HDNPTT与镉显色反应的研究

应用合成的新试剂 1- (2 -羟基 - 3 ,5 -二硝基苯 ) - 3 - (4 -苯基 - 2 -噻唑 ) -三氮烯 (HDNPTT) ,研究了在表面活性剂TritonX - 10 0存在下 ,它与Cd2 的显色反应。结果表明 ,在 pH 8 0～ 10 0范围内 ,Cd2 与该试剂形成的配合物 ,其最大吸收峰位于 5 35nm处 ,摩尔吸光系数为 1 89× 10 5L·mol-1·cm-1。Cd2 在 0mg/L～ 0 32mg/L范围内符合比尔定律。此法用于环境水样和人发样品中微量镉的测定 ,结果满意。     

2-(2-喹啉偶氮)-4-二乙氨基苯甲酸光度法测定镍的研究

合成了新试剂 2 -( 2 -喹啉偶氮 ) -4 -二乙氨基苯甲酸 ( QADEABA) ,并研究了其与镍的显色反应 ,在 p H=8.0的硼酸 -磷酸二氢钾缓冲介质中 ,吐温 -80存在下 ,QADEABA与镍反应生成 2∶ 1稳定络合物 ,λmax=5 90 nm ,ε=1 .1 8× 1 0 5L· mol-1· cm-1。镍含量在 0～ 0 .4 mg/ L内符合比耳定律 ,方法用于水样中镍含量的测定 ,结果令人满意     

太湖铜锈环棱螺对氮磷的降解作用

太湖的五湖里湾是一个富营养湖,水质亟待改善。铜锈环棱螺是太湖的常见种群,通过在五里湖的一些室内外实验,研究了螺对水体透明度,总磷、氨氮、溶解氧的作用,发现它能交水体透明度从０．５ｍ左右提高到１．３ｍ,使室内水体浊度迅速降低,降解总磷的幅度能达到５０％,分析为铜锈环棱螺的絮凝作用所致;并且,在其水域氨氮深度大幅度降低,使实验点高达５ｍｇ／Ｌ以上的氨氮浓度降至２ｍｇ／Ｌ以下,从感观和水质指标两方面有效     

Effect of Sb dopant amount on the structure and electrocatalytic capability of Ti/Sb-SnO2 electrodes in the oxidation of 4-chlorophenol

Ti/Sb-SnO_2 anodes were prepared by thermal decomposition to examine the influence',of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol.The physicochemical properties of the Sb-SnO_2 coating were markedly influenced by different amounts of Sb dopant.The electrodes,which contained 5% Sb dopant in the coating, presented a much more homogenous surface and much smaller mud-cracks,compared with Ti/Sb-SnO_2 electrodes containing 10% or 15% Sb dopant,which exibited larger mud cracks and pores on the surface.However,the main microstructure remained unchanged with the addition of the Sb dopant.No new crystal phase was observed by X-ray diffraction(XRD).The electrochemical oxidation of 4-chlorophenol on the Ti/SnO_2 electrode with 5% Sb dopant was inclined to electrochemical combustion;while for those containing more Sb dopant,intermediate species were accumulated.The electrodes with 5% Sb dopant showed the highest efficiency in the bulk electrolysis of 4-chlorophenol at a current density of 20 mA/cm~2 for 180 min;and the removal rates of 4-chlorophenol and COD were 51.0% and 48.9%,respectively.     

Emission of CO2, CH4 and N2O from freshwater marsh in northeast of China

The wetlands play an important role in carbon storage, especially at high latitudes, at which they store nearly one-third of global soil carbons. However, few studies have investigated the emissions of CO(2), CH(4) and N(2)O in the long-term, especially effects of freeze-thaw cycles on these gases emissions in freshwater marsh ecosystems. In this paper, we collected greenhouse gas emission data from a freshwater marsh area in China for 4 years, evaluated their release variables and speculated on their potential atmospheric impact. For this paper, we report on the CO(2), CH(4) and N(2)O emission rates recorded from June 2002 to November 2005 in the Sanjiang Plain of northeast China. We measured their interannual variations and fluctuations, as well as factors affecting their emissions, and estimated their regulation and freeze-thaw cycle impacts. Our results revealed obvious CO(2) and CH(4) emission fluctuations during the winter months, and during the freeze-thaw cycle, and a strong interannual variation during the growing season. Overall, we documented a close relationship between the CO(2) and CH(4) emissions, implicating some regulatory commonality. We determined that the marsh was a N(2)O sink during the winter, but a significant source of N(2)O during the freeze-thaw cycle as the temperature increased, especially in early summer. During the thaw-freeze period, the N(2)O levels were positively correlated with the water depth. Additionally, water depth greatly governed the interannual variation of the N(2)O emissions from the marshes during the thaw-freeze period.     

Crosslinking and stabilization of high fractional free volume polymers for gas separation

Crosslinkable poly(4-methyl-2-pentyne) (PMP) membranes were cast from carbon tetrachloride solutions containing PMP and either 4,4′-diazidobenzophenone or 4,4′-(hexafluoroisopropylidene)diphenyl azide. The composite membranes were transparent and homogeneous and were crosslinked by UV irradiation at room temperature or thermal treatment at 180 °C. Low levels of the bis(aryl azide) (1–4.5 wt%) were effective in rendering the membranes insoluble in cyclohexane and carbon tetrachloride, both are good solvents for PMP, thus PMP can easily be converted to mechanically stable membranes with permeabilities and selectivities comparable or higher than those of the well-known poly(dimethylsiloxane) (PDMS). The permeabilities of O₂, N₂, H₂, CH₄ and CO₂ were measured. Compared to pure PMP, the crosslinked membranes containing bis(aryl azide) had lower permeabilities and higher selectivities, consistent with a reduction in free volume.     

Deterioration of water quality of Surma river

Surma River is polluted day by day by human activities, poor structured sewerage and drainage system, discharging industrial and household wastes. The charas (natural channels) are responsible for surface runoff conveyance from its urban catchments to the receiving Surma River. Water samples have been collected from a part of Surma River along different points and analyzed for various water quality parameters during dry and monsoon periods. Effects of industrial wastes, municipal sewage, and agricultural runoff on river water quality have been investigated. The study was conducted within the Chattak to Sunamganj portion of Surma River, which is significant due to the presence of two major industries – a paper mill and a cement factory. The other significant feature is the conveyors that travel from India to Chattak. The river was found to be highly turbid in the monsoon season. But BOD and fecal coliform concentration was found higher in the dry season. The water was found slightly acidic. The mean values of parameters were Conductivity 84–805 μs; DO: dry-5.52 mg/l, monsoon-5.72 mg/l; BOD: dry-1mg/l, monsoon-0.878 mg/l; Total Solid: dry-149.4 mg/l, monsoon-145.7 mg/l. In this study, an effort has been taken to investigate the status of concentration of phosphate (PO⁻⁴) and ammonia–nitrogen (NH₄–N) at four entrance points of Malnichara to the city, Guali chara, Gaviar khal and Bolramer khal. Data has been collected from March–April and September–October of 2004. Concentrations have been measured using UV Spectrophotometer. Although the phosphate concentration has been found within the limit set by DOE for fishing, irrigation and recreational purposes, however ammonia–nitrogen has been found to exceed the limit.     

Modified grey model for estimating traffic tunnel air quality

This study compared three forecasting models based on the mean absolute percentage errors (MAPE) of their accuracy in forecasting air pollution in a traffic tunnel: the Grey model (GM), the combination model used four sample point and five sample point prediction with GM (1,1)(GM(1,1)^4 + 5), and the modified grey model (MGM). An MGM was combined using the four points of the original sequence using the original grey prediction GM (1,1) for short-term forecasting. The proposed method cannot only enhance the prediction accuracy of the original grey model, but can also solve the jump data forecasting problem something for which the original grey model is inappropriate. The MAPE was applied to the models, and the MGM found the proposed method to be simple and efficient. The MAPE of MGM, calculated over 3 h of forecasts, were as follows: 10.12 (Upwind), 10.07 (Middle) and 7.68 (Downwind) for CO; 10.79 (Upwind), 6.05 (Middle) and 5.98 (Downwind) for NO _x , and 11.67 (Upwind), 7.32 (Middle) and 4.56 (Downwind) for NMHC. The MGM model results reveal that the combined forecasts can significantly decrease the overall forecasting error. Results of this demonstrate that MGM can accurately forecast air pollution in the Kaohsiung Chung–Cheng Tunnel.     

改性沸石对2,4-二氯苯酚的去除作用

采用溴化十六烷基三甲铵(HDTMAB)制备改性沸石,在与天然沸石对比的基础上,研究了改性沸石在动态条件下去除2,4-DCP的效果。并对影响去除率的主要因素,包括沸石粒径、进水浓度,进水流速,沸石用量,进水pH值等进行研究。结果表明,细粒改性沸石在pH2.5左右时处理低浓度2,4-DCP溶液时,能取得较好的去除效果,流速较低时去除率最高可达80%以上。     

偶氮染料4BS光解动力学和总氮脱除的初步研究

采用单独紫外光氧化降解偶氮染料直接耐酸大红(4BS),研究了不同因素对4BS光解效果的影响,并初步考察了光解对4BS溶液总氮的去除效果. 结果表明,单独紫外光氧化法对4BS及溶液中的总氮有一定的去除效果. 在非强碱性条件下,4BS的光解过程符合准一级反应动力学模型. 速率常数随紫外光强的增强而增大,并且与初始ρ(4BS)呈负相关关系. 溶液pH是影响光解反应的重要因素,速率常数随pH升高而增加显著,强碱性条件下光解速率最快. 光解对溶液中总氮的去除分为三步,含氮结构的发色基团易吸收紫外光,在反应初期被降解而生成气态含氮物,生成的中间产物比较稳定,需要经过一段时间的能量积累才能继续降解,从而总氮的去除率再次升高.