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1. 题目: Highly efficient U(VI) capture from nuclear wastewater by an easily synthesized lignin-derived biochar: Adsorption performance and mechanism
文章编号: N23020709
期刊: Environmental Research
作者: Lijun Guo, Liangqiong Peng, Jiheng Li, Wenhua Zhang, Bi Shi
更新时间: 2023-02-07
摘要:
The efficient recycling of uranium (U) by adsorbents remains challenging due to the strong interference from coexisting impurities, insufficient desorption efficiency, and weak irradiation instability. In this work, a novel lignin-derived biochar (AL/BC) with high surface area and abundant functional groups was developed through a green and simple pyrolysis process, and an adsorbent for U(VI) capture was used. The optimist AL/BC-600 exhibited ultrahigh adsorption capacity for U(VI) of 4007 mg/g, possessing a wide pH range of 1–11, and powerful anti-interference ability when coexisting with various common cations and anions. In addition, AL/BC-600 showed high tolerance even under strong irradiation at a dose of 350 kGy. Most importantly, after the tenth round of the adsorption-desorption cyclic utilization, the adsorption efficiency and desorption rate of AL/BC-600 were actually over 95% and 80%, respectively. Hence, this study provides a green and simple process for synthesizing a novel adsorbent for highly efficient U(VI) capture, not only paving a path for alleviating the increasingly serious energy crisis, but also facilitating the low-carbon and circular development of lignin.
2. 题目: Contrasting distribution and speciation of sedimentary organic phosphorus among different basins of the Baltic Sea
文章编号: N23020708
期刊: Limnology and Oceanography
作者: Emil Rydin, Elias Broman, Kasper Reitzel, Kaarina Lukkari, Martijn Hermans, Linda Kumblad, Magnus Karlsson, Anna Apler, Bo Ek, Per J R Sjöberg
更新时间: 2023-02-07
摘要: Recycling of phosphorus (P) from deoxygenated sediments perpetuates eutrophic conditions in parts of the Baltic Sea. Sedimentary organic P is a major source of dissolved P to the water column, but also a sink for permanent P burial. The mechanisms behind these two pathways are, however, largely unknown. Using new methods, we determined P in DNA and phospholipids, which are both found in all organisms. We also identified inositol phosphates that are particularly important in eukaryotes. Sediment cores were collected from contrasting basins in the Baltic Sea to study their relative contribution to the total P pool. We found high DNA-P/phospholipid-P ratios in surface sediments from the Bothnian Bay and Bothnian Sea. However, these ratios were low throughout profiles in euxinic Baltic Proper sediments. The elevated ratios present in sediments overlain by oxic bottom waters might indicate the presence of a microbial community stimulated by bioturbation, whereas the low DNA-P/phospholipid-P ratios in Baltic Proper sediments likely indicate an energy-limited microbial community, typical to the “deep biosphere” environment. Inositol-P was almost absent in euxinic Baltic Proper sediments that had a low total P amount compared to those in the other basins. We suggest that variability in the composition of sedimentary microbial communities among the Baltic Sea basins might cause differences in organic P forms that in turn affects its turnover.
3. 题目: Exploring within-ecodistrict lake organic matter variability and identifying possible environmental contaminant biomarkers using sedimentomics
文章编号: N23020707
期刊: Science of the Total Environment
作者: B R B Gregory, M A Bell, A Sproule, S W Shields, D P Overy, J M Blais
更新时间: 2023-02-07
摘要:
Sedimentomics methods offer insight into the physiological parameters that influence freshwater sediment organic matter (sedOM). To date, most sedimentomics studies characterized variations across large spatial and environmental gradients; here we examine whether sedimentomics methods capture subtle sedOM variations within a relatively homogeneous study area in southwestern Nova Scotia, Canada. Additionally, we explore the lake sedimentome for candidate biomarkers related to ongoing carnivorous animal farming in the region. Sediment cores were recovered from seven lakes across a trophic (oligo- to eu- trophic) and anthropogenic land use gradient (carnivorous animal farming in catchment, downstream of farming, no farming nearby). Subsamples that dated prior to 1910 (pre-carnivorous animal farming) and later than 2010 (during carnivorous animal farming) were analyzed using UHPLC-HRMS in both negative (ESI−) and positive (ESI+) electrospray ionization modes. Cluster analysis (k-means) showed replicate samples from a given lake clustered distinctly from one another in both ESI modes, indicating sedOM captured subtle variations between lake systems. PCA combined with multiple linear regression indicated carnivorous animal farming and OM source explained most of the observed variation in lake sedOM. Principal component analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA) of ESI− and ESI+ data sets identified 103 unique candidate biomarkers. Ten strong candidate biomarkers were identified using graphical methods; more research is required for biomarker verification and molecular characterization. Our results indicate sedimentomics could be used in environmentally homogeneous areas, offering insight into the controls of sedOM cycling. Additionally, we identified prospective biomarkers related to carnivorous animal farming that could be used to understand relative contributions of farming to ongoing eutrophication issues in southwestern Nova Scotia.
4. 题目: Transition of carbon-nitrogen coupling under different anthropogenic disturbances in subtropical small mountainous rivers
文章编号: N23020706
期刊: Science of the Total Environment
作者: Li-Chin Lee, Gabriele Weigelhofer, Thomas Hein, Shin-Chien Chan, Ying-San Liou, Chien-Sen Liao, Fuh-Kwo Shiah, Yu-Lin Yu, Tsung-Yu Lee, Jr-Chuan Huang
更新时间: 2023-02-07
摘要:
The commonly observed inverse relationship between dissolved organic carbon (DOC) and nitrate (NO3−) concentrations in aquatic systems can be explained by stoichiometric and thermodynamic principles regulating microbial assimilation and dissimilation processes. However, the interactive effects of human activities and dissolved oxygen (DO) on the DOC and DIN (dissolved inorganic nitrogen, mainly composed of NO3−-N and NH4+-N) relations are not well identified, particularly in subtropical small mountainous rivers (SMRs). Here, we investigated the exports and relations of DOC-DIN in 42 Taiwan SMRs under different anthropogenic disturbances. Results showed that the island-wide mean concentrations of the three solutes in streams are generally low, yet the abundant rainfall and persistent supply contrarily lead to disproportional high DOC and DIN yields. The inverse DOC-NO3−-N relation does not appear under well‑oxygenated conditions, regardless of low or high human disturbance. However, a significant inverse relationship between DOC-NO3−-N would emerge in highly-disturbed watersheds under low-oxygenated conditions (mean annual DO <6.5 mg L−1), where excess N accumulates as NH4+-N rather than NO3−-N. The controlling mechanism of DOC-DIN relations would shift from energetic constraints to redox constraints in low-oxygenated conditions. Although riverine concentrations of DOC, NO3−-N, and NH4+-N could be elevated by human activities, the transition of DOC-DIN relation pattern is directly linked to DO availability. Understanding the mechanism that drives C
N coupling is critical for assessing the ecosystem function in the delivery and retention of DOC and DIN in aquatic ecosystems.
5. 题目: The removal of dissolved organic matter by marine sponges is a function of its composition and concentration: An in situ seasonal study of four Mediterranean species
文章编号: N23020705
期刊: Science of the Total Environment
作者: M Ribes, G Yahel, C Romera-Castillo, R Mallenco, T M Morganti, R Coma
更新时间: 2023-02-07
摘要:
Sponges are unique among metazoans in their ability to use dissolved organic matter (DOM), the largest pool of organic matter in the ocean, as a major food source. The effect of variations in DOM abundance and composition on its uptake by sponges has rarely been studied. We examined, in situ, the seasonal uptake of DOM by four sponges [2 species with high microbial abundance (HMA) and 2 with low microbial abundance (LMA)] in the northwestern Mediterranean. Dissolved organic carbon (DOC) showed a strong seasonality with 3-fold higher concentrations in fall-winter (256 ± 16 μmol L−1, mean ± SE) than in spring-summer (88 ± 3 μmol L−1). Dissolved organic nitrogen (DON) showed the opposite trend, with higher summer concentrations (8.9 ± 0.4 μmol L−1) and mean concentrations of 2.5–3.4 μmol L−1 in the other seasons. DOC removal by all sponge species increased linearly with its ambient concentration, but only above a DOC removal threshold that was threefold higher in fall-winter (198 μmol L−1) than in spring-summer (74 μmol L−1). All species showed a concentration-dependent DON removal, but LMA sponges removed more DON than HMA sponges. The DOC removal rate (normalized to sponge volume) was 2–3 times higher in fall-winter, when ambient DOC levels were high, than in spring-summer. Sponges efficiently removed clusters of the fluorescent DOM (FDOM) associated with protein-rich DOM, but not those associated with humic material. The clear threshold for DOC removal and the protein-like FDOM uptake pattern suggest that the quality and quantity of DOM control its removal and transformation by marine sponges. Our results indicate that marine sponges transform the composition of the coastal DOM pool, thereby affecting its fate. It is postulated that the DOM excreted by the sponges is more recalcitrant; consequently, sponge activity enhances carbon sequestration in benthic habitats in a similar fashion to that of the oceanic ‘microbial pump’.
6. 题目: Microstructural tailoring of porous few-layer graphene-like biochar from kitchen waste hydrolysis residue in molten carbonate medium: Structural evolution and conductive additive-free supercapacitor application
文章编号: N23020704
期刊: Science of the Total Environment
作者: Xinhang Du, Zhiwen Lin, Yongkui Zhang, Panyu Li
更新时间: 2023-02-07
摘要:
Biomass-derived graphene-like material is a promising candidate for supercapacitor electrodes, while it is critical to controllably convert biomass into structure-tunable graphene. Herein, few-layer graphene-like biochar (FLGBS) were successfully fabricated from waste biomass in molten carbonate medium. Molten carbonate acted as the effective catalyst for graphitizing and the liquid medium for microcrystal relinking to achieve the rearrangement of carbon structure. It was found that the stacking of graphene layer and formation of porous structure were influenced by the volume of reaction medium and biomass pre‑carbonation. Namely, increasing the dosage of molten K2CO3 was in favor to form few layer-type graphene structure, but excess dosage could destroy the nanopore structure to expand the aperture. In addition, pre‑carbonation at high temperature impeded the exfoliation of graphene layers. When FLGBSs were applied to fabricate conductive additive-free electrode, they displayed a superior supercapacitor performance (up to 237.4 F g−1 at 0.5 Ag−1). This excellent performance should be attributed to the large specific surface area, hierarchical pore structure and graphene-like structure. In short, this work could help to get insights into the structural evolution of biomass carbon to graphene-like biochar in molten carbonate medium and achieve the tailoring of microstructure for further application in energy storage.
7. 题目: Enzyme activities and organic matter mineralization in response to application of gypsum, manure and rice straw in saline and sodic soils
文章编号: N23020703
期刊: Environmental Research
作者: Muhammad Shaaban, Yupeng Wu, Avelino-Nunez Delgado, Yakov Kuzyakov, Qi-An Peng, Shan Lin, Ronggui Hu
更新时间: 2023-02-07
摘要:
Saline and alkaline soils are a challenge for sustainable crop production. The use of organic and inorganic amendments is a common practice to improve salt-affected soils that can trigger carbon (C) and nitrogen (N) cycling. In this study, we examined the effects of gypsum (Gyps), farm manure (Manure) and rice straw (Straw) on enzyme activities, organic matter mineralization and CO2 emissions in two salt-affected soils [Solonchak (saline); pH: 8, electrical conductivity (EC): 6.5, sodium adsorption ratio (SAR): 2.5, and Solonetz (alkaline sodic); pH: 8.9, EC: 1.6, SAR: 17]. Gypsum addition decreased soil pH up to 0.62 and 0.30 units, SAR 1.2 and 5.2 units, and EC 2.9 and 1.4 units in Solonchak and Solonetz, respectively. Dissolved organic C, microbial biomass C, dissolved organic N, mineral N (NO3− and NH4+), enzyme activities (urease, invertase, catalase, phosphatase, phenol-oxidase), alkali extractable phenols, and available phosphorous also increased with the application of all the amendments in both soils. Solonetz released more CO2 than Solonchak, whereas maximum CO2 emissions were common after manure application (3140 mg kg−1 in Solonchak, and 3890 mg kg−1 in Solonetz). Based on the results, we conclude that high SAR and low EC may increase CO2 emissions through accelerated C and N cycling in Solonetz soils.
8. 题目: Identifying the critical activated carbon properties affecting the adsorption of effluent organic matter from bio-treated coking wastewater
文章编号: N23020702
期刊: Science of the Total Environment
作者: Wenli Fan, Guangxi Sun, Qi Wang, Fan Yang, Yingxin Gao, Min Yang
更新时间: 2023-02-07
摘要:
Activated carbon is widely used to remove effluent organic matter (EfOM) from bio-treated coking wastewater. However, the critical carbon properties affecting adsorption performance are still unclear. Nine commercial powdered activated carbons (PACs) with different pore structures, surface functional groups, and surface charges were used to adsorb EfOM from bio-treated coking wastewater, which was fractionated according to their molecular weight (MW) and hydrophobicity. Good correlations were observed between the adsorption of biopolymers (MW > 20,000 Da, 7 %) and macropore volume (>50 nm), as well as between the adsorption of humics (MW = 1000 ~ Da, 36 %) and mesopore volume (2–50 nm), suggesting that the adsorption sites of EfOM depended on their molecular size. Higher isoelectric points and fewer acidic groups promoted the adsorption of the most negatively charged hydrophobic acids (HPOA, 39.5 %). According to variation partitioning analysis (VPA), mesopore-macropore greatly contributed to the adsorption capacities of EfOM (71.3 %), whereas the sum of phenolic hydroxyl and carboxyl (26.3 %) and isoelectric point (12.2 %) affected the normalized adsorption capacities of EfOM. In conclusion, PAC with a higher mesopore volume, fewer acidic groups, and a higher isoelectric point was desirable for removing EfOM from bio-treated coking wastewater. This study provides guidance for the selection of PAC for the removal of EfOM from bio-treated coking wastewater.
9. 题目: Tomato waste biochar in the framework of circular economy
文章编号: N23020701
期刊: Science of the Total Environment
作者: Marinos Stylianou, Psichoula Terpsithea, Simona Bennici, Patrick Dutournie, Lionel Limousy, Agapios Agapiou, Iliana Papamichael, Besma Khiari, Mejdi Jeguirim, Antonis A Zorpas
更新时间: 2023-02-07
摘要:
Tomato pomace was slowly pyrolyzed at 350 and 550 °C (under an N2 flow of 50 l/h) at a rate of 6 °C/min and a residence time of 1:30 h to produce two biochars named B350 and B550, respectively. In addition, the two biochars were chemically activated with ΚΟΗ (at a ratio of 1:10 w/v) at 800 °C to produce two new materials named BA350 and BA550. The four biochars produced were characterized physically and chemically (pH, yield, calorific value). They were also analyzed by scanning electron microscopy (SEM), Brunauer–Emmett–Teller (B.E.T), elemental analysis (EA), and thermogravimetric analysis (TGA). The results showed that as the pyrolysis temperature increased (350 to 550 °C), the specific surface area (SSA) increased. The latter was also significantly increased by the activation process. EA showed a variation in the mineral content of the produced biochars, resulting in a different content of the biochars after activation. The parameters studied showed that biochars from tomato waste could be used as an organic amendment to improve soil fertility in agricultural. In addition, because of their ability to absorb water, they could be used as a water reservoir in soils in arid areas.
10. 题目: Accelerating the humification mechanism of dissolved organic matter using biochar during vermicomposting of dewatered sludge
文章编号: N23020609
期刊: Waste Management
作者: Jiachen Xie, Hui Xia, Mengxin Guan, Kui Huang, Jin Chen
更新时间: 2023-02-06
摘要: The use of biochar can accelerate the vermicomposting process of dewatered sludge. However, the underlying mechanism of vermicompost maturity with biochar is still unclear. This study investigated the effect of biochar on sludge maturation during vermicomposting by analyzing the spectroscopic characteristics of dissolved organic matter. For this, dewatered sludge mixed with and without 5 % biochar were separately vermicomposted. The results showed that the biochar could significantly increase the biomass of earthworms as well as the activity and abundances of bacteria and eukaryotes (P < 0.05) during vermicomposting of sludge. The addition of biochar resulted in a 23.35 % increase in the ratio of absorbances at wavelengths of 250 nm and 365 nm (E250/E365), and a 20.50 % decrease in aromatic proteins of sludge during vermicomposting, compared to the control. The ratio of fulvic acid to humic acid contents rapidly increased from 10 to 15 days in biochar added treatment, which was earlier than that in the control. Compared to control, the biochar addition enhanced the contents of fulvic acid and humic acid in sludge vermicompost by 79.97 % and 91.54 %, respectively. During vermicomposting, the DOM maturated parameter displayed stronger correlation (P < 0.05) between each other in the treatment with biochar, rather than the control. This study suggests that the biochar addition significantly modifies the degradation pathway of dissolved organic matter, thus promoting sludge maturation during vermicomposting.
11. 题目: Relating Algal-Derived Extracellular and Intracellular Dissolved Organic Nitrogen with Nitrogenous Disinfection By-Product Formation
文章编号: N23020608
期刊: Water Research
作者: N.R.H. Rao, K.L. Linge, X Li, C.A. Joll, S.J. Khan, R.K. Henderson
更新时间: 2023-02-06
摘要: The dissolved organic nitrogen (DON) pool from algal-derived extracellular and intracellular organic matter (EOM and IOM) comprises proteins, peptides, free amino acids and carbohydrates, of which, proteins can contribute up to 100% of the DON. Previous reports of algal-derived DON character have focussed on bulk properties including concentration, molecular weight and hydrophobicity. However, these can be similar between algal species and between the EOM and IOM even when the inherent molecular structures vary. A focus on bulk character presents challenges to the research on algal-derived nitrogenous-disinfection by-product (N-DBP) formation as N-DBP formation is sensitive to the changes in molecular structure. Hence, the main aim of this study was to characterise algal EOM and IOM-derived DON, specifically proteinaceous-DON, using a combination of bulk and molecular characterisation techniques to enable a more detailed exploration of the relationship between the character of algal-derived proteins and the N-DBP formation potential. DON from the EOM and IOM of four commonly found algae and cyanobacteria in natural waters were evaluated, namely Chlorella vulgaris, Microcystis aeruginosa, Dolichospermum circinale, and Cylindrospermopsis raciborskii. It was observed that 77-96% of total DON in all EOM and IOM samples was of proteinaceous origin. In the proteins, DON concentrations were highest in the high molecular weight fraction of IOM-derived bulk proteins (0.13-0.75 mg N L−1) and low to medium molecular weight fraction of EOM-derived bulk proteins (0.15-0.63 mg N L−1) in all species. Similar observations were also made via sodium dodecyl sulphate polyacrylamide gel electrophoresis and liquid chromatography-high resolution mass spectrometry. Solid-state 15N nuclear magnetic resonance (NMR) spectroscopy of the EOM and IOM revealed the existence of common aliphatic and heterocyclic N-groups in all samples, including a dominant 2° amide peak. Species dependent variability was also observed in the spectra, particularly in the EOM; e.g. nitro signals were found only in the Cylindrospermopsis raciborskii EOM. Dichloroacetonitrile (DCAN) and N-nitrosamine concentrations from the EOM of the species evaluated in this study were lower than the guideline limits set by regulatory agencies. It is proposed that the dominant 2° amide in all samples decreased N-DBP formation upon chlorination. For chloramination, the presence of nitro groups and aliphatic and heterocyclic N-DBP precursors could cause variable N-nitrosamine formation. Compared to non-algal impacted waters, algae-laden waters are characterised by low organic carbon: organic nitrogen ratios of ∼7-14 and elevated DON and protein concentrations. Hence, relying only on bulk characterisation increases the perceived risk of N-DBP formation from algae-laden waters.
12. 题目: Microbial reduction of Fe(III) in nontronite: Role of biochar as a redox mediator
文章编号: N23020607
期刊: Geochimica et Cosmochimica Acta
作者: Hailiang Dong, Ethan S. Coffin, Yizhi Sheng, Matthew L. Duley, Yehia M. Khalifa
更新时间: 2023-02-06
摘要: Biochar naturally occurs in soils and sediments as a result of wildfire, but its role in Fe redox cycling is poorly known. In this study, bioreduction experiments were conducted with lactate as the electron donor, Fe(III) in nontronite (NAu-2) or ferric citrate as the electron acceptor, and Shewanella putrefaciens CN32 as the Fe(III)-reducing bacterium in the absence and presence of biochar. High biochar concentrations increased but low concentrations decreased the reduction rate and extent. When NAu-2 was replaced with ferric citrate [aqueous Fe(III)-citrate complex], while the rate was enhanced, the extent of bioreduction remained unchanged at low biochar concentration but declined at high biochar concentration. These different redox behaviors of biochar can be explained by the interplay among four factors: the electron shuttling role of biochar; 2) the electron buffering capacity of biochar; 3) the effect of biochar surface on cell distribution; 4) the effect of biochar on cell attachment and growth. In the absence of biochar, the electron transfer pathway is from cells directly to Fe(III) (Pathway 1). However, in the presence of biochar, there is a second pathway (Pathway 2), i.e., from attached cells to biochar and from biochar to Fe(III). At low biochar concentrations, the presence of biochar decreases the efficiency of Pathway 1 because some cells are diverted to biochar surface, but this deficiency is not made up by Pathway 2 because of physical separation between negatively-charged biochar and NAu-2 particles. Therefore, even though biochar particles receive electrons from attached cells, they are not able to transfer them to NAu-2, thus retaining a proportion of electrons. Possible cell clumping on biochar surface may decrease effective cell concentration and thus pose additional inhibition of NAu-2 bioreduction. However, in the treatment of soluble Fe(III)-citrate complex, Pathway 2 is still effective, because there is no physical barrier between biochar and soluble Fe(III). The electron shuttling role of biochar actually increases the rate of Fe(III) bioreduction. As biochar concentration increases, large surface area of biochar spreads out cells and increases the probability of encounter between cells and NAu-2 particles. In this case, both pathways are effective. Increasing biochar concentrations result in fewer electron retention per gram of biochar. Possible cell growth on biochar surface would further enhance Pathway 2. Therefore, the overall result is the enhanced rate and extent of Fe(III) bioreduction in NAu-2. However, for soluble Fe(III)-citrate complex, both pathways may be impaired because high concentration of biochar would accumulate toxic substances and decrease concentration of cells, which would inhibit Fe(III) bioreduction. As biochar accumulates in soils, the role of biochar is expected to greatly impact Fe redox reactions and other environmental processes.
13. 题目: Effects of organic matter on the aggregation of anthropogenic microplastic particles in turbulent environments
文章编号: N23020606
期刊: Water Research
作者: Xiaoteng Shen, Hong Huo, Ying Zhang, Yuliang Zhu, Michael Fettweis, Qilong Bi, Byung Joon Lee, Jerome P.-Y. Maa, Qiqing Chen
更新时间: 2023-02-06
摘要: Biofilm-coated microplastics are omnipresent in aquatic environments, carrying different organic matter (OM) that in turn influences the flocculation and settling of microplastic aggregates. In this study, the effects of chitosan, guar gum, humic acid, and xanthan gum on the flocculation of anthropogenic microplastics are examined under controlled shear through the mixing chamber experiments. The results show that all of the selected OMs have positive effects on biofilm culturing and thus enhance the growth of microplastic flocs, with more evident promoting effects for cationic and neutral OMs (i.e., chitosan and guar gum) than anionic OMs (i.e., humic acid and xanthan). No critical shear rate is observed in the size vs. shear relationship based on our measurements. In addition, the quadrature-based two-class population balance model is employed to track the development of bimodal floc size distributions (FSDs) composed of small and large microplastic flocs. The model predictions show reasonable agreement with the observed FSDs. The largest error of settling flux from the two-class model is 7.8% in contrast with the reference value measured by the camera-based FSDs with 30 bins. This study highlights the role of different OMs on microplastic flocculation and indicates that a two-class model may be sufficient to describe microplastic transport processes in estuaries.
14. 题目: Permanganate preoxidation affects the formation of disinfection byproducts from algal organic matter
文章编号: N23020605
期刊: Water Research
作者: Moshan Chen, Carter A Rholl, Shane L Persaud, Zixuan Wang, Zn He, Kimberly M Parker
更新时间: 2023-02-06
摘要: During harmful algal blooms (HABs), permanganate may be used as a preoxidant to improve drinking water quality by removing algal cells and degrading algal toxins. However, permanganate also lyses algal cells, releasing intracellular algal organic matter (AOM). AOM further reacts with permanganate to alter the abundance of disinfection byproduct (DBP) precursors, which in turn affects DBP formation during disinfection. In this study, we evaluated the impacts of preoxidation by permanganate applied at commonly used doses (i.e., 1-5 mg/L) on DBP generation during chlorination and chloramination of AOM. We found that permanganate preoxidation increased trichloronitromethane (TCNM) formation by up to 3-fold and decreased dichloroacetonitrile (DCAN) formation by up to 40% during chlorination, indicating that permanganate oxidized organic amines in AOM to organic nitro compounds rather than organic nitrile compounds. To test this proposed mechanism, we demonstrated that permanganate oxidized organic amines in known DBP precursors (i.e., tyrosine, tryptophan) to favor the production of TCNM over DCAN during chlorination. Compared to the decreased formation of DCAN during chlorination, permanganate increased DCAN formation by 30-50% during chloramination of AOM. This difference likely arose from monochloramine's ability to react with non-nitrogenous precursors (e.g., organic aldehydes) that formed during permanganate preoxidation of AOM to generate nitrogen-containing intermediates that go on to form DCAN. Our results also showed that permanganate preoxidation favored the formation of dichlorobromomethane (DCBM) over trichloromethane (TCM) during chlorination and chloramination. The increased formation of DBPs, especially nitrogenous DBPs that are more toxic than carbonaceous DBPs, may increase the overall toxicity in finished drinking water when permanganate preoxidation is implemented.
15. 题目: An improved method of MgFe-layered double hydroxide/ biochar composite synthesis
文章编号: N23020604
期刊: Journal of Cleaner Production
作者: Haohao Bian, Cheng Shen, Wanpeng Liu, Yu Bon Man, Ming Hung Wong, Peter Christie, Shengdao Shan, Minyan Wang, Jin Zhang
更新时间: 2023-02-06
摘要: Layered double hydroxides (LDHs) and their composites are a promising platform for a wide range of applications, especially in the environmental field. However, the facile and efficient synthesis of high-quality LDHs and their composites remains a challenge. Here, an improved co-pyrolysis method has been developed to synthesize LDH/biochar composites. A composite material was prepared by directly anchoring MgFe-LDH on corn stover by co-precipitation with FeCl3 and Mg(OH)2, and then through pyrolysis. The main features of this improved method are the use of the solubility product Mg(OH)2 to maintain the pH of the mixture at ∼10 (the optimum for LDH precipitation), eliminating the cumbersome pH control steps of the traditional co-precipitation method, and the low rate of solid-liquid reaction to obtain high LDH crystallinity and purity. This produces improved properties of the MgFe-LDH/biochar composite after pyrolysis: higher loading of MgFe-LDH, larger specific surface area of the composite, a more stable layered structure, and a more customizable LDH. The theoretical maximum adsorption capacity of phosphorus for the composite was 379.4 mg L−1 according to an adsorption isotherm study, and the dominant adsorption mechanism is chemical adsorption accompanied by physical adsorption. In actual wastewater applications, >80% of total phosphorus in biogas slurry was removed via adsorption, indicating that the composite is highly efficient in phosphorus selectivity in wastewaters with complex components. Here, a more sustainable synthesis method of LDH/biochar composite has been developed with high application potential.
16. 题目: Unraveling the over-oxidation inhibition mechanism during the hybrid ozonation-coagulation process: Immediate entrapment and complexation between intermediate organic matter and coagulants
文章编号: N23020603
期刊: Water Research
作者: Xin Jin, Mengwen Liu, Yukai Zong, Shiyi Hu, Yao Li, Lu Xu, Xue Bai, Xuan Shi, Pengkang Jin, Jina Song, Xiaochang C Wang
更新时间: 2023-02-06
摘要: Pre-ozonation coagulation process had a very low and narrow range of ozone dosages for enhancing the dissolved organic matter (DOC) removal efficiency, in which over-oxidation may occur if the ozone dosage was not strictly controlled. In contrast, the proposed hybrid ozonation-coagulation (HOC) process with higher oxidation ability notably inhibited over-oxidation in this study, and exhibited improved DOC removal efficiency compared with coagulation at a much wider range of ozone dosages at different initial pH for the treatment of WWTP effluent. The HOC process also had a higher DOC removal efficiency than pre-ozonation coagulation. According to zeta potential analysis, a rising trend indicated that complexation between organic matter and metal coagulants persisted throughout the HOC process. However, the zeta potential remained almost unchanged during subsequent coagulation after pre-ozonation at high ozone dosages. Synchronous fluorescence spectroscopy analysis revealed that immediate entrapment and complexation between hydrolysed coagulants and oxidized intermediate organic matter occurred in the HOC process. Furthermore, FT-IR analysis showed that more oxygen-containing functional groups were generated, which were effectively trapped by metal coagulants and readily flocculated. To further prove the immediate entrapment and complexation during the HOC process, UPLC-Q-TOF-MS was applied to analyze the intermediate organic matter in the supernatant and flocs. The results implied that C21- organic matter was oxidized and decomposed into C11-C20, and C11-C20 intermediate organic matter was trapped and complexed by metal coagulants once formed, which led to the increase of C11-C20 in the flocs. Nevertheless, the catalytic ozonation process (γ-Al2O3/O3) with the same oxidation ability as the HOC process decomposed the organic matter into C1-C10. XPS analysis further confirmed the immediate entrapment and removal of aliphatic/aromatic carbon and oxygen-containing functional groups during the HOC process. Therefore, over-oxidation can be effectively inhibited, and wide range of ozone dosages was obtained during the HOC process, which facilitate the application of the HOC process.
17. 题目: The suitability and mechanism of polyaluminum-titanium chloride composite coagulant (PATC) for polystyrene microplastic removal: Structural characterization and theoretical calculation
文章编号: N23020602
期刊: Water Research
作者: Beibei Liu, Yue Gao, Qinyan Yue, Kangying Guo, Baoyu Gao
更新时间: 2023-02-06
摘要: Microplastics (MPs) particles bring potential threats to the aqueous environment, and the coexistence of natural organic matter (NOM) enhances their toxicity. Coagulation is an efficient method for particle removal and exploring the binding sites and modes of the coagulant hydrolysates with MPs in the presence of NOM is essential to understand the coagulation mechanism. In this study, a novel polymerized polyaluminum-titanium chloride composite coagulant (PATC) was prepared and used to remove polystyrene (PS). It was found that PATC could compress or even destroy the surface layer of the negatively charged PS. In comparison to PAC and PTC, PATC was more efficient in decreasing the energy barrier of the PS particles and increasing their aggregation rate over a wider pH range. The results of the Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) calculation revealed that the interaction between the hydrolysates of PATC and PS was mainly polar interaction (VAB), such as hydrogen bonding. The peak intensity and peak shift in Fourier-transformed infrared (FTIR) and X-ray photoelectron spectra (XPS) were analyzed to further explore the interaction between the hydrolysates of PATC and PS. It was found that hydrogen bonding existed between the -OH group of PATC and the aliphatic C-H and C=O groups of PS. And the main interaction between HA and PS was the π-π* conjugation and hydrogen bonding between the -COOH, -OH, and C=O groups of HA and the C=O and aliphatic C-H groups of PS. Therefore, in the HA@PS system, the active sites of HA (e.g. -COOH and -OH) and PS (e.g., C=O and aliphatic C-H) binding with the coagulants were occupied, which accordingly led to the dramatic decline in the removal efficiency of both HA and PS. In actual lake water treatment, although the removal efficiency of PS was significantly poor, PATC performed better for PS removal than PAC and PTC. Besides, the effluent pH was maintained at 6.81±0.08, which met the requirements of the subsequent water treatment process. This study provides systematic knowledge for understanding the interaction between PS, NOM, and coagulant hydrolysates, and further confirms the application potential of PATC for MPs removal.
18. 题目: Changes of dissolved organic matter fractions and formation of oxidation byproducts during electrochemical treatment of landfill leachates: development of spectroscopic indicators for process optimization
文章编号: N23020601
期刊: Water Research
作者: Bi-Cun Jiang, Ye-Chao Tian, Ai-Min Li, Yu-Ze Han, Ze-Tao Wu, Chang Lu, Hai-Ou Song, Rong Ji, Wen-Tao Li, Gregory V Korshin
更新时间: 2023-02-06
摘要: Electrochemical oxidation (EO) is an attractive option for treatment of dissolved organic matter (DOM) in landfill leachate but concerns remain over the energy efficiency and formation of oxidation byproducts ClO3− and ClO4−. In this study, EO treatment of landfill leachates was carried out using representative active and nonactive anode materials, cell configurations and current densities. Size exclusion chromatograms coupled with 2D synchronous and asynchronous correlation analysis showed that the sensitivity of DOM fractions to EO degradation was dependent on the anode material. The nonactive boron-doped diamond (BDD) anode demonstrated the best performance for DOM oxidation. The humic acid-like fraction (HA, 2.5–20 kDa) predominated the visible absorbance of landfill leachates at λ ≥400 nm, and it generally had the highest reaction rates except the occurrence of the pH-induced denaturation and precipitation of the proteinaceous biopolymer fraction (BP, >20 kDa). During the EO treatment of landfill leachate with BDD anode, the UV absorbance spectra of landfill leachates at wavelengths <400 nm were affected by the formation of free chlorine. Instead, the decrease of Abs420 was found to be a good indicator of the shift of the oxidation from predominantly HA fraction to the proteinaceous BP fraction. The behavior of the Abs420 parameter was also indicative of the transition from the energy-efficient oxidation of DOM to the dominance of side reactions of chlorine evolution and the subsequent formation of ClO3− and ClO4−. These findings suggest that the EO treatment of landfill leachate can be optimized by adjusting the current density with feedback signals from the online monitoring of Abs420, to achieve a trade-off between degradation of DOM and control of ClO3− and ClO4−.
19. 题目: Investigation of cytotoxic cadmium in aquatic green algae by synchrotron radiation-based Fourier transform infrared spectroscopy: Role of dissolved organic matter
文章编号: N23020513
期刊: Science of The Total Environment
作者: Zhiqiang Shi, Mengjing Guo, Haiyan Du, Keli Yang, Xin Liu, Huacheng Xu
更新时间: 2023-02-05
摘要: The heavy metal Cd can cause severe toxicity on aquatic algae, but there are few studies on the cytotoxicity of heavy metal on algae based on synchrotron radiation technology. In this study, synchrotron radiation-based Fourier transform infrared spectromicroscopy (SR-FTIR) was used to characterize in vivo the toxic effects of Cd on Cosmarium sp. cells, emphasizing the influence of dissolved organic matter (DOM) on Cd toxicity. Results showed that, in the absence of DOM, obvious growth inhibition, cell volume reduction, and photosynthesis disruption could be observed with increasing Cd concentrations (0–500 μg/L). Based on the SR-FTIR imaging and functional group quantification, it was shown that the biosynthesis of biomolecules such as proteins, lipids, and carbohydrates was inhibited in algal cells. However, the addition of DOM caused significant heterogeneities in biomacromolecule biosynthesis that an increased biosynthesis of carbohydrates and structural lipids but an inhibited biosynthesis of proteins and storage lipids were observed. Furthermore, the correlation analysis and principal component analysis showed a good correlation between v(C-OH)/Amide II and biochemical parameters, indicating that changes of carbohydrates could be used as the biomarker to indicate the cytotoxicity of heavy metals to algal cells. These findings provide insight into the mechanisms of heavy metal cytotoxicity to aquatic algae and systematic cytotoxicity assessment under various aquatic conditions.
20. 题目: Mixing Machilus pauhoi with Cerasus campanulata improves soil P availability and changes the soil G+/G- in a mid-subtropical region of China
文章编号: N23020512
期刊: Plant and Soil
作者: Chaobin Xu, Yunni Chang, Josep Penuelas, Jordi Sardans, Dongliang Cheng, Baoyin Li, Quanlin Zhong
更新时间: 2023-02-05
摘要: Aims Broad-leaved tree species are important group building tree species of typical zonal vegetation in subtropical China. Yet, the impacts of mixed broad-leaved plantations on microbial community and enzymatic stoichiometry are not well understood. Methods We evaluated soil microbial community structure and enzymatic stoichiometry using rhizosphere and non-rhizosphere soil samples of Machilus pauhoi from three forest plantation (pure M. pauhoi forest (CK), M. pauhoi with Cerasus campanulata mixed forest (MC), M. pauhoi with Manglietia glauca mixed forest (MM)) in subtropical China. Results P concentration of rhizosphere soil in MC was higher than that in CK, and soil TC, TN, SOC, DOC of non-rhizosphere soil in MC were higher than those in MM. Different mixed plantations had significant effects on G+/G−, being its value lower in MC than in CK and MM. The microbial P limitation in rhizosphere soil was higher than that in non-rhizosphere soil. The relative microbial C limitation did not change significantly amongst different treatment. Soil TC, TN, SOC and DOC are critical factors affecting the microbial community structure. Conclusion Mixing with Cerasus campanulata is more beneficial to reducing soil P deficiency and improving soil microbial community structure of young M. pauhoi afforestation in a mid-subtropical region of China.