胶束增强陶瓷膜处理镧离子废水的研究

将十二烷基硫酸钠(SDS)与孔径5nm的陶瓷膜结合,探索胶束增强陶瓷膜法处理镧离子废水的可行性.考察了SDS摩尔浓度、跨膜压差(TMP)、溶液pH值等因素对陶瓷膜过滤性能的影响.结果表明,随着SDS摩尔浓度的增大,陶瓷膜对La3+的截留率从70％增大到99.9％;当SDS摩尔浓度大于临界胶束浓度(CMC)后,膜对La3+的截留率略有降低,大约维持在95％～97％左右;膜通量则随SDS摩尔浓度增大先减小后增大,最后趋于65 L/(m2·h).随着TMP提高,膜通量基本呈线性关系增大,膜对SDS和La3+的截留率略增大.随着溶液pH的升高,渗透通量略有下降,膜对La3+和SDS的截留率均显著增加.采用体积浓度为0.5％的稀硝酸清洗污染的陶瓷膜,膜的纯水通量可恢复到95％以上,重复性好.     

胶束强化超滤技术在重金属废水处理中的研究进展

胶束强化超滤技术(MEUF)作为一种新兴的水处理技术,在重金属废水净化方面有着较好的应用前景。本文通过总结前人的研究结果,综合讨论了影响金属离子截留效果的各个因素,为优化MEUF提出了一些建议。并就当前采用胶束强化超滤法处理金属离子技术的最新发展与表面活性剂的循环再利用作了简要的介绍。     

聚偏氟乙烯/聚二甲基硅氧烷复合纳米纤维膜的渗透汽化脱盐性能研究

以静电纺丝聚偏氟乙烯(PVDF)纳米纤维膜为多孔支撑层,在其上涂覆聚二甲基硅氧烷(PDMS)为致密分离层,制备了PVDF/PDMS复合纳米纤维膜,并对复合膜的渗透汽化脱盐性能进行了研究。在涂覆操作前,使用堵孔剂聚乙二醇处理PVDF纳米纤维膜,以降低涂覆过程的孔渗问题,有效提高了复合膜对盐离子的截留能力。通过扫描电子显微镜、热重分析仪和红外光谱仪等手段表征了复合膜的微观形貌、热稳定性和表面官能团形式。结果表明:聚乙二醇浓度为12%(wt,质量分数,下同)为最佳处理条件。操作温度为25℃时,渗透汽化脱盐通量可达6.46L/(m~2·h),NaCl截留率为98.8%;升温至75℃,通量可达19.3L/(m2·h),NaCl截留率为95.6%。     

PLA和PE包装袋对西兰花贮藏品质的影响

目的考察聚乳酸(PLA)与聚乙烯(PE)袋对西兰花贮藏品质的影响。方法利用透氧仪和透湿仪对市售的PLA和PE膜进行阻隔性测试,并采用该PLA和PE袋包装西兰花,利用色度计和顶空分析仪研究室温和冷藏条件下2种包装袋对西兰花保鲜效果的影响。结果 PLA膜的透湿系数和透氧系数分别为1.241×10-13 g·cm/(cm2·s·Pa)和5.07×10-10 m L·cm/(m2·s·Pa),PE膜的透湿系数和透氧系数分别为1.125×10-14 g·cm/(cm2·s·Pa)和2.87×10-10 m L·cm/(m2·s·Pa)。随着贮藏时间的延长,西兰花的色度由绿变红,由蓝变黄,明度由黑变白;袋中O2气氛浓度先减少后增加,CO2浓度先上升后下降。结论 PLA膜的透湿性和透氧性高于PE膜,冷藏条件下,PLA比PE袋能更有效地抑制西兰花的呼吸作用。     

液相氧化-低温煅烧脱除Silicalite-1膜模板剂及其性能研究

采用原位生长法在管状大孔α-Al2O3载体外表面上合成致密连续Silicalite-1沸石膜,利用双氧水和稀硝酸混合液液相氧化-低温煅烧方法脱除Silicalite-1沸石膜的模板剂,并用扫描电镜(SEM)、气体渗透测试,渗透蒸发(PV)等表征手段对沸石膜的性能进行评价.结果表明所制备的Silicalite-1膜表面晶粒交互生长,致密,连续,膜的厚度约为10 μm.在293K,0.1 MPa压差条件下,N2的渗透速率为8.16×10-7mol/(m2·s·Pa),N2/i-C4H10理想分离系数为达到425.在428 K下,CO2/N2的理想分离系数为2.89.在333 K下,渗透蒸发分离5%乙醇/水混合液,乙醇/水的分离系数αA/W达到40.3,通量J为0.83 kg/(m2·h).     

聚醚砜基膜热稳定性对复合纳滤膜性能的影响

研究聚醚砜超滤基膜的热稳定性对界面聚合法制备复合纳滤膜性能的影响.加入TiO_2纳米粒子可显著改善超滤膜的热稳定性,并随着基膜中TiO_2的增加,超滤基膜的热稳定性也随之增加.基膜TiO_2含量增至8%时,纳滤膜的水通量从27 L/(m~2·h)逐渐增加到38 L/(m~2·h),对NaCl的截留率从48%增加到58%,而对MgSO_4的截留率保持不变.研究表明,提高微滤基膜的热稳定性有助于提高复合纳滤膜的水通量和截留率.     

聚合物辅助超滤技术处理含铈废水

使用聚乙烯亚胺(PEI)辅助超滤法处理放射性废水中的铈(Ce).着重研究了pH,聚合物/金属离子质量比(P/M),离子浓度以及操作压力、运行时间对铈离子(Ce3+)截留率和膜渗透通量的影响.研究结果显示:使用聚合物PEI辅助超滤时,最佳实验条件为pH=5,P/M=15;在最适pH和P/M比值下,3种截留分子量超滤膜对Ce3+截留率分别为88.23%(5kDa)、87.01%(10kDa)和89.78%(30kDa);当溶液中存在Na+和Ca2+时,膜对Ce3+的截留率将会降低.膜通量随着操作压力的增加呈线性增加;3种膜通量均随着运行时间的增加有减小的趋势,且下降率顺序为30kDa10kDa5kDa.     

新型聚芳醚酰胺超滤膜的结构与性能研究

以杂萘联苯聚芳醚酰胺(PPEA)为膜材料,N,N-二甲基乙酰胺(DMAc)为溶剂通过相转化法制备超滤膜.研究了PPEA浓度、添加剂种类和用量对膜结构和性能的影响.结果表明,PPEA浓度提高,膜孔结构由宽的指状孔向海绵孔转变,膜表层致密化,膜的水通量降低而截留率提高;添加剂乙二醇甲醚(EG-ME)含量增加,膜孔结构趋于疏松,通量上升,截留率先有增加后下降;添加剂乙醚则使膜表面更致密.EGME含量10%时,膜的通量达到480L/(m2·h)左右,对聚乙二醇(PEG)10000截留率约93%;乙醚含量10%时,对PEG6000的截留率达到100%,而通量降低至56L/(mg·h)左右.     

陶瓷膜法处理退浆废水工艺研究及工业化装置运行评价

针对以聚甲基丙烯酸甲酯为主要成分的退浆废水,采用孔径为50nm的陶瓷膜过滤,实现废水的资源化利用.采用两级串联先循环后浓缩的操作方式.循环过滤时,拟稳态通量为423L/(m2·h)和453L/(m2·h).循环结束后进行浓缩,浓缩倍数达到22倍时通量为66L/(m2·h)和54L/(m2·h);膜对COD的截留率为87.5%,产水浊度低于1NTU,废水中的氢氧化钠等小分子物质均透过膜层进入渗透液;膜污染是以聚甲基丙烯酸酯在膜表面形成滤饼为主;碱洗及酸洗膜通量恢复至新膜的95%以上.陶瓷膜出水回用于生产过程;工业化陶瓷膜运行稳定,经济效益显著.     

NaA分子筛改性聚砜超滤膜的通量及截留性能

利用溶液相转化法,在铸膜液中加入分子筛NaA和PEG来协同提高聚砜超滤膜的水通量和截留率,研究了分子筛的含量对聚砜超滤膜的形貌结构,表面粗糙度,水通量,蛋白质截留率和亲水性的影响。利用场发射扫描电镜、扫描探针原子力显微镜、膜评价仪和接触角仪分别对该膜的形貌、水通量、蛋白质截留率和亲水性进行表征。结果表明分子筛含量从0g增加到3.0g,聚砜超滤膜的水通量从140L/(m2·h)提高到500L/(m2·h),对胃蛋白酶的截留率从78.8%提高到92.7%,对牛血清蛋白的截留率从97.6%增加到99.0%以上。分子筛NaA可以协同提高聚砜超滤膜的水通量和蛋白质截留率。     

改性沸石对电镀废水中Pb2+、Zn2+、Ni2+的吸附

将天然沸石进行处理制备出多孔质改性沸石颗粒。在静态条件下，研究了改性沸石颗粒对重金属离子Pb^2 ,Zn^2 ,Ni^2 的吸附效果及条件，含Pb^2 ,Zn^2 ,Ni^2 的电镀废水经改性沸石颗粒吸附后，废水中Pb^2 ,Zn^2 ,Ni^2 的含量低于国家排放标准。     

NpO 2 + -UO 2 2+ cation-cation interaction in NaCl-KCl-CsCl and LiCl-KCl-CsCl eutectic melts

Absorption spectra of the NpO ₂ ⁺ ion in UO ₂ ²⁺ -containing NaCl-KCl-CsCl (0.300:0.245:0.455) and LiCl-KCl-CsCl (0.575:0.165:0.260) eutectic melts in the region of the 5f-5f transitions, 700–2000 nm, were studied at 650 and 500°C, respectively. Processing of the spectra allowed the previously discovered phenomenon, cation-cation interaction of actinides in melts, to be interpreted for the first time in terms of the mass action law. It was shown that, at the concentrations of the interacting components studied (C _Np = 0.2 M and C _U = 0.1–2 M), a 1: 1 NpO ₂ ⁺ ·UO ₂ ²⁺ cation-cation complex is formed. Its concentration stability constant was estimated at 0.06(6) and 0.11 1 mol^?1 for the NaCl-KCl-CsCl and LiCl-KCl-CsCl systems, respectively.     

胶团强化超滤中SDS胶团对Cd^2＋，Zn^2＋和Pb^2＋的竞争吸附

胶团强化超滤法是一种将表面活性剂技术和超滤技术结合的新型、高效的重金属废水治理方法.以十二烷基硫酸钠(SDS)为表面活性剂,对含单一镉、锌、铅溶质以及混合溶质体系进行了胶团强化超滤研究,考察了胶团对Cd2 ,Zn2 ,Pb2 的竞争吸附性能.研究发现,当溶液中多种二价重金属离子存在时,各离子之间存在与SDS胶团的竞争吸附,竞争能力为Pb2 ＞Zn2 ＞Cd2 ;Cd-Zn有明显的协同吸附效应,而Cd-Pb,Zn-Pb则表现为拮抗吸附.     

Observable effects of Ca2+ buffers on local Ca2+ signals

Calcium signals participate in a large variety of physiological processes. In many instances, they involve calcium entry through inositol 1,4,5-trisphosphate (IP(3)) receptors (IP(3)Rs), which are usually organized in clusters. Recent high-resolution optical experiments by Smith & Parker have provided new information on Ca(2+) release from clustered IP(3)Rs. In the present paper, we use the model recently introduced by Solovey & Ponce Dawson to determine how the distribution of the number of IP(3)Rs that become open during a localized release event may change by the presence of Ca(2+) buffers, substances that react with Ca(2+), altering its concentration and transport properties. We then discuss how buffer properties could be extracted from the observation of local signals.     

锰矿尾渣对Cu2+和Ni2+的吸附性能研究

研究了锰矿尾渣对重金属离子Cu2 和Ni2 的吸附性能,分析了锰矿尾渣的吸附动力学,就吸附时间、Cu2 和Ni2 浓度及pH值等因素对锰矿尾渣吸附性能的影响作了系统考察,并对锰矿尾渣的吸附机理进行了初步探讨.结果表明,在温度为25°℃、pH值为7.5的条件下,锰矿尾渣对Cu2 和Ni2 的吸附容量可达到1.6 mg/g以上,去除率均可达到97.5%以上,适宜于处理含低浓度Cu2 或Ni2 的废水.锰矿尾渣的吸附机理为离子交换吸附和表面配位吸附.     

酸改性膨润土吸附去除镍镉离子的研究

在静态条件下,研究了改性膨润土对重金属离子的吸附性能和吸附机理,着重探讨了改性膨润土去除模拟水样中重金属离子Ni2 ,Cd2 的适宜条件及改性膨润土的再生方法.结果表明,改性膨润土对Ni2 ,Cd2 具有较好的吸附性能;pH值是影响改性膨润土对重金属离子吸附的重要因素,不同的金属离子都有其适宜的pH值范围.吸附的最佳条件是pH值5.0～7.0,废水中Ni2 ,Cd2 含量不大于45 mg/L,搅拌时间约60 min.利用改性膨润土吸附处理Ni2 ,Cd2 含量小于45 mg/L的模拟水样,效果很好,Ni2 ,Cd2 的去除率均可分别达到98.5%以上,出水可达到国家排放标准.     

ESR of Cu2+and Tl2+ in thallium borate glasses

The electron spin resonance (ESR) and optical absorption spectra of Cu²⁺ were measured in thallium borate glasses in order to investigate the effects of glass transition temperature,T _g, upon the responses of cupric ion in alkali borate glasses. The ESR of Tl²⁺ induced by-ray irradiation was also obtained. An abrupt increase in the covalency of in-plane Cu²⁺-O-bonding was observed in the Tl₂O system as well as in the Na₂O system in a similar B₂O₃ composition range althoughT _g for the Tl₂O glasses has little dependency on the composition compared with the Na₂O glasses. The trend in the variation of the S-character of the Tl²⁺ unpaired electron with composition agreed with that of the covalency of in-plane Cu²⁺-O-bonding. The structure of the anion group present in Tl₂O glasses was also examined by laser reman spectroscopy.     

Characterization of various Eu2+ sites in Ca2SiO4:Eu2+ and Ba2SiO4:Eu2+ by high-pressure spectroscopy

Photoluminescence of Ba₂SiO₄ and Ca₂SiO₄ activated with Eu²⁺ was investigated at various temperatures (from 10 K to 300 K) and pressures (from ambient to 200 kbar). At ambient pressure and room temperature, under UV excitation both phosphors yielded a green emission band with maxima at 505 nm and 510 nm for Ba₂SiO₄ and Ca₂SiO₄, respectively. The energies of these bands depended on pressure; the pressure shifts were ?12:55 cm^?1/kbar for Ba₂SiO₄:Eu²⁺; and ?5:59 cm^?1/kbar for Ca₂SiO₄:Eu²⁺. In the case of Ca₂SiO₄:Eu²⁺, we observed additional broadband emission at lower energies with a maximum at 610 nm (orange band). The orange and green emission in Ca₂SiO₄:Eu²⁺ had different excitation spectra: the green band could be excited at wavelengths shorter than 470 nm, whereas the orange band — at wavelengths shorter than 520 nm. The pressure caused a red shift of orange emission of 7.83 cm^?1/kbar. The emission peaked at 510 nm was attributed to the 4f⁶5d→4f⁷(⁸S₇₌₂) transition of Eu²⁺ in the β — Ca₂SiO₄:Eu²⁺ phase, whereas the emission peaked at 610 nm — to the γ — Ca₂SiO₄:Eu²⁺ phase. The emission of Ba₂SiO₄:Eu²⁺ peaked at 505 nm was attributed to the 4f⁶5d→ 4f⁷(⁸S_7/2) transition of Eu²⁺ in the β — Ba₂SiO₄ phase.     

Cation and anion disorder in HgBa2Can−1CunO2n+2+δ

Cu and C substitution for Hg in Hg-based cuprate superconductors is discussed. The large Hg Debye-Waller factor usually obtained from refinements based on diffraction data should be interpreted as an indication of carbon substitution for the Hg cations. This assumption is corroborated by HREM, powder x-ray anomalous dispersion, and powder neutron diffraction investigations.     

Phase Composition of the Products of Fe Oxidation in Fe + C + NaCl + H2O + O2 Exothermic Mixtures

Using thermodynamic analysis of the Fe–C–NaCl–H₂O–O₂ system and experimental studies (x-ray diffraction and Mössbauer spectroscopy) of exothermic mixtures containing Fe metal, activated carbon, water, and NaCl, we identified the state of Fe and determined the phase composition of the reaction products at different stages of oxidation with atmospheric oxygen. The calculation and experimental results are in reasonable agreement. Under the conditions of restricted access for air, the main oxidation product is magnetite, Fe₃O₄. Free access for air leads to the formation of hydrous ferric oxide, Fe₂O₃ · nH₂O. The most stable phase under the conditions of interest is goethite, Fe₂O₃ · H₂O (-FeOOH). Storage of incompletely oxidized samples away from air for 7–14 days leads to partial reduction of iron(III) oxide phases to Fe₃O₄ and -Fe.