电渗析技术在大豆低聚糖溶液脱盐上的应用

从甜浆中提取的大豆低聚糖粗提液中含有很多的盐类,影响糖液的纯度。该试验通过离子交换膜辅助的电渗析法对大豆低聚糖模拟溶液进行脱盐处理,确定了较好的试验操作参数。试验结果表明:电渗析法对大豆低聚糖模拟液进行脱盐是可行的,且脱盐效果较好,脱盐率达到96.07%;该试验条件下较佳的工作电压为20 V,流量为60 L/h,样品稀释倍数为15倍。通过以上条件处理后,大豆低聚糖的保留率达到83.82%。     

电渗析与酸淋洗模拟紫色土酸化的效果比较

为了比较电渗析与酸淋洗试验模拟紫色土酸化的效果,在重庆地区采集了不同pH(5.00和7.06)的2个紫色土,分别进行不同天数(1,2,5,7,10天)的电渗析和酸淋洗试验处理,并分析了试验处理前后土壤的酸度特征和交换性盐基成分含量变化。结果表明,在整个10天的淋溶处理过程中,2种紫色土的pH均无显著变化,说明紫色土具有一定的酸缓冲能力,短期的酸雨淋溶不能实现紫色土的严重酸化。而采用电渗析处理10天后,中性紫色土和酸性紫色土的pH分别降低3.4和1.1个单位。在整个电渗析处理过程中,土壤的交换性酸含量显著升高,盐基离子大量淋失。电渗析可以实现对紫色土的快速酸化处理。2种紫色土中,电渗析处理后中性紫色土的酸化程度大于酸性紫色土。这是由于中性紫色土的表面负电荷量更高,导致更多致酸离子吸附在土壤胶体表面,最终造成中性紫色土的酸化程度更加严重。因此,电渗析处理比酸雨淋溶处理对紫色土酸化效果更好,且可用于紫色土的酸化机理研究。进一步结合2种方法的技术可操作性,认为电渗析法是研究紫色土酸化问题的一种有效技术手段。     

Advanced treatment of swine wastewater by electrodialysis with a tubular ion exchange membrane

To remove the excess nitrogen and phosphorus in swine wastewater, an electrodialysis technique was applied to an advanced treatment method. The laboratory‐scale swine wastewater treatment system constructed for the present study consisted of an activated sludge process, as the main treatment unit, and electrodialysis, as an advanced treatment unit. This system was operated for 200 days and the processing performance was evaluated. By electrodialysis, approximately 99% of NO₃^– and PO₄^3– in the activated sludge‐treated water (AT solution) was removed during operation. Furthermore, electrodialysis decreased the color density of the AT solution at a rate of 58%. The advanced treatment of swine wastewater by electrodialysis proved to be an efficient technique to remove excess nitrogen and phosphorus, and decrease color density.     

微地形下紫色土的矿物组成和pH的耦合特征

为了研究微地形下紫色土的矿物组成和土壤酸度之间的关系,采集了重庆合川丘陵地区典型的紫色土壤,通过电渗析模拟酸化,并通过X射线衍射光谱分析电渗析前后的矿物组成以及酸度变化。结果表明:不同地形部位的紫色土随着地形部位的降低,土壤原生矿物的比重逐渐降低,土壤的发育程度越来越高。紫色母岩及其发育的土壤pH大小关系为母岩石骨子土半沙半泥土豆瓣泥。pH变化与土壤中的方解石、钠长石和钾长石等矿物的含量有紧密关系。电渗析模拟土壤酸化后发现,石骨子土和半沙半泥土的pH分别降低了4.3,3.8个单位,同时土壤原生矿物分解风化,表明土壤原生矿物(如长石类矿物)可以缓冲土壤的酸化。     

膜分离法的应用

介绍了膜分离法的优点和五种膜分离法,即电渗析、微滤、超滤、反渗透、纳滤的现状和存在的问题,以及它们在食品加工工业、谷氨酸和柠檬酸生产中的应用.     

Electrodialytic remediation of fluorine contaminated soil using 2-electrolysis compartment

Fluorine pollutants, emitted from numerous anthropogenic actions, can enter the surrounding environment and lead to soil pollution by fluorine. The aim of this study is to evaluate the remediation possibility and efficiency of fluorine contaminated soil by EDR (electrodialytic remediation) with the 2-electrolysis compartment, compared to EDR with 3-electrolysis compartment. Four runs of EDR experiments were carried out using the 3-compartment (run A, run C) and 2-compartment electrolysis bath (run B, run D). Important electrodialytic parameters such as electric current, electroosmotic flow, the removal efficiency and energy consumption were investigated. The results showed that the removal efficiency of fluorine in run A, B, C and D was 61.6%, 80.5%, 49.1% and 58.8%, respectively. And 2-electrolysis compartment positively affected the fluorine removal because of higher electric current and soil pH, which led to more desorption of F ions from the contaminated soil and more electro-migration of F ions into the electrolyte, but 2-electrolysis compartment consumed more energy (run A: 0.13 kwh kg^?1, run B: 0.24 kwh kg^?1, run C: 0.08 kwh kg^?1 and run D: 0.12 kwh kg^?1). After EDR, fluorine of contaminated soil was mainly bound to stable and low toxic RESF (the residual fraction of fluorine).     

大豆酱油电渗析脱盐工艺参数对其脱盐率及品质的影响

为了降低大豆酱油的含盐量,该文利用电渗析技术对大豆酱油进行脱盐处理,通过单因素试验探讨了电压、流速、pH值对电渗析脱盐效果的影响,确定了较佳电渗析工艺。结果表明在电压为9 V,流速为2.4 cm/s,pH值为4.2,电渗析50 min时脱盐效果较好,氨基酸态氮损失较小,氨基酸态氮损失19.4%,脱盐率达到81.6%。利用氨基酸自动分析仪和气相色谱-质谱联用仪（gas chromatography-mass spectrometry）分析了电渗析前后游离氨基酸及挥发性风味物质的变化规律,结果表明电渗析过程中氨基酸及风味物质均有损失。几种苦味氨基酸如组氨酸、精氨酸、赖氨酸损失较大,分别损失了23.79%、26.39%和28.5%;电渗析过程中,酱油风味物质中醇类、酚类损失较大,尤其是4-乙基愈创木酚损失最多,但因其气味阈值较低,因此对酱油风味影响较小。研究结果为减盐酱油系列产品的生产提供了参考和依据。     

电渗析法研究紫色土、黄壤和砖红壤的酸化特征

【目的】研究紫色土、黄壤和砖红壤在快速酸化过程中的酸化特征。【方法】将3种供试土壤在15 V·cm^-1的外加直流电压梯度下进行连续30次,每次8 h的电渗析。并通过测定电渗析前后土壤的酸度指标、盐基离子含量以及在电渗析过程中土壤所释放的盐基离子含量来分析土壤的酸化特征。【结果】电渗析法可在短时间内实现土壤的快速酸化,3种土壤的pH均降低至4.5以下的强酸化水平。电渗析后,3种土壤的交换性酸、交换性H⁺和交换性Al³⁺含量显著增加。紫色土、黄壤和砖红壤的交换性酸含量分别从3.35、0.23和0.76 cmol(+)·kg^-1增加至18.9、7.0和5.8 cmol(+)·kg^-1,可见紫色土的酸化程度最为严重。土壤酸化后,水溶性和交换性K⁺、Na⁺、Ca²⁺和Mg²⁺含量降低,其中Ca²⁺、Mg²⁺的降低幅度较大。酸化导致土壤的交换性盐基总量和盐基饱和度下降,紫色土、黄壤和砖红壤的盐基饱和度从电渗析前的96.8%、82.6%和47.3%降低至电渗析后的20.5%、11.8%和12.2%。尽管紫色土的交换性酸含量远大于黄壤和砖红壤,但交换性盐基离子总量和盐基饱和度也大于黄壤和砖红壤。由于各土壤的交换性Ca²⁺和Mg²⁺含量大于交换性K⁺和Na^＋含量,且相对于K⁺和Na^＋,Ca²⁺和Mg²⁺与带负电的土壤颗粒间具有更强的静电引力,因此在酸化过程中,一价盐基离子K⁺和Na^＋在3种土壤中均表现为快速释放,而二价盐基离子Ca²⁺和Mg²⁺表现出缓慢释放和波动释放的规律。3种供试土壤,随着土壤发育程度增加,土壤的潜在酸化风险下降（紫色土>黄壤>砖红壤）,但土壤的盐基饱和度表现出紫色土>黄壤≈砖红壤。可以看出,紫色土的酸化特征表现出这种明显的“双面性”,由于紫色土具有较高的CEC值,导致土壤酸化后的交换性酸含量显著高于黄壤和砖红壤,使酸化紫色土上生长的植物存在较高的铝毒害风险;同时,由于紫色土丰富的矿物组分能够对盐基离子进行及时补充,紫色土酸化后仍含有相对较高的盐基离子含量和盐基饱和度,保证了植物生长对盐基养分离子需求,也能在一定程度上缓解紫色土的进一步酸化。【结论】电渗析法可用于模拟土壤的快速酸化过程;土壤的表面负电荷量和复盐基离子能力是决定土壤酸化特征的关键因素;紫色土具有异于地带性土壤黄壤和砖红壤的“双面性”酸化特征。