浓海水纳滤膜分离实验研究

采用美国海德能公司ESNA1-LF-4040纳滤膜,在不同温度、压力等操作条件下,对海水淡化浓海水进行了分离实验研究。实验结果表明:操作压力提高,膜通量增大的同时截留率也略有提高;料液温度上升,膜通量增大但截留率下降;在操作压力为1.4 MPa,料液温度为28℃时该纳滤膜对浓海水中一价离子(Na+、Cl-、K+)的截留率均小于15%,对二价离子(Ca2+、Mg2+、SO24-)的截留率均大于35%,其中对SO24-的截留率可达97%以上,从而为纳滤膜在浓海水中的综合利用提供了可行的工艺参数。     

有机纳滤膜法盐水脱硝技术的应用研究

文章介绍了采用有机纳滤膜除去盐水中部分SO24-,考察了纳滤膜通量与浓缩液浓度、时间与压力的变化情况以及膜截留率的变化情况。结果表明,盐水在浓缩3倍,SO24-达到36 g/L的情况下,清液在最高压力下(2 000 kPa)SO24-<1 g/L,平均截留率97.0%,得到盐水符合烧碱企业所用的一次盐水质量要求。     

低聚糖的纳滤分离技术

确定了低聚异麦芽糖和低聚果糖纳滤分离高纯化工艺.首先根据纳滤膜截留相对分子质量和截留率选择适用的纳滤膜,然后进行纳滤分离工艺和操作条件的探索,随着纯化倍数递增,单糖或二糖逐渐被去除,产品纯度、低聚糖收得率和产品出率发生规律性变化.应用纳滤分离技术使低聚异麦芽糖纯度IMO≥90%,低聚果糖纯度FOS≥95%.     

纳滤膜浓缩混合油过程中的操作条件研究

为解决传统的混合油浓缩过程中溶剂回收能耗高的问题,本文分别采用3种不同截留分子量的纳滤膜进行溶剂回收,并考察了操作压力、料液浓度等条件对分离性能的影响。在0.3MPa下,料液浓度在20%左右,采用NF-400膜,大豆油的截留率在20%以上,膜的渗透通量为0.33L/（m~2·h）。     

超滤-纳滤联用优化聚苹果酸的分离纯化工艺

采用超滤-纳滤联用技术对出芽短梗霉发酵产生的聚苹果酸进行分离纯化。优化的工艺条件为:选用截留分子量为10 ku的超滤膜进行超滤,温度45℃,操作压力0.4 MPa,洗脱4次,此时聚苹果酸透过率为78.1%;采用截留分子量为300 u的纳滤膜进行纳滤,纳滤温度50℃,操作压力0.8 MPa,洗脱4次,此时离子去除率为81.6%。在超滤和纳滤的最优条件下对发酵液中的聚苹果酸进行分离纯化,最终聚苹果酸得率为67.6%,纯度为92.3%。     

对两种纳滤膜脱盐和乳糖截留效果的比较研究

纳滤是一种可以将乳超滤透过液中的盐分和乳糖分离的过程,采用单因素试验测定两种纳滤膜在一定压力下透过液的膜通量、电导率、各种离子和乳糖的截留率,比较两种纳滤膜的脱盐和乳糖截留情况,旨在筛选出脱盐效果好且截留乳糖质量分数较高的纳滤膜.结果表明,在0.30～0.50 MPa范围内两种纳滤膜可使用,NF-1812纳滤膜比NF-270纳滤膜脱盐效果好,但截留乳糖效果差.NF-270纳滤膜适合脱盐而得到乳糖.     

聚丙烯腈纳滤膜的制备及对造纸废水的截留性能

以聚丙烯腈膜为基膜 ,壳聚糖为改性剂 ,采用紫外辐射法制备了一种新型纳滤膜。研究了纳滤膜的制备工艺及性能 ,并将纳滤膜用于处理蓝桉化学热磨机械浆 (CTMP)废水。研究结果表明 :在所选择的条件下制备的 #4纳滤膜 ,其离子交换容量和膜电阻分别为 3 5× 1 0 - 3 mmol/cm2 、3 52× 1 0 3 Ω ;采用 #4纳滤膜处理CTMP废水 ,其对钠的截留率为 40 1 % ,并且浓缩液中的固形物含量、燃烧热比原废液大大增加 ,可以满足碱回收工段的要求。     

膜分离应用于花生根中白藜芦醇初级纯化

为利用花生根中白藜芦醇资源,将膜分离应用于花生根提取液中白藜芦醇的初级纯化,以膜通量和膜渗透性、白藜芦醇和水溶性糖截留率为评价指标,考察由超滤和纳滤组成膜分离系统的工艺参数与影响因素。结果如下:超滤膜UE030和纳滤膜NF4适宜于花生根提取液中白藜芦醇的分离纯化;提取液p H会显著影响纳滤膜对白藜芦醇的截留能力;操作压力会显著影响纳滤膜通量和渗透性,但对白藜芦醇和水溶性糖的截留率无显著影响;最佳膜分离工艺为花生根提取液经过1 MPa、400 r/min、UE030超滤后,透过液调节至p H6.0,采用3 MPa,400 r/min搅拌,NF4纳滤后,水溶性糖浓度从(1.1832±0.0718)mg/m L下降到(0.0475±0.0007)mg/m L,白藜芦醇浓度为(4.4730±0.0129)μg/m L,回收率为55.84%±0.16%。以上结果证明,膜分离可用于白藜芦醇的初级分离纯化,促进从花生根中制备白藜芦醇的工业化发展。     

再生纤维素基交联改性纳滤膜的制备及对无机盐截留性能的研究

以竹纤维素再生膜为基膜,海藻酸钠和羧甲基纤维素的共混溶液为涂覆液,环氧氯丙烷为交联剂,采用交联法制备了一种新型纤维素复合纳滤膜。研究了纳滤膜的制备工艺和对NaCl、Na_2SO_4、MgCl_2、MgSO_4、CaCl_2(500 mg/L)的截留性能。结果表明,在海藻酸钠与羧甲基纤维素共混溶液质量分数2.0%、共混比1∶3、环氧氯丙烷质量分数3.0%条件下,纤维素复合纳滤膜的膜通量为13.75 L/(m~2·h),Na Cl截留率为48.15%,较纤维素再生膜的膜通量(487.81 L/(m~2·h))下降明显,较纤维素再生膜的截留率(1.52%)有明显提高。对几种无机盐的截留性能顺序为:Na_2SO_4﹥Mg SO4﹥Na Cl﹥Mg Cl2﹥Ca Cl2。相比纤维素再生膜,纤维素复合纳滤膜的抗张力为83.31 N,比纤维素再生膜的抗张力(46.65 N)提高了44.0%,膜伸长量4.7 mm,伸长率9.40%,抗张强度5.554 k N/m,机械性能相对提高。     

芦荟水提液的除杂浓缩

采用膜分离技术对芦荟水提液进行除杂、浓缩,以提高芦荟多糖的纯度.试验比较了微滤膜10K和微滤膜20K的除杂效果,选用更合适的微滤膜20K:可使芦荟多糖透过率高达97.6%、杂质截留率达17.8%;比较了纳滤膜MWC和纳滤膜GMC的浓缩效果,选用更合适的纳滤膜MWC:芦荟多糖截留率高达98.3%,浓缩液芦荟多糖的纯度达73.6%.     

基于纳滤技术的质检萃取液脱色预处理方法

为提高纺织品及皮革甲醛检测效率和准确性,通过界面聚合法,将采用St?ber方法制备的无机颗粒与聚酰胺复合制备有机-无机杂化纳滤膜,用于纺织品和皮革萃取液脱色预处理。分别采用扫描电子显微镜、X射线光电子能谱仪和接触角仪,对颗粒形貌、纳滤膜表面元素及分离层接触角进行分析;通过纯水通量、无机盐和染料截留等对纳滤膜分离性能进行考察;并分析了纳滤脱色预处理法纺织品和皮革甲醛检测的加标回收率。结果表明:粒径分布均匀的球形二氧化硅及银离子修饰的二氧化硅颗粒成功地负载于亲水性良好的纳滤膜分离层;适量颗粒的添加有利于提高纳滤膜的纯水通量;银离子修饰的二氧化硅颗粒改善了纳滤膜对二价阳离子盐及阳离子染料的截留性能,回收率满足纺织品和皮革甲醛检测的要求。     

Microbial fuel cell operation with continuous biological ferrous iron oxidation of the catholyte

The oxygen reduction rate at the cathode is a limiting factor in microbial fuel cell (MFC) performance. In our previous study, we showed the performance of an MFC with ferric iron (Fe3+) reduction at the cathode. Instead of oxygen, ferric iron was reduced to ferrous iron (Fe2+) at the cathode with a bipolar membrane between the anode and cathode compartment. This resulted in a higher cathode potential than is usually obtained with oxygen on metal-based chemical catalysts in MFCs. In this study, we investigated the operation of the same MFC with ferric iron reduction at the cathode and simultaneous biological ferrous iron oxidation of the catholyte. We show that the immobilized microorganism Acidithiobacillus ferrooxidans is capable of oxidizing ferrous iron to ferric iron at a rate high enough to ensure an MFC power output of 1.2 W/m2 and a current of 4.4 A/m2. This power output was 38% higher than in our previous study at a similar current density without ferrous iron oxidation. The bipolar membrane is shown to split water into 65-76% of the needed protons and hydroxides. The other part of the protons was supplied as H2SO4 to the cathode compartment. The remaining charge was transported by K+ and HSO4-/SO4(2-) from the one compartment to the other. This resulted in increased salt concentrations in the cathode. The increased salt concentrations reduced the ohmic losses and enabled the improved MFC power output. Iron could be reversibly removed from the bipolar membrane by exchange with protons.     

蒜氨酸酶的分离纯化及其动力学特性

采用 (NH4 ) 2 SO4 盐析、SephadexG 2 0 0凝胶过滤和ConA Sepharose亲和层析方法对蒜氨酸酶进行了部分纯化 ,并研究了其酶动力学特性 ,结果表明其最适反应温度为 3 0℃ ,最适pH值为6 2 4,以蒜氨酸为底物 ,最大反应速度Vmax =1 2 0u/mg(蛋白质 ) ,米氏常数 Km =6 0 2× 1 0 - 3mol/L。文中同时研究了抑制与激活剂对蒜氨酸酶活性的影响     

结晶添加剂对硫酸钾结晶过程影响研究

本文研究了NH+ 4 、K+ 、Cl-、SO2 -4离子的混合体系中K2 SO4晶习、晶形特性 ,考查了不同结晶添加剂对K2 SO4结晶的影响 ,探讨了各种离子对硫酸钾在混合体系中结晶过程影响机制。试验结果表明 ,Mg2 + 和十二烷基苯磺酸钠有促进K2 SO4晶体结晶作用 ,而Fe3 + 、Al3 + 对结晶有一定的抑制作用     

西台吉乃尔盐湖卤水等温蒸发实验研究

文章依据K+、Na+、Mg2+∥Cl-、SO2-—H2O五元体系介稳相图,对青海西台吉乃尔盐湖井采卤水进行了等温蒸发实验研究及相图分析,确定盐湖井采卤水盐类结晶析出顺序和各阶段的分离点,为该盐湖卤水的综合开发利用提供了理论依据。     

Field measurements of aerosol particle dry deposition on tropical foliage at an urban site

This paper presents dry deposition of major ions on tropical foliage (leaves of Ashok (Polyalthia longifolia) and Cassia (Cassia siamea)) at St. John's, Agra, an urban site of tropical India on nonrainy, nondewy, and nonfoggy days. The deposition flux was higher on Cassia leaf than Ashok leaf probably due to a rougher surface as shown by scanning electron microscopy. Dry deposition of cations varies from 0.46 to 12.16 mg m(-2) day(-1) while anions vary from 0.04 to 3.24 mg m(-2) day(-1). The percentage contribution of alkaline components is greater than that of acidic components, indicating the alkaline nature of dry deposition. Two-way analysis of variance results reveal significant seasonal variation only for K+, SO4(2-), and F-; however, values varied season to season for Na+, Ca2+, Mg2+, Cl-, NO3-, and NH4+ also. The large seasonal variation in deposition flux may be due to meteorological conditions, diameter of particles, and variation in atmospheric level. SO42- and NO3- show significant correlation, indicating their origin from similar sources while significant correlation between Ca2+ and Mg2+ implies their origin from soil. Poor correlation between Ca2+ and SO4(2-), Ca2+ and NO3-, and Mg2+ and SO4(2-) indicates that in addition to soil other sources also contribute to dry deposition. Low dry deposition fluxes of SO2- and NO3- compared to Ca2+ and Mg2+ may be due to low mass medium diameters of SO4(2-) and NO3- and may be due to uptake through the stomatal pores abundant on leaf surfaces. Factor analysis was employed to identify the sources. F-, Cl, SO4(2-), NO3-, and K+ are grouped together in the first factor, indicating their probable contribution from combustion, Ca2+, Mg2+, and NH4+ are grouped in factor II, which may be attributed to road dust and soil, and factor III includes mainly Na+ and F-, probably contributed from brick-kiln industries. Atmospheric concentrations of F-, Cl-, NOs-, SO4(2-), Na+, K+, Ca2+, Mg2+, and NH4+ were found to be 0.38, 2.28, 1.31, 2.74, 0.44, 0.59, 1.21, 1.2, and 2.29 microg m(-3), respectively.     

Nanofiltration for trace organic contaminant removal: structure, solution, and membrane fouling effects on the rejection of perfluorochemicals

The use of nanofiltration (NF) membranes for water recycling requires an improved understanding of the factors that govern rejection of potentially harmful organic trace contaminants. Rejections of 15 perfluorochemicals (PFCs)--5 perfluorinated sulfonates, 9 perfluorinated carboxylates, and perfluorooctane sulfonamide (FOSA)--by four nanofiltration membranes (NF270, NF200, DK, and DL) were measured. Rejections for anionic species were >95% for MW >300 g/mol. FOSA (MW = 499 g/mol), which is uncharged at the pH of deionized water (5.6), was rejected as little as 42% (DL membrane). Decreasing the pH to less than 3 decreases rejection by up to 35%, effectively increasing the MWCO of NF270 by >200 g/mol, while a 2500 mg/L NaCl equivalent increase in ionic strength reduces rejections <1%. An alginate fouling layer increases transmission, where quantifiable, by factors of 4-8. Accumulation of PFCs on membranes was measured after the completion of rejection experiments. Based on rejection kinetics and the extent of sorption, we infer that two different sorption processes are significant: charged species adsorb quickly to the membrane surface, whereas the uncharged FOSA absorbs within the membrane matrix in a much slower process.     

Influence of agricultural biomass burning on aerosol size distribution and dry deposition in southeastern Brazil

The size distributed composition of ambient aerosols is used to explore seasonal differences in particle chemistry and to show that dry deposition fluxes of soluble species, including important plant nutrients, increase during periods of biomass (sugar cane trash) burning in S?o Paulo State, Brazil. Measurements were made at a single site centrally located in the State's sugar cane growing region but away from the immediate vicinity of burns, so that the airsampled was representative of the regional background. Calculation of ion equivalent balances showed that during burning periods smaller particles (Aitken and accumulation modes) were more acidic, containing higher concentrations of SO4(2-), oxalate, NO3-, HCOO-, CH3COO-, and CI-, but insufficient NH4+ and K+ to achieve neutrality. Larger particles showed an anion deficit due to the presence of unmeasured ions and comprised resuspended dusts modified by accumulation of nitrate, chloride, and organic anions. Increases of resuspended particles during the burning season were attributed to release of earlier deposits from the surfaces of burning vegetation as well as increased vehicle movement on unsurfaced roads. During winter months the relative contribution of combined emissions from road transport and industry diminished due to increased emissions from biomass combustion and other activities specifically associated with the harvest period. Positive increments in annual particulate dry deposition fluxes due to higher fluxes during the sugar cane harvest were 44.3% (NH4+), 42.1% (K+), 31.8% (Mg2+), 30.4% (HCOO-), 12.8% (CI-), 6.6% (CH3COO-), 5.2% (Ca2+), 3.8% (SO4(2-)), and 2.3% (NO3-). Na+ and oxalate fluxes were seasonally invariant. Annual aerosol dry deposition fluxes (kg ha(-1)) were 0.5 (Na+), 0.25 (NH4+), 0.39 (K+), 0.51 (Mg2+), 3.19 (Ca2+), 1.34 (Cl-), 4.47 (NO3-), 3.59 (SO4(2-)), 0.58 (oxalate), 0.71 (HCOO-), and 1.38 (CH3COO-). Contributions of this mechanism to combined aerosol dry deposition and precipitation scavenging (inorganic species, excluding gaseous dry deposition) were 31% (Na+), 8% (NH4+), 26% (K+), 63% (Mg2+), 66% (Ca2+), 32% (Cl-), 33% (NO3-), and 36% (SO4(2-)).