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25321. 题目: Removal of micropollutants and cyanobacteria from drinking water using KMnO4 pre-oxidation coupled with bioaugmentation
文章编号: N18100715
期刊: Chemosphere
作者: Zhiyu Jian, Yaohui Bai, Yangyang Chang, Jinsong Liang, Jiuhui Qu
更新时间: 2018-10-07
摘要: Increasing micropollutant and cyanobacterial contamination of drinking water threatens human health worldwide. However, these contaminates are not efficiently removed by common drinking water treatment processes, and thus additional treatments are frequently required. Recent investigations have demonstrated that KMnO4 pre-oxidation can efficiently remove some micropollutants and cyanobacteria but the release of cyanobacterial toxins and Mn2+ limit its use. To overcome these problems, we proposed a KMnO4 pre-oxidation coupled with bioaugmentation (e.g., sand filtration) method to treat micropollutant- and cyanobacteria-laden water. We used 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (BP-4, a common micropollutant in drinking water sources) and Microcystis aeruginosa (a widely distributed cyanobacterial species) as model pollutants to verify the feasibility of the proposed method. Results revealed that KMnO4 pre-oxidation efficiently removed existing natural organic matter and Microcystis aeruginosa but failed to remove BP-4 and released Mn2+ and microcystin-LR (MC-LR) during treatment. Following the addition of a manganese-oxidizing bacterial strain (Pseudomonas sp. QJX-1) to the KMnO4-treated solution, we found that the bacteria could transform Mn2+ to Mn(III&IV) oxides, with the formed Mn oxides then able to remove BP-4 and MC-LR. Overall, the proposed method exhibited advantages in the removal of natural organic matter (i.e., decreasing disinfection byproduct formation), micropollutants, and cyanobacteria as well as preventing the release of Mn2+, and thus may be considered a good alternative for treating polluted drinking water.
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25322. 题目: Dual impact of dissolved organic matter on cytotoxicity of PVP-Ag NPs to Escherichia coli: Mitigation and intensification
文章编号: N18100714
期刊: Chemosphere
作者: Weicheng Zhang, Jiaolong Huang, Lei Liang, Lunguang Yao, Tao Fang
更新时间: 2018-10-07
摘要: Cytotoxicity of silver nanoparticles (Ag NPs) is attributed to silver internalization, which can be depressed by dissolved organic matter (DOM) to form Ag-DOM. Ag-DOM are bioavailable and then silver internalization could be increased. Herein, 3 and 48-h Escherichia coli viability bioassays were employed to evaluate effect of fulvic acid and humic acid (10 mg L−1) on cytotoxicity of 30 and 100 nm PVP-Ag NPs. Moreover, zebrafish embryos were used as reference model to understand silver internalization routes. Ag ions or Ag-DOM internalization varied in routes to Escherichia coli and zebrafish embryos. Cytotoxicity mechanisms of PVP-Ag NPs are dynamic. In 3-h bioassays, cytotoxicity of PVP-Ag NPs mainly involves Ag particle-related toxicity. DOM significantly mitigated cytotoxicity of PVP-Ag NPs (p < 0.05) through adhering on surface of PVP-Ag NPs. Ag ions or Ag-DOM were hardly internalized into Escherichia coli cells during 3-h exposures duration. In 48-h bioassays, cytotoxicity of PVP-Ag NPs is dependent on Ag ion-related and particle-related toxicity. Silver was internalized into Escherichia coli via Ag-DOM consumption as an indirect route. Thus, DOM promoted silver internalization into Escherichia coli but not into zebrafish embryos, significantly intensifying cytotoxicity (p < 0.05). The results suggested DOM has a dual impact on cytotoxicity of PVP-Ag NPs: mitigation and intensification. For risk assessment, it should be considered that cytotoxicity mechanisms of PVP-Ag NPs are dynamic and threats can be intensified by DOM during prolonged exposure.
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25323. 题目: Characterizations of dissolved organic matter and bacterial community structures in rice washing drainage (RWD)-based synthetic groundwater denitrification
文章编号: N18100713
期刊: Chemosphere
作者: Qiaochong He, Chuanping Feng, Nan Chen, Dongqing Zhang, Tingting Hou, Jingwen Dai, Chunbo Hao, Bingchun Mao
更新时间: 2018-10-07
摘要: In this study, characteristics of dissolved organic matter (DOM) and bacterial community structure in rice washing drainage (RWD)-based groundwater denitrification systems inoculated with and without seeding sludge were investigated. Complete nitrate removal was achieved with a maximum denitrification rate of 64.1 mg NO3−-N·(gVSS·h)−1. Analysis of three-dimension fluorescence excitation-emission matrix (FEEM) identified three main compositions of DOM associated with tryptophan protein-like, aromatic protein-like, and polycarboxylate humic acid-like substances in the inoculated system, while one composition associated with tryptophan protein-like substance in the un-inoculated system. Illumina sequencing analysis revealed a distinguished bacterial community structure in two systems over time. Notably, the microbial diversity was significant lower in the un-inoculated system than that in the system inoculated with seeding sludge. The predominant phyla shifted from Proteobacteria (49.2%), Bacteroidetes (20.5%) and Chloroflexi (14.8%) in the seeding sludge to Bacteroidetes (56.3%) and Proteobacteria (37.7%) after the RWD addition in the inoculated system. With RWD as sole microbe source, temporal changes in the bacterial structure from Proteobacteria (99.4%) and Bacteroidetes (5.3%) to Proteobacteria (88.8%) and Bacteroidetes (10.3%) were observed in the un-inoculated system. Specific comparison down to the genus level showed the dominant denitrifying bacteria of Thiobacillus, Anaerolineaceae and Methylophilaceae in the seeding sludge. Ideonella, Cloacibacterium and Enterobacter were dominant after the RWD addition in the inoculated system, while Stenotrophomonas and Enterobacter were dominant genera when RWD as sole bacteria source in the un-inoculated system. This finding indicates that both RWD addition and inoculation had strong impacts on bacterial community structure.
25324. 题目: Biochar amendment and water stress alter rhizosphere carbon and nitrogen budgets in bauxite-processing residue sand under rehabilitation
文章编号: N18100712
期刊: Journal of Environmental Management
作者: Mehran Rezaei Rashti, Maryam Esfandbod, Ian R. Phillips, Chengrong Chen
更新时间: 2018-10-07
摘要: Nitrogen (N) bioavailability is one of the main limiting factors for microbial activity and vegetation establishment in bauxite-processing residue sand (BRS). Although beneficial effects of biochar on reducing N loss in the early stages of BRS rehabilitation have been observed previously, the underlying mechanisms of this complicated process, particularly the interactions between applied biochar and the plant rhizosphere is largely unknown. This glasshouse study (116 days), investigated the coupled effects of biochar and water stress on N bioavailability in the rhizosphere of ryegrass (Lolium rigidum) grown in BRS amended with di-ammonium phosphate (DAP) fertiliser (at rates of 0 or 2.7 t ha−1) with and without biochar amendment. The applied biochar was characterised as either aged acidic (AC) or alkaline pine (PC) and was mixed with BRS at a rate of 5% v/v under four moisture regimes (50%, 40%, 20% and 7.5% water holding capacity). Amending BRS with AC and PC biochars increased NH4+ retention and decreased cumulative NH3 volatilization within both the rhizosphere and root-free zones compared with fertiliser only treatment. These effects were more pronounced for the AC than PC biochar, suggesting that aged acidic biochar has the great potential for use in rapid establishment of vegetation in BRS disposal areas. The biochar amendment increased cumulative nitrous oxide emissions compared with DAP only treatment, with no significant differences among different moisture regimes. The Control and 20% water holding capacity (WHC) treatment showed the highest dissolved organic carbon (DOC) concentrations compared with other treatments and moisture regimes in the ryegrass rhizosphere, while the highest dissolved organic N concentration were observed in the DAP + AC treatment. Reducing moisture levels below 20% WHC generally decreased microbial biomass carbon (MBC) concentrations and activity in both the rhizosphere and root-free zones of all treatments, while total N generally decreased as moisture levels decreased from 50% to 7.5% WHC. Plant took up more N in the DAP + AC treatment compared with DAP + PC and DAP only treatments, while increasing water stress generally resulted in decreased aboveground biomass.
25325. 题目: Yield of Trihalomethane, Haloacetic Acid and Chloral upon Chlorinating Algae after Coagulation-Filtration: Is Pre-oxidation Necessarily Negative for Disinfection By-product Control?
文章编号: N18100711
期刊: Journal of Hazardous Materials
作者: Min Ma, Min Wang, Xinkai Cao, Yuxian Li, Junnong Gu
更新时间: 2018-10-07
摘要: Effect of pre-chlorination and pre-ozonation on Microcystis aeruginosa (MA) and Coccomyxa subellipsoidea (CS) as disinfection by-products (DBPs) precursors was investigated after coagulation-filtration. Pre-chlorination considerably decreased the autofluorescence of algae cells but barely influenced cell granularity. In comparison, after pre-ozonation more algae cells were associated with decreased cell size; yet less reduction in the autofluorescence was observed. In MA case, pre-chlorination increased the residual algae density after coagulation-filtration by 132%-146% while pre-ozonation enhanced the algae removal by 26%-28%. In CS case, algae removal was improved by pre-chlorination (32%-45%) and pre-ozonation (7%-45%). Pre-chlorination enhanced the removal of algogenic organic matters (AOM) by coagulation-filtration, especially for tryptophan-like and soluble microbial products. Effect of pre-ozonation on the fluorescence intensity of AOM after coauglation-filtration depended on AOM species and the ratio of [ozone dose]:[algae density]. In both MA and CS cases, chlorine increased the yields of trihalomethane (THM, 25%-78% and 51%-103%), haloacetic acid (HAA, 140%-360% and 167%-233%) and chloral (50%-161% and 68%-108%), respectively. Pre-ozonation decreased the total DBPs yields. For MA-added suspensions, ozone decreased the production of THM, HAA and chloral by 15%-37%, 28%-39% and 60%, respectively. In CS case, chloral yield was decreased by 12%-31% while THM formation was largely unchanged. HAA production varied by ± 1.5 μg/L.
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25326. 题目: Phytoextraction of Cd from a contaminated soil by tobacco and safe use of its metal-enriched biomass
文章编号: N18100710
期刊: Journal of Hazardous Materials
作者: Yang Yang, Yichen Ge, Pengfei Tu, Hongyuan Zeng, Xihong Zhou, Dongsheng Zou, Kelin Wang, Qingru Zeng
更新时间: 2018-10-07
摘要: Successful phytoextraction produces a large quantity of contaminated biomass, which will cause secondary pollution unless properly treated. This study investigated the disposal of contaminated tobacco biomass after phytoextraction. We detected significantly high Cadmium concentrations in tobacco, especially in their stems and leaves. From the latter, nearly all the Cd and nicotine were removed by extractions with 0.5% HCl + 70% ethanol, and the nicotine completely recovered via steam distillation, whereas the protein content remained unaffected in the leaves, thus making them safe for use as animal feed. The highest biochar yield was 47%, obtained after slow pyrolysis at 300°C. In this case, the biochar contained the highest amount of nutrients and metals. From stem biochar, 87% of Cd and a large amount K along with several other elements were extracted by deionized water at pH 1. After acid-extraction, metals were formed precipitation and then separated from the K-enriched solution when the pH was adjusted to 11 by using drops of 40% KOH. Therefore, with improved technology to remove metals and recover nutrients and nicotine from biomass, tobacco is an ideal candidate as profit yielding crop for use in phytoextraction while also providing renewable resources.
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25327. 题目: Mobility and retention of indium and gallium in saturated porous media
文章编号: N18100709
期刊: Journal of Hazardous Materials
作者: Kerstin Ringering, Yasmine Kouhail, Yinon Yecheskel, Ishai Dror, Brian Berkowitz
更新时间: 2018-10-07
摘要: Transport of indium and gallium is reported in laboratory column experiments using quartz sand as a model porous medium representative of a groundwater system. With increased use of indium and gallium in recent years, mainly in the semiconductor industry, concerns arise regarding their environmental effects. The transport and retention behavior of these two metals were quantified via batch and column experiments, and numerical modeling. The effect of natural organic matter on indium and gallium mobility was studied by addition of humic acid (HA). Measured breakthrough curves from column experiments demonstrated different binding capacities between indium and gallium, stronger for indium, with the presence of HA affecting retention dynamics. For indium, the binding capacity on quartz decreases significantly in the presence of HA, leading to enhanced mobility. In contrast, gallium exhibits slightly higher retention and lower mobility in the presence of HA. In all cases, the binding capacity of gallium to quartz is much weaker than that of indium. These results are consistent with the assumption that indium and gallium form different types of complexes with organic ligands, with gallium complexes appearing more stable than indium complexes. Quantitative modeling confirmed that metal retention is controlled by complex stability.
25328. 题目: High resolution spatiotemporal sampling as a tool for comprehensive assessment of zinc mobility and pollution in sediments of a eutrophic lake
文章编号: N18100708
期刊: Journal of Hazardous Materials
作者: Zengfeng Jin, Shiming Ding, Qin Sun, Shuaishuai Gao, Zhen Fu, Mengdan Gong, Juan Lin, Dan Wang, Yan Wang
更新时间: 2018-10-07
摘要: To assess zinc (Zn) pollution risk from sediments, this study investigated the monthly changes of dissolved Zn and labile Zn in sediment-overlying water profiles in a eutrophic bay (Meiliang Bay) of Lake Taihu (China) using high-resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) at a 4 mm vertical resolution. In February and March, Mn oxides reduction caused high concentrations of DGT-labile Zn (14 ~ 235 μg L-1), as evidenced by the significant correlation between DGT-labile Zn and DGT-labile Mn in sediments. In June and July, algal blooms reduced concentrations of dissolved Zn via algal assimilation. From August through October, concentrations of dissolved Zn in overlying water (338 ~ 1023 μg L-1) exceeded the water quality limit for fisheries in China (100 μg L-1). This was attributed to reductive dissolution of Mn oxides in sediments caused by algal degradation followed by complexation of dissolved organic matter (DOM), which was identified in a simulated algal bloom experiment. In the winter, decreased Zn mobility was mainly attributed to adsorption by Mn oxides. It was concluded that enhanced Zn pollution risk from sediments is worthy of concern especially during algal degradation in eutrophic lakes.
25329. 题目: Contribution of dissolved organic matter to the photolysis of methylmercury in estuarine water
文章编号: N18100707
期刊: Marine Chemistry
作者: Jihee Kim, Jisook Yang, Yunho Lee, Giehyeon Lee, Woojin Lee, Seunghee Han
更新时间: 2018-10-07
摘要: The photodemethylation (PD) is a dominant degradation process of methylmercury (MeHg) in sunlit surface seawater, leading to the decreased bioaccumulation of MeHg in pelagic organisms. This study investigated the PD rate constant of MeHg in artificial estuarine water under UV-A irradiation, with the addition of various types of dissolved organic matter (DOM) to understand the PD pathway. In the PD simulation with ~167 μmol C L−1 of DOM, microbial fulvic acid showed a higher rate constant (k = 0.16 m2 E−1) than that of terrestrial humic acid (k = 0.11 m2 E−1) and fulvic acid (k = 0.12 m2 E−1). Adding sodium azide and isopropyl alcohol decreased the PD rate constant by 44–74% in the presence of humic and fulvic acids, implying the considerable involvement of 1O2 and ∙OH. On the contrary, the direct PD of MeHg-Cl was a major process in the presence of non-thiol aromatic ligands with the rate constant ranging from 0.033 to 0.036 m2 E−1. When glutathione was added to the artificial estuarine water, the rate constant increased to 0 0.15 m2 E−1 with MeHg-glutathione as a major MeHg species, implying that as the HgC bond is weakened by the formation of MeHg-thiol complex, the PD rate constant is increased. It is noteworthy that the addition of thiosalicylic acid to simulated estuarine water produced an exceptionally high rate constant (k = 4.1 m2 E−1); however, such a high value was not obtained from natural coastal water (k = 0.15–0.18 m2 E−1). The results suggest that the ordinary contents of DOM in estuarine water are likely to increase the PD rate of MeHg via the production of 1O2 and ∙OH, and the formation of MeHg-aliphatic thiol complexes facilitating intramolecular charge transfer.
25330. 题目: Origin of condensates and natural gases in the Almond Formation reservoirs in southwestern Wyoming, USA
文章编号: N18100706
期刊: Organic Geochemistry
作者: Mei Mei, K.K. (Adry) Bissada, Thomas B. Malloy, L. Mike Darnell, Zhengfan Liu
更新时间: 2018-10-07
摘要: Condensates and natural gases are significant resources that frequently occur together in many petroleum systems. Unraveling their origins is crucial for effective petroleum exploration and exploitation. This is often a challenge because light crudes are volatile, deficient in biomarkers, and commonly altered. The origin of condensates and natural gases in the Upper-Cretaceous Almond Formation in southwestern Wyoming was unraveled through use of improved analytical and interpretative geochemical approaches constrained by regional geologic perspectives and basin modeling. Here, an improved GC–MS/MS method allowed simultaneous determination of saturate and aromatic biomarkers, diamondoids, and organo-sulfur compounds in the whole crudes. Furthermore, basin-specific calibration of diamondoid-based thermal maturity parameters, through correlation of measured indices for diamondoids in rock extracts versus measured reflectance of vitrinite from the same rocks, allowed reliable interpretation of maturity of the most likely source rocks. Modified interpretation schemes for C7-hydrocarbon distributions, and compositions of C1-C30 alkanes, aromatic and organosulfur compounds, and δ13C1-C5 together indicated that the condensate and natural gas from each well are likely co-generated and thermogenic products from non-marine source rocks, although methane is partially biogenic. The bulk thermogenic petroleum are too mature to have originated in the rocks adjacent to the producing reservoirs. The geochemical, geologic, and modeling interpretations collectively indicate that the condensates and associated natural gases were most likely generated, expelled, and migrated from the downdip, highly mature, near-shore/transitional humic source rocks of the Almond Formation/Mesaverde Group in the Washakie Basin and Great Divide Basin at >1.3% Ro and ∼30 Ma.
25331. 题目: Shrinkage Characteristics of Lime Concretion Black Soil as Affected by Biochar Amendment
文章编号: N18100705
期刊: Pedosphere
作者: Cuilan WEI, Weida GAO, William Richard WHALLEY, Baoguo LI
更新时间: 2018-10-07
摘要: Studies have reported that biochar is a sustainable amendment that improves the chemical and physical properties of soil. In this study, an incubation experiment was conducted to investigate the effects of different application rates of biochar on the cracking pattern and shrinkage characteristics of lime concretion black soil after three wetting and drying cycles. Biochar derived from the corn straw and peanut shell mixture was applied to the soil at rates of 0, 50, 100, and 150 g kg−1 dry weight, representing the treatments T0, T50, T100, and T150, respectively. During the wetting and drying cycles, the cracking pattern and shrinkage characteristics of the unamended and amended soil samples were recorded. Application of biochar significantly increased soil organic carbon content in the samples. During soil desiccation, biochar significantly reduced the rate of water loss. Cracks propagated slowly and stopped due to the relatively higher water content in the soil applied with biochar. The cracking area density (ρc), equivalent width, fractal dimension, and cracking connectivity index decreased during the drying process with increasing application rate of biochar. The ρc value of the T50, T100, and T150 treatments decreased by 33.6%, 52.1%, and 56.9%, respectively, after three wetting and drying cycles, whereas the T0 treatment exhibited a marginal change. The coefficient of linear extensibility, an index used to describe onedimentional shrinkage, of the unamended soil sample (T0) was approximately 0.23. Application of 100 and 150 g kg−1 biochar to the soil significantly reduced the shrinkage capacity by 41.45% and 45.54%, respectively. The slope of the shrinkage characteristics curve, which indicates the ralationship between soil void ratio and moisture ratio, decreased with increase in the application rate of biochar. Furthermore, compared with the T0 treatment, the proportional shrinkage zone of the shrinkage characteristic curve of the T50, T100, and T150 treatments decreased by 5.8%, 13.1%, and 12.1%, respectively. Differences were not observed in the moisture ratio at the maximum curvature of the shrinkage characteristic curve among the treatments. The results indicate that biochar can alter the cracking pattern and shrinkage characteristics of lime concretion black soil. However, the effects of biochar on the shrinkage of lime concretion black soil are dependent on the number of wetting and drying cycles.
25332. 题目: Impact of a Biochar or a Compost-Biochar Mixture on Water relation, Nutrient uptake and Photosynthesis of Phragmites karka
文章编号: N18100704
期刊: Pedosphere
作者: Abideen Zainul, Hans-Werner KOYRO, Bernhard HUCHZERMEYER, Bilquees GUL, M. Ajmal KHAN
更新时间: 2018-10-07
摘要: Soil water and nutrient status both are of major importance for the plant appearance and its growth performance. The objective of this research was therefore to study the effect of biochar (1.5% BC) and a biochar-compost mixture (1.5% BC + 1.5% Co) on the performance of Phragmites karka plants grown in a nutrient poor sandy clay (control, 50% sand 30% clay and 20% gravel) soil. The indicators of plant performance such as growth, lignocellulosic biomass, water relations, mineral nutrition status, leaf gas exchange, chlorophyll fluorescence parameters of P. karka, as well as soil respiration activity, were assessed. The sole amendment of BC led to higher growth rate and lignocellulosic biomass production in P. karka plants compared to the non-treated control. There was also significant increase in soil respiration with biochar treatments that stimulated microbial interaction. The increase in the water holding capacity after BC amendment caused a significant improvement in plant water status (water potential, osmotic potential, leaf turgidity) and plant ion content (K+, Mg++ and Ca++) leading to an increase of net photosynthesis but also a higher energy use efficiency of the Photosystem II. Additionally, the BC plants managed to avoid oxidative stress, improved water use efficiency (WUE) and decreased dark respiration. However, the amendment of a biochar-compost mixture (BC + Co) led to even better improvement of physiological parameters such as growth, leaf turgor, photosynthesis and nutrient content and soil gas exchange of P. karka. Our results suggested that BC and Co promote plant growth with respect to nutrient uptake, water balance, and efficiency of the photosynthetic system. In summary both soil amendments might open an opportunity for P. karka to sequester CO2 and to produce higher fodder, bio-active compounds and biomass for bio-energy on nutrient poor degraded soils.
25333. 题目: Biochar Increases the Sorption and Reduces the Potential Contamination of Subsurface Water with Diuron in Sandy Soil
文章编号: N18100703
期刊: Pedosphere
作者: Fabiano André. PETTER, Tamara S. FERREIRA, Adilson P. SINHORIN, Larissa B. LIMA, Fernandes A. ALMEIDA, Leandro P. PACHECO, Alexandre F. SILVA
更新时间: 2018-10-07
摘要: The objective of this study was to verify the long-term effect of biochar application on the kinetics of sorption and desorption of diuron in a Cerrado Haplic Plinthosol. The samples were collected in an experiment conducted in the field in a randomized block design consisting of the combination of two levels of fertilizer application (0 and 300 kg ha−1 of 05-25-15 formula of NPK fertilizer) and three doses of biochar (0, 16 and 32 Mg ha−1). The Freundlich isotherm properly described the sorption of diuron in all treatments. The application of biochar increased sorption (Kf) and reduced desorption of diuron. This effect is attributed to the contribution of biochar to the levels of total organic carbon and C-humin, and to the increase in the reactivity of the humic acid and humin fractions. The reactivity of the humic acid and humin fractions was highly correlated with Kf (r = 0.99**). The positive correlation between the partition coefficient of organic carbon and Kf confirms the importance of the soil organic compartment for the sorption of diuron. The higher and lower capacity of sorption and desorption respectively of diuron in sandy soils with biochar application reduces the potential risk of leaching and contamination of subsurface waters.
25334. 题目: Photoinduced disinfection in sunlit natural waters: Measurement of the second order inactivation rate constants between E. coli and photogenerated transient species
文章编号: N18100702
期刊: Water Research
作者: Efraim A. Serna-Galvis, Jean A. Troyon, Stefanos Giannakis, Ricardo A. Torres-Palma, Claudio Minero, Davide Vione, Cesar Pulgarin
更新时间: 2018-10-07
摘要: This work uncovers the implications of the estimation of exogenous inactivation rates for E. coli after the initial lag phase, and presents a strategy for the determination of the second-order inactivation rate constants (k2nd) of these bacteria with relevant transient species promoted by solar light in natural waters. For this purpose, specific precursors were considered (nitrate ion, rose bengal, anthraquinone-2-sulfonate) as well as the respective photo-generated transient species (i.e., hydroxyl radical (•OH), singlet oxygen (1O2) and triplet excited states). Under these conditions and by using suitable reference compounds (acesulfame K and 2,4,6-trimethylphenol in different series of experiments), the k2nd values were obtained after developing a proper competition kinetics methodology. The k2nd values were (2.5±0.9)×1011, (3.8±1.6)×107 and (1.8±0.7)×1010 M−1 s−1 for the inactivation of E. coli by •OH, 1O2 and the triplet state of anthraquinone-2-sulfonate (3AQ2S*), respectively. The measurement of a reaction rate constant that is higher than the diffusion-control limit for small molecules in aqueous solution implies that bacteria behave differently from molecules, e.g., because of the large size difference between bacteria and the transients. The obtained k2nd values were used for the modeling of the bacteria inactivation kinetics in outdoor systems (both water bodies and SODIS bottles), limited to the exponential decay phase that follows the initial lag time. Afterwards, the role of dissolved organic matter (DOM) as precursor of transient species for bacterial elimination was systematically studied. The interaction of different sunlight wavelength regions (UV-B, UV-A, blue, green and yellow light) with Suwannee river (SW) and Nordic Lake organic matter (ND) was tested, and the photoinduced disinfection exerted by DOM isolates (SW DOM, Suwannee River Humic Acid, Suwannee River Fulvic Acid or Pony Lake Fulvic Acid) was compared. It was not possible to achieve a complete differentiation of the individual contributions of DOM triplet states (3DOM*) and 1O2 to bacterial inactivation. However, the application of competition kinetics to E. coli under solar irradiation in the presence of SW led to a k2nd value of (2.17±0.40)×1010 M−1 s−1, which is very near the value for inactivation by 3AQ2S* and suggests that the latter behaved very similar to SW-3DOM* and was a good 3DOM* proxy in the present case. The determination of the second-order inactivation rate constants of E. coli with •OH, 3DOM* and 1O2 represents a significant progress in the understanding of the external inactivation pathways of bacteria. It also allows predicting that, after the lag phase, 1O2 would contribute to photoinactivation to a far lesser extent than •OH and 3DOM*.
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25335. 题目: Peroxymonosulfate activation by iron(III)-tetraamidomacrocyclic ligand for degradation of organic pollutants via high-valent iron-oxo complex
文章编号: N18100701
期刊: Water Research
作者: Hongchao Li, Chao Shan, Wei Li, Bingcai Pan
更新时间: 2018-10-07
摘要: Herein, we proposed a new catalytic oxidation system, i.e., iron(III)-tetraamidomacrocyclic ligand (FeIII-TAML) mediated activation of peroxymonosulfate (PMS), for highly efficient organic degradation using p-chlorophenol (4-CP) as a model one. PMS/FeIII-TAML is capable of degrading 4-CP completely in 9 min at the initial 4-CP of 50 μM and pH=7, whereas the recently explored system, H2O2/FeIII-TAML, could only result in ∼22% 4-CP removal in 20 min under otherwise identical conditions. More attractively, inorganic anions (i.e., Cl−, SO42−, NO3−, and HCO3−) exhibited insignificant effect on 4-CP degradation, and the negative effect of natural organic matters (NOM) on the degradation of 4-CP in PMS/FeIII-TAML is much weaker than the sulfate radical-based oxidation process (PMS/Co2+). Combined with in-situ XANES spectra, UV-visible spectra, electron paramagnetic resonance (EPR) spectra, and radical quenching experiments, high-valent iron-oxo complex (FeIV(O)TAML) instead of singlet oxygen (1O2), superoxide radical (O2•−), sulfate radicals (SO4•−) and hydroxyl radicals (HO•) was the key active species responsible for 4-CP degradation. The formation rate (kI) and consumption rate (kII) of the FeIV(O)TAML in PMS/FeIII-TAML were pH-dependent in the range of 6.0-11.5. As expected, increasing the FeIII-TAML and PMS dosage resulted in a higher steady-state concentration of FeIV(O)TAML and enhanced the 4-CP degradation accordingly. In addition, the oxidation capacity of PMS was almost totally utilized in PMS/FeIII-TAML for 4-CP oxidation due to the two-electron abstraction from 4-CP by one PMS. We believe this study will shed new light on effective PMS activation by Fe-ligand complexes to efficiently degrade organic contaminants via nonradical pathway.
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25336. 题目: Effect of aqueous concentration of humic acid on the sorption of polychlorinated biphenyls onto soil particle grain sizes
文章编号: N18100624
期刊: Journal of Soils and Sediments
作者: Gbadebo Clement Adeyinka, Brenda Moodley
更新时间: 2018-10-06
摘要: Purpose: The role of initial aqueous humic acid concentrations (dose), as well as secondary environmental conditions on the sorption of PCB congeners PCB 28, 52, 77, 101, 105, 138, 153, and 180 onto soil particle grain sizes, was investigated in this study. Materials and methods: Scanning electron microscopy equipped with energy dispersive X-ray and Fourier transform infrared spectroscopy were used for the internal morphology and qualitative elemental analysis, as well as identification of possible functional groups found in commercial HA. Batch adsorption experiments were used for sorption studies. Results and discussion: The results showed that the sorption of PCBs onto soil decreased with an increase in the aqueous HA concentrations. The adsorption of the selected PCBs onto the soils was found to decrease with an increase in the solution pH of humic acid. Thermodynamic studies showed that the partition coefficient values increased with an increase in solution temperature. All the standard free energy were negative indicating the spontaneity and feasibility of the sorption process with positive and high enthalpy and entropy values of the system. The sorption was best fitted with the Freundlich isotherm with the intensity parameter 1/n found to be greater than 1. Conclusions: The outcome of this study revealed that secondary pollution of river water may possibly be altered depending on variations in the environmental conditions such as pH and temperature. The presence of organic pollutants in alkaline soils having less organic matter content could increase the chances of leaching of organic pollutants causing groundwater contamination.
25337. 题目: Quantification of lignin oxidation products as vegetation biomarkers in speleothems and cave drip water
文章编号: N18100623
期刊: Biogeosciences
作者: Inken Heidke, Denis Scholz, and Thorsten Hoffmann
更新时间: 2018-10-06
摘要: Here we present a sensitive method to analyze lignin oxidation products (LOPs) in speleothems and cave drip water to provide a new tool for paleo-vegetation reconstruction. Speleothems are valuable climate archives. However, compared to other terrestrial climate archives, such as lake sediments, speleothems contain very little organic matter. Therefore, very few studies on organic biomarkers in speleothems are available. Our new sensitive method allows us to use LOPs as vegetation biomarkers in speleothems.
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25338. 题目: Relative distribution of Cd2+ adsorption mechanisms on biochars derived from rice straw and sewage sludge
文章编号: N18100622
期刊: Bioresource Technology
作者: Li-Yang Gao, Jin-Huan Deng, Guo-Fu Huang, Kai Li, Kun-Zheng Cai, Yan Liu, Fei Huang
更新时间: 2018-10-06
摘要: Qualitative and quantitative characterization of Cd2+ adsorption mechanisms was performed with rice-straw and sewage-sludge biochars produced at different temperature (300-700°C), respectively. The pH effect, adsorption kinetics and isotherms were investigated, and chemical analyses of Cd2+-loaded biochars were conducted by SEM-EDS, XRD, FTIR and Boehm titration. This demonstrated that rice-straw biochars (RSBs) have greater adsorption capacities for Cd2+ than sewage-sludge biochars (SSBs), which was mainly due to precipitation and cation exchange mechanisms, with their contribution proportion to total adsorption from 76.1% to 80.8%. While in SSBs, both mechanisms were overshadowed by coordination with π electrons mechanism accounting for 59.2%-62.9% of total adsorption, even the role of cation exchange was negligible in the adsorption mechanisms accounting for 2.3%-6.7%. The relationship of each mechanism with biochar’s properties were discussed, which further deepen our understanding of adsorption on biochars. These results suggest RSBs have great potential for removing Cd2+ from aqueous solutions.
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25339. 题目: Lignin materials for adsorption: current trend, perspectives and opportunities
文章编号: N18100621
期刊: Bioresource Technology
作者: Nontipa Supanchaiyamat, Kaewta Jetsrisuparb, Jesper T.N. Knijnenburg, Daniel C.W. Tsang, Andrew J. Hunt
更新时间: 2018-10-06
摘要: Lignin is a highly aromatic low value biomass residue, which can be utilized for chemicals, fuels and materials production. In recent years significant attention has focused on adsorbent materials from lignin. However, only 5% of available lignin is exploited worldwide, thus significant opportunities still exist for materials development. This review summarizes recent research advances in lignin-based adsorbents, with a particular emphasis on lignin, its modification and carbon materials derived from this abundant feedstock. Lignin derived activated carbons have been utilized for air pollutant adsorption (e.g. CO2, SO2 and H2S), while modified lignin materials have been developed for the removal of organic dyes and organics (like methylene blue, Procion Blue MX-R and phenols), heavy metals (such as Cu, Zn, Pb and Cd), or recovery of noble metals (e.g., Pd, Au and Pt). Future perspectives highlight how green chemistry approaches for developing lignin adsorbents can generate added value processes.
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25340. 题目: Investigation into Role of CO2 in Two-Stage Pyrolysis of Spent Coffee Grounds
文章编号: N18100620
期刊: Bioresource Technology
作者: Youkwan Kim, Jechan Lee, Haakrho Yi, Yiu Fai Tsang, Eilhann E. Kwon
更新时间: 2018-10-06
摘要: As a way of improving process efficiency of pyrolysis of waste biomass, the effect of carbon dioxide (CO2) on pyrolysis of spent coffee grounds (SCGs) was examined using a two-stage pyrolysis reactor consisting of a region with increasing temperature and an isothermal region. It was experimentally validated that CO2 accelerates thermal cracking of organic compounds formed during the pyrolysis of SCGs. The expedited thermal cracking attributed to employing CO2 in pyrolysis of SCGs led to changing pyrolytic products in gas, liquid, and solid phases. The production of gaseous carbon monoxide was increased when using CO2 as the pyrolysis medium. In liquid pyrolytic products, the formation of phenolic compounds was hindered in the CO2-assited pyrolysis. Biochar morphology (solid pyrolytic product) was also changed with different pyrolysis environments. This study shows that CO2 can help improve applicability of pyrolysis of waste biomass by modifying three phase pyrolytic products in a two-stage pyrolyzer.