Phenol removal from aqueous environments by natural & chemically modified kaolin clay

Natural, acid and base modified kaolin clays were studied for the sake of phenol and 4-chlorophenol removal from aqueous environments and their application to real ground and industrial wastewater samples. Scanning electron microscope (SEM), infrared spectroscopy (IR), X-ray diffraction (XRD), Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), and Surface area analysis were employed for characterization of the adsorbents microstructure. Operating factors such as adsorbent dose, solution pH, initial phenol concentration, and contact time were studied. The experimental data displayed that the increase of the adsorbent dose, contact time, and pH value from 2 to 7 increases the efficiency of the removal process. Optimal conditions for phenolic removal were; contact time of 300 min, primary phenol solution of 25 mg/L, pH 7 and 2.5 g/L as an appropriate adsorbent dose using crude (natural), acid modified and base modified kaolin clays. The higher phenolic removal efficiencies were obtained at 5 mg/L as 90, 97, 96.2%, respectively, for the adsorbents in the previously mentioned order. The adsorption capacity in the removal of phenol and 4-chlorophenol were 7.481 and 4.195, 8.2942 and 3.211, and 8.05185 and 18.565 mg/g, respectively, for the adsorbents in the same mentioned order. The adsorption equilibrium data were fitted and analyzed with four isotherm models, namely, Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm equations. The adsorption process of phenol on studied adsorbents was exothermic, spontaneous and thermodynamically favorable proved by the negative values of their thermodynamic parameters ΔH° and ΔG°. The correlation coefficient (R²) for all concentrations was higher than 0.94, which indicates that in the studied system, the data suitably fit the first-order kinetics. The % desorption capacity was amounted to 96%, 91.11%, and 87.06% of adsorbed phenol, respectively, for the adsorbents in the previous order using 0.1N NaOH and 10% V/V ethanol solutions as eluents at 25°C, indicating the reusability of the adsorbents. Kaolin and its modified forms can be introduced as eco-friendly and low-cost adsorbents in water remediation implementation.     

甘薯细胞悬浮培养的建立及其生长研究

由甘薯叶片诱导出愈伤组织,并由此建立起悬浮培养细胞系．分析其生长表明：南薯８８和８１２９４两种细胞系生长曲线均呈“Ｓ”型,其中南薯８８生长较快,是８１２９４的３倍以上,１０ｄ培养物的鲜重是初始鲜重的１０倍．培养条件研究结果表明：南薯８８细胞悬浮培养的最佳２,４Ｄ质量浓度为１．０ｍｇＬ－１,最佳蔗糖质量浓度为３０ｇＬ－１,椰乳和酵母汁能明显促进其生长;对于８１２９４,２,４Ｄ最佳质量浓度为２．５ｍｇＬ－１、蔗糖最佳质量浓度１５ｇＬ－１,酵母汁可促进其生长,但椰乳却无效;谷氨酰胺、色氨酸和脯氨酸不能促进甘薯悬浮细胞的生长,水解酪蛋白对其生长的促进作用亦不大;葡萄糖则抑制其生长     

HMX基钝感传爆药制备技术

为获得性能更佳的钝感传爆药,以奥克托今(HMX)原料为基础,采用溶剂-非溶剂重结晶技术,并辅以超声喷雾工艺制备细化HMX,同时,通过试验方法制备以丙烯酸酯橡胶(ACM)、F2602和Viton A等3种材料为黏结剂的包覆HMX,并分别测试分析其安全性.结果表明:经过细化后,HMX的热稳定性和热敏感性降低,而撞击安定性则...     

抛煤机链条炉烟尘超标的改进措施

抛煤机链条炉属于半悬浮燃烧型锅炉 ,具有着火条件好、燃烧强烈、煤种适应性强和负荷调节灵敏等其他炉型所不具备的优点 ,但在实际运行中 ,该炉型又有排烟黑度高、含尘浓度大的缺点 ,大大超过环保要求的锅炉排烟标准 ,其生产及应用受到极大限制 ,因此 ,有效解决抛煤机链条炉消烟除尘问题具有十分现实的意义。本文对抛煤机链条炉普遍存在的排烟超标、出力不足、热效率低下等问题进行了详细分析 ,并结合实际提出了改进措施     

基于健康监测系统的大跨度多荷载悬索桥的疲劳与可靠度评估(英文)

在过去的几十年,世界各地建立了许多大跨度悬索桥。通常这些桥梁需承受多种动力荷载,尤其是一些处于多台风地区的公铁两用桥梁。为了保证这些大跨悬索钢桥在运营期内的安全和正常使用,有必要以一定的时间间隔进行桥梁的疲劳和可靠度评估。有鉴于此,许多大跨悬索桥都安装了健康监测系统,但是如何运用其进行准确的疲劳评估仍然是一个问题。本文通过结合计算机模拟技术和健康监测系统的测量数据,以香港青马大桥为例,分析了在多荷载作用下的大跨度悬索桥的疲劳和可靠度。同时,作为利用结构健康监测技术进行结构健康状态评估的这一重要研究方向的有益实践,该研究发展了一系列方法用于评估桥梁的疲劳,以及通过考虑存在于结构的物理模型和计算机模拟中的不确定性用以评估疲劳的可靠度。     

大跨度钢结构人行悬索桥受力性能对比分析

为了提高大跨度钢结构人行悬索桥的安全性能,以某实际工程为依托,采用有限元软件Midas/Civil建立整体空间模型,分析单缆体系和双缆体系在人群荷载和风荷载作用下的受力特点以及自振频率特性。结果表明:人群荷载作用下,双缆体系的底缆承担更多荷载,主梁挠度相比单缆体系减小约15%;风荷载作用下,两种结构体系主梁弯矩和挠度的变化趋势比较相似,双缆体系的弯矩和挠度均小于单缆体系;双缆体系的侧弯频率、竖弯频率、竖振频率以及侧振频率相比单缆体系均有所增加。双缆体系具有更优的力学性能,提高了工程安全性,并为类似工程的桥型选择提供有力参考。     

Release-controlled microcapsules of thiamethoxam encapsulated in beeswax and their application in field

Abstract

Using beeswax as wrapping matrix, two types of release-controlled TM (thiamethoxam)/BK(beeswax-kaolin) microcapsules were prepared by adsorbing TM on kaolin and then encapsulated with beeswax, or directly wrapping TM with beeswax. The structure and morphology of the TM/BK microcapsules were characterized. The effects of different preparation methods, the particle size, pH conditions and different additives on the release property of the TM/BK microcapsules were investigated in water and soil column to compare the advantages of the two approaches. Finally, the insecticidal effect of the TM/BK microcapsules against sugarcane borer and rice planthopper was tested. The results show that the TM/BK microcapsules have a better sustained-release in both water and soil, and the release rate is different under different pH conditions. In addition, the releasing time of the TM/BK microcapsules can be modified by different preparation methods and combination of different additives. In the field applications, the insecticidal activity of the TM/BK microcapsules was better than that of non-sustained control group. Especially in the rice field test, 45?days after the application, the control group lost the activity against rice planthopper because of drug loss, whereas the TM/BK microcapsule group still retained about 90% of the insecticidal activity. The results suggest that the microcapsules have better agricultural application for insect control.     

不同覆盖材料对沉积物P、N释放的抑制效果

以百花湖沉积物为实验对象,选取沸石、粘土、生物炭、褐铁矿和高岭土等5种覆盖材料开展模拟柱静态实验,研究上覆水中总氮(TN)、总磷(TP)和氨氮变化规律。在静态模拟柱90 d实验过程中,第45天时上覆水中TN、氨氮浓度最高,分别为8.79和6.10 mg/L。第45天时氨氮浓度最低的是生物炭组,为1.62 mg/L,第45天时TN浓度最低的是粘土组,为1.92 mg/L。第45天后上覆水TN、氨氮浓度下降,实验结束时生物炭组TN和氨氮浓度均最低,其浓度分别为0.74和0.42 mg/L。实验过程中TP浓度不断上升,到实验结束时空白组TP浓度0.42 mg/L,高岭土组TP浓度最低为0.027mg/L。百花湖水质主要超标指标为TP,而高岭土覆盖对沉积物中P释放的抑制优于其他4种材料,且在百花湖地区易获得、无污染,故建议以高岭土为百花湖原位覆盖材料。     

高岭土对淡水藻类的聚合氯化铝强化混凝去除技术研究

以温州市内桌一富营养化水体为研究对象,考察本地粘土矿物高岭土联合聚合氯化铝（PAC）混凝沉降工艺的除藻效能,并获得处理工艺的最佳条件,为恢复河流水体生态自净功能提供理论基础。试验结果表明,PAC最佳投加量为40mg／L;高岭土的最优投加方式为在混凝剂PAC前5rain投加;其最佳投加量为3g／L;最佳搅拌方式为200rpm搅拌4min;最佳静置时间为20min;在酸性或中性水体的处理效果尤佳。     

锆改性高岭土原位改良技术控制重污染河道底泥磷释放效果

采用锆对高岭土进行改性,通过批量吸附实验考察了锆改性高岭土对水中磷酸盐的吸附性能,并通过底泥培养实验考察了锆改性高岭土原位改良技术对底泥磷释放的控制效果.结果表明,锆改性高岭土对水中磷酸盐的吸附能力随改性所用锆投加量的增加而增加.在制备锆改性高岭土过程中,溶液沉淀p H值由8增加到10时,锆改性高岭土对水中磷酸盐的吸附能力增加;沉淀p H值由10增加到11时,锆改性高岭土对磷的吸附能力基本不变;沉淀p H值由11增加到12时,锆改性高岭土的吸磷能力则下降.沉淀p H值为10时制备得到的锆改性高岭土对水中磷酸盐的吸附平衡数据可以采用Langmuir模型加以描述.大部分被锆改性高岭土中锆所吸附的磷酸盐(84%左右)主要以Na OH提取态磷(Na OH-P)和残渣态磷(Res-P)形态存在,低溶解氧情况下不容易被重新释放出来,同时重污染河道底泥会释放出大量的溶解性磷酸盐进入上覆水体;向重污染河道底泥中添加锆改性高岭土可以极大地削减底泥中磷向上覆水体迁移的通量.采用锆改性高岭土对底泥进行改良不仅增强了底泥对水中磷的吸附能力,而且降低了底泥的磷吸附-解吸平衡浓度(EPC0).因此,应用锆改性高岭土作为底泥改良剂可以有效控制重污染河道底泥磷释放.