Removal of nanoparticles by coagulation

<正>Nanoparticles(NPs)from anthropogenic sources have applications in several commercial products,including cosmetics,pharmaceuticals,and materials.There is evidence that during their usage and disposal,engineered nanoparticles can and will be released into wastewater(Gottschalk et al.,2013;Pasricha et al.,2012;Westerhoff et al.,2013;Zheng et al.,2015).If water and wastewater treatment plants are inefficient or incapable of removing NPs from water,NPs will be released with the treated effluent,entering drinking water sources and natural aquatic environments,increasing exposure for plants,microorganisms,     

新常态下我国商业银行碳金融业务发展对策探究

新常态下发展低碳经济已经成为主要趋势,碳金融将进入快速发展阶段,因此作为重要中介机构的商业银行面临着巨大的机遇和挑战,把握契机开拓碳金融业务发展新进程迫在眉睫。通过对我国商业银行碳金融业务发展现况及存在的系统性、机构性和业务性障碍的分析,结合新常态的经济背景,为我国商业银行发展碳金融业务提供了一些建议。     

Cattle manure biochar and earthworm interactively affected CO2 and N2O emissions in agricultural and forest soils: Observation of a distinct difference

• Earthworms increase CO₂ and N₂O emissions in agricultural and forest soil. • 10% biochar suppresses CO₂ and N₂O emissions in forest soil. • Biochar interacted with earthworm to significant affect CO₂ and N₂O emissions. The application of manure-derived biochar offers an alternative to avoid the direct application of manure to soil causing greenhouse gas emission. Soil fauna, especially earthworms, can markedly stimulate carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions from soil. This study therefore investigated the effect of cattle manure biochar (added at rates of 0, 2%, or 10%, coded as BC0, BC2 and BC10, respectively) application, with or without earthworm Aporrectodea turgida, on emissions of CO₂ and N₂O and changes of physic-chemical properties of agricultural and forest soils in a laboratory incubation experiment. The BC10 treatment significantly enhanced cumulative CO₂ emissions by 27.9% relative to the untreated control in the agricultural soil. On the contrary, the BC2 and BC10 treatments significantly reduced cumulative CO₂ emissions by 16.3%–61.1% and N₂O emissions by 92.9%–95.1% compared to the untreated control in the forest soil. The addition of earthworm alone significantly enhanced the cumulative CO₂ and N₂O fluxes in agricultural and forest soils. Cumulative CO₂ and N₂O fluxes were significantly increased when BC2 and BC10 were applied with earthworm in the agricultural soil, but were significantly reduced when BC10 was applied with earthworm in the forest soil. Our study demonstrated that biochar application interacted with earthworm to affect CO₂ and N₂O emissions, which were also dependent on the soil type involved. Our study suggests that manure biochar application rate and use of earthworm need to be carefully studied for specific soil types to maximize the climate change mitigation potential of such management practices.     

Wastewater treatment meets artificial photosynthesis: Solar to green fuel production,water remediation and carbon emission reduction

• Mitigating energy utilization and carbon emission is urgent for wastewater treatment. • MPEC integrates both solar energy storage and wastewater organics removal. • Energy self-sustaining MPEC allows to mitigate the fossil carbon emission. • MPEC is able to convert CO₂ into storable carbon fuel using renewable energy. • MPEC would inspire photoelectrochemistry by employing a novel oxidation reaction. Current wastewater treatment (WWT) is energy-intensive and leads to vast CO₂ emissions. Chinese pledge of “double carbon” target encourages a paradigm shift from fossil fuels use to renewable energy harvesting during WWT. In this context, hybrid microbial photoelectrochemical (MPEC) system integrating microbial electrochemical WWT with artificial photosynthesis (APS) emerges as a promising approach to tackle water-energy-carbon challenges simultaneously. Herein, we emphasized the significance to implement energy recovery during WWT for achieving the carbon neutrality goal. Then, we elucidated the working principle of MPEC and its advantages compared with conventional APS, and discussed its potential in fulfilling energy self-sustaining WWT, carbon capture and solar fuel production. Finally, we provided a strategy to judge the carbon profit by analysis of energy and carbon fluxes in a MPEC using several common organics in wastewater. Overall, MPEC provides an alternative of WWT approach to assist carbon-neutral goal, and simultaneously achieves solar harvesting, conversion and storage.     

Protective effect of exogenous nitric oxide and salicylic acid on the photosynthetic apparatus of tomato seedling leaves under NaCl stress北大核心CSCD

Using the tomato variety 'Qin Feng Bao Guan' as experimental material, and by the hydroponics nutrient solution method, we investigated the effects of single and compound applications of nitric oxide (NO) donor sodium nitroprusside (SNP) and salicylic acid (SA) on the gas exchange and chlorophyll fluorescence parameters, RuBisCO activation, CO2 response curve, photosynthetic pigment content, and xanthophyll cycle in seedling leaves under an NaCl stress of 100 mmol/L. The main findings were as follows: (1) Single or combined applications of SNP and SA could increase the net photosynthetic rate (Pn), stomatal conductance (Gs), PS II maximal photochemistry efficiency (Fv/Fm), antenna conversion efficiency (Fv'/Fm'), practical photochemical efficiency (φPS?), photochemical fluorescence quenching coefficient (qP), and chlorophyll fluorescence decay rate (Rfd) of tomato seedling leaves at different rates, and significantly reduce the intercellular CO2 concentration (Ci), original fluorescence (Fo), and PS II non-photochemical fluorescence quenching coefficient (NPQ), after NaCl stress treatment. The strongest effect was observed after applying a combination of SNP and SA. (2) Under NaCl stress, the decrease of CO2 carboxylation efficiency (CE), RuBP maximum regeneration rate (Jmax), RuBisCO and its activation enzyme activity, and the maximum carboxylation rate (Vc max) in tomato seedling leaves could be effectively relieved by SNP, SA, or SNP + SA applications; however, SNP + SA treatment had the strongest effect. (3) Single or combined applications of SNP and SA could effectively inhibit the decrease of the contents of photosynthetic pigments (chlorophyll a, chlorophyll b, and carotenoids), the ratio of chlorophyll a and chlorophyll b, xanthophyll cycle pool size (V + A + Z), and the increase of the de-epoxidation extent of the xanthophyll cycle (A + Z)/(V + A + Z). The combined application of SNP and SA had the most prominent effect. In conclusion, the heat dissipation of the antenna, which is dependent on the xanthophyll cycle, is not the physiological mechanism for the protection of the photosynthetic apparatus by exogenous NO, SA alone, or compound treatment in tomato seedling leaves under NaCl stress. It is the main reason for the increase of photosynthetic function and enhanced salt tolerance of leaves tomato seedlings that the protection of PS II and its primary electron acceptor quinone (QA) downstream electron transfer patency, and the improvement of CO2 assimilation activity by application of exogenous NO, SA alone, or a combination of the two; synergistic effects were observed after using a combination of SNP and SA. © 2018 Science Press. All rights reserved.     

Enhanced reductive degradation of carbon tetrachloride by carbon dioxide radical anion-based sodium percarbonate/Fe(II)/formic acid system in aqueous solution

Complete CT degradation was achieved by SPC/Fe(II)/FA system.Formic acid established the reductive circumstance by producing CO₂·^–.CO₂·^– was the dominant active species responsible for CT degradation.CT degradation was favorable in the pH range from 3.0 to 9.0.SPC/Fe(II)/FA system may be suitable for CT remediation in contaminated groundwater.The performance of sodium percarbonate (SPC) activated with ferrous ion (Fe(II)) with the addition of formic acid (FA) to stimulate the degradation of carbon tetrachloride (CT) was investigated. Results showed that CT could be entirely reduced within 15 min in the system at a variety of SPC/Fe(II)/FA/CT molar ratios in experimental level. Scavenging tests indicated that carbon dioxide radical anion (CO2·^–) was the dominant reactive oxygen species responsible for CT degradation. CT degradation rate, to a large extent, increased with increasing dosages of chemical agents and the optimal molar ratio of SPC/Fe(II)/FA/CT was set as 60/60/60/1. The initial concentration of CT can hardly affect the CT removal, while CT degradation was favorable in the pH range of 3.0–9.0, but apparently inhibited at pH 12. Cl^– and HCO₃^– of high concentration showed negative impact on CT removal. Cl^– released from CT was detected and the results confirmed nearly complete mineralization of CT. CT degradation was proposed by reductive C-Cl bond splitting. This study demonstrated that SPC activated with Fe(II) with the addition of FA may be promising technique for CT remediation in contaminated groundwater.     

GC-C-IRMS测定污染场地土壤中苯系物单体碳同位素比值

选取苯系物中的代表性组分苯、甲苯和二甲苯等化合物,通过热脱附、气相色谱质谱条件的优化及方法学考察,建立了热脱附进样-气相色谱-同位素比值质谱(GC-C-IRMS)测定苯系物单体碳同位素比值的方法。结果表明,单体化合物进样量在0.3μg以上均能满足测定要求;与直接进样方式相比,热脱附进样对单体碳同位素比值测定无分馏影响;标准溶液和苯系物土壤样品测定结果的RSD分别为1.0%~1.7%和0.3%~2.6%。     

Initial carbon release characteristics, mechanisms and denitrification performance of a novel slow release carbon source

External carbon source addition is one of the effective methods for the treatment of wastewater with low carbon to nitrogen ratio (C/N). Compared with fast-release liquid carbon sources, slow-release solid carbon sources are more suitable for the denitrification process. A novel slow-release solid carbon source (corncob-polyvinyl alcohol sodium alginate- poly-caprolactone, i.e. CPSP) was prepared using corn cob (CC) and poly-caprolactone with polyvinyl alcohol sodium alginate as hybrid scaffold. The physical properties and carbon release characteristics of CPSP and three other carbon sources were compared. CPSP had stable framework and good carbon release performance, which followed the second order release equation. The formic acid, acetic acid, propionic acid and butyric acid released from CPSP accounted for 8.27% ± 1.66 %, 56.48% ± 3.71 %, 18.46% ± 2.69% and 16.79% ± 3.02% of the total released acids respectively. The start-up period of CPSP was shorter than that of the other carbon sources in denitrification experiment, and no COD pollution was observed in the start-up phase (25–72 h) and stable phase (73–240 hr). The composition and structure of the dissolved organic compounds released by CPSP and other carbon sources were analyzed by UV-Vis absorption spectroscopy and three-dimensional fluorescence spectroscopy, which indicated that CPSP was more suitable for denitrification than the other studied carbon sources.

1. Download : Download high-res image (143KB)
2. Download : Download full-size image

     

Spray and explosion characteristics of methanol and methanol-benzene blends near azeotrope formation: Effects of temperature,concentration, and benzene content

The explosion hazard of flammable liquids leaking to form spray in storage and transportation at ambient temperature has not been systematically investigated. This work presents new results from experimental investigations of the atomization and explosion characteristics of methanol, and methanol-benzene blends forming near the azeotrope under different initial conditions (initial temperature (298.15–318.15 K), methanol concentration (198–514.8 g/m³) and benzene content (41–81%)) in a 20-L spherical vessel. The empirical formulas for Sauter Mean Diameter (SMD) of the droplets and the maximum explosion pressure with respect to the initial temperature and methanol concentration were obtained from the quantitative analysis. Compared to the explosion hazard of pure methanol and methanol-benzene blends spray, the results showed that the maximum rate of pressure rise and maximum explosion temperature of methanol-benzene blends were relatively low. Furthermore, the effect of carbon soot formation on the explosion hazard during explosion development was analyzed.