Study on the Effectiveness of Simultaneous Recovery and Concentration of 1-Ethyl-3-methylimidazolium Chloride Ionic Liquid by Electrodialysis with Heterogeneous Ion-Exchange Membranes

Due to the extensive range of ionic liquids (ILs) used in industry, an efficient recovery method is needed. In this study, the effectiveness of a simultaneous concentration and recovery method was investigated for 1-ethyl-3-methylimidazolium chloride ([Emim]Cl), an IL that was recovered using electrodialysis (ED). The optimal operational parameters for electrodialytic recovery were determined empirically. The variables that were investigated included the concentration of IL, applied voltage, linear flow velocity and the diluate-to-concentrate volume ratio. The recovery of [Emim]Cl, the concentration degree, the [Emim]Cl flux across membranes, the current efficiency, as well as the energy consumption were determined. The results of the experiments confirmed that [Emim]Cl concentration and recovery can be achieved using ED. The highest ED efficiency was obtained when a 2 V electric potential per one membrane pair was applied, using a 2 cm/s linear flow velocity, and by adjusting to 0.2 M IL in the feed solution. By using ED, a 2.35-fold concentration of [Emim]Cl with a recovery of 90.4% could be achieved when the diluate-to-concentrate volume ratio was 2. On the other hand, a 3.35-fold concentration of [Emim]Cl with a recovery of 81.7% could be obtained when the diluate-to-concentrate volume ratio was increased to 5.

Flow velocity and cell pair number effect on current efficiency in plating wastewater treatment through electrodialysis

Electrodialysis has been used for treating toxic substances such as heavy metals and minimizing secondary environmental pollution problems effectively. However, electrodialysis depends on the operating parameters as well as fluid dynamics and electrical properties. This study provides design elements for the treatment of heavy metal-containing wastewater by electrodialysis. We found that the limiting current density (LCD) is proportional but not completely linear to the diluate concentration over a threshold value. In contrast, it is linear to the linear flow velocity for the whole range. As the number of cell pairs increases, because linear flow velocity and LCD increase, the removal efficiency of heavy metals also increases. Therefore, for highly concentrated wastewater, increasing the linear flow velocity, the applied voltage, and the number of cell pairs can effectively improve removal efficiency. It was found that the current efficiency is as low as 17% when the removal efficiency of heavy metals exceeds 95%. Thus, it is necessary to select an operating range that optimizes the operating and initial investment costs for the effective removal of heavy metals using electrodialysis.

Significance of Brownian Motion for Nanoparticle and Virus Capture in Nanocellulose-Based Filter Paper

Pressure-dependent breakthrough of nanobioparticles in filtration was observed and it was related to depend on both convective forces due to flow and diffusion as a result of Brownian motion. The aim of this work was to investigate the significance of Brownian motion on nanoparticle and virus capture in a nanocellulose-based virus removal filter paper through theoretical modeling and filtration experiments. Local flow velocities in the pores of the filter paper were modeled through two different approaches (i.e., with the Hagen–Poiseuille equation) and by evaluating the superficial linear flow velocity through the filter. Simulations by solving the Langevin equation for 5 nm gold particles and 28 nm ΦX174 bacteriophages showed that hydrodynamic constraint is favored for larger particles. Filtration of gold nanoparticles showed no difference in retention for the investigated fluxes, as predicted by the modeling of local flow velocities. Filtration of ΦX174 bacteriophages exhibited a higher retention at higher filtration pressure, which was predicted to some extent by the Hagen–Poiseuille equation but not by evaluation of the superficial linear velocity. In all, the hydrodynamic theory was shown able to explain some of the observations during filtration.

Evaluation of systemic circulation at laparoscopic surgery for ectopic pregnancy

Aim. To study the effect of tension carboxyperitoneum on central circulatory parameters of patients undergoing laparoscopy.Methods. Vascular wall condition, linear blood flow velocity, pulse wave velocity, vascular wall rigidity, general and specific peripheral resistance (by the method of volumetric compression oscillometry) were evaluated. The study included patients with tubal pregnancy undergoing endovideosurgery. In the first group, 76 patients, the operation was performed without introducing carbon dioxide into the abdominal cavity; operational volume has been created using the original retractor of the anterior abdominal wall. In the second group (67 patients), classical technique of laparoscopic surgery with the use of carboxyperitoneum was applied. Measurements of systemic circulatory parameters were performed in patients twice - in the group where no gas was used - before and 15 minutes after introducing laparoscopic devices, in the group of carboxyperitoneum - before and 15 minutes after carbon dioxide introduction.Results. The changes of systemic circulatory parameters were non-significant in patients of the first group and did not lead to statistically significant changes of mean, lateral and systolic blood pressure. Endovideosurgery using carboxyperitoneum lead to systemic circulatory disorders: blood pressure instability, increased cardiac output and index, decreased total peripheral vascular resistance, and the actual and specific peripheral resistance, as well as linear flow velocity and vascular rigidity.Conclusion. Laparoscopic surgery using carbon dioxide are associated with the vessel compression and increased heart load, clinically manifesting as blood pressure disorders.

Synergy of hydromechanical and hydrochemical parameters in formation of solid deposits in geothermal and other waters

This paper deals with synchronised influences of hydromechanical and hidrochemical parameters on the formation of solid deposits in geothermal and other waters which compose complex heterogeneous and micro-heterogeneous system of liquid-solid. Constituents of these waters in ionic, colloidal and micro-heterogeneous suspended state of liquid-solid are responsible for the creation of the carbonates, sulphates and other solid matters. In these processes one cannot eliminate the influence of hydromechanical parameters with flow velocity and water flow criteria (laminar or turbulent flow) as vital factors. Experiments were conducted on the laboratory pilot installation with glass pipes diameter of 2, 4, 6, 8 and 10 mm respectively, and the flow was monitored by means of digital peristaltic pump with the flow rate of 2 ml/min to 5000 ml/min. The paper gives the results of the investigation of the impact of the linear flow velocity on the relative decrease of the initial water hardness in geothermal waters of Sijarinska Banja spa, Niska Banja spa and the estuary water of Medijana, Nis. From the obtained dependences, according to the linear regression model, for each diameter critical values for linear velocities as an important parameter for the understanding of the synergism of the hydromechanical and hydrochemical parameters were determined.

Determination of limiting current density for different electrodialysis modules

Limiting current density of ammonium nitrate solution in laboratory-, pilot-, and industrial-scale electrodialysis modules were determined to provide a method for the prediction of the limiting current density of ammonium nitrate solutions at any conditions. The current-voltage curve was measured in each case and the limiting current density was evaluated using the dependence of the derivative, dI/dU, on the electric current, I. The limiting current was determined as a current at which the derivative dI/dU equals zero. The developed method enables not only the prediction of the limiting current density but the limiting cut and limiting flux can be determined concurrently at any linear flow velocity of the diluate and inlet ammonium nitrate concentration. It could help to prevent working in the overlimiting region and to avoid undesirable decrease of current efficiency and pH changes. The limiting cut is the maximal cut that can be obtained at certain linear flow velocity and module geometry irrespective of the inlet ammonium nitrate concentration and it is very useful information when designing a new electrodialysis unit for specific application.