Amperometric Detection of Pesticides Using Polymer Electrodes

Abstact The real time monitoring of some organophosphorus based pesticides is of great concern to environmentalists because the widespread use of pesticides is causing severe health hazards to all living beings and also hampering our ecological balance. The traditional methods of measurement of pesticide residues are time consuming, need sample pre-treatment, and lack desired specificity and accuracy. We have developed an amperometric biosensor for indirect measurement of the pesticide concentration precisely in ppb level. The method is based on the action of two enzymes namely acetylcholine esterase and choline oxidase which are uniquely immobilized in a polymeric porous network directly on the working electrode of a screen-printed sensor. Polyacrylamide matrix has been prepared by copolymerisation of acrylamide andN,N′-methylenebisacrylamide using Potassium peroxodisulphate (K₂S₂O₈) as initiator. A linear relationship was obtained between the range of 0 to 10 ppb.     

不同电荷的聚丙烯酰胺对焦化废水的絮凝性能研究

以聚合氯化铝铁(PAFC)为混凝剂,以阴离子型、阳离子型和非离子型聚丙烯酰胺(PAM)分别为助凝剂,研究了三种PAM对焦化废水的絮凝性能。从对废水初始浊度变化的适应性、絮凝剂用量、处理效果和处理费用等几个方面比较了三种PAM絮凝性能的差异,并对絮凝机理进行了分析。对于焦化废水的絮凝处理,发现三种PAM中非离子PAM具有最好的应用性。最后对非离子PAM的最佳用量及影响因素进行了考察。最佳条件下,浊度去除率可达85%以上,但是COD去除率较低为6%左右,这与悬浮颗粒对COD的贡献较小有关。     

阴离子型聚丙烯酰胺在离子交换膜上的吸附规律

研究了阴离子交换膜对阴离子型聚丙烯酰胺的吸附规律和影响因素.采用静态吸附的方法,测定了不同温度、不同浓度的阴离子型部分水解聚丙烯酰胺(HPAM)溶液在阴离子交换膜上的吸附量、吸附平衡时间,考察了初始HPAM溶液浓度、pH值以及溶液中其他离子浓度对其在离子交换膜上吸附的影响,目的是阐明阴离子交换膜对HPAM分子的吸附动力学过程、探讨各影响因素对吸附过程的影响.结果表明,阴离子型部分水解聚丙烯酰胺在阴离子交换膜上有明显的吸附作用,但在阳离子交换膜上吸附量几乎为0;阴离子交换膜对聚合物的吸附平衡时间随聚合物溶液初始浓度的增大而延长,且不同浓度、不同温度下的吸附过程动力学特征都能很好地遵循准二级动力学模型;303、308和313 K温度下,阴离子交换膜对聚合物的等温吸附可用Freundlich等温吸附模型很好地拟合,相关系数R2均达到0.99以上,温度越高,吸附量越大;聚合物溶液pH值和离子浓度对吸附效果有显著影响:pH=6时,吸附量达到最大值;吸附量随着离子浓度的增加而增大.     

一株聚丙烯酰胺降解菌的降解性能和机理

从大庆油田筛选到一株聚丙烯酰胺降解菌,经16SrDNA序列分析鉴定其为褐栗芽孢杆菌(Bacillus badius),命名为JHW-1.将降解菌扩培后,接种至以聚合物为唯一有机营养源的培养基,在4l℃、pH=7.2条件下培养7d,聚合物粘度较无菌对照降低48.5%.在培养基中分别添加少量FeSO4和MnSO4、酵母粉、葡萄糖后,聚合物粘度较对照降低了57.4%、72.5%、86.2%.降解菌在同时添加了FeSO4、MnSO4和葡萄糖的聚合物培养基中培养7d后,聚合物降粘率达到91.4%,相对分子量由106～107降至103～106,且聚合物质量减少约8%.降解菌能够利用分泌到培养液中的胞外酶水解聚合物的酰胺基团,使其变为羧酸;同时,降解菌在生长过程中还会释放非蛋白还原性物质,它们同胞外酶共同作用使碳链断裂.     

反相乳液聚合制备阳离子聚丙烯酰胺及其絮凝性能评价

研究了单体浓度、单体配比、反应温度、引发剂用量等因素对所制备的阳离子聚丙烯酰胺特性粘度、转化率、阳离子度的影响,并对产品的污水絮凝性能进行了评价。较佳的制备条件为:单体浓度为45%,单体配比为7∶3,引发剂用量m(引发剂)/m(单体)为0.5%,引发温度为45℃。用红外光谱对共聚物进行了结构表征,结果表明聚合物中有六元氮杂环的存在,达到预定要求。对共聚物进行了油田污水絮凝性能评价,研究表明单独使用自制阳离子聚丙烯酰胺(CPAM)时浊度的去除率为86.22%,COD去除率为87.95%,与聚合氯化铝复配使用时浊度去除率提高到92.91%,COD去除率提高到92.68%。     

二硫代氨基甲酸盐絮凝处理模拟油田聚合物驱采油废水的效果研究

在碱性条件下,端氨基聚醚Jeffamine-T403与二硫化碳反应合成了二硫代氨基甲酸盐型絮凝剂DTC(T403).考察了DTC(T403)对模拟聚合物驱采油废水的絮凝除油性能,研究了DTC(T403)、水解聚丙烯酰胺(HPAM)、Fe2+和Fe3+的投加量以及pH值对除油效果的影响.结果发现,DTC(T403)与Fe2+络合形成的网状螯合物通过网捕作用取得良好的絮凝除油效果;HPAM的存在影响絮凝除油效果;在同时投加Fe2+和DTC(T403)且二者的投加量分别为10mg/L和25mg/L的条件下,HPAM含量在0～900mg/L范围和含油量约300mg/L的模拟水样经絮凝处理后其含油量均可降到10mg/L以下.DTC(T403)的絮凝除油效果受pH値的影响,在pH7.5条件下可取得良好的除油效果.DTC(T403)适用于含Fe2+的聚合物驱采油废水的处理.     

天然Na基膨润土吸附处理高浓度PAM废水的研究

研究了PAM在天然钠基膨润土上的吸附行为,将其应用于含高浓度PAM（100～200 mg/L）的生产废水处理。静态条件下,膨润土的吸附平衡时间为1.5 h,最有效的吸附材料投加量为100 mg/100 mL水样。实验证明,低温度变化范围和弱酸、弱碱条件对PAM的吸附行为不产生显著影响。在最佳吸附动力学条件下,以活性炭做参比,利用实验的结论对化工厂中PAM生产废水进行吸附处理,结果表明,在对PAM废水中对PAM的吸附量分别可达到30.1和22.4 mg/g,膨润土是性价比较高的吸附处理材料。     

改性聚丙烯酰胺固定化苯酚降解菌的研究

利用自制的改性聚丙烯酰胺为载体包埋苯酚降解菌,考查了该载体对细胞性能的影响,比较了4种固定化方法--改性聚丙烯酰胺法、聚丙烯酰胺法、海藻酸钙法和聚乙烯醇-海藻酸钙法包埋微生物细胞的优劣.实验结果表明,单体丙烯酰胺经改性后制得的改性聚丙烯酰胺对微生物细胞活性无影响.以其为载体固定苯酚降解菌,其细胞相对活性比聚丙烯酰胺法高出了42.4%;比海藻酸钙法高出了16.4%;比聚乙烯醇.海藻酸钙法高出了44.3%,表明改性聚丙烯酰胺包埋细胞更有利于细胞的增殖和活性恢复.重复应用实验表明,改性聚丙烯酰胺法得到的细胞凝胶,机械强度好,有弹性,可多次重复利用.改性聚丙烯酰胺作为细胞固定化载体其优点是交联速度快、聚合放热温度低、在侧链发生交联反应、抗水解能力强、无毒、凝胶寿命长.     

长链季铵盐的絮凝性能

采用FTIR技术对自制的长链季铵盐絮凝剂环氧丙基十二烷基二甲基氯化铵进行了表征,研究了该絮凝剂对高岭土悬浊液的絮凝效果,考察了絮凝剂加入量、溶液pH和絮凝时间对絮凝率的影响;并与常用絮凝剂聚丙烯酰胺的絮凝效果进行了对比。表征结果显示,合成的目标产物为环氧丙基十二烷基二甲基氯化铵。实验结果表明：在絮凝剂加入量8 mg/L、溶液pH 9、絮凝时间50 min的条件下,絮凝率达到84.84%;在相同絮凝剂加入量的条件下,环氧丙基十二烷基二甲基氯化铵的絮凝效果优于聚丙烯酰胺。     

Production and the application of anaerobic granular sludge produced by landfill

Sludge granulation is considered to be the most critical parameter governing successful operation of an upflow anaerobic sludge blanket and expanded granular sludge bed (EGSB) reactors. Pre-granulated seeding sludge could greatly reduce the required start-up time. Two lab-scale and a pilot-scale EGSB reactors were operated to treat Shaoxing Wastewater Treatment Plant containing wastewater from real engineering printing and dyeing with high pH and sulfate concentration. The microbiological structure and the particle size distribution in aerobic excess sludge, sanitary landfill sludge digested for one year, and the granular sludge of EGSB reactor after 400 d of operation were analyzed through scanning electron microscopy (SEM) and sieves. The lab-scale EGSB reactor seeded with anaerobic sludge after digestion for one year in landfill showed obviously better total chemical oxygen demand (TCOD) removal efficiency than one seeded with aerobic excess sludge after cation polyacrylamide flocculation-concentration and dehydration. The TCOD removed was 470.8 mg/L in pilot scale EGSB reactor at short hydraulic retention time of 15 h. SEM of sludge granules showed that the microbiological structure of the sludge from different sources showed some differences. SEM demonstrated that Methanobacterium sp. was present in the granules of pilot-scale EGSB and the granular sludge produced by landfill contained a mixture of anaerobic/anoxic organisms in abundance. The particle size distribution in EGSB demonstrated that using anaerobic granular sludge produced by sanitary landfill as the seeding granular sludge was feasible.