Natural organic matter (NOM) can inhibit the photocatalytic degradation of organic micropollutants (OMPs) through inner filter effect, reactive oxygen species (ROS) scavenging, and competitive ...adsorption. However, previous studies have focused solely on the bulk properties of NOM and our understanding of the inhibition mechanism by NOM fractions during photocatalytic degradation of OMP is still fragmentary. In this study, five well-characterized different NOM samples (i.e., secondary treated wastewater, river water, and three standard NOM surrogates) were used to elucidate the inhibition mechanisms during photocatalytic degradation of carbamazepine (a model OMP) using TiO2 and its composites with carbon nanotubes (CNT-TiO2) under UVC and solar-light irradiation. The results indicated that terrestrially derived NOM with high aromaticity, a low oxygen/carbon atom ratio, and large molecular weight is the major fraction that participates in ROS scavenging, competitive adsorption, and inner filter effect. Furthermore, the modeling analysis suggested that inner filter effect due to NOM and ROS scavenging was the most influential inhibitory mechanism. In the case of secondary treated wastewater, the presence of high concentrations of inorganic species (e.g., PO43−, Cl−, and NO3−) together with NOM significantly reduced the photocatalytic degradation of carbamazepine. Overall, the methods and the results of this study provide a comprehensive understanding of the effects of NOM fractions on photocatalysis and highlight the need to further consider the interplay between NOM and background inorganic constituents in photocatalytic degradation of OMP.
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•The inhibition was studied with NOM surrogates, river water, and wastewater.•Aromatic terrestrially derived NOM with high MW inhibit photocatalysis.•Inhibition mechanism: ROS scavenging > inner filter effect > competitive adsorption.
The high concentrations of pharmaceuticals and personal care products (PPCP) that found in water in many locations are of concern. Among the available water treatment methods, heterogeneous ...photocatalysis using TiO2 is an emerging and viable technology to overcome the occurrence of PPCP in natural and waste water. The combination of carbonaceous materials (e.g., activated carbon, carbon nanotubes and graphene nanosheets) with TiO2, a recent development, gives significantly improved performance. In this article, we present a critical review of the development and fabrication of carbonaceous-TiO2 and its application to PPCP removal including its influence on water chemistry, and the relevant operational parameters. Finally, we present an analysis of current priorities in the ongoing research and development of carbonaceous-TiO2 for the photodegradation of PPCP.
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•The review considers studies on PPCPs' degradation by C–TiO2 over the past decade.•Studies on the performance of C–TiO2 under environmentally relevant are limited.•Cheap, scalable and environment-friendly method for C–TiO2 preparation is needed.
Increasing number of application of ultrahigh-resolution mass spectrometry (UHR-MS) to natural organic matter (NOM) characterization requires an efficient and accurate formula assignment from a ...number of mass data. Herein, we newly developed two automated batch codes (namely TRFu and FuJHA) and assessed their formula assignment accuracy together with frequently used open access algorithms (i.e., Formularity and WHOI). Overall assignment accuracy for 8719 NOM-like emerging chemicals with known molecular formulae (mass range from 68 Da to 1000 Da) was highest (94%) for TRFu. Further, TRFu showed up to 99.1% formula assignment ratio for a total 76,880 UHR-MS peaks from 35 types of NOM (e.g., aquatic, soil/sediment, biochar). Therefore, as a reliable and practically feasible tool, the automated batch TRFu (freely available at ChemRxiv, https://doi.org/10.26434/chemrxiv.9917399) can precisely characterize UHR-MS spectra of various NOM and could be extended to non-target screening of NOM-like emerging chemicals in natural and engineered environments.
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•Two automated batch codes were newly developed for natural organic matter (NOM).•For the first time, the formula assignment was compared for different NOM types.•The TRFu code provided high assignment accuracy (94%) for NOM-like chemicals.•The TRFu code can be useful for non-target screening of NOM-like chemicals.•The freely available TRFu code provides a useful tool for NOM research community.
A simple and cost-effective route has been utilized for the preparation of a novel lamellar structured FeOCl/g-C3N5 nanocomposite as Z-scheme photocatalyst. The preparation method was performed under ...the ambient temperature conditions without any hazardous chemicals. Various characterization techniques, namely XRD, FESEM, TEM, FT-IR, UV–Vis, DRS, and PL were carried out to analyse the nanocomposite for confirmation of FeOCl/g-C3N5 nanocomposite. To evaluate its and visible light degradation performances tetracycline (T-C) was used as target pollutant. Among the optimum loading for the g-C3N5 incorporated FeOCl binary nanocomposites, the g-C3N5/FeOCl exhibited a superlative degradation performance toward the T-C antibiotic pollutant. The results confirmed that 95% of T-C was degraded within 40 min under photodegradation mechanism. The improved photodegradation performance in degradation of T-C was mainly due to the reduction in electron-hole recombination, broadening in the light absorption by g-C3N5 incorporation, which leads to shortening the degradation time. Furthermore, the hydroxyl and superoxide radicals played a major role in the photodegradation process and the possible mechanism was elucidated and proposed. The present work implies a novel, sustainable, and efficient Z-scheme system that may deliver a convenient method for environment remediation.
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•A simple cost-effective method has been utilized for nanocomposite preparation.•To evaluate its degradation performances tetracycline was used as model.•The hydroxyl and superoxide radicals played a major role in the photodegradation.•The present work presents a sustainable, Z-scheme system for environment remediation.
Understanding the reaction mechanism of OH•-mediated oxidation of organic micropollutants (OMPs) contributes to the assessment and development of advanced oxidation processes (AOPs) for removal of ...OMPs in water environment. In this study, a theoretical approach using quantum chemical calculation (QCC) was employed to investigate the prediction accuracy of the reaction mechanism (i.e., reaction site and rate) for OH•-mediated oxidation of phenol, where the hydroquinone and catechol are generated as transformation products (TPs) via radical and electrophilic reactions. We compared three different levels of theory (Hartree-Fock, B3LYP, and M06-2X) with 6-311 + G (2d,2p)/SMD, and the reaction site and rate constants were predicted by the Fukui function and transition state theory, respectively. Overall, the prediction accuracy of the TPs formation mechanism was the highest in the calculations using M06-2X. For example, the initial OH• addition to phenol was predicted to occur with a probability of 77% for the ortho position and 23% for the para position, which was consistent with the experimental observation. By applying the transition state theory, the rate constants toward TPs formation pathway can be reasonably reproduced, suggesting that M06-2X has an effective function for polycyclic reactions. However, the observed discrepancies in rate constants are inferred from dispersion effects and the multi-reference property in the computational system or derived from mismatch of target reactions between theoretical calculations and experiments. Overall, this study provides an insight into QCC application for investigating the formation mechanism of TPs in AOPs for removal of OMPs in water environment.
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•Phenol oxidation were computed by using HF, B3LYP, and M06-2X.•Reaction site and rate were determined by Fukui function and transition state theory.•M06-2X showed the highest accuracy for prediction of TPs formation.•This study provides insights into theoretical approach for OMP degradation mechanism.
Brominated and/or chlorinated organic compounds (referred to as organohalogens) are frequently detected in natural and engineered environments. However, ultrahigh-resolution mass spectrometry ...(UHR-MS)-based nontargeted identification of organohalogens remains challenging because of the coexistence of a vast number of halogenated and nonhalogenated organic molecules. In this study, a new algorithm, namely, the NOMDBP code, was developed to simultaneously identify organohalogens and non-organohalogens from the UHR-MS spectra of natural and engineered waters. In addition to isotopic patterns, for the first time, three optional filter rules
, selection for minimum nonoxygen heteroatoms, inspection of the presence of newly formed halogenated disinfection byproducts (Xn-DBPs), and of their precursors were incorporated into our code, which can accurately identify DBP-associated peaks and further elucidate Xn-DBP generation and transformation mechanisms. The formula assignment ratio against 2815 previously reported organohalogens, and their 11,583 isotopologues exceeded 97%. Application of our algorithm to disinfected natural organic matter indicated that oxygen-containing Xn-DBP species accounted for a majority of the Xn-DBPs. Furthermore, brominated Xn-DBPs (Br-DBPs) were characterized by a higher degree of unsaturation compared to chlorinated Xn-DBPs. In addition to electrophilic substitution and electrophilic addition reactions, the decomposition/transformation pathway was found to be another important mechanism in Br-DBP formation. The results of this study highlight the superior potential of our code for the efficient detection of yet unknown organohalogens (including organohalogens bearing nonoxygen heteroatoms) in a nontargeted manner and for the identification of their generation mechanism occurring during the disinfection process.
Here we present a new compact design of a vertical water distillation tower based on solar stills. The experimental setup consisted of a vertical tower with five water trays, supported by a metal ...duct and surrounded by a glass enclosure. The water yield and thermal, exergic, and economic features of the tower were investigated and analyzed. A new performance prediction hybrid model was also developed. A powerful artificial intelligence tool called the random vector functional link (RVFL) neural network was integrated with the Runge Kutta optimizer (RUN) to predict the water yield and temperature of the established tower. The model efficiency was compared to that of pure RVFL and an optimized RVFL model using a particle swarm optimizer (PSO). The drinkable water yield of the proposed design was 2.1 L/m2 (considering the tray area) and 5.3 L/m2 (considering the land use area); energy and exergy efficiencies were ∼31.7% and ∼3.3%, respectively. The cost of the produced drinkable water was approximately $0.013/L. The developed system provides considerable improvement compared with conventional designs of solar stills. The proposed RVFL–RUN model outperformed the pure RVFL and RVFL–PSO models for predicting system performance. The coefficients of determination between the experimental water productivity and water temperature and the predicted values, using the RVFL–RUN model, were 0.91 and 0.97, respectively.
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•A new compact design of a vertical water distillation tower based is developed.•The tower was tested under actual coastal conditions.•The produced drinkable water had a low cost of $0.013/L.•The system performance was predicted by a hybrid machine learning model.
•LCFAs-inhibition found to be saturation index, temperature, and concentration dependent.•Syntrophus, Syntrophothermus, Syntrophomonas and Thermosyntropha can degrade LCFAs.•Cations supplementation ...catalyzed LCFA salt formation.•Natural adsorbents can enhance AD process via LCFAs capture.
The inhibition of the anaerobic digestion (AD) process, caused by long chain fatty acids (LCFAs), has been considered as an important issue in the wastewater treatment sector. Proper understanding of mechanisms behind the inhibition is a must for further improvements of the AD process in the presence of LCFAs. Through analyzing recent literature, this review extensively describes the mechanism of LCFAs degradation, during AD. Further, a particular focus was directed to the key parameters which could affect such process. Besides, this review highlights the recent research efforts in mitigating LCFAs-caused inhibition, through the addition of commonly used additives such as cations and natural adsorbents. Specifically, additives such as bentonite, cation-based adsorbents, as well as zeolite and other natural adsorbents for alleviating the LCFAs-induced inhibition are discussed in detail. Further, panoramic evaluations for characteristics, various mechanisms of reaction, merits, limits, recommended doses, and preferred conditions for each of the different additives are provided. Moreover, the potential for increasing the methane production via pretreatment using those additives are discussed. Finally, we provide future horizons for the alternative materials that can be utilized, more efficiently, for both mitigating LCFAs-based inhibition and boosting methane potential in the subsequent digestion of LCFA-related wastes.
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Ultrahigh-resolution mass spectrometry (UHR-MS) coupled with isotope labeling has attracted significant attention in elucidating the mechanisms of the transformation of dissolved organic matter ...(DOM). Herein, we developed a novel formula assignment algorithm based on deuterium (D)-labeled UHR-MS, namely, FTMSDeu, for the first time. This algorithm was employed to determine the precursor molecules of halogenated disinfection byproducts (X n -DBPs) and to evaluate the relative contribution of electrophilic addition and substitution reactions in X n -DBP formation according to the H/D exchange of DOM molecules. Further, tandem mass spectrometry with homologous-based network analysis was used to validate the formula assignment accuracy of FTMSDeu in the identification of iodinated disinfection byproducts. Electrophilic substitution accounted for 82–98, 71–89, and 43–45% of the formation for Cl-, Br-, and I-containing X n -DBPs, respectively, indicating the dominant role of the electrophilic substitution in chlorinated disinfection byproducts with low Br and I concentrations. The absence of putative precursors in some X n -DBPs also suggests that X n -DBP formation includes secondary reactions (e.g., oxidation and hydrolysis) in addition to the electrophilic addition and/or substitution of halogens. These findings highlight the significance of isotopically labeled UHR-MS techniques in revealing the transformation of DOM in natural and engineered systems.
•Anammox baffled reactor (AnBR) revealed moderate start-up period of 53 days.•Anammox sludge characteristics have statistically robust relationships.•ANN effectively simulated AnBR with R2 and MSE of ...0.99 and 0.002, respectively.•AnBR at NLR of 4.04 kg-N/m3/day exhibited net present value of $48100.9.
Anammox baffled reactor (AnBR) had a moderate start-up period of 53 days. Interestingly, tangled relationships between key parameters affecting anammox performance were observed, i.e., polynomial function for nitrogen loading rate (NLR) with extracellular polymeric substances (EPS), linear relationships between EPS with granules diameter, granules diameter with settling velocity, and settling velocity with biomass concentration. The correlation coefficients (R2) were 0.97, 0.84, 0.86, and 0.88, respectively. Furthermore, a multi-layered feed forward artificial neural network (ANN) was utilized for simulating and predicting the performance of AnBR. An ANN structure of two hidden layers with four neurons at 1st layer and eight neurons at 2nd layer achieved the best goodness of fit with the minimum mean squared error (MSE) and maximum R2 of 0.002 and 0.99, respectively. Additionally, economic assessment stated that using AnBR at NLR of 4.04 ± 0.10 kg-N/m3/day achieved the maximum net present value of $48100.9.
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