Salty water desalination using carbon nanotube sheets
Desalination 258 (2010) 182?186
Maryam Ahmadzadeh Tofighy, Toraj Mohammadi
Research Centre for Membrane Separation Processes, Faculty of Chemical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran, Iran
In this paper, an actual experiment (not molecular dynamics simulation) was performed to investigate desalination using carbon nanotube (CNT) sheets. The sheets were used as adsorbents for removing salt from water.
CNT sheets were synthesized through the method of chemical vapor deposition. In the CVD method, ferrocene is dissolved in cyclohexanol with N2 at 7500C to produce as-synthesized CNT sheets. The resulting product was then oxidized with concentrated nitric acid at room temperature (oxidized CNT sheets). Afterwards, adsorption experiments were done by soaking 100 mg of the produced CNT sheets in 25 mL of NaCl solutions at room temp.
The study looked at the effects of adsorption time and initial salt concentration on the desalination performance of the CNT sheets. It was found that for as-synthesized CNT sheets, pH of the NaCl solution increases upon adsorption of Na+, signifying that as-synthesized sheets have more basic functional groups. On the other hand, upon oxidation, the basic functional groups of the CNT sheets were replaced with acidic ones. Effect of adsorption time on conductivity was also shown. Moreover, it was found that both Langmuir and Freundlich isotherm models matched the experimental data very well. Overall, the study was able to show the feasibility of using oxidized CNT sheets as adsorbents because of their high adsorption capacity and because they will not cause CNT leakage (i.e., problem regarding the removal of CNT from the treated water).
Contribution and application:
This study was able to show another use of CNTs for desalination, other than as a membrane for processes like RO, NF, and FO. This study was also helpful in order to connect simulations to the real world (i.e., how to fabricate actual CNTs, etc.)
By: Hannah Ebro