天然膨润土还原吸附Cr（Ⅵ）

以天然膨润土为吸附剂,还原吸附处理含Cr（Ⅵ）模拟废水。实验结果表明：以（NH₄）₂FeSO₄为还原剂吸附效果最佳;在还原剂加入量为理论值的0.8倍、膨润土加入量为6 g/L、吸附时间为30 min、吸附温度为30 ℃、初始Cr（Ⅵ）质量浓度为1 mg/L的条件下,Cr（Ⅵ）去除率可达99.6%,处理后模拟废水中总铬质量浓度低至0.003 mg/L。天然膨润土对Cr（Ⅵ）的还原吸附符合准二级动力学模型及Freundlich等温吸附模型。     

Polychlorinated dibenzo-p-dioxin and dibenzofuran in urban air of an Andean city

Particle-bound polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in ambient air were monitored together with particulate matter less than 10 μm (PM₁₀) at three sampling sites of the Andean city of Manizales, Colombia; during September 2009 and July 2010. PCDD/Fs ambient air emissions ranged from 1 fg WHO-TEQ m⁻³ to 52 fg WHO-TEQ m⁻³ in particulate fraction. The PM₁₀ concentrations ranged from 23 μg m⁻³ to 54 μg m⁻³. Concentrations of PM₁₀ and PCDD/Fs in ambient air observed for Manizales - a medium sized city with a population of 380 000 - were comparable to concentrations in larger cities. The highest concentrations of PCDD/Fs and PM₁₀ found in this study were determined at the central zone of the city, characterized by public transportation density, where diesel as principal fuel is used. In addition, hypothetical gas fractions of PCDD/Fs were calculated from theoretical K_p data. Congener profiles of PCDD/Fs exhibited ratios associated with different combustion sources at the different sampling locations, ranging from steel recycling to gasoline and diesel engines. Taking into account particle and gas hypothetical fraction of PCDD/Fs, Manizales exhibited values of PCDD/Fs equivalent to rural and urban-industrial sites in the southeast and center of the city respectively. Poor correlation of PCDDs with PM₁₀ (r = −0.55 and r = 0.52) suggests ambient air PCDDs were derived from various combustion sources. Stronger correlation was observed of PCDFs with PM₁₀. Poor correlation between precipitation and reduced PM₁₀ concentration in ambient air (r = −0.45) suggested low PM₁₀ removal by rainfall.     

Decay profile and metabolic pathways of quinalphos in water, soil and plants

The widespread occurrence of pesticide residues in different agricultural and food commodities has raised concern among the environmentalists and food chemists. In order to keep a proper track of these materials, studies on their decay profiles in the various segments of ecosystem under varying environmental conditions are needed. In view of this, the metabolites of quinalphos in water and soil under controlled conditions and in plants, namely tomato and radish in field conditions have been analysed and possible pathways suggested. In order to follow the decay of the pesticide, an HPLC procedure has been developed. Studies conducted in water at different temperatures, pH and organic content reveal that the persistence of the pesticide decreases with the increase in all the three variables. In the three different types of soils studied, the effect of pH is more or less apparent on a similar line. On an average a faster decay is observed in the case of plants than in water and soil. The decay profiles in all these cases follow first order kinetics. The metabolites were identified by GC-MS. The investigations reflect that degradation occurs through hydrolysis, S-oxidation, dealkylation and thiono-thiol rearrangement. The pathways seem to be complex and different metabolites were observed with the change in the matrix. Quinalphos oxon, O-ethyl-O-quinoxalin-2-yl phosphoric acid, 2-hydroxy quinoxaline and quinoxaline-2-thiol were observed in all the matrices. Results further indicate that the metabolites, 2-hydroxy quinoxaline and oxon, which are more toxic than parent compound, persist for a longer time.     

上海城市样带土壤有机碳空间变异性研究

为揭示城市化、工业化等人为活动对土壤有机碳的影响,选择能反映上海城郊乡梯度差异的城市样带,采用地统计学方法对表层土壤样品土壤有机碳的空间变异结构和分布格局进行了分析。结果表明：城市表层土壤有机碳含量均属中等变异,徐汇区土壤有机碳含量呈正态分布,奉贤区、闵行区和所研究样带土壤有机碳含量呈对数正态分布。半方差函数模型拟合结果显示徐汇和闵行区土壤有机碳符合指数模型,奉贤和所研究样带土壤有机碳符合球状模型。通过泛克里格插值得到城市表层土壤有机碳含量空间分布图,发现徐汇、闵行区土壤有机碳呈岛状,奉贤区呈条带状,而所研究样带呈条带和岛状分布相结合的特点。土壤有机碳含量城郊乡梯度差异明显,工业化、城市化、肥料投入与管理等人为因素对城市土壤有机碳空间分布密切相关     

有机物降解产气率模型研究

根据重庆市生活垃圾的组成特点,自配垃圾试样进行有机物降解实验,根据实验期间试样的质量变化,结合降解反应方程式,计算试样的产气量,并建立产气率模型.实验结果表明,试样质量随时间逐渐降低,呈指数型衰减规律.试样在实验初期产气率增加较快,达到产气高峰后逐渐降低.用建立的产气率模型进行计算,计算结果与实测数据比较接近,说明该产...     

电除尘器进口矩形烟道气流分布改进的CFD模拟

应用CFD软件对某电厂电除尘器进口矩形烟道内气流分布进行数值模拟.结果表明:电除尘器原进口矩形烟道监测截面的气流分布极其不均匀,数值模拟结果与实验结果速度分布趋势比较吻合.基于此,通过多次改变电除尘器进口矩形烟道内导流板的数量、位置、尺寸等结构参数,使得改造后烟道监测截面风量偏差降到了±2.2%,气流分布相对均方根值均...     

不同来源废水COD、TOC与Cl-的关系

通过对含盐化工废水(A)、受潮汐影响的河流水(B)、城市生活污水处理厂排水(C)、采油废水(D)4种不同来源废水进行为期15 d的采样监测,测定了其COD、TOC和Cl-浓度,分析比较了3种废水指标之间的关系,其中COD分别使用重铬酸钾法、氯气校正法和碘化钾碱性高锰酸钾法3种方法进行测定.实验结果表明,4种废水Cl-浓...     

烟气NO氧化催化剂Cu-V/Ti-PILCs的制备及其硫水稳定性

采用等体积浸渍法制备了以钛交联粘土为载体,Cu与V氧化物为活性组分的烟气NO氧化催化剂(Cu-v/Ti-PILCs),并考察了各种制备条件下催化剂的活性及稳定性.结果显示,当V水/V丙酮 =1∶2,负载4%CuO和2%V2O5,并在500℃煅烧时制得的Cu-V/Ti-PILCs催化剂,在NO浓度为350 mg/m3,O...     

活性炭纤维(ACF)应用于有机废气回收和净化的进展

活性炭纤维(ACF)有比普通活性炭吸附量大、吸附和脱附速度快等优点,因此应用于有机废气的回收和净化,具有良好的经济、环境和社会效益。文中介绍了ACF的微观结构、表面化学以及吸附性能,并综述了近年来ACF在有机废气回收和治理方面的国内概况。     

半干法烟气脱硫除尘多级功能处理装置技术与应用

文中介绍了一种炉窑烟气调质、烟气除尘、烟气脱硫在一个单体结构中的一体化装置和在烟气除尘脱硫技术上的应用,并对该脱硫除尘装置与传统的半干法烟气脱硫除尘装置进行了比较。