离子交换树脂脱除地下水中的硝酸盐

地下水是我国华北地区最重要的饮用水水源之一,特别是华北农村生活饮用水几乎全部来自地下水。然而,华北又是我国地下水硝酸盐污染比较严重的地区。研究开发适合华北农村分散式供水特点的地下水脱硝酸盐技术,对于保障农村的饮水安全具有十分重要的意义,为此把简单、高效且投资和运行费用相对较低的离子交换法用于脱除地下水中的硝酸盐。考察了普通强碱性阴离子交换树脂Purolite A 300E和硝酸盐选择性强碱性阴离子交换树脂Purolite A 520E脱除地下水中硝酸盐的效果,比较了地下水中SO42-和Cl-等阴离子对两类不同树脂交换性能的影响。结果表明,Purolite A 300E和Purolite A 520E树脂均能有效地去除地下水中的硝酸盐,两者的NO3--N饱和交换容量分别为49.02和48.54 mg/g。但是,当地下水中含有较高浓度的SO42-或Cl-时,Purolite A 520E脱除硝酸盐的效果明显优于Purolite A 300E。     

硝铵废水离子交换法处理方案探讨

针对硝铵装置目前混合废水排放不达标的现状,对采用阴离子固定床除去NO3-,净水入冷凝液系统和先汽提、后脱盐,净水回收利用两种处理方案进行了分析及成本核算比较,并提出建议。     

离子交换法连续流处理受硝酸盐污染的地下水

采用普通阴离子交换树脂（Purolite A 300E）和硝酸盐选择性离子交换树脂（Purolite A 520E）处理受硝酸盐污染的模拟地下水,通过树脂床层的水流速度越慢,相应的穿透体积越大;用氯化钠水溶液再生饱和的离子交换树脂时,需要的再生液体积随氯化钠浓度的下降而增加,但实际消耗的氯化钠量却随其浓度的下降而减少,氯化钠适宜浓度在3％左右;当地下水中硫酸盐含量较高时,应采用硝酸盐选择性离子交换树脂,但该树脂比普通树脂难再生;树脂再生过程中产生的废液可用SBR工艺进行反硝化脱氮,硝态氮浓度为550m#L的再生废液在SBR池中搅拌反应10h,就能实现完全反硝化。     

离子交换法生产高纯硝酸钾的工艺研究

介绍了以农用硝酸铵和氯化钾为原料,采取离子交换法生产高纯硝酸钾的工艺。该工艺操作容易,稳定性好。好蒸发设备的选型进行了评价。     

High Performance Ion Exchange Membranes Prepared via Direct Polyacylation of Racemic and (S)‐1,1′‐Binaphthyl‐Based Cationic/Anionic Monomers

Side‐chain‐type sulfonated/quaternized aromatic polyelectrolytes with precisely controlled contents of ionized groups are successfully synthesized via direct polyacylation of sulfonated/quaternized monomers based on 2,2′‐dihydroxy‐1,1′‐binaphthyl (DHBN). Both proton exchange membranes (PEMs) and anion exchange membranes (AEMs) of the corresponding polyelectrolytes exhibit outstanding properties. Proton conductivity (116 mS cm^?1 at 30 °C) higher than Nafion 115 for the PEMs and OH^– conductivity (28.5–53.7 mS cm^?1 at 30 °C) comparable to Tokuyama A901 for the AEMs are accomplished. In addition, the AEMs can withstand 60 days’ aging in 1 mol L^?1 NaOH at 60 °C without degradation, as proved by ¹H NMR. More intriguingly, when starting from optically active (S)‐DHBN instead of racemic DHBN, an enhancement in proton conductivity of PEMs is observed for the first time, which opens a new door to optically active ion exchange membranes.     

Adsorptive Removal of Nitrate and Phosphate from Water by a Purolite Ion Exchange Resin and Hydrous Ferric Oxide Columns in Series

Elevated concentrations of nitrate and phosphate in surface and ground waters can lead to eutrophication, and nitrate can also cause health hazards to humans. The adsorption process is generally considered to be an efficient technique in removing these ions provided that the adsorbent is highly selective for these ions. Removal of nitrate and phosphate from a synthetic water (50 mg N/L as nitrate, 15 mg P/L as phosphate) and a wastewater (12.9 mg N/L as nitrate, 5.9 mg P/L as phosphate) using a Purolite A500P anion exchange resin and a hydrous ferric oxide (HFO) columns (60 cm height, 2 cm diameter, flow rate 1 m/h) in series containing 1–10% (w/w) of these adsorbents and the remainder anthracite (90–99%) were studied. Data from batch adsorption experiment at various concentrations of adsorbents satisfactorily fitted to Langmuir adsorption isotherm for nitrate and phosphate on Purolite with adsorption maxima of 64 mg N/g and 7 mg P/g and only for phosphate on HFO with adsorption maxima of 14 mg P/g. Both batch and column experiments showed that Purolite selectively removed nitrate and HFO selectively removed phosphate. The Purolite column BTC time was greater for nitrate than for phosphate. At the highest percentage by weight of Purolite almost all nitrate was removed in batch study and up to 1000 min in column study, but it was not able to remove a comparatively high percentage of phosphate. However, when the effluent from the Purolite column was passed through the HFO column almost all phosphate was removed. The two columns when set up in series also removed almost all nitrate and phosphate from the wastewater.     

Production of Hexanoic Acid by Free and Immobilised Cells of Megasphaera elsdenii: Influence of in-situ Product Removal Using Ion Exchange Resin

The objective of this work was to improve the production of hexanoic acid by the anaerobic rumen bacterium, Megasphaera elsdenii, using product removal and immobilised cell approaches. Hexanoic acid, the major product of glucose metabolism by M. elsdenii strain ATCC25940, was produced at concentrations of 2–3 g dm⁻³ in stirred batch cultures. With pH controlled manually at 7, maximum concentrations of hexanoic acid increased to 6–8 g dm⁻³ with yields (g product per g glucose used) of approximately 30%. When an anion exchange resin, Amberlite IRA 400, was added during early stages of culture to minimise product inhibition, growth was not impaired and cell lysis, which was commonly seen during the stationary phase in control fermentations, was prevented. The presence of resin in pH-controlled, stirred batch fermentations increased the rate of glucose consumption and doubled hexanoic acid productivity: the equivalent of 11 g dm⁻³ of hexanoic acid was made with an estimated yield of up to 39%. Cells were immobilised successfully in κ-carrageenan and, when cell densities in inocula were sufficiently high, rates of glucose consumption and product formation were similar to free cells. Including resin in cultures of immobilised cells had effects similar to those above. Using a fed-batch mode with immobilised cells cultured in the presence of resin further increased final concentrations of hexanoic acid (up to 19 g dm⁻³) but yields were lower (20–30%) and productivity did not increase. These results show that production of volatile fatty acids can be improved significantly by product stripping onto an anion exchange resin. © 1997 SCI.     

Anhydrous esterification of myristic acid with propylene: Ion exchange resin and acid-treated clay as catalysts

Anhydrous esterification of myristic acid with propylene was carried out in the temperature range of 110–145°C and pressure from 190–195 psig in the presence of Amberlyst-15 (cation exchange resin) and Filtrol-24 (acid-treated clay) as catalysts. The product ester, isopropyl myristate finds use in cosmetic and topical medicinal preparations where good absorption through the skin is desired. Filtrol-24 is the catalyst of choice, and the recommended operating temperature is 130°C with a pressure of 190 psig.