Phosphate removal from aqueous solution by Donnan dialysis with anion-exchange membrane

The removal of phosphate from aqueous solution by Donnan dialysis with anion-exchange membrane was investigated.The results show that phosphate could be removed from aqueous solution without supplying external high pressure or electrical potential.Under the conditions of influent phosphate of 2.0 mg/L,counterion(Cl-)concentration of 0.1 mol/L,stirring speed of 500 r/min and phase temperature of 298 K,the removal of phosphate achieves 70.0%.Decreasing counterion concentration has little influence on the removal of phosphate,but phosphate amount in anion-exchange membrane increases significantly.With the increase of stirring speed and phase temperature,the removal efficiency of phosphate greatly is improved.Existing forms of phosphate in aqueous solution affected transport of phosphate and only strong acidic pH of feed solution(pH=3.0)decreases the removal of phosphate.Transport of phosphate is also accompanied by change of pH value of feed solution.In consequence,it might be a promise potential process for phosphate advanced wastewater treatment,especially in the area where high salted nature water can be utilized.

One-Step Fabrication of Methylthiazole-Functionalized Anion Exchange Membranes for Diffusion Dialysis

Anion exchange membranesusing brominated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) as starting material were prepared from one-step functionalization by 4-methylthiazole (MTz). The obtain membranes with high thermal stability and mechanical strength showed satisfied diffusion dialysis performance for acid recovery. Specifically, when the optimal membrane was evaluated to recover acid from the simulated iron polishing waste solution (1.0 mol·L-1 FeCl2 + 0.2 mol·L-1 HCl), its acid diffusion coefficient (UH+) was 0.019 m h-1 and separation factor was 40.1 at 25°C, both of these two parameters are much higher than the corresponding values of the commercial DF-120 membrane, suggesting the great potential in the practical application for acid recovery.

Study of Dialyzer Membrane (Polyflux 210H) and Effects of Different Parameters on Dialysis Performance

Problems frequently encountered in kidney malfunction include abnormal fluid levels in the body, increased acid levels, abnormal levels of Urea, Glucose, Endothelin, β2-Microglobulin and Complement Factor D. Parameters characterizing the structure of dialyzers are very important because they decide overall clearance of toxin molecules and at the same time should allow retaining useful molecules in the blood. In this paper, a cross sectional image of the dialyzer membrane with details of the porosity is presented. A multilayered membrane model with different porosity for each layer, describes the actual structure of Polyflux 210H membrane. This model is developed using Finite Element Software—COMSOL Multiphysics 4.3. A blood flow with substances like—Urea, Glucose, Endothelin, β2-Microglobulin, Complement Factor D and Albumin is introduced. For a certain blood flow rate, the toxins diffuse through the membrane and on the other side of the membrane a dialysate flow removes the toxins. Here, different parameters, such as flow rate of blood and dialysate, length and radius of the fiber are changed to simulate how these changes affect toxin clearance and the removal of useful molecules.

Two dimensional MoS_(2) finding its way towards constructing high-performance alkaline recovery membranes

The available alkaline recovery membranes are currently dominated by polymeric materials,but they suffer from a permeation-selectivity trade-off and inferior chemical resistance.Robust two dimensional(2D) lamellar membranes with sub-nanometer wide channels are promising candidates for discerning OH^(-)and other anions.Here,we report the development of alkaline recycling membranes through stacking MoS_(2) nanosheets.Benefiting from the ordered and narrow 2D channels,MoS_(2) membranes show excellent alkaline recovery performances.The OH^(-)dialysis coefficient (U_(OH)-) and separation factor (S)towards simulated OH^(-) and WO_(4)^(2-) across the 500 nm thick MoS_(2) laminates reach 6.9×10^(-3)m·h^(-1)and 34.3 respectively.Furthermore,the chemical environments of MoS_(2) laminates were modulated by intercalating ionic poly(sodium 4-styrene sulfonate)(PSS@MoS_(2)).The U_(OH)-and S values of PSS@MoS_(2) membrane further improve to 11.7×10^(-3)m·h^(-1)and 49.8 respectively.Besides,both MoS_(2) and PSS@MoS_(2) membranes exhibit promising stability.

ACID RECOVERY FROM WASTE SULFURIC ACID BY DIFFUSION DIALYSIS

In the process of sulfuric acid production from pyrite, there is a lot of waste acid produced in fume washing with dilute acid. Acid recovery from this sort of waste sulfuric acid by diffusion dialysis is studied in the paper. The mass transfer dialysis coefficient of sulfuric acid of the membrane AFX is measured, the effect of the flowrate of the feed and ratio of feed to water is investigated, and the two kinds of membrane (AFX and S203) are compared. The results show that diffusion dialysis process can separate the metal cation from sulfuric acid effectively, but it is difficult to separate non cation impurities as As - and F -. The contrast tests of the two membranes show that the dialysis mass transfer coefficient of the membrane AFX is larger, while capacity of the removing impurities of membrane S203 is somewhat better.

STUDY ON THE DIFFUSION OF Cu^(2+)-H^+ COUPLE IN A CATION EXCHANGE MEMBRANE——A RAPID METHOD TO DETERMINE SELF-DIFFUSION COEFFICIENTS OF COUNTER-IONS WITH UNEQUAL VALENCE

1 INTRODUCTIONKnowledge of the basic transport phenomena of ions in an ion exchange membrane isimportant for the application of such a membrane.Various studies on the developmentof mathematical models for predicting and correlating membrane transport rate havebeen published in recent years.More exact estimation of the diffusion coefficientshas been the subject of chief concern in many of these papers.For a bi-ionic systemwith the same valence,Sato et al.gave a method for estimating diffusion coefficients

Extended adsorption transport models for permeation of copper ions through nanocomposite chitosan/polyvinyl alcohol thin affinity membranes

Transport of copper ions through nanocomposite chitosan/polyvinyl alcohol thin adsorptive membranes has been mathematically investigated in the current study. Unsteady-state diffusive transport model was coupled with the Freundlich isotherm to predict the concentration of the ions in dialysis permeation operation. Pristine model was not successful in predicting the experimental data based upon its low coefficients of determination（0.1

A NEW PRODUCTION METHOD OF AMMONIUM METATUNGSTATE—DONNAN DIALYSIS METHOD

A new method for production of ammonium metatungstate (AMT) directly from ammonium tungstate solution—Donnan dialysis method is advanced. Laboratory experiments are conducted by a Donnan dialysis cell with the membrane area of 140 mm×200 mm. The result shows that the transformation rate of AMT reaches 370 g WO 3/(m 2·h), the recovery ratio of AMT by the Donnan dialysis method is nearly 100%, and the loss of tungsten is less than 0.2%. It has been proved that the Donnan dialysis method is effective for production of AMT.

A RAPID METHOD TO DETERMINE DIFFUSION COEFFICIENTS OF COUNTER-IONS IN AN ION-EXCHANGE MEMBRANE

1 INTRODUCTIONRapid and precise methods to obtain the diffusion coefficients of counter-ions are im-portant for the characterization of ion exchange membranes.Many theoreticaldescriptions of ion transport in ion exchange membranes have been developed by usingthe principles of irreversible thermodynamics,or the Nernst-Planck equations.Fick’s law can also be used for the description of the transport of ions with equaldiffusivity.However,for counter-ions of different diffusivities,Nerst-Planck

Donnan Dialysis Removal of Nitrate from Water: Effects of Process Parameters

Excess or lack of levels of nitrate in drinking water is harmful to the human health, the concentration of NO-3 ions must be maintained at 50 mg/l. Donnan dialysis (DD) used as a driving force of the concentration gradient is an effective and simple technique for nitrate removal. In this paper, the transport of nitrate through an AMX anion-exchange membrane has been studied as a function of driving ion nature, receiver phase concentration, flow rate, temperature and agitation rate under Donnan dialysis condition. It was observed that the hydrodynamic conditions and temperature were the main variables affecting the transmembrane flow. As the driving ion, the chloride ion is more efficient than the hydrogeneocarbonate ion. The systematic study of the different parameters involved showed that the nitrate removal efficiency obtained with a feed synthetic nitrate solution (62 ppm) was off 96%. This efficiency slightly decreases for a tap water containing the same nitrate concentration;it was about 84%. This can be attributed to the complex ionic composition of the natural water.

Application of Donnan Dialysis Coupled to Adsorption onto Activated Alumina for Chromium (VI) Removal

The aim of this paper is the assessment of Donnan dialysis coupled to adsorption process for the removal of chromium from aqueous solutions. This study was conducted in order to benefit from each process, and it was an original and new combination. The coupling was a solution to improve the contact time and the amount of chromium (VI) removed. The coupling was successfully performed with 90% of chromium (VI) removed after 6 hours.

Optimization of Chromium (Vi) Removal by Donnan Dialysis

The removal of chromium (VI) from aqueous solutions by Donnan dialysis has been investigated in this paper. In this process, two anion-exchange membranes (AEMs) were used: Selemion? AMV and Neosepta? AFN. The amount of chromium (VI) removed was determined in terms of the following parameters: initial concentration of chromium (VI), type of anion-exchange membrane, concentration of counter-ion and magnetic stirring rate. A 24 full factorial design analysis was performed to screen the parameters affecting the Cr (VI) removal efficiency. Using the experimental results, a linear mathematical model representing the influence of the different parameters as well as their interactions was obtained. Analysis of the variance (ANOVA), the F-test and the student’s test shows that the type of anion-exchange membrane is the most significant parameter affecting the chromium (VI) removal. The statistical analysis of the experimental data assumes it to be a normal distribution.

Peritoneal Membrane Transport Characteristics in Uni-PET with Preceding Icodextrin Dwell as Compared to Classic PET with Preceding Glucose Dwell: A Prospective Study

Background: In subjects on CAPD who use icodextrin for long night dwell, it has been recommended that nocturnal exchange be replaced by dextrose dwell whenever PET is to be performed as preceding exchange with icodextrin temporarily increases peritoneal membrane permeability and therefore, gives high D/PCr and low D/D0 glucose values. Whether this temporary change is also seen with use of Uni-PET (which involves one hour dwell of 1.5% dextrose followed by 4-hour dwell of 4.25% dextrose) is not known. Methods: In this self, controlled study, subjects on CAPD, who were using icodextrin for long nocturnal dwell for at least 3 months, were screened for enrolment. Pregnancy or lactation, history of any PD related infectious complication in the past one month, present or past malignancy, and poor functional status were exclusion criteria. Enrolled subjects underwent classic PET with preceding 2.5% dextrose long nocturnal dwell on day 1 followed by Uni-PET with preceding 7.5% icodextrin long nocturnal dwell on day 2. Difference in D/PCr and D/D0 glucose between the two PETs was primary objectives. The study was approved by Institute Ethics Committee. Results: 15 out of 26 screened subjects were enrolled over a period of 18 months (July 2015-December 2016). The mean (±SD) age of study population was 60.8±9.1 years. Majority were males and diabetes was the most common cause of CKD. Mean D/PCr were 0.68 ± 0.11 and 0.64 ± 0.08 in classic PET and Uni-PET, respectively. The difference between the two values was not significant [mean difference between D/PCr (classic PET-Uni-PET): 0.040 ± 0.86;95% CI (-0.007 to 0.088);p = 0.09]. Similarly, D/D0 glucose between classic PET and Uni-PET was also similar [mean difference between D/D0 glucose (classic PET-Uni-PET): -0.02 ± 0.09;95% CI (-0.06 to 0.03);p = 0.448]. Conclusion: Peritoneal membrane small solute transport characteristics in Uni-PET with preceding icodextrin dwell are similar to classic PET with preceding glucose dwell. If Uni-PET is used, it may not be necessary to replace preceding nocturnal exchange of icodextrin with that of dextrose as is currently advised.

基线腹膜转运特性对CAPD患者腹膜蛋白丢失、生存率及腹膜炎发生率的影响

目的:观察基线腹膜转运特性对持续不卧床腹膜透析(CAPD)患者腹膜蛋白丢失、腹膜炎发生率及生存率的影响。方法:回顾性分析2014年01月—2021年01月在我院行腹膜透析手术并规律CAPD治疗≥1年的91例患者作为研究对象,根据术后首次的腹膜平衡试验(PET)结果,将患者分为4组:高转运组(H)、高平均转运组(HA)、低平均转运组(LA)及低转运组(L),比较各组腹膜蛋白清除率(PrC)及腹膜炎发生率,分析终末期肾脏病(ESRD)不同原发病与其基线腹膜转运特性之间的关系。Kaplan-Meier生存曲线比较HT组(H和HA)和LT组(LA和L)患者的生存情况。结果:PrC水平在H、HA、LA及L四组间存在显著差异,H组的PrC水平显著高于HA、LA及L组,而其血清白蛋白水平显著低于其余三组(P<0.05)。不同ESRD原发病的患者,其基线腹膜转运特性也存在差异,糖尿病肾病患者的基线腹膜转运特性多为HA及H,而慢性肾小球肾炎患者的基线腹膜转运特性多为LA及HA。腹膜炎发生率及生存率在HT组和LT组差异无统计学意义(P>0.05)。结论:ESRD原发病不同可影响其基线腹膜转运特性的分布,不同基线腹膜转运特性PD患者间PrC水平存在显著差异,腹膜高转运特性的患者多伴有高的PrC水平和低的血白蛋白水平,而腹膜转运特性对CAPD患者的腹膜炎发生率及生存率无显著影响。

扩散渗析法回收废铅膏电解液中硫酸的实验研究

工业废旧铅蓄电池电解产生的酸性废水中含有大量硫酸,对其中的硫酸进行回收利用。以工业废铅膏为原料进行固相电解,产生硫酸浓度约20 g/L的废酸。采用7171阴离子交换膜,通过扩散渗析法对废铅膏电解液中的硫酸进行回收,两段酸回收率约75.2%。根据废铅膏电解液杂质含量情况,选择钠离子对硫酸的回收进行实验分析,结果表明酸的浓度不同,钠离子的浓度变化不同;钠离子扩散渗析是一个独立的过程,与溶液的酸浓度无关,只与自身的浓度差有关;硫酸的扩散渗析过程与溶液的硫酸浓度有关。扩散渗析模拟实验验证了扩散渗析能有效的回收硫酸。

钠-葡萄糖协同转运蛋白2抑制剂在腹膜透析中的研究及应用前景

钠-葡萄糖协同转运蛋白2抑制剂(SGLT2i)作为一种新型口服降糖药,对2型糖尿病或非糖尿病患者都表现出良好的心肾保护作用,并可改善慢性肾脏病患者的心肾结局。虽然目前临床试验已将纳入人群的估算肾小球滤过率(eGFR)扩展至更低水平,但仍排除了eGFR<20 mL/(min·1.73 m 2)的患者,SGLT2i的心肾保护作用能否延续至维持性透析期是临床关注的重点。此外,SGLT2i的抗炎和抗纤维化作用可能对腹膜透析(PD)患者维持腹膜功能有益。因此,SGLT2i在PD患者中的应用值得进一步探索。

Proteomic study provides new clues for complications of hemodialysis caused by dialysis membrane

The complications of hemodialysis accompanied the hemodialysis and threaten the patients’life.Besides the loss of nutrient substance,such as amino acid and vitamin,we found new clues that the adsorbed proteins on common-used polysulfone-based dialysis membrane might be the reason according to the qualitative proteomic study by ionic liquid assisted sample preparation method.Our results indicated that the adsorbed proteins on the membrane were related with complement activation,blood coagulation,and leukocyte-related biological process.The quantitative proteome further demonstrated some significant changes of signal proteins in the post-dialysis plasma after the hemodialysis,such as beta-2-microglobulin and platelet factor-4,which would further verify these new clues.

基于道南渗析去除水中亚硝酸盐的实验研究

亚硝酸盐是自然界中氮循环产物中毒性较大的一种存在形式。道南渗析是一种通过浓度梯度驱动的选择性膜过程,具有操作方便,能耗低等优点。目前国内外基于道南渗析技术去除亚硝酸盐的方法鲜有报道。通过研究使用AMX阴离子交换膜来去除污水中的NO_(2)^(-)离子,开展单因素实验,探讨接受侧驱动离子的种类、驱动离子与NO_(2)^(-)离子质量比、渗析环境的温度以及pH值对渗析效果的影响。通过实验得出:使用AMX阴离子交换膜、选用Cl^(-)离子作为驱动离子、温度为35℃、NaNO_(2)质量浓度为12.5 mg/L、溶液pH值=7时具有较高的去除效果。这表明利用道南渗析法去除废水中的亚硝酸盐具有潜在的应用前景。

以低浓度废酸驱动中和渗析脱盐的模拟与验证

低浓度废酸的资源化长期困扰着相关涉酸工艺。基于Donnan渗析原理,提出以低浓度废酸驱动中和渗析地表水脱盐,借助模拟和实验来探索耦合工艺的可行性。首先,基于Nernst-Planck、Navier-Stokes方程和电中性条件,面向中和渗析过程数学建模,研究废酸浓度对脱盐率、脱盐速度和体系pH等脱盐效果的影响。模拟结果表明,常规低浓度废酸(pH=0.5~2)足以有效驱动中和渗析脱盐过程,且提高酸浓度也未得到明显强化。进而,以均相或异相离子交换膜构建中和渗析膜堆,开展条件实验,获得了系列与模拟结果相吻合的实验规律。实验也表明,对于高浓度废酸,异相膜较显著的同离子泄漏现象会严重劣化脱盐效率。综合研究表明,耦合新工艺有望为低浓度废酸的资源化开辟新途径。

类紫杉醇脂质体体外释放的桨膜结合分析法研究

体外释放度是评价脂质体制剂质量的重要指标,目前各国药典中均未收载脂质体体外释放度评价方法,致使脂质体质量评价缺乏统一标准和无法提供安全性保障。本研究以自制类紫杉醇脂质体为例,通过优化外部释放条件建立的桨膜结合法模拟了在生理条件下类紫杉醇药物12 h的释放情况,结果表明以0.5%SDS-HEPES作为释放介质,采用截留分子量为1000 kD的透析袋对脂质体水溶液进行释放的结果满足要求,且具有区分能力,为载药脂质体体外释放方法开发提供参考。