EDI对于去除太空用水中弱电解质--氨的研究

研究了太空站水的总循环开发中EDI膜堆电流、进水的总氨浓度、进水流量等因素对EDI去除氨的影响,并对各影响因素进行了解释．实验结果显示：在氨进水质量浓度高达208．3mg／L的情况下,出水总氨的质量浓度为0．072mg／L,EDI对氨的去除率为99．97％．     

均相电渗析膜堆淡化性能测试与分析

为了进行均相电渗析测试分析以及设计选型需要,采用国产均相电渗析TRHE-JACM-5W-12060/100膜堆,通过装配自控式中试实验机,测试不同盐、不同电流及电压、不同流速状态下的单程脱盐率,计算出相应的电流效率及吨水能耗,并得出了膜堆的脱盐基本规律.低浓度淡化均相电渗析膜堆的单程脱盐率随着进水盐含量的降低而升高;随着电流密度的增加而升高;随着膜表面流速的降低而升高;与进水盐种类也有关,基本的脱盐率大小规律为:NaClNa_2SO_4(NH_4)_2SO_4NaCl+Na_2SO_4NaCl+MgSO_4NH_4ClNaHCO_3MgSO_4.以3 000 mg/L的NaCl为原料液,膜表面流速为4 cm/s,平均每对跨膜电压为0.5 V时,电流密度可以达到0.5 A/m~2,单程脱盐率可以达到32%,本体直流能耗为0.23 kW·h/m~3;当平均每对跨膜电压为0.8 V时,单程脱盐率可以达到55%,本体直流能耗为0.7 kW·h/m~3.     

电去离子过程脱除低浓度铜离子的研究

采用一级两段的膜堆,以模拟废水为对象,考察了电去离子(EDI)过程脱除低浓度铜离子的性能,为开发一种更环保更经济的重金属废水处理技术提供理论与实验基础.研究证实,脱除铜离子的EDI存在"增强传质"和"电再生"两种模式.在"增强传质"模式操作时,淡室的树脂保持为盐型,阴膜的浓室侧表面无结垢产生.在"电再生"模式下,树脂被水解离产生的H 和OH-所再生,EDI可将铜离子从 50mg/L 左右脱除至火焰原子吸收分光光度法无法检出,同时在阴膜浓室侧表面形成黑色的CuO结垢.选择适当的膜堆形式和工艺条件能够防止结垢,获得一个连续稳定的EDI过程.     

内部热能回收式多效膜蒸馏用于海水淡化及浓盐水深度浓缩

利用自制的具有高效内部热量回收功能的多效膜蒸馏组件对不同浓度的氯化钠水溶液进行浓缩研究.考察进料温度、浓度、流速对膜通量、造水比和脱盐率的影响.实验结果表明,料液加热温度T3升高时膜通量和造水比随之明显增加,而脱盐率保持不变;料液流速增加使膜通量增加,而造水比随之降低,脱盐率几乎不受影响;随着料液浓度的增加,膜的通量和造水比逐渐降低,脱盐率略微减小但影响很小.当料液中氯化钠浓度较低时,该过程的最大膜通量为6.8L/(m2·h),造水比为12.5;当料液中氯化钠浓度大于15％时,膜通量为5.2 L/(m2·h),造水比为6.2,脱盐率可达99.99％.实验结果表明,多效膜蒸馏技术可有效应用于海水淡化及常规海水淡化过程,例如反渗透和多效蒸发过程所副产浓盐水的深度浓缩和淡水生产.     

TiO2纳滤膜对重金属离子的截留性能

采用孔径为1.5 nm的TiO2纳滤膜,在压力0.4～0.8 MPa,pH值3～7的条件下,考察了膜对浓度范围为50～500 mg/L的Cu(NO3)2、Ni(NO3)2、ZnC12和CdC12四种单组份重金属溶液的截留性能.结果表明:除Cd2+外,膜对重金属离子的截留率随溶液浓度的增大先增大,当浓度达到200 mg/L后趋于稳定;升高压力膜的离子截留率会略有增加;当pH=6时,膜对Ni2+和Cd2+的截留率最低,而对Cu2+和Zn2+的截留率在pH=5～6时达到最高.TiO2膜对Cu2+、Ni2+、Zn2+和Cd2+的最高截留率分别可以达到96.9％、95.9％、92.5％和83.2％.     

微乳液-中空纤维膜萃取钕的工艺研究

提出了一种新的膜分离过程即非离子W/O型微乳液-中空纤维膜萃取,所用非离子型微乳液体系为(OP-7 OP-4)/苯甲醇/D2EHPA/煤油/盐酸.在不同微乳液流速、料液流速、微乳液内相盐酸浓度、料液浓度、以及不同中空纤维膜数等条件下进行了微乳液-中空纤维膜逆流萃取Nd3 的研究.结果表明,微乳液和料液流速越小,萃取率越高,内相富集倍数越大.微乳液内相盐酸浓度越大,萃取率越高,但富集倍数反而减小.料液初始浓度越小,萃取率和富集倍数越大.当微乳液流速为6 mL/min、料液与微乳液流速比为3∶1、微乳液内相盐酸浓度为4 mol/L、料液浓度为200 mg/L时,经过微乳液在三个中空纤维膜萃取器中的串联萃取,Nd3 的萃取率达96.3%,内相Nd3 浓度为4238 mg/L,是萃余料液浓度的572.7倍,内相富集倍数为21.2.膜萃取过程与膜溶剂萃取相比对Nd3 有更高的萃取效率.     

气隙式膜蒸馏法浓缩氢氧化钠溶液的实验研究

利用能量回收气隙式膜蒸馏组件浓缩氢氧化钠溶液,研究了进料温度、流速、浓度对膜通量、造水比和截留率的影响.结果表明,膜通量和造水比随着进料温度T_3升高而增大,随着进料浓度的增加而减小;料液流量增加时膜通量增大,造水比降低.当料液浓度为110g/L,进料温度T_1为40.0℃,T_3为95.0℃、流量为15L/h时,膜通量为6.3kg/(m~2·h),造水比为5.1,截留率可达99.9%.     

扩散渗析回收含铜退镀液中的硝酸

采用扩散渗析法回收含铜退镀液中的HNO3,考察流量、流量比、温度等因素对硝酸的回收率、回收液中硝酸浓度以及铜和镍离子截留率的影响.将单级扩散渗析仪改装成新的三级扩散渗析仪,考察了三级逆流扩散渗析对实验结果的影响.单级扩散渗析的结果表明,最佳条件:水/料的流比为1∶1、流量90 mL/h、温度19℃,其硝酸回收率为86.95％、回收浓度6.04 mol/L、Cu2+和Ni2+的截留率分别为90.19％、92.71％.相对于单级扩散渗析,自行改装的三级扩散渗析过程能达到更高回收酸浓度和单位时间内处理更多的料液.在含铜退镀液体系下,利用国产扩散膜实现了扩散渗析对于H+和金属离子具有良好的分离,同时达到了回收硝酸浓度高于原退镀液的效果.     

酒石酸柱撑水滑石吸附水中的Ni~(2+)的特性研究

采用离子交换法制得酒石酸插层MgAl水滑石(MgAl-TA LDHs),并进行了XRD、IR、SEM、比表面积及孔径分析表征。考察了MgAl-TA LDHs吸附剂对溶液中Ni 2+的吸附能力,探讨了水滑石吸附剂投加量、Ni 2+溶液浓度、pH值以及吸附温度对Ni 2+吸附率的影响,并进行了动力学和热力学特征的研究。结果表明,适宜的水滑石投加量为2g/L,pH值以中性为宜,对于Ni 2+浓度不超过100 mg/L的溶液室温下Ni 2+吸附率在60%以上,而高温有利于提高Ni 2+吸附率。吸附过程符合二级动力学模型,吸附等温曲线可用R-P模型来描述。吸附过程能够自发进行,为吸热过程,属于化学吸附。     

树脂分层填充EDI膜堆实验研究

介绍了阴、阳离子交换树脂分层填充EDI膜堆的特征,考察了一级两段式膜堆每段填充层数对EDI过程的影响.实验表明:每段填充2和16层的膜堆,在稳态条件下运行的电压一电流密度曲线呈现出一定的规律性;EDI膜堆浓水pH值随电流密度增加先下降后升高,最后稳定在碱性范围;两个膜堆均能在一定条件下持续、稳定生产17 MΩ·cm以上高纯水.最终,当两个膜堆在120 V下达到稳态运行时,填充的阴、阳树脂均具有一定的再生程度.     

溴水的膜吸收性能研究

研究了溴水的膜吸收分离性能,并采用回归正交试验设计方法优化溴水膜吸收工艺条件.以NaOH溶液作为吸收剂,采用PVDF中空纤维膜,研究了吸收时间、溴水温度、吸收液浓度及其流速等操作条件对溴水膜吸收性能的影响.结果表明:溴的吸收率随吸收时间的增加而增大,溴水膜吸收过程进料温度与传质系数之间符合阿伦尼斯关系.吸收液侧NaOH的浓度从0.003 mol/L增加至0.01 mol/L时,传质系数从4.75×10-4 cm/s增至6.02×10-4cm/s,对应的膜通量从2.4×10-3 kg/(m2·h)增至3×10-3 kg/(m2·h).吸收液的流体动力学条件对于溴水膜吸收过程通量无显著影响.采用回归正交试验确定的PVDF膜溴水膜吸收分离最佳工艺为:当NaOH吸收溶液浓度为0.01 mol/L,流量为2 L/h时,浓度为220 mg/L的溴水在进料温度为50℃、进料流速为22.24 cm/s的条件下,膜吸收通量达到6.17×10-3kg/(m2·h).     

Treatment of Terasil Red R Dye Wastewater using H2O2/pyridine/Cu(II) System

The H₂O₂/pyridine/Cu(II) advanced oxidation system was used to assess the efficiency of the treatment of a 1 g L⁻¹ Terasil Red R dye solution. This system was found to be capable in reducing the concentration of chemical oxygen demand (COD) of the dye solution up to 90%, and achieving 99% in decolorization at the optimal concentration of 5.5 mM H₂O₂, 38 mM pyridine and 1.68 mM Cu(II). The final concentration of COD was recorded at 117 mg L⁻¹ and color point at 320 PtCo. Full 2⁴ factorial design and the response surface methodology using central composite design (CCD) were utilized in the screening and optimization of this study. Treatment efficiency was found to be pH independent. The amount of sludge generation was in the range of 100–175 mg L⁻¹ and the sludge produced at the optimal concentration was 170 mg L⁻¹.     

The influence of Na2CO3 content and Ni concentration on the physicochemical properties of nanometer Y-substituted nickel hydroxide

Nanometer Y-substituted nickel hydroxide was prepared by supersonic co-precipitation method with Na₂CO₃ as a buffer and NiCl₂ as a nickel source. The crystal structure, morphology, particle size distribution and electrochemical performance affected by the buffer (Na₂CO₃) content and Ni²⁺ concentration are characterized. The results indicate most of the samples are co-existence with α and β phases and the proportion of α-Ni(OH)₂ increases with the increase of Na₂CO₃, but decreases with the increase of Ni²⁺ concentration. The primary particles of samples are nanometer particles and the shape of primary particles transform from acicular to quasi-spherical with increasing Na₂CO₃ content, but converse process for the increase of Ni²⁺ concentration. The average particle size decreases initially and then increases. Complex electrodes were prepared by mixing 8 wt.% nickel hydroxides with commercial micro-size spherical nickel. The discharge capacities of samples increase initially and then decrease with increasing Na₂CO₃ content or decreasing Ni²⁺ concentration. When Na₂CO₃ content is 0.08 g and Ni²⁺ concentration is 0.2 mol/L, the sample has better electrochemical performance, such as larger discharge capacity (316.3 mAh/g at 0.2 C rate), lower charge voltage and higher discharge plateau, than those of other samples.     

Investigating the performance of ammonium sulphate draw solution in fertilizer drawn forward osmosis process

This work investigated the performance of ammonium sulphate as a draw solution in a fertilizer drawn forward osmosis (FDFO) desalination process using thin-film composite (TFC) membrane. Performance has been assessed by the water flux, reverse permeation and the forward rejection of the feed solutes. A logarithmic relation has been determined between flux and ammonium sulphate concentration. As water flux increased, the specific reverse solute flux (SRSF) of NH₄ ⁺ and SO₄ ^2? ions dropped, which is a favourable condition. Reverse permeation values obtained at flux less than 10 L/m²/h are significantly higher than that for flux more than 10 L/m²/h. Thus, it is recommended to operate the process at a flux higher than 10 L/m²/h to avoid loss of draw solute by reverse permeation. SRSF was almost constant irrespective of ammonium sulphate concentration. TFC membrane used in this study exhibited high rejection of feed solution ions for almost all draw solution concentrations except when operated at low ammonium sulphate concentration and high feed solution concentration. In conclusion, ammonium sulphate is an efficient draw solution for FDFO process when run at water flux more than 10 L/m²/h exhibiting high osmotic pressure, low reverse solute permeation and high rejection of feed solute.     

Long-term exposure of bacterial and protozoan communities to TiO2 nanoparticles in an aerobic-sequencing batch reactor

Abstract

Titanium dioxide (TiO₂) nanopowders at different concentrations (0–50 mg L^?1) were injected into an aerobic-sequencing batch reactor (SBR) to investigate the effects of long-term exposure to nanoparticles on bacterial and protozoan communities. The detection of nanoparticles in the bioflocs was analyzed by scanning electron microscopy, transmission electron microscopy, and energy-dispersive x-ray spectroscopy. The SBR wastewater experiments were conducted under the influence of ultraviolet light with photocatalytic TiO₂. The intrusion of TiO₂ nanoparticles was found both on the surface and inside of the bioflocs. The change of microbial population in terms of mixed liquor-suspended solids and the sludge volume index was monitored. The TiO₂ nanoparticles tentatively exerted an adverse effect on the microbial population, causing the reduction of microorganisms (both bacteria and protozoa) in the SBR. The respiration inhibition rate of the bacteria was increased, and the viability of the microbial population was reduced at the high concentration (50 mg L^?1) of TiO₂. The decreasing number of protozoa in the presence of TiO₂ nanoparticles during 20 days of treatment with 0.5 and 1.0 mg L^?1 TiO₂ is clearly demonstrated. The measured chemical oxygen demand (COD) in the effluent tends to increase with a long-term operation. The increase of COD in the system suggests a decrease in the efficiency of the wastewater treatment plant. However, the SBR can effectively remove the TiO₂ nanoparticles (up to 50 mg L^?1) from the effluent.     

Sorption, diffusion, and pervaporation characteristics of dimethylformamide/water mixtures using sodium alginate/polyvinyl pyrrolidone blend membranes

Separation of aqueous dimethylformamide (DMF) solutions in the concentration range of 0-100 wt% were studied using sodium alginate (NaAlg)/polyvinyl pyrrolidone (PVP) blend membranes. The NaAlg was blended in different ratios with PVP. Prepared membranes were crosslinked with CaCl₂ for testing in pervaporation (PV) separation of DMF/water mixtures. Effects of feed composition (0-100 wt%), operating temperature (30-50 °C), and membrane thickness were investigated. Best results were obtained at the conditions of 75/25 NaAlg/PVP blend ratio (w/w), 40 °C temperature, 20 wt% DMF concentration, and 70 μm membrane thickness. Blending of PVP with NaAlg increased permeation flux whereas it decreased the separation factor. NaAlg/PVP membranes gave separation factors of 5.5-27 for permeation flux of 0.96-1.81 kg/m²h depending on the operating temperature and the feed mixture composition. Arrhenius plot of permeation flux data versus reciprocal of temperature exhibited linear trends. Permeation activation energy of DMF and water in the PV was calculated as 6.76 and 1.88 kcal/mol, respectively, using an Arrhenius type relationship. Sorption-diffusion properties of the NaAlg/PVP membranes were also investigated at the operating temperature and the feed composition.     

Crystallinity enhancement of flame-made LiCo0.25Ni0.75O2 nanoparticles by heat-treatment

LiCo_0.25Ni_0.75O₂ nanoparticles of 22.8 nm in geometric mean diameter were synthesized by flame spray pyrolysis from aqueous droplets of nitrate compounds of lithium, cobalt and nickel. The crystallinity of the as-prepared LiCo_0.25Ni_0.75O₂ particles was enhanced by post-heat-treatment at various conditions, such as temperature, duration, and atmospheric gas with different flow rates. The effect of heat-treatment on the particle morphology and crystallinity was investigated systematically. Higher heat-treating temperature under normal air atmosphere improved hexagonal ordering and sufficient O₂ flow during the heat-treatment reduced the cation mixing problem.     

Solute effects on solvent electromigration in dilute alloys

The effects of a small concentration of solute on solvent electromigration are due to an enhancement effect of the solute atoms on the solvent diffusivity (which gives rise to the factor b′) and a ”vacancy flow effect” proportional to the flux of solute and to the term L_AB/L_BB. The theoretical expressions of b′ and L_AB/L_BB are given for f.c.c. and b.c.c. alloys. This dependence of solvent electromigration on the solute concentration can be combines with the solute diffusivity and solvent-enhanced diffusion to determine the various vacancy jump frequency ratios in binary dilute alloys.The validity and the interest of this new method are illustrated by the first experiments, performed on $\text{Ag}$Zn, $\text{Ag}$Cd and $\text{Al}$Cu.     

Micellar enhanced ultrafiltration of eosin dye using hexadecyl pyridinium chloride

Surfactant-based separation of toxic eosin dye is studied to estimate the potential of micellar enhanced ultrafiltration (MEUF) using cetyl(hexadecyl) pyridinium chloride (CPC) as the cationic surfactant. The optimum feed CPC concentration is found from the experimental results of pure CPC solution in a batch cell. It is in the range of 10-20 kg/m(3) to have a reasonable permeate flux and lower surfactant concentration in the permeate. Selecting 10 kg/m(3) as the feed surfactant concentration, MEUF experiments are conducted to study the retention characteristics of eosin dye in the continuous cross flow system. The effects of operating conditions, i.e., feed dye concentration, operating pressure and cross flow rate on the permeate flux and observed retention of dye are investigated.