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25761. 题目: Synergistic oxidation of Bisphenol A in a heterogeneous ultrasound-enhanced sludge biochar catalyst/persulfate process: Reactivity and mechanism
文章编号: N19121613
期刊: Journal of Hazardous Materials
作者: Zeng-Hui Diao, Fu-Xin Dong, Liu Yan, Zhi-Liang Chen, Wei Qian, Ling-Jun Kong, Zai-Wang Zhang, Tao Zhang, Xue-Qin Tao, Jian-Jun Du, Dan Jiang, Wei Chu
更新时间: 2019-12-16
摘要: Recently, clean-up of resistant organic compounds has attracted growing attention. In this study, a novel heterogeneous ultrasound-enhanced sludge biochar catalyst/persulfate (BC/PS/US) process was firstly developed for the degradation of bisphenol A (BPA) in water. The results revealed that BC/PS/US process could successfully achieve a positively synergistic effect between sonochemistry and catalytic chemistry on the degradation of BPA compared to its corresponding comparative process. Nearly 98% of BPA could be degraded within 80 min at optimum reaction conditions. The coexisting substances including Cl−, SO42- and NO3− had no obvious inhibition on the BPA degradation, whereas HCO3− and humic acid (HA) had significant inhibition effects on that. PS decomposition of BC/PS/US process was superior to that of BC/PS or US/PS process. Both SO4― and HO participated in the degradation of BPA, but SO4― was predominant radical in the BC/PS/US process. A possible pathway of BPA degradation was proposed, and the BPA molecule was attacked by SO4― and degraded into five kinds of intermediate products through hydroxylation and demethylation processes. This study helps to comprehend the application of sludge biochar catalyst as a persulfate activator for the degradation of organic compounds under ultrasound irradiation, and provides a new strategy in wastewater treatment.
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25762. 题目: Removal of metronidazole from aqueous media by C. vulgaris
文章编号: N19121612
期刊: Journal of Hazardous Materials
作者: Sufia Hena, Leo Gutierrez, Jean-Philippe Croué
更新时间: 2019-12-16
摘要: This current study investigated the removal of metronidazole from aqueous media by C. vulgaris. Two different initial sizes of inoculum (0.05 and 0.5 g L−1) were tested for a wide concentration range of metronidazole (1–50 μM). The effect of metronidazole concentrations on biomass production was studied for 20 days. The exopolymeric substances (EPS) were quantified and correlated with the removal of antibiotics from aqueous media. Specifically, MDZ stimulated the production of EPS in C. vulgaris, which played the major role in the adsorption of this antibiotic. Also, metronidazole significantly influenced the zeta potential of C. vulgaris in the test cultures, indicating a change in surface characteristics. This decrease in surface negative charge caused auto-flocculation phenomena at a stationary phase. Chronic and acute toxicity experiments showed that metronidazole was harmful to C. vulgaris at stationary phase. Results from this study would advance our knowledge on the treatment of metronidazole-contaminated waters with C. vulgaris as a green technology-oriented process.
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25763. 题目: Novel pectin based composite hydrogel derived from grapefruit peel for enhanced Cu(II) removal
文章编号: N19121611
期刊: Journal of Hazardous Materials
作者: Wei Zhang, Jianyang Song, Qiulai He, Hongyu Wang, Wanlin Lyu, Huijuan Feng, Wenqi Xiong, Wenbin Guo, Jing Wu, Ling Chen
更新时间: 2019-12-16
摘要: Novel biochar/pectin/alginate hydrogel beads (BPA) derived from grapefruit peel were synthesized and used for Cu(II) removal from aqueous solution. FTIR, SEM-EDS, XRD, TGA and XPS, etc. were applied for characterization analysis. The synergistic reinforcing effect of polymer matrix and biochar fillers improved the adsorptive, mechanical and thermostabilized performance of BPA. Factors like component contents of biochar and pectin, pH, contact time, Cu(II) concentration and coexisting inorganic salts or organic ligands were systematically investigated in batch mode. The adsorption isotherms were fitted well by the Freundlich model and the experimental maximum adsorption capacity of optimized BPA-9 beads (mass ratio of pectin to alginate = 10:1) with 0.25% biochar, was ∼80.6 mg/g at pH 6. Kinetic process was well described by the pseudo-second-order model and film diffusion primarily governed the overall adsorption rate, followed by intraparticle diffusion. Thermodynamics analysis suggested spontaneous feasibility and endothermic nature of adsorption behavior. Moreover, BPA also showed better environmental adaptability in the presence of NaCl, MgCl2, CaCl2, EDTA-2Na and CA as well as good adsorption potential for other heavy metal [e.g. Pb(III)]. Crucially, the BPA beads showed good regeneration ability after five cycles. All these results indicated the potential of BPA for removing heavy metal from water.
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25764. 题目: Enhanced passivation of lead with immobilized phosphate solubilizing bacteria beads loaded with biochar/ nanoscale zero valent iron composite
文章编号: N19121610
期刊: Journal of Hazardous Materials
作者: Zedong Teng, Wen Shao, Keyao Zhang, Fulu Yu, Yaoqiang Huo, Min Li
更新时间: 2019-12-16
摘要: Phosphate solubilizing bacteria (PSBs) can effectively enhance the stability of lead via the formation of insoluble Pb-phosphate compounds. This research presents a bio-beads, which was implemented with the help of a self-designed porous spheres carrier, by immobilized PSBs strains Leclercia adecarboxylata (hereafter referred as L1-5). In addition, the passivation efficiency of lead via bio-beads under different conditions and its mechanism were also investigated in this study. The results indicated that phosphate solubilized by bio-beads could reach 30 mg/L in Ca3(PO4)2 medium containing 1 mM Pb2+, and the highest removal rate of Pb2+ in beef peptone liquid medium could reach 93%, which is better than that of free bacteria. Furthermore, it was also concluded that the lead could be transformed into stable crystal texture, such as Pb5(PO4)3Cl and Pb5(PO4)3OH. Both hydrophobic and hydrophilic groups in the bio-beads could capture Pb2+, which indicated that electrostatic attraction and ion-exchange were also the mechanism of Pb2+ adsorption. All the experimental findings demonstrated that this bio-bead could be consider as an efficient way for the lead immobilization in contaminated soil in the future.
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25765. 题目: Synergistic removal of copper and tetracycline from aqueous solution by steam-activated bamboo-derived biochar
文章编号: N19121609
期刊: Journal of Hazardous Materials
作者: Rong-Zhong Wang, Dan-Lian Huang, Yun-Guo Liu, Chen Zhang, Cui Lai, Xin Wang, Guang-Ming Zeng, Qing Zhang, Xiao-Min Gong, Piao Xu
更新时间: 2019-12-16
摘要: Steam-activated biochar (SBC) was prepared and showed excellent performance for synergistic removal of Cu2+ and tetracycline (TC). The adsorption capacity of SBC and mutual effect of TC and Cu2+ were investigated via single and binary system and the adsorption isotherm. The adsorption capacity of TC was significantly enhanced when it coexisted with Cu2+. Likewise, increased amounts of Cu2+ were adsorbed in the presence of TC. The presence of NaCl exerted a negative influence on the adsorption of Cu2+, while the inhibitory effect of salinity on TC was neutralized by bridge enhancement in the binary system. Bridge enhancement and site competition were involved in the synergistic removal of TC and Cu2+. Considering the stable application in simulated and real water samples, SBC showed great potential for synergistic removal of antibiotics and heavy metals.
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25766. 题目: Participation of soil active components in the reduction of Cr(VI) by biochar: Differing effects of iron mineral alone and its combination with organic acid
文章编号: N19121608
期刊: Journal of Hazardous Materials
作者: Zibo Xu, Xiaoyun Xu, Daniel C.W. Tsang, Fan Yang, Ling Zhao, Hao Qiu, Xinde Cao
更新时间: 2019-12-16
摘要: Biochar as a soil amendment could be involved in redox process of elements which would be affected by soil-redox-active components including minerals and organic acids. This study evaluated the effects of Fe mineral and lactate on reducing capacity of biochar for Cr(VI) reduction and the underlying mechanisms. Fe minerals inhibited the reduction of Cr(VI) by biochar, with the decrease of Cr(VI) reduction rate constant obtained by pseudo first-order reaction model from 2.18 to 2.47 × 10−2 h-1 to 0.71–1.51 × 10−2 h-1. The decrease of reduction rate constant was because (1) the loss of electron donating moieties in biochar; and (2) inhibition of electron transfer between biochar and Cr(VI) due to surface coverage by biochar-Fe complex. However, the coexistence of Fe minerals with lactate enhanced the reduction of Cr(VI) by biochar, with the rate constant increasing from 2.58 to 3.05 × 10−2 h-1 to 2.91–27.2 × 10−2 h-1. The positive effect was also attributed to two reasons: (1) lactate can decrease the surface Fe-coverage of biochar through chelating process; (2) electron from lactate can be shuttled by Fe(II) and thus enhancing the Cr(VI) reduction. Our results revealed that different soil redox-active components could have varying effects on biochar amendment for Cr(VI) reduction, which should be further considered during the application of biochar.
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25767. 题目: Dynamic processes in conjunction with microbial response to disclose the biochar effect on pentachlorophenol degradation under both aerobic and anaerobic conditions
文章编号: N19121607
期刊: Journal of Hazardous Materials
作者: Yan Xu, Jiaqi Liu, Wenshan Cai, Jiayin Feng, Zhijiang Lu, Haizhen Wang, Ashley E. Franks, Caixian Tang, Yan He, Jianming Xu
更新时间: 2019-12-16
摘要: Organochlorines are critical soil contaminants and the use of biochar has recently shown potential to improve soil remediation. However, little is known about biochar-microbe interactions nor the impact on environmental processes such as the immobilization and biodegradation of organochlorine compounds. In this study, we performed microcosm experiments to elucidate how biochar affected the biodegradation and sequestration of pentachlorophenol (PCP). Our results showed that the amendment of biochar markedly inhibited PCP biodegradation due to a strong sorption affinity for PCP under both aerobic and anaerobic conditions. Notably, the inhibitory effect was relatively weaker under anaerobic conditions than under aerobic conditions. The addition of biochar can dramatically shift the bacterial community diversity in the PCP-spiked soils. Under aerobic conditions, biochar significantly stimulated the growth of PCP-degrading bacteria Bacillus and Sphingomonas, but reduced the opportunities for microbes to contact with PCP directly. Under anaerobic conditions, the non-strict organohalide-respiring bacteria Desulfovibrio, Anaeromyxobacter, Geobacter and Desulfomonile were the main drivers of PCP transformation. Our results imply that the use of biochar as a soil remediation strategy for organochlorine compounds should be cautious.
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25768. 题目: Parallel faction analysis combined with two-dimensional correlation spectroscopy reveal the characteristics of mercury-composting-derived dissolved organic matter interactions
文章编号: N19121606
期刊: Journal of Hazardous Materials
作者: Hong-Yang Cui, Shu-Bo Zhang, Mao-Yuan Zhao, Yue Zhao, Zi-Min Wei
更新时间: 2019-12-16
摘要: Dissolved organic matter (DOM) is regarded as the environmentally friendly substance. Strong complexes could be formed between DOM and heavy metals. Thus, the distribution, bioavailability, toxicity, and fate of heavy metals could be controlled in the environment. The widely spread method for characterizing metal-organic interactions is restricted to combine parallel faction analysis (PARAFAC) with the complexation model. However, a DOM PARAFAC component always contains two or more peaks. Therefore, the traditional method cannot reveal the inner changes of PARAFAC components or whether all the DOM peaks in one PARAFAC component are bound with metal during the metal-organic binding process. In this work, two-dimensional correlation spectroscopy (2DCOS) combined with PARAFAC and the complexation model were employed to reveal the binding speed and ability of different fluorescent peaks from DOM PARAFAC components during the binding process of mercury (Hg2+) to DOM. The results in this study showed that during the Hg2+-DOM binding process, fluorescent peaks in tryptophan-like component all presented Hg2+-binding ability. However, only humic-like component ligands showed Hg2+-binding ability. With these promising results, the true Hg2+ binding rate and ability of different DOM ligands can be revealed, which is helpful for addressing environmental pollution.
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25769. 题目: Effect of Fe-metabolizing bacteria and humic substances on magnetite nanoparticle reactivity towards arsenic and chromium
文章编号: N19121605
期刊: Journal of Hazardous Materials
作者: Anneli Sundman, Anna-Lena Vitzthum, Konstantin Adaktylos-Surber, Adriana I. Figueroa, Gerrit van der Laan, Birgit Daus, Andreas Kappler, James M. Byrne
更新时间: 2019-12-16
摘要: Magnetite is a magnetic, Fe(II)-Fe(III)-mineral formed through abiogenic and biogenic pathways. It constitutes an attractive material for remediation due to its reactivity, large surface-area-to-volume ratio when present as nanoparticles, and magnetic recoverability. Magnetite can be repeatedly microbially oxidized or reduced, but it is unclear how this influences the reactivity of magnetite towards toxic metal or metalloid contaminants. In this study, magnetite (both abiogenic and biogenic) was exposed to microbial Fe(II) oxidation and Fe(III) reduction, before reacted with hexavalent chromium (Cr(VI)) or pentavalent arsenic (As(V)). Results showed microbial reduction of both magnetite types improved the removal rate of Cr(VI) from solution, though surprisingly microbial Fe(II)-oxidation also showed enhanced reactivity towards Cr(VI) compared to un-treated magnetite. Synchrotron based analysis confirmed the formation of Cr(III) at the surface of the magnetite. Reactivity with As was less dramatic and showed un-treated material was able to remove As(V) from solution faster than microbially Fe(III)-reduced and Fe(II)-oxidized magnetite. The presence of humic substances was also shown to lead to a decreased reactivity of biogenic and abiogenic magnetite towards As(V) and Cr(VI). Our results imply that Fe-metabolizing bacteria influence the immobilization of contaminants and should be considered when evaluating remediation schemes, especially where Fe-metabolizing bacteria are active.
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25770. 题目: The mechanism of aquatic photodegradation of organophosphorus sensitized by humic acid-Fe3+ complexes
文章编号: N19121604
期刊: Journal of Hazardous Materials
作者: Jing Liu, Jiajun Fan, Tianyu He, Xiaofang Xu, Yulu Ai, Haoran Tang, Hao Gu, Tao Lu, Yanhui Liu, Guo Liu
更新时间: 2019-12-16
摘要: Organic phosphorus is an important source of eutrophication. In this study, to understand the mechanism of organophosphorus photodegradation, humic acid-Fe3+ (HA-Fe3+) complexes were prepared as a sensitizer, and glyphosate (GP) was used as a substrate for photodegradation. The effects of the initial GP concentration, HA concentration, Fe3+ concentration and microbial factors on photodegradation were investigated. The initial concentrations of GP, HA and Fe3+ could significantly affect the degradation rate of GP. Phosphate is the main product of GP photodegradation. Based on the identification of the active species in the reaction process, t-butanol was found to have the most significant inhibitory effect on the degradation. The reaction rate after t-butanol treatment was reduced from 0.017 to 0.003. This confirmed that OH was the main oxidant in the system, which was also demonstrated by EPR spectroscopy. A possible mechanism of GP photodegradation sensitized by HA-Fe3+ complexes was revealed for the first time. The HA-Fe3+ complexes in the reaction system were photodegraded and oxidized to finally produce OH, which promotes GP photodegradation. This study facilitates understanding the phosphorus cycle in a water environment and provides a scientific basis for the restoration of eutrophic lakes.
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25771. 题目: The duet of surface and radical-based carbocatalysis for oxidative destructions of aqueous contaminants over built-in nanotubes of graphite
文章编号: N19121603
期刊: Journal of Hazardous Materials
作者: Yuxian Wang, Jiaxin Xi, Xiaoguang Duan, Weiguang Lv, Hongbin Cao, Chunmao Chen, Zhuang Guo, Yongbing Xie, Shaobin Wang
更新时间: 2019-12-16
摘要: Metal-free mesoporous graphitic frameworks with built-in nanotubes (CPGs) were synthesized via facile co-pyrolysis of cyclodextrin and a cobalt salt with subsequent acid pickling to remove the embedded metal species. Due to the high graphitic degree and built-in few-layer nanotubes, the as-synthesized carbonaceous materials possess a higher catalytic ozonation activity than that of the state-of-the-art carbon nanotubes (CNTs) and LaMnO3 perovskite catalysts for the destruction of different aqueous contaminants. For recalcitrant oxalic acid removal, 50 mg L−1 oxalic acid was completely degraded in 20 min. Compared with other nanocarbons, the as-synthesized materials also demonstrated robust structural stability and reusability. The electron paramagnetic resonance (EPR) and selective radical quenching tests revealed that the destruction of the aqueous organics predominantly relied on surface-adsorbed complexes (O*ad and O2*) from activated ozone molecules. Owing to the occurrence of this surface oxidation pathway, the compatibility of the CPGs/O3 system was significantly enhanced for treatment of real wastewater, where the inorganic anions and organic natural organic matter would inhibit radical oxidation as radical scavengers. Furthermore, by employing organics with different ionization potentials (IPs) as the target pollutants, the CPGs/O3 system was discovered to obtain a high oxidation potential.
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25772. 题目: Application of vacuum-ultraviolet (VUV) for phenolic homologues removal in humic acid solution: Efficiency, pathway and DFT calculation
文章编号: N19121602
期刊: Journal of Hazardous Materials
作者: Ting-ting Cao, Xu Tie-fu, Mu-nan Zhao, Jiang Xu, Chong-wei Cui
更新时间: 2019-12-16
摘要: Vacuum-ultraviolet (VUV) photo-initiated oxidation of phenolic homologues in simulative natural water were investigated, including phenol, o-dihydroxybenzene (ODB), m-dihydroxybenzene (MDB), p-dihydroxybenzene (PDB), paranitrophenol (PNP) and o-chlorophenol (OCP). Results showed the phenolic homologues removal rate reached at least 90% in pure water, which was dependent on temperature, pH, concentration of HA, and functional group of HA. Experimental results indicated that 0.2 mg/L HA might be a critical point. Additionally, the rate constant of the six phenolic homologues reduced by 76.85%, 77.81%, 71.91%, 79.15%, and 55.69%, respectively in the MDB solution, and 79.73%, 82.80%, 95.36%, 80.38%, and 92.64%, respectively in the benzoic acid (BA) solution, compared to the rate constant in pure water. Moreover, quantum chemistry calculation indicated that the variances between phenolic compounds in removal rate were attributed to the substituent on the benzene ring. And, to some extent, the carboxy group of HA was supposed to arose the suppression for phenolic homologues removal rate. Mechanism involved phenolic homologues degradation using vacuum-ultraviolet (VUV) was summarized, where it underwent the formation of quinone structures, ring opening, short-chain organic acid, even eventually the transformation into NO3− and Cl− of PNP and OCP.
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25773. 题目: Importance of hydrogenotrophic, aceticlastic and methylotrophic methanogenesis for methane production in terrestrial, aquatic and other anoxic environments: A mini review
文章编号: N19121601
期刊: Pedosphere
作者: Ralf CONRAD
更新时间: 2019-12-16
摘要: Microbial methanogenesis is a major source of the greenhouse gas methane (CH4). It is the final step in the anaerobic degradation of organic matter when inorganic electron acceptors such as nitrate, ferric iron, or sulfate have been depleted. Knowledge of this degradation pathway is important for the creation of mechanistic models, prediction of future CH4 emission scenarios, and development of mitigation strategies. In most anoxic environments, CH4 is produced from either acetate (aceticlastic methanogenesis) or hydrogen (H2) plus carbon dioxide (CO2) (hydrogenotrophic methanogenesis). Hydrogen can be replaced by other CO2-type methanogenesis, using formate, carbon monoxide (CO), or alcohols as substrates. The ratio of these two pathways is tightly constrained by the stoichiometry of conversion processes. If the degradation of organic matter is complete (e.g., degradation of straw in rice paddies), then fermentation eventually results in production of acetate and H2 at a ratio of > 67% aceticlastic and < 33% hydrogenotrophic methanogensis. However, acetate production can be favored when heterotrophic or chemolithotrophic acetogenesis is enhanced, and H2 production can be favored when syntrophic acetate oxidation is enhanced. This typically occurs at low and elevated temperatures, respectively. Thus, temperature can strongly influence the methanogenic pathway, which may range from 100% aceticlastic methanogenesis at low temperatures to 100% hydrogenotrophic methanogenesis at high temperatures. However, if the degradation of organic matter is not complete (e.g., degradation of soil organic matter), the stoichiometry of fermentation is not tightly constrained, resulting, for example, in the preferential production of H2, followed by hydrogenotrophic methanogenesis. Preferential production of CH4 by either aceticlastic or hydrogenotrophic methanogenesis can also happen if one of the methanogenic substrates is not consumed by methanogens but is, instead, accumulated, volatilized, or utilized otherwise. Methylotrophic methanogens, which can use methanol as a substrate, are widespread, but it is unlikely that methanol is produced in similar quantities as acetate, CO2, and H2. Methylotrophic methanogenesis is important in saline environments, where compatible solutes are degraded to methyl compounds (trimethyl amine and dimethyl sulfide) and then serve as non-competitive substrates, while acetate and hydrogen are degraded by non-methanogenic processes, e.g., sulfate reduction.
25774. 题目: Surrogates for the removal by ozonation of the cytotoxicity and DNA double-strand break effects of wastewater on mammalian cells
文章编号: N19121513
期刊: Environment International
作者: Ye Du, Yang Yang, Wen-Long Wang, Yu-Ting Zhou, Qian-Yuan Wu
更新时间: 2019-12-15
摘要: Effluents from wastewater treatment plants (WWTPs) may contain various pollutants with potential toxic effects. Ozonation is widely applied to purify wastewater, which may influence the toxicity and water quality indices simultaneously. The main goal of this study was to reveal influence of ozonation on toxicity of WWTP effluents and to find the surrogates for toxicity changes. Cytotoxicity and DNA double-strand break (DSB) effect of WWTP effluents were measured based on Chinese hamster ovary (CHO) cells. Changes of water quality parameters and molecular weight distribution of WWTP effluents were also measured. The organic extracts in WWTP effluents were shown to decrease the cell viability. Besides, an increased level of DNA DSBs was found in cells when exposed to the organic extracts. Ozonation significantly eliminated cytotoxicity and DNA DSB-based genotoxicity of WWTP effluents, with removal rates of 53–66% and 51–76% for cytotoxicity and genotoxicity, respectively, with 10 mg/L ozone dose. Although the DOC contents in WWTP effluents were hardly removed by ozonation, the chromophores and fluorophores were significantly eliminated. Organic matter in WWTP effluents mainly consists of fractions with molecular weight (MW) < 500 Da. Ozonation generally decreased the fluorescence intensity and UV254 values of all the MW fractions, but increased the DOC contents of the 100–500 Da fraction. During ozonation, the removal rates of UV254 and SUVA254 were significantly correlated to the removal rates of both cytotoxicity and genotoxicity. UV254 might be an ideal surrogate for cytotoxicity and genotoxicity reduction during wastewater ozonation.
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25775. 题目: Effects of biochar nanoparticles on seed germination and seedling growth
文章编号: N19121512
期刊: Environmental Pollution
作者: Kun Zhang, Yaofeng Wang, Jiefei Mao, Baoliang Chen
更新时间: 2019-12-15
摘要: As a soil amendment, the prospect of biochar application is excellent. However, environmental risks of biochar need to be investigated for its substantial use. The environmental risks of BNPs need urgent attention because at present little knowledge is available. Therefore, the effects of six types of BNPs on seed germination and growth of rice, tomato and reed seedlings were investigated. The BNPs were collected from biochars derived from two feedstocks (rice straw and wood sawdust) under 300 °C (low-temperature), 500 °C (mid-temperature) and 700 °C (high-temperature). The BNPs collected from high-temperature biochar inhibited seed germination of rice. However, all of the BNPs had a stimulating effect on rice seedling growth that significantly increasing the length of its root and shoot. Furthermore, the BNPs collected from high-temperature biochar and lignin-rich feedstock had an inhibiting effect on reed that dramatically decreased shoot length and biomass. Inhibitory effects of BNPs were caused not only by phenolic compounds on its surface, but also by the blocking effect on epidermal openings resulting in a reduced transfer of nutrients and water. No evidence was found that BNPs would affect the seed gemination and seedling growth of tomato plants. This study indicates that the eco-toxicity of BNPs is a potential environmental risk of biochar. Our findings provide new evidence for the necessity of establishing environmental risk management of biochar.
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25776. 题目: Remediation of cadmium-contaminated soil with biochar simultaneously improves biochar’s recalcitrance
文章编号: N19121511
期刊: Environmental Pollution
作者: Zhen Qiu, Jiawen Tang, Jinhuan Chen, Qiuzhuo Zhang
更新时间: 2019-12-15
摘要: Biochar sequesters cadmium (Cd) by immobilisation, but the process is often less effective in field trials than in the laboratory. Therefore, the involvement of soil components should be considered for predicting field conditions that could potentially improve this process. Here, we used biochar derived from Spartina alterniflora as the amendment for Cd-contaminated soil. In simulation trials, a mixture of kaolin, a representative soil model component, and S. alterniflora-derived biochar immobilised Cd by forming silicon-aluminium-Cd-containing complexes. Interestingly, the biochar recalcitrance index value increased from 48% to 53%–56% because of the formation of physical barriers consisting of kaolinite minerals and Cd complexes. Pot trials were performed using Brassica chinensis for evaluating the effect of S. alterniflora-derived biochar on plant growth in Cd-contaminated soil. The bio-concentration factor values in B. chinensis were 24%–31% after soil remediation with biochar than in control plants. In summary, these results indicated that soil minerals facilitated Cd sequestration by biochar, which reduced Cd bioavailability and improved the recalcitrance of this soil amendment. Thus, mechanisms for effective Cd remediation should include biochar-soil interactions.
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25777. 题目: Effect of sulfamethazine on surface characteristics of biochar colloids and its implications for transport in porous media
文章编号: N19121510
期刊: Environmental Pollution
作者: Wen Yang, Tongtong Feng, Markus Flury, Baoguo Li, Jianying Shang
更新时间: 2019-12-15
摘要: Antibiotics are contaminants of emerging concern due to their potential effect on antibiotic resistance and human health. Antibiotics tend to sorb strongly to organic materials, and biochar, a high efficient agent for adsorbing and immobilizing pollutants, can thus be used for remediation of antibiotic-contaminated soil and water. The effect of ionizable antibiotics on surface characteristics and transport of biochar colloids (BC) in the environment is poorly studied. Column experiments of BC were conducted in 1 mM NaCl solution under three pH (5, 7, and 10) conditions in the presence of sulfamethazine (SMT). Additionally, the adsorption of SMT by BC and the zeta potential of BC were also studied. The experimental results showed that SMT sorption to BC was enhanced at pH 5 and 7, but reduced at pH 10. SMT sorption reduced the surface charge of BC at pH 5 and 7 due to charge shielding, but increased surface charge at pH 10 due to adsorption of the negatively charged SMT species. The mobility of BC was inhibited by SMT under acidic or neutral conditions, while enhanced by SMT under alkaline conditions, which can be well explained by the change of electrostatic repulsion between BC and sand grains. These findings imply that pH conditions played a crucial role in deciding whether the transport of BC would be promoted by SMT or not. Biochar for antibiotics remediation will be more effective under acidic and neutral soil conditions, and the mobility of BC will be less than in alkaline soils.
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25778. 题目: Influence of humic acid on arsenic bioaccumulation and biotransformation to zebrafish: A comparative study between As(III) and As(V) exposure
文章编号: N19121509
期刊: Environmental Pollution
作者: Xiaoyan Wang, Liping Liu, Xiangrui Wang, Jinqian Ren, Pei Jia, Wenhong Fan
更新时间: 2019-12-15
摘要: Previous studies have indicated that natural organic matter in the aquatic environment could affect arsenic bioaccumulation and biotransformation to aquatic organisms. However, the differences between the effects of arsenite and arsenate exposure have not been studied and compared in fish exposure models. In this study, adult zebrafish (Danio rerio) were exposed to 5 mg/L inorganic As solutions, in the presence of a range of humic acid (HA) concentrations (1, 2.5, 5, 10, 20 mg/L) in 96 h waterborne exposure. Results showed that in the presence of HA, total As bioaccumulation was significantly reduced in zebrafish following arsenite exposure, while this reduction was not observed during arsenate exposure. The reduction in total arsenic bioaccumulation for arsenite exposure can be explained by the fact that HA forming a surface coating on the cell surface, hindering transport and internalization. However, this reduction in total As was not observed due to differences in uptake pathways for arsenate exposure. Results also showed that Arsenobetaine (AsB) was the main biotransformation product in zebrafish following inorganic As exposure, accounting for 44.8%–64.7% of extracted arsenic species in all exposure groups. The addition of HA caused levels of MMA and As(III) to decrease, while the distribution of AsB significantly increased in arsenite exposure groups. The increase in AsB could be because the As(III)-HA complex was formed, affecting the methylation of As(III). In contrast, the addition of HA to arsenate exposure groups, did not affect the reduction of As(V) to As(III) and therefore, an increase in the distribution of AsB was not observed in arsenate exposure groups. This study provides useful information on the mechanisms of toxicity, for improved risk assessment of As in natural aquatic environments.
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25779. 题目: Experimental and modeling study of proton and copper binding properties onto fulvic acid fractions using spectroscopic techniques combined with two-dimensional correlation analysis
文章编号: N19121508
期刊: Environmental Pollution
作者: Tingting Li, Fanhao Song, Jin Zhang, Shijie Tian, Nannan Huang, Baoshan Xing, Yingchen Bai
更新时间: 2019-12-15
摘要: Fulvic acid (FA) significantly influences the bioavailability and fate of heavy metals in environments, while its acid-base characters and metal binding processes are still unclear. Here, spectroscopic techniques combined with multiple models (e.g., NICA-Donnan model) and two-dimensional correlation spectroscopy (2D COS) were applied to explore the proton and copper binding properties of FA sub-fractions (FA3-FA13). The charge densities, average contents of carboxylic and phenolic groups, average dissociation constants pKa1 and pKa2 of sub-fractions ranged 0–16 meq∙g∙C−1, 5.03–9.58 meq∙g∙C−1, 2.52–4.67 meq∙g∙C−1, 4.15–4.33 and 8.52–9.72, respectively. FA sub-fractions had a relatively narrow distribution of carboxyl group and a broad distribution of phenolic group. FA sub-fractions also exhibited roughly two phenolic hydroxyl groups per every 1–3 phenyl rings. Differential absorbance spectra (DAS) derived Gaussian bands were associated to the inter-chromophore interactions, the changes of molecular conformations and functional groups with copper addition. Differential spectra slopes (DSlope275-295&325-375) were more significant with higher copper concentration and copper amounts bonded to carboxylic groups. UV–Vis and fluorescence spectra with 2D heterospectral COS revealed the copper binding heterogeneities and sequential orders of chromophores and fluorophores, quantitatively confirming by the order of conditional stability constants (log KCu: 4.64–5.56). Salicylic-/polyhydroxyphenolic, hydroxyl and amino groups were strongly associated to the basic units for fluorophores. Sequential changes followed the order of humic-like→fulvic-like materials for FA3/FA5, humic-like→fulvic-like→tryptophan-like materials for FA7, and humic-like→tryptophan-like→fulvic-like→tyrosine-like materials for FA9/FA13. Spectroscopic techniques combined with various models (especially for 2D COS) are beneficial to elucidate the binding heterogeneity and sensitivity for metal-organic matters at the functional group level.
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25780. 题目: Elucidating the structural variation of membrane concentrated landfill leachate during Fenton oxidation process using spectroscopic analyses
文章编号: N19121507
期刊: Environmental Pollution
作者: Chunying Teng, Kanggen Zhou, Zhang Zhang, Changhong Peng, Wei Chen
更新时间: 2019-12-15
摘要: Membrane concentrated landfill leachate (MCLL) contains large amounts of recalcitrant organic matter that cause potential hazards to the environment. Knowledge on the compositional variation of MCLL during treatment is important for a better understanding on the degradation pathway of organic pollutants. In this work, the structural change of MCLL during Fenton oxidation process was examined using spectroscopic techniques. The removal rates of COD, TOC and UV254 reached 78.9 ± 1.3%, 70.2 ± 1.4% and 90.64 ± 1.6%, respectively, under the optimal condition (i.e., dosage of H2O2 = 9.0 mL/200 mL, H2O2/Fe(II) molar ratio = 3.0, pH = 3.0, time = 40 min). Spectral analyses suggested that aromatic/CC structure and CO bonds in MCLL can be successfully destroyed by Fenton oxidation, resulting in a decrease in molecular weight. One fulvic-like and one humic-like components were identified in MCLL, both of which can be removed by Fenton treatment. In addition, two-dimensional correlation spectroscopic analyses suggested the oxidative changes of MCLL structure in the order of fulvic-like component/unsaturated conjugated bond > aromatic structure > humic-like component. The results may provide a new insight to the understanding on the structure variation of MCLL during treatment, which is beneficial for the design of cost-effective treatment strategies.
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