Characteristic of emissive spectrum and the removal of nitric oxide in N2/O2/NO plasma with argon additive

Although the approach using non-thermal plasma (NTP) for deNOx has been studied for over 15 years,how to achieve higher removal efficiency with lower cost is still a barrier for its industrial application.In order to investigate the impact of the argon additive on the electron density,energy and the nitric oxide reduction process in plasma,the spectrum of the dielectric barrier discharge at atmospheric pressure in a coaxial reactor was measured using the monochromater with high resolution and the comparative experiments for NO reduction were carried out simultaneously in the N2/O2/NO plasma stream with and without argon,respectively.The nitrogen molecular spectrum which is attributed to the energy level transition (C3πu→B3πg ) was compared in the wavelength range 300-480 nm and the electron density and temperature were determined by the calculation based on the relative intensities and Stark broadening width of spectral lines.The spectrum results indicated that the argon additive could enhance the intensity of emissive spectrum of plasma,thus the electron concentration as well as the energy was increased,and finally prompted the ionization rate to produce active N,O and O3.The results of NO reduction showed that the NO conversion efficiency increased in the range of 10%-30% with 5% addition of argon in stream comparing with the condition without argon additive.This study will play a positive role in the industrial application of dielectric barrier discharge deNOx reactor.     

Bayesian calibration of the nitrous oxide emission module of an agro-ecosystem model

Nitrous oxide (N₂O) is the main biogenic greenhouse gas contributing to the global warming potential (GWP) of agro-ecosystems. Evaluating the impact of agriculture on climate therefore requires a capacity to predict N₂O emissions in relation to environmental conditions and crop management. Biophysical models simulating the dynamics of carbon and nitrogen in agro-ecosystems have a unique potential to explore these relationships, but are fraught with high uncertainties in their parameters due to their variations over time and space. Here, we used a Bayesian approach to calibrate the parameters of the N₂O submodel of the agro-ecosystem model CERES-EGC. The submodel simulates N₂O emissions from the nitrification and denitrification processes, which are modelled as the product of a potential rate with three dimensionless factors related to soil water content, nitrogen content and temperature. These equations involve a total set of 15 parameters, four of which are site-specific and should be measured on site, while the other 11 are considered global, i.e. invariant over time and space. We first gathered prior information on the model parameters based on the literature review, and assigned them uniform probability distributions. A Bayesian method based on the Metropolis–Hastings algorithm was subsequently developed to update the parameter distributions against a database of seven different field-sites in France. Three parallel Markov chains were run to ensure a convergence of the algorithm. This site-specific calibration significantly reduced the spread in parameter distribution, and the uncertainty in the N₂O simulations. The model’s root mean square error (RMSE) was also abated by 73% across the field sites compared to the prior parameterization. The Bayesian calibration was subsequently applied simultaneously to all data sets, to obtain better global estimates for the parameters initially deemed universal. This made it possible to reduce the RMSE by 33% on average, compared to the uncalibrated model. These global parameter values may be used to obtain more realistic estimates of N₂O emissions from arable soils at regional or continental scales.     

不同水分管理方式下水稻生长季N_2O排放量估算:模型应用

基于田间原位测定结果,作者建立了不同水分管理方式下稻田N2O排放估算的统计模型.在模型验证和输入参数检验的基础上,本研究应用模型估算了20世纪50～90年代我国稻田水稻生长季N2O直接排放量.结果表明,由于水稻种植面积和氮输入量的增加、以及水分管理方式的变化,稻田N2O-N季节排放量从20世纪50年代平均每年9.55 Gg增加到了90年代每年32.26 Gg,同期伴随着水稻单产的增加.在20世纪50～90年代间,我国水稻生产的N2O-N排放量以平均每10 a 6.74 Gg的速度递增.20世纪50年代和90年代稻田N2O-N季节排放通量平均分别为0.32 kg·hm-2和1.00 kg·hm-2,相当于季节氮输入总量的0.37%和0.46%.本研究模型估算50～90年代间稻田N2O季节排放量的不确定性为59.8%～37.5%.就全国稻田的不同种植区域而言,长江中下游地区稻田水稻生长季N2O排放量占全国稻田N2O排放总量的51%～56%.20世纪90年代水稻生长季N2O排放量约占我国农田N2O年总排放量的8%～11%.相对于旱地作物而言,过去几十年水稻生产的发展在很大程度上减缓了我国农业生产的N2O排放.然而,随着水稻生产中节水灌溉的推广和氮肥施用量的增加,我国稻田N2O季节排放量预计将相应增加.     

污水短程硝化反硝化和同步硝化反硝化生物脱氮中N2O释放量及控制策略

采用SBR反应器考察了短程硝化反硝化和同步硝化反硝化脱氮过程中N_2O的释放.通过实时控制策略实现了短程硝化反硝化生物脱氮,亚硝化率可维持在90%以上.在溶解氧水平为0.5、 1.0、 1.5和2.0 mg/L条件下,考察N_2O的释放和亚硝化率的变化情况.结果表明,溶解氧1.5 mg/L时最有利于维持稳定的亚硝化率,同时N_2O逸出量最小,每去除1 g氨氮释放N_2O 0.06 g;在碳纤维填料SBR反应器中,通过维持较低溶解氧水平和分段投加碳源的运行方式成功实现了同步硝化反硝化,同步硝化反硝化率在79%以上.在溶解氧水平为0.2、 0.4、 1.0和1.5 mg/L时,考察N_2O的逸出情况.结果表明,溶解氧在1.0 mg/L时最有利于控制N2O的释放,每去除1g氨氮释放N2O 0.021 g,其N_2O释放量仅为短程硝化反硝化的1/3.     

Mass transfer in the absorption of SO2 and NOx using aqueous euchlorine scrubbing solution

Attempts have been made to generate euchlorine gas by chlorate-chloride process and to utilize it further to clean up SO2 and NOx from the flue gas in a lab scale bubbling reactor.Preliminary experiments were carried out to determine the gas and liquid phase mass transfer coefficients and their correlation equations have been established.Simultaneous removal of SO2 and NOx from the simulated flue gas using aqueous euchlorine scrubbing solution has been investigated.Euchlorine oxidized NO into NO2 completely and the later subsequently absorbed into the scrubbing solution in the form of nitrate.SO2 removal efficiency of around 100% and NOx removal efficiency of around 72 % were achieved under optimized conditions.Mass balance has been confirmed by analyzing the sulfate, nitrate, euchlorine and chloride ion using ion chromatograph/auto-titrator and comparing it with their corresponding calculated values.     

Fe_2O_3-TiO_2光催化降解水中酸性橙Ⅱ研究

通过溶胶-凝胶法制备TiO2/Fe2O3复合半导体催化剂,用SEM、X-ray衍射仪对催化剂进行表征,设计了光催化降解反应装置以研究光催化降解水中酸性橙。探讨了Fe2O3-TiO2催化剂对可见光吸收性能,以及降解水中酸性橙Ⅱ的催化性能影响。实验结果表明:Fe2O3修饰的TiO2出现明显的红移,20%wFe2O3修饰的TiO2催化剂催化效率较高;TOC结果表明,低pH值条件有利于酸性橙Ⅱ的矿化。     

UiO-66-(COOH)2对水溶液中In(Ⅲ)的吸附性能

以水作溶剂,采用简单的回流法合成了一种稳定的金属有机骨架材料UiO-66-(COOH)2,并首次将其用于In(Ⅲ)离子的吸附分离。采用傅里叶变换红外光谱(FTIR)、热重分析(TGA)、N2吸附-脱附和X射线衍射(XRD)等手段对材料进行了表征。通过静态吸附试验,探讨了pH值、接触时间和溶液初始质量浓度等因素对材料吸附In(Ⅲ)离子性能的影响。结果表明,在pH值为3.0、温度为303 K的条件下,UiO-66-(COOH)2对In(Ⅲ)的最大饱和吸附容量可达84.29 mg/g,优于大多数文献的报道值;整个吸附过程在90 min左右完成,且符合Langmuir等温吸附方程,而吸附动力学可以用准二级动力学模型进行描述。其可能的吸附机理是UiO-66-(COOH)2中的羧基与In(Ⅲ)离子的配位作用。此外,该材料能够实现重复使用,且在Na(Ⅰ)、K(Ⅰ)、Mg(Ⅱ)、Cu(Ⅱ)、Zn(Ⅱ)和Ni(Ⅱ)等竞争性金属离子的存在下,对In(Ⅲ)仍具备较好的吸附选择性。研究结果为含铟废水的处理提供了一种有效的新途径,也进一步拓展了MOFs材料的实际应用。     

Effect of elevated tropospheric ozone on methane and nitrous oxide emission from rice soil in north India

Physiological changes in crop plants in response to the elevated tropospheric ozone (O₃) may alter N and C cycles in soil. This may also affect the atmosphere-biosphere exchange of radiatively important greenhouse gases (GHGs), e.g. methane (CH₄) and nitrous oxide (N₂O) from soil. A study was carried out during July to November of 2007 and 2008 in the experimental farm of Indian Agricultural Research Institute, New Delhi to assess the effects of elevated tropospheric ozone on methane and nitrous oxide emissions from rice (Oryza sativa L.) soil. Rice crop was grown in open top chambers (OTC) under elevated ozone (EO), non-filtered air (NF), charcoal filtered air (CF) and ambient air (AA). Seasonal mean concentrations of O₃ were 4.3 ± 0.9, 26.2 ± 1.9, 59.1 ± 4.2 and 27.5 ± 2.3 ppb during year 2007 and 5.9 ± 1.1, 37.2 ± 2.5, 69.7 ± 3.9 and 39.2 ± 1.8 ppb during year 2008 for treatments CF, NF, EO and AA, respectively. Cumulative seasonal CH₄ emission reduced by 29.7% and 40.4% under the elevated ozone (EO) compared to the non-filtered air (NF), whereas the emission increased by 21.5% and 16.7% in the charcoal filtered air (CF) in 2007 and 2008, respectively. Cumulative seasonal emission of N₂O ranged from 47.8 mg m⁻² in elevated ozone to 54.6 mg m⁻² in charcoal filtered air in 2007 and from 46.4 to 62.1 mg m⁻² in 2008. Elevated ozone reduced grain yield by 11.3% and 12.4% in 2007 and 2008, respectively. Global warming potential (GWP) per unit of rice yield was the least under elevated ozone levels. Dissolved organic C content of soil was lowest under the elevated ozone treatment. Decrease in availability of substrate i.e., dissolved organic C under elevated ozone resulted in a decline in GHG emissions. Filtration of ozone from ambient air increased grain yield and growth parameters of rice and emission of GHGs.     

脱氮型生物反应器填埋场中N_2O产生潜势分析

阐述了微生物硝化和反硝化过程中N2O的产生机理以及影响因素,重点介绍底物浓度、O2量、含水率、pH、温度等因素对N2O产生的影响。根据N2O产生机理及影响因素分析,结合脱氮型生物反应器填埋场运行过程中不同影响因素的变化,对脱氮型生物反应器填埋场N2O的产生进行了分析探讨。认为相比于其他生物反应器填埋场,脱氮型生物反应器填埋场可能会增加N2O的产生量,该问题需要进行深入研究。     

氧化钙改性粉煤灰对酸性橙的吸附脱色性能试验研究

本文选择氧化钙为改性剂对粉煤灰进行改性试验,研究其对酸性橙染料的吸附脱色性能,结果表明:氧化钙和粉煤灰的质量比为1∶8、灼烧温度为400℃、不调节pH值、改性灰的投加量为14 g/L时,对浓度为25 mg/L酸性橙的脱色率可达95.5%,且碱性条件有利于吸附反应的发生;粉煤灰对酸性橙的吸附可用Langmuir吸附等温模...