Adsorptive removal of nitrate and phosphate anions from aqueous solutions using functionalised SBA‐15: Effects of the organic functional group

Adsorption of nitrate and monovalent phosphate anions from aqueous solutions on mono, di‐ and tri‐ammonium‐functionalised mesoporous SBA‐15 silica was investigated. The adsorbents were prepared via a post‐synthesis grafting method, using either 3‐aminopropyltrimethoxysilane (N‐silane) or [1‐(2‐aminoethyl)‐3‐aminopropyl]trimethoxysilane (NN‐silane) or 1‐[3‐(trimethoxysilyl)‐propyl]‐diethylenetriamine (NNN‐silane), followed by acidification in HCl solution to convert the attached surface amino groups to positively charged ammonium moieties. The nominal loading of amino moieties on the SBA‐15 surface was varied from 5% to 20% as organoalkoxysilane/silica molar ratio. The adsorption experiments were conducted batchwise at room temperature. Results showed that adsorption capacity increased with increasing the concentration of monoammonium groups on the SBA‐15 adsorbent. Nitrate adsorption capacity increased from 0.34 to 0.66 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent while phosphate adsorption capacity increased from 0.34 to 0.63 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent when the molar ratio organoalkoxysilane/silica was varied from 5% to 20%, respectively. Also, for the same organoalkoxysilane/silica molar ratio of 10%, the adsorption capacity increased with the increase of the number of protonated amines in the functional groups. Therefore, maximum adsorption capacities of 0.80, 1.16 and 1.38 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent and 0.72, 0.82 and 1.17 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent were obtained using mono‐, di‐ and triammonium functionalised SBA‐15 adsorbents, respectively. © 2011 Canadian Society for Chemical Engineering     

Understanding the detrimental effect of nitrate presence on EBPR systems: effect of the plant configuration

The interaction between enhanced biological phosphorus removal (EPBR) and biological nitrogen removal may result in EBPR failure in full‐scale wastewater treatment plants (WWTPs). This work studies one of the common causes of this failure: the presence of nitrate in the anaerobic phase, which may act as an inhibitor for polyphosphate accumulating organisms (PAO) activity or may activate the competition between PAO and denitrifying bacteria for the carbon source. Several batch experiments were performed with different carbon sources (acetic acid, propionic acid and sucrose) at different nitrate concentrations using PAO‐enriched sludge from two different pilot plants: an anaerobic/aerobic sequential batch reactor (SBR) and an anaerobic/anoxic/aerobic (A²/O) continuous plant. The results imply that the operational conditions of the A²/O pilot plant selected a PAO population capable of i) coexisting with nitrate without an inhibitory effect and ii) outcompeting denitrifying bacteria for the carbon source, in contrast to the SBR pilot plant where nitrate had an inhibitory effect on EBPR. Copyright © 2012 Society of Chemical Industry     

Counter-current Electrophoresis

Abstract

Historical development, principal operation, different ways of experimental realization, and typical examples of application of countercurrent electrophoresis are reviewed. The separation process is principally capable of being applied to all types of ions, as far as any difference is shown in their ionic behavior. Different types of columns can be adapted to varying amounts of substance from approximately 10^?6 mole up to several moles (in the laboratory scale). The production of high purity components and the use of the column as an absolute ion filter are further possible applications.     

聚磷酸铵对环氧树脂固化反应动力学的影响

采用动态DSC分析法,利用Kissinger和Crane方程研究了阻燃剂聚磷酸铵对环氧树脂固化反应动力学的影响。结果表明:随着阻燃剂用量的增大,固化反应向高温方向移动,表观活化能从45.7 kJ/mol增大到48.4 kJ/mol,而反应级数基本不变,均为0.88,说明聚磷酸铵的加入增大了环氧树脂的固化反应难度,但不影响其固化反应机理;在同等阻燃剂用量下,环氧树脂固化反应热值随着升温速率的增大而减小;而在一定的升温速率下,固化反应热值随着阻燃剂用量的增大而减小。     

中铬黄生产过程中硝酸钠的回收及水的循环使用

对铅铬颜料生产过程中产生的废水中的硝酸钠进行了专门研究,将生产过程中产生的母液水及梯度提浓含硝酸钠的水重复用于化学合成前的溶料和制作硝酸铅工序中,经多次循环使用,使硝酸钠浓度成倍提高,再对其进行浓缩结晶,经检测,副产品硝酸钠的品质可达工业级。     

Separation of Ethyl Esters of Eicosapentaenoic Acid and Docosahexaenoic Acid by Circulating Liquid Membranes Using Silver Nitrate as a Carrier. Uphill Transport by Use of Temperature and Solvent Dependencies of Distribution Ratio

Abstract

Experiments on the separation of ethyl ester of eicosapentaenoic acid (EPA-Et) and that of docosahexaenoic acid (DHA-Et) contained in ethyl ester of bonito oil (bonito oil-Et) were performed using circulating liquid membranes (CIRLMs) containing sliver nitrate as a carrier. In this liquid membrane system an aqueous silver nitrate solution was circulated between a stirred vessel containing an organic solution of bonito oil-Et and another stirred vessel containing a receiving organic solvent. Using the CIRLM, two types of uphill facilitated transport of EPA-Et and DHA-Et in bonito oil-Et were demonstrated. The first type utilizes the distribution ratio of EPA-Et and DHA-Et, defined as the ratio of the concentration in the aqueous phase to that in the organic phase at equilibrium, which is remarkably dependent on the temperature, and the second uphill transport was based on the fact that the distribution ratio is considerably dependent on the solvent of the organic phase. A model of permeation through the circulating liquid membrane was proposed to explain the experimental results.     

硝酸铵水溶液在工业炸药生产中的应用

将硝酸铵水溶液直接应用于工业炸药的生产,不仅使硝酸铵生产厂家节省了结晶能耗、包装材料成本及包装的人工成本,又使炸药生产厂家节约破碎人工成本和溶解的能耗。针对其它研究者对硝酸铵水溶液使用的研究,以及本公司在使用中存在的一些问题,对硝酸铵水溶液的应用系统、质量要求、安全性、效益性及存在的问题进行了分析。     

150kt/a多孔硝酸铵装置建设投产总结

介绍了150 kt/a多孔硝酸铵装置的建设和投产情况以及工艺流程、设备选型、设备制造、关键设备的使用效果。针对装置的施工建设情况和设计中存在的不足进行了总结和改进,提出了相应的措施。多孔硝酸铵装置投产后,运行平稳、匹配合理,各项工艺指标均达到预期的运行效果,在短期内即达到了80%～90%的设计生产负荷。     

不同有机物对硝酸盐氮测试的影响

研究了红糖、葡萄糖、乙酸钠、甲醇、乙醇、乙酸、丙酸、丁酸、正戊酸、混合有机溶剂等10种不同有机物对麝香草酚光谱法和离子色谱法测试硝酸盐氮的影响。结果表明,溶液中含有红糖或葡萄糖时,均会对麝香草酚法测试硝酸盐氮造成影响,使得测试结果偏大;在无硝酸根离子存在时,红糖和葡萄糖的质量浓度与硝酸盐氮的测试浓度非线性相关;而乙酸钠、甲醇、乙醇、乙酸、丙酸、丁酸、正戊酸和混合有机溶剂则对麝香草酚法测试硝酸盐氮没有影响。实验发现,红糖和葡萄糖在浓硫酸的作用下与麝香草酚发生Molisch反应,形成有色复合物和红棕色不溶性沉淀。实验采用离子色谱法测试硝酸盐氮时,红糖和葡萄糖等糖类有机物对测试结果均无影响。     

短程反硝化耦合厌氧氨氧化工艺及其应用前景研究进展

短程反硝化以其碳源消耗量、废污泥产量、温室气体排量极低及无需曝气等优势,被认为是最具研究潜势的厌氧氨氧化底物供给技术,成为近年来研究热点。本文首先介绍了短程反硝化工艺原理;其次从污泥源、反应时间、碳源类型、碳源量及pH等5个方面总结了影响短程反硝化工艺启动因素;随后综述了短程反硝化耦合厌氧氨氧化工艺的重要研究进展,同时指出了耦合工艺实验研究与工程应用的不足,并提出了解决实验与工程应用缺陷的方案;最后展望了耦合工艺处理城市污水和工业硝酸盐废水的可行性及应用前景,认为全面分析工业硝酸盐废水化学组分与基于分子生物学水平的宏基因组学测序、元转录组学技术是未来耦合工艺同步处理城市污水和工业硝酸盐废水的研究重点。