efficient pretreatment to reduce the impacts of EDWs. In the present study, the influences of coagulation pretreatment on the characteristics of EDWs of three typical Chinese crude oils, Liaohe heavy oil (LHO), Karamay heavy oil (KHO) and Daqing light oil (DLO), were investigated. The stability of three raw EDWs was broken and the contents of organic pollutants were significantly reduced by aluminum sulfate coagulation. More soluble COD and polar oils were removed from LHO-EDW (1241 and 98 mg L-1) and KHO-EDW (779 and 57 mg L-1) compared to DLO-EDW (417 and 11 mg L-1). Coagulation significantly changed the compositions of the organic pollutants of two heavy oil EDWs; however, slightly influenced DLO-EDW, particularly the polar organic pollutants. Most types of aromatic compounds, aliphatic acids and Ox polar compounds were removed from two heavy oil EDWs, but mainly alkanes were removed from DLO-EDW. As such, the differences in the types of dominant polar compounds became insignificant among treated heavy oil and light oil EDWs. Coagulation notably decreased the acute biotoxicity and improved the biodegradability of all treated EDWs. The residual organic nitrogen compounds in treated KHO-EDW contributed to a higher residual biotoxicity compared to treated LHO-EDW. The results demonstrate that coagulation can effectively improve the qualities of heavy oil EDWs by lowering the contents of organic pollutants and removing recalcitrant compounds, thus guaranteeing the efficiency of refinery WWTPs.