scholarly journals Engineering Water and Solute Dynamics and Maximal Use of CNT Surface Area for Efficient Water Desalination

ACS Omega ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 6826-6847 ◽  
Author(s):  
Asieh Sadat Kazemi ◽  
Ali Akbar Noroozi ◽  
Anousha Khamsavi ◽  
Ali Mazaheri ◽  
Seiyed Mossa Hosseini ◽  
...  
Author(s):  
Abdelkarim Maamar Abdelkader, Bounegta Bachir Mohammed

Algeria, like many countries belonging mostly to the Third World, has considerable water resources saline (salt content ranging between 1500 and 2000 ppm, exceeding the required standards for drinking water and therefore unfit for consumption). We must therefore think of making use these huge reserves interested in desalination techniques. The stain majored is therefore to achieve a distiller solar plan which meets these needs in drinking water. The absorber surface of the modified solar still is coated with black enamel paint and covered with copper chips. The evaporation rate of the water in the solar still is directly proportional to the exposure area of the water. Thus the productivity of the solar still increases with the free surface area of the water in the basin. The distillate yield was found to have improved considerably, especially when the water depth was high. The study also indicated some design features that would further enhance the improvement in output due to the modification made, the evaporation rate is proportional to the temperature of the free surface area of the water only. A general model based on heat transfer balances in each component of the system was developed to predict the mass of freshwater. The efficiency of this still was about 65% and can produce about 5.13 l/m2 per day, experimental studies and the outcomes are discussed in the article. We propose a new design of the cascading solar desalination still with obstacles and preheating of inlet water.


2018 ◽  
Vol 124 (11) ◽  
Author(s):  
Javad Eslami ◽  
Yaser Abdi ◽  
Anousha Khamsavi ◽  
Zahra EbrahimNataj ◽  
Asieh S. Kazemi

2020 ◽  
Author(s):  
Ashish Karn ◽  
Jonathan Ambs ◽  
Shashank Singh Deo ◽  
Ayush Vyas ◽  
Ayush Dwivedi ◽  
...  

Enhancing evaporation rates are of great practical interest in many technological applications such as water desalination or drying in industry. Since the conventional methods of increasing evaporation viz. increasing temperature, surface area etc. may not be always practically feasible or economical, novel methods of evaporation enhancement are necessary. The current study explores the possibility of evaporation enhancement by introducing a Tetrafluoroethane gas ambient under different conditions of heating and circulation. Depending upon the temperature and circulation conditions, as enhancement of 58 to 375% in evaporation rate has been measured and physical explanations into the underlying mechanism have been suggested.


Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4932
Author(s):  
Gabriela Hristea ◽  
Mihai Iordoc ◽  
Andreea Culcea

The relative performance of different porous solids in different applications is highly dependent on the internal pore structure of each material. Highly porous carbon materials can be prepared by evaporative drying and the pyrolysis of resorcinol-formaldehyde gels. By determining the correct synthesis parameters, the pore system of such materials can be reshaped. Depending on some important processing factors such as the dilution ratio or the initial pH of the precursor solution, various porous or non-porous carbon materials can be synthesized. This paper addresses carbon xerogels (CX) designed as a material electrode in capacitive deionization (CDI) systems for water desalination. In this work CX materials were synthesized via poly-condensation reactions of resorcinol with formaldehyde (RF) on a carbon felt sheet followed by pyrolysis. The resulting sheets were used as electrodes to develop a CDI experimental multi-cell laboratory system. The initial pH of the RF solution and the dilution ratio effect on the resulting carbon surface area and structure were analyzed. Surface area measurements using the BET method and an electrochemical capacitance evaluation of the obtained xerogels through electrochemical impedance spectroscopy were also performed. Finally, using our experimental CDI multi-cell laboratory system based on the obtained CX, we discuss the experimental data for the desalination rate as a function of the voltage and salt concentration. As a result, the developed model’s efficiency is demonstrated. The main goal of this work was to develop an efficient electrode-based novel carbon that could be commercially competitive, as well as to create guidelines for future desalination research using CX electrode materials.


Author(s):  
Dengsong Zhang ◽  
Liyi Shil ◽  
Jianhui Fang ◽  
Kai Dai

Modified multiwall carbon nanotubes (MWCNTs) were used as the electrodes of flow–through capacitor for the desalination, which were cost–cutting, energy–saving, and enviromnent–friendly and could be expected to be an altemative technology for reverse osmosis membrane for sea water desalination. Investigated by transmission electron microscope (TEM) and nitrogen adsorption/desorption for modified MWCNTs, it was confirmed that after modification treatment by immersion in diluted HNO3 solution with ultrasonic and then milling by ball at a high velocity, the metal catalyst particles at the tip of MWCNTs disappeared, the MWCNT length became short, the cap at the tip of nanotube was opened, the internal surface area could be effectively used, leading to the increase of the specific surface area and pore volume, and thus MWCNTs modified by that method had the best desalination performance. This modification technique is simple and the efficiency is high.


Author(s):  
A. Legrouri

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.


Author(s):  
M. Marko ◽  
A. Leith ◽  
D. Parsons

The use of serial sections and computer-based 3-D reconstruction techniques affords an opportunity not only to visualize the shape and distribution of the structures being studied, but also to determine their volumes and surface areas. Up until now, this has been done using serial ultrathin sections.The serial-section approach differs from the stereo logical methods of Weibel in that it is based on the Information from a set of single, complete cells (or organelles) rather than on a random 2-dimensional sampling of a population of cells. Because of this, it can more easily provide absolute values of volume and surface area, especially for highly-complex structures. It also allows study of individual variation among the cells, and study of structures which occur only infrequently.We have developed a system for 3-D reconstruction of objects from stereo-pair electron micrographs of thick specimens.


1996 ◽  
Vol 76 (05) ◽  
pp. 682-688 ◽  
Author(s):  
Jos P J Wester ◽  
Harold W de Valk ◽  
Karel H Nieuwenhuis ◽  
Catherine B Brouwer ◽  
Yolanda van der Graaf ◽  
...  

Summary Objective: Identification of risk factors for bleeding and prospective evaluation of two bleeding risk scores in the treatment of acute venous thromboembolism. Design: Secondary analysis of a prospective, randomized, assessor-blind, multicenter clinical trial. Setting: One university and 2 regional teaching hospitals. Patients: 188 patients treated with heparin or danaparoid for acute venous thromboembolism. Measurements: The presenting clinical features, the doses of the drugs, and the anticoagulant responses were analyzed using univariate and multivariate logistic regression analysis in order to evaluate prognostic factors for bleeding. In addition, the recently developed Utrecht bleeding risk score and Landefeld bleeding risk index were evaluated prospectively. Results: Major bleeding occurred in 4 patients (2.1%) and minor bleeding in 101 patients (53.7%). For all (major and minor combined) bleeding, body surface area ≤2 m2 (odds ratio 2.3, 95% Cl 1.2-4.4; p = 0.01), and malignancy (odds ratio 2.4, 95% Cl 1.1-4.9; p = 0.02) were confirmed to be independent risk factors. An increased treatment-related risk of bleeding was observed in patients treated with high doses of heparin, independent of the concomitant activated partial thromboplastin time ratios. Both bleeding risk scores had low diagnostic value for bleeding in this sample of mainly minor bleeders. Conclusions: A small body surface area and malignancy were associated with a higher frequency of bleeding. The bleeding risk scores merely offer the clinician a general estimation of the risk of bleeding. In patients with a small body surface area or in patients with malignancy, it may be of interest to study whether limited dose reduction of the anticoagulant drug may cause less bleeding without affecting efficacy.


Sign in / Sign up

Export Citation Format

Share Document