Dispersive solid phase extraction of chlorophenols using carbon-coated magnetic nanoparticles

Abstract

Carbon-coated magnetic nanoparticles were modified with cationic surfactant and used for the dispersive solid phase extraction of chlorophenols from aqueous samples. Surfactant adsorbed on the surface of the nanoparticles resulted in mixed hemimicelles for high extraction efficiency of chlorophenols. Under optimized conditions, calibration curves were linear from 0.5–20?mg L^?1 for analytes with limit of detection between 0.2 and 0.4?mg L^?1. The method was applied to extraction of chlorophenols from tap water, well water and industrial effluent. Recoveries were in the range of 94.0–99.4%, suggesting that sample matrix had little effect on the yields of extraction.     

From pioneering to organised business: the development of ecological farming in China

ABSTRACT

Small-scale ecological farming and their associated alternative food networks, are increasingly important in China, as a response to poor farm incomes and as a contribution to widespread concerns about environmental degradation and food safety. However, despite the enormous market potential and the notable success of some ventures, this type of farming remains at the margins, with many businesses struggling to develop beyond their start-up phase and consumers struggling to build confidence in the new produce and routes to market. Many of these farms display the classic elements of pioneer businesses, including high reliance on charismatic individuals, insecure land rights, high transaction and monitoring costs and fragile routes to market. Empirically, many of these businesses fail because they cannot grow out of the pioneer phase before the pioneer grows tired of the business. While this is a problem for all small businesses, it is particularly acute in business sectors like ecological farming in China, where there is little evidence of suitable and sustainable developmental models. Using Bernardus Lievegoed's work on organisational development applied to two case study farms, we suggest that there are Western developmental models that are applicable to small-scale ecological farming and that have the potential to offer insights into how this might be achieved with Chinese characteristics. We conclude by arguing that, Chinese ecological farms have to plan explicitly for a form of development that allows them to remain committed to their ideals while moving them away from dependence on charismatic people, family labour and volatile customer bases.     

基于数字锁相技术的飞机货舱火灾烟雾光学参数方法研究*

为解决飞机货舱火灾光学探测易受环境杂光和空气中灰尘、水汽干扰,误报率高的问题,提出1种基于数字锁相的双波长火灾烟雾探测方法。利用数字锁相技术调制双波长光源,选择性地提取微弱光散射信号,并设计前、后双向散射光探测光路。采用常见火灾材料及干扰源进行真假火源实验,依据米氏散射理论及不同粒径气溶胶颗粒对不同波长光的散射效应差异,以不对称比（AR）和双波长光强比（DWIR）作为火灾检测参数对不同粒径颗粒进行区分,根据2种火灾检测参数建立数据样本,利用BP神经网络进行分析,并加入复合式传感器实验作为对比。研究结果表明:基于数字锁相技术的火灾烟雾光学探测方法能够在一定程度上区分火灾烟雾和干扰源,误报率小于3.5%。     

Room-temperature solid phase surface engineering of BiOI sheets stacking g-C3N4 boosts photocatalytic reduction of Cr(VI)

Cr(VI)-based compounds pollution have attracted global concern due to serious harm to humans and environment. Hence, it is crucial to exploit an effective technique to eliminate Cr(VI) in water. Herein, we in-situ grown BiOI on graphitic carbon nitride to prepare the BiOI/g-C3N4 (BCN) direct Z-scheme heterojunction by solid phase engineering method at room temperature. Experimental result shown the photocatalytic activity of pure BiOI were obviously enhanced by constructing Z-scheme BCN heterostructure, and BCN-3 heterostructure exhibited the optimal photocatalytic degradation of RhB with 98％yield for 2.5 h and reduction of Cr(VI) with more than 99％yield for 1.5 h at pH=2. Stability test shows BCN-3 still kept more than 98％reduction efficiency after 6 cycles. In addition, we also studied the reduction mechanism that shown the ·O2-radicals essentially helped to reduce the Cr(VI) in aqueous solution under illumination, verified the direct Z-scheme charge transfer path by X-ray photoelectron spectroscopy (XPS) and the free radical trapping experiment. The work open a new way for rationally designing photo-catalyst heterostructure to reduce Cr(VI) to Cr(III).     

三相好氧生物流化床污水处理技术研究应用进展

阐述了三相好氧生物流化床污水处理技术的工艺特点和发展概况，介绍了三相好氧生物流化床在污水处理领域的研究及应用现状，并分析了其存在的问题和未来的发展方向。     

吸附相反应技术制备微弱光响应的多组分掺杂TiO2催化剂

利用弱光(紫外和可见)激发Ti O2光降解污染物是拓展多相光催化实际应用的关键之一.以吸附相反应技术为基础,利用N掺杂以及共掺杂两种方式制备多组分Ti O2光催化剂,并研究其在弱光下光降解甲基橙的过程.结合紫外可见漫反射光谱、X射线衍射、X射线电子能谱以及光致发光光谱等表征手段,探索焙烧温度、N掺杂量以及共掺杂对催化剂光吸收和可见光响应拓展的影响,进而研究弱光下催化剂活性的变化规律.结果发现,N掺杂可以显著增强催化剂的光吸收,从而显著提升其在弱紫外光下光降解甲基橙催化活性,所有N掺杂催化剂的活性均优于商用P25光催化剂.N掺杂对催化剂的可见光响应拓展作用不大,因而单一N掺杂后大部分催化剂在弱可见光下没有活性,仅5%N掺杂催化剂在900℃热处理后有微弱活性.N和Fe2O3二元耦合形成的共掺杂催化剂中,两者之间的协同作用既增强了复合光催化剂的光吸收,也显著拓展了催化剂的可见光响应,因而得到了在弱可见光下具有良好活性的复合光催化剂.     

Rapid detection of multiple class pharmaceuticals in both municipal wastewater and sludge with ultra high performance liquid chromatography tandem mass spectrometry

This work described the development, optimization and validation of an analytical method for rapid detection of multiple-class pharmaceuticals in both municipal wastewater and sludge samples based on ultrasonic solvent extraction, solid-phase extraction, and ultra high performance liquid chromatography-tandem mass spectrometry quantification. The results indicated that the developed method could effectively extract all the target pharmaceuticals （25） in a single process and analyze them within 24 min. The recoveries of the target pharmaceuticals were in the range of 69%-131% for wastewater and 54%-130% for sludge at different spiked concentration levels. The method quantification limits in wastewater and sludge ranged from 0.02 to 0.73 ng/L and from 0.02 to 1.00μg/kg, respectively. Subsequently, this method was validated and applied for residual pharma- ceutical analysis in a wastewater treatment plant located in Beijing, China. All the target pharmaceuticals were detected in the influent samples with concentrations varying from 0.09 ng/L （tiamulin） to 15.24 μg/L （caffeine）; meanwhile, up to 23 pharmaceuticals were detected in sludge samples with concentrations varying from 60 ng/kg （sulfamethizole） to 8.55 mg/kg （ofloxacin）. The developed method demonstrated its selectivity, sensitivity, and reliability for detecting multiple-class pharmaceuticals in complex matrices such as municipal wastewater and sludge.     

固相萃取-高效液相色谱法测定水中苯胺研究

采用固相萃取-高效液相色谱法对水中苯胺含量进行定性、定量分析.结果显示：苯胺含量在2 mg/L∽ 50 mg/L之间呈良好线性关系,回归方程为Y=8.852 5X-3.174 4,相关系数为0.99964,最低检出限为0.1mg/L,样品加标回收率在72.42％ ∽78.65％之间,相对标准偏差（RSD）为2.53％ ∽4.11％ （n =7）.该方法操作简便、快捷,是水中苯胺含量快速而准确的检测方法.     

含砷废渣高温烧结过程砷的矿物相结构变化与环境释放行为

研究了含砷废渣高温烧结过程引起的砷挥发和砷发生的矿物相结构变化,并分析了烧结体的砷浸出释放行为.在10MPa下加压成型制样,进空气流量为2 000 mL·min-1,烧结温度1 000～1 350℃,烧结时间60 min.结果表明,烧结温度对砷挥发的影响很小,As的固定率保持在90%以上,但对砷浸出毒性的影响明显.烧结温度低于1 000℃时,FeAsS被氧化生成钙砷、铝砷和铁砷,以Ca3（AsO4）2矿物相为主,导致砷的浸出释放水平提高;烧结温度达到1 200℃,Ca3（AsO4）2被玻璃熔融态所包围,并被转换为硅钙砷酸盐化学键接,导致砷的浸出水平显著降低.从烧结体的环境安全性考虑,最佳烧结温度为1 200℃.     

自动固相萃取-气相色谱质谱法测定饮用水源地水中有机氯农药的研究

建立了自动固相萃取-气相色谱质谱仪测定饮用水源地水体中8种痕量有机氯农药的检测法.采用Supelclean ENVI-18固相萃取柱以10 mL/min流速富集500 mL水样,再依次用7.5 mL乙酸乙酯和10 mL二氯甲烷进行洗脱.8种物质在0.188 mg/L~2.04 mg/L范围内线性良好,相关系数均在0.997以上;检出限为0.011μg/L~0.034μg/L;实际水样加标回收率为82.9%~103%,相对标准偏差为0.7%~8.3%.该方法自动化程度高、检出限低、灵敏度高、结果准确,适用于饮用水源地水体中痕量有机氯农药的测定.