Adsorption behavior of light green anionic dye using cationic surfactant-modified wheat straw in batch and column mode

An agricultural by-product, natural wheat straw (NWS), was soaked in 1 % cationic surfactant (hexadecylpyridinium bromide, CPB) solution for 24 h (at 293 K), and modified wheat straw (MWS) was obtained. Analysis of FTIR, XFR, and nitrogen element showed that CPB was adsorbed onto surface of NWS. Then, MWS was used as adsorbent for the removal of light green dye (LG, anionic dye) from aqueous solution. The experiment was performed in batch and column mode at room temperature (293 K). Sodium chloride (up to 0.1 mol/L) existed in solution was not favor of LG dye adsorption. The equilibrium data were better described by Langmuir isotherm, and adsorption capacity of q _m from Langmuir model was 70.01?±?3.39 mg/g. In fixed-bed column adsorption mode, the effects of initial LG concentration (30, 50, 70 mg/L) and flow rate (6.5, 9.0, 14.5 mL/min) on adsorption were presented. Thomas and modified dose–response models were used to predict the breakthrough curves using nonlinear analysis method, and both models can fit the breakthrough curves. Theoretical and experimental breakthrough curves were drawn and compared. The results implied that MWS can be used as adsorbent material to remove LG from aqueous solution.     

机械清洗法对MBR膜泥饼层的影响

膜污染是制约MBR发展的瓶颈。考察投加ABS颗粒对MBR膜组件上膜泥饼层的影响,并设对照实验。结果表明,对照MBR膜通量下降速度快,膜污染严重,膜表面上累积厚厚的泥饼层,而在ABS MBR中膜通量下降速度则缓慢的多,且膜上泥饼层积累量则明显少于对照MBR;曝气量越大,颗粒运行的速度也越快,泥饼层被撞落量也越多;颗粒以碰撞角度为45°冲刷膜的情况下,泥饼层掉落效果明显增加;泥饼层包裹的膜丝根数越多,泥饼层的静摩擦力和保持泥饼层不被破坏的力也越大,泥饼层就越难被冲刷掉。SEM照片显示,ABS MBR的膜孔堵塞要严重于对照MBR,表面的褶皱要较对照MBR多。     

A sensitive monoclonal antibody-based enzyme-linked immunosorbent assay for chlorpyrifos residue determination in Chinese agricultural samples

A monoclonal antibody-based competitive antibody-coated enzyme-linked immunosorbent assay (ELISA) was developed and optimized for determining chlorpyrifos residue in agricultural products. The IC(50) and IC(10) of this ELISA were 3.3 ng/mL and 0.1 ng/mL respectively. The average recoveries in six agricultural products were between 79.5% and 118.0%, with the intra-assay coefficient of variation being less than 8 %. The limit of detection for all tested products was 30 ng/g. To the best of our knowledge, this assay has the best specificity among all the published research on ELISAs for chlorpyrifos.     

酸性体质乃百病之源

身体一旦酸碱不平衡,也就是说偏酸性时,会感到周身乏累、腰酸腿疼、头晕耳鸣、失眠健忘、便秘或腹泻等,久而久之就会形成疾病。     

历史上的灾难年2007

2007年是历史上的灾难年。由于受全球气候变暖影响,我国多个省市发生了各种自然灾害,如干旱、洪水、泥石流、滑坡、飓风等,尤其是洪涝灾害,经济损失惨重。另有朝鲜、缅甸以及南亚的印度、孟加拉国、尼泊尔也成了一片泽国;就连美国也未幸免于洪灾。现简述如下。     

铝盐絮凝剂及其环境效应

概述了铝盐絮凝剂的结构、形态分布及铝盐絮凝剂对环境所产生的一些不良影响,描述了铝盐絮凝剂对人体及各种生物体的毒性作用,同时,介绍了对污水后续处理的影响,并作了简要的评述。     

USSB反应器预处理聚酯生产废水

采用上流式分段污泥床（upflow staged sludge bed）反应器对聚酯废水进行了预处理试验研究.反应器内厌氧污泥经过近70 d的培养驯化后,用于处理聚酯废水.当进水COD值为800～2000 mg/L,HRT约为16～20 h时,其COD去除率基本能稳定在50%～55%之间;聚酯废水经预处理后,其BOD5/COD值由原来的0.3左右提高到约为0.6,取得了较好的预处理效果.但系统的总产气量由培养期的约13 L/d降至0.8 L/d左右,其中甲烷气体的含量也由50%下降至约6%.     

生物活性炭法深度处理纺织废水二级出水中生物活性的研究

采用上流式曝气生物活性炭法处理碱减量印染废水二级生物处理出水，利用TTC-脱氢酶活性（DHA）法监测反应器内DHA生物活性分布。研究发现反应器内生物炭表面附着生物膜活性较高，特别是反应器上部生物碳粒同样具有较高的DHA活性，这与反应器运行一年多能够保持对COD、色度和UV等较高去除率有一定关系。还研究了活性炭吸附、反应器反冲洗对DHA活性的影响。本研究为曝气生物活性炭法有效去除印染碱减量废水中难降解有机物提供了一定的理论依据。     

污水处理中的人工湿地强化技术研究

人工湿地作为一种新型污水生态处理工艺受到越来越广泛的重视,在生活污水、特种工业废水、采矿污水、农业和畜牧业污水以及水产养殖废水等处理中得到了广泛的应用.但是其本身的局限却限制了它在高浓度废水、某些工业废水处理等方面的应用,在寒冷地区的应用也受到限制.本研究分析了一些强化技术(如湿地内部要素强化、工艺强化和工程强化等)在提高人工湿地的净化效能以及扩大其应用范围的可能性.     

Determination of the residue dynamics and dietary risk of thiamethoxam and its metabolite clothianidin in citrus and soil by LC-MS/MS

A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method was developed for the determination of thiamethoxam and its metabolite clothianidin in citrus (including the whole citrus, peel and pulp) and soil samples by liquid chromatography-tandem mass spectrometry. The sample was extracted with acetonitrile and purified with octadecylsilane. The detection limits of both compounds were 0.0001–0.0002?mg kg^–1, while the limit of quantification of thiamethoxam was 0.002?mg kg^–1 and the limit of quantitation of metabolites was 0.001?mg kg^–1. The recovery was 70.37%–109.76%, with inter-day relative standard deviations (RSD) (n?=?15) values ≤9.46% for the two compounds in the four matrices. The degradation curve of thiamethoxam in whole citrus and soil was plotted using the first-order kinetic model. The half-life of the whole citrus was 1.9–6.2?days, and the half-life of the soil was 3.9–4.2?days. The terminal residue of thiamethoxam (the sum of thiamethoxam and clothianidin, expressed as thiamethoxam) was found to be concentrated on the peel. The final residual amount of thiamethoxam in the edible portion (pulp) was less than 0.061?mg kg^–1. The risk quotient values were all below 1, indicating that thiamethoxam as a citrus insecticide does not pose a health risk to humans at the recommended dosage.