The prediction of adsorption isotherms of ester vapors on hypercrosslinked polymeric adsorbent

Adsorption isotherms of methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate and ethyl propionate on hypercrosslinked polymeric resin (ND- 100) were measured at 303K, 318K and 333K,respectively, and well fitted by Dubinin–Astakhov (DA) equation. The plots of the adsorbed volume (q _v ) versus the adsorption potential (ε) at three different temperatures all fell basically onto one single curve for every ester. A predicted model based on DA equation was obtained on the basis of adsorption equilibrium data of methyl acetate, ethyl acetate and ethyl propionate at 318K. The model equation successfully predicted the adsorption isotherms of methyl acetate, ethyl acetate and ethyl propionate on ND-100 at 303K, and 333K, and also gave accurate predictive results for adsorption isotherms of the other two ester compounds (propyl acetate and isopropyl acetate) on ND-100 at 303K, 318K and 333K. The results proved the effectiveness of DA model for predicting the adsorption isotherms of ester compounds onto ND-100. In addition, the relationship between physico-chemical properties of adsorbates and their adsorption properties was also investigated. The results showed that molecular weight, molar volume and molar polarizability had good linear correlations with the parameter E (which represents adsorption characteristic energy) of DA equation.     

Wastewater-nitrogen removal using polylactic acid/starch as carbon source: Optimization of operating parameters using response surface methodology

The use of PLA/starch blends for nitrogen removal was achieved. The influence of different operating parameters on responses was verified using RSM. The conditions for desired responses were successfully optimized simultaneously. Blends material may have a promising application prospect in the future. Nitrogen removal from ammonium-containing wastewater was conducted using polylactic acid (PLA)/starch blends as carbon source and carrier for functional bacteria. The exclusive and interactive influences of operating parameters (i.e., temperature, pH, stirring rate, and PLA-to-starch ratio (PLA proportion)) on nitrification (Y₁), denitrification (Y₂), and COD release rates (Y₃) were investigated through response surface methodology. Experimental results indicated that nitrogen removal could be successfully achieved in the PLA/starch blends through simultaneous nitrification and denitrification. The carbon release rate of the blends was controllable. The sensitivity of Y₁, Y₂, and Y₃ to different operating parameters also differed. The sequence for each response was as follows: for Y₁, pH>stirring rate>PLA proportion>temperature; for Y₂, pH>PLA proportion>temperature>stirring rate; and for Y₃, stirring rate>pH>PLA proportion>temperature. In this study, the following optimum conditions were observed: temperature, 32.0°C; pH 7.7; stirring rate, 200.0 r·min^-1; and PLA proportion, 0.4. Under these conditions, Y₁, Y₂, and Y₃ were 134.0 μg-N·g-blend^-1·h^-1, 160.9 μg-N·g-blend^-1·h^-1, and 7.6 × 10³ μg-O·g-blend^-1·h^-1, respectively. These results suggested that the PLA/starch blends may be an ideal packing material for nitrogen removal.     

Photochemical indicators of ozone sensitivity: application in the Pearl River Delta,China

Surface O₃ production has a highly nonlinear relationship with its precursors. The spatial and temporal heterogeneity of O₃-NO _x -VOC-sensitivity regimes complicates the control-decision making. In this paper, the indicator method was used to establish the relationship between O₃ sensitivity and assessment indicators. Six popular ratios indicating ozone-precursor sensitivity, HCHO/NO _y , H₂O₂/ HNO₃, O₃/NO _y , O₃/NO _z , O₃/HNO₃, and H₂O₂/NO _z , were evaluated based on the distribution of NO_x- and VOC-sensitive regimes. WRF-Chem was used to study a serious ozone episode in fall over the Pearl River Delta (PRD). It was found that the south-west of the PRD is characterized by a VOCsensitive regime, while its north-east is NO _x -sensitive, with a sharp transition area between the two regimes. All indicators produced good representations of the elevated ozone hours in the episode on 6 November 2009, with H₂O₂/HNO₃ being the best indicator. The threshold sensitivity levels for HCHO/NO_y, H₂O₂/HNO₃, O₃/NO _y , O₃/NO _z , O₃/HNO₃, and H₂O₂/NO _z were estimated to be 0.41, 0.55, 10.2, 14.0, 19.1, and 0.38, respectively. Threshold intervals for the indicators H₂O₂/HNO₃, O₃/NO _y , O₃/NO _z , O₃/HNO₃, and H₂O₂/NO _z were able to identify more than 95% of VOC- and NO _x -sensitive grids. The ozone episode on 16 November 16 2008 was used to independently verify the results, and it was found that only H₂O₂/HNO₃ and H₂O₂/NO _z were able to differentiate the ozone sensitivity regime well. Hence, these two ratios are suggested as the most appropriate indicators for identifying fall ozone sensitivity in the PRD. Since the species used for indicators have seasonal variation, the utility of those indicators for other seasons should be investigated in the future work.

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改性核桃壳对石油烃类物质的吸附试验研究

为了研究改性制备核桃壳对石油烃吸附程度,以化学改性制备核桃壳为吸附剂,考察了溶液p H值、时间和温度对改性核桃壳吸附石油烃效果的影响。结果表明:当温度为298 K,p H为7.0,0.2 g改性核桃壳吸附处理100 m L浓度为60 mg/L的柴油溶液,80 min后吸附量最大,可达到12.57 mg/g。该吸附过程符合准二级动力学方程,其相关系数达到0.9999。在3种温度(298,308,318 K)条件下的吸附等温曲线更符合Freundlich模型。通过热力学计算证实,该吸附过程是吸热的、自发的过程,一定程度上的升温有助于石油烃的吸附。     

钢铁行业废水零排放技术探索

针对钢铁行业废水特点,分析了目前钢铁行业各工序及全厂主要废水污染控制措施,重点分析了二级反渗透工艺的主要流程及进出水水质,以及该工艺存在的主要问题。通过对大型钢铁集团的现场调研,以太钢采用的反渗透和蒸发结晶工艺为例分析了钢铁行业真正实现废水零排放的技术可行性。该技术可以很好解决钢铁行业浓盐水的外排问题。     

桂林中小河流洪涝气象风险预警系统设计

基于自动站、数值预报和雷达估测降水等多种雨量资料,利用ArcGIS技术提取河流的经纬度、流域范围,利用泰森多边形技术计算流域面雨量,结合对桂林中小河流域的历史暴雨洪涝风险个例分析结果,确定临界面雨量,建立桂林中小河流域洪涝灾害风险等级预警系统。利用数学内插技术进行雨量精细化插值,实现全市100多个水库、200多条河流关键点的雨量监测、预报、预警。利用Web和GIS技术实现桂林中小河流洪涝预警网页发布。     

汞在海洋浮游植物中的生物累积和毒性效应

浮游植物是海洋生态系统的主要初级生产者,同时作为食物也是许多水生生物摄取汞的主要途径。本文综述了近年来汞在海洋浮游植物中的最新研究进展,包括汞在浮游植物中的吸收、累积规律及其影响因素,汞对浮游植物的毒性效应(生长抑制、光合作用影响)以及生物的适应机制(汞的还原、螯合解毒、矿化固定等),最后对浮游植物中汞累积和毒性的未来研究方向进行了展望。     

Responses of bacterial strains isolated from drinking water environments to N-acyl-L-homoserine lactones and their analogs during biofilm formation

Often as a result ofbiofilm formation, drinking water distribution systems （DWDS） are regularly faced with the problem of microbial contamination. Quorum sensing （QS） systems play a marked role in the regulation of microbial biofilm formation; thus, inhibition of QS systems may provide a promising approach to biofilm formation control in DWDS. In the present study, 22 bacterial strains were isolated from drinking water-related environments. The following properties of the strains were investigated： bacterial biofilm formation capacity, QS signal molecule N-acyl-L-homoserine lactones （AHLs） production ability, and responses to AHLs and AHL analogs, 3-chloro-4-（dichloromethyl）-5-hydroxy-2（5H）- furanone （MX） and 2（5H）-furanone. Four AHLs were added to developed biofilms at dosages ranging from 0.1 nmol.L J to 100nmol.L1. As a result, the biofilm growth of more than 1/4 of the isolates, which included AHL producers and non-producers, were significantly promoted. Further, the biofilm biomasses were closely associated with respective AHLs concentrations. These results provided evidence to support the idea that AHLs play a definitive role in biofilm formation in many of the studied bacteria. Meanwhile, two AHLs analogs demon- strated unexpectedly minimal negative effects on biofilm formation. This suggested that, in order to find an applicable QS inhibition approach for biofilm control in DWDS, the testing and analysis of more analogs is needed.     

MiRNA-451 is a potential biomarker for estrogenicity in mouse uterus

The uterotrophic assay has been commonly used to test environmental estrogens in vivo, however, it is often not sensitive enough sometimes. An alternative way is to evaluate estrogenicity through biomarker genes. MicroRNA （miRNA） is a class of regulatory gene, which has been shown to be a good biomarker for many diseases and toxicological effects in recent years, and some evidences showed that estrogen induced response was partially mediated by miRNAs. In this study, two types of microarrays were used to test the 17[3-estradiol （E2） induced miRNA expression profile at different time points in the immature mouse uterus. Statistical analysis showed the aldehyde slide based array had less variation than the amino slide based array, and 11 dysregulated miRNAs were screened out for significant fold change. Real-time PCR was performed to further confirm that 4 out of 7 selected miRNAs, namely miR-451, miR-155, miR-335- 5p, and miR-365, are E2 regulated miRNAs in the uterus. The function of the predicted targets of these miRNAs is involved in cell grow control, which is consistent with the main E2 function in the uterus. MiR-451 had similar strong responses to E2 in the uterus of both immature and overiectomized mice, and could be a potential biomarker for estrogenicity in the uterus.