Plasma Treated Active Carbon for Capacitive Deionization of Saline Water

Aiping Zeng,Victor F Neto,Keliang Wang,Qi Hua Fan,Maheshwar Shrestha,Bárbara Gabriel

doi:10.1155/2017/1934724

Abstract

The plasma treatment on commercial active carbon (AC) was carried out in a capacitively coupled plasma system using Ar + 10% O2 at pressure of 4.0 Torr. The RF plasma power ranged from 50 W to 100 W and the processing time was 10 min. The carbon film electrode was fabricated by electrophoretic deposition. Micro-Raman spectroscopy revealed the highly increased disorder of sp2 C lattice for the AC treated at 75 W. An electrosorption capacity of 6.15 mg/g was recorded for the carbon treated at 75 W in a 0.1 mM NaCl solution when 1.5 V was applied for 5 hours, while the capacity of the untreated AC was 1.01 mg/g. The plasma treatment led to 5.09 times increase in the absorption capacity. The jump of electrosorption capacity by plasma treatment was consistent with the Raman spectra and electrochemical double layer capacitance. This work demonstrated that plasma treatment was a potentially efficient approach to activating biochar to serve as electrode material for capacitive deionization (CDI).

Highlights

With increasing worldwide demands for fresh water, brackish water is considered a potential source especially in those areas with limited renewable water resources [1,2,3]
Where C0 is the initial molar concentration of salt solution, C is the concentration after adsorption, V is the volume of solution (L) and m is the mass of the active carbon (g), and MNaCl is the molar mass of NaCl (g/molar)
energy dispersive Xray analysis (EDX) (Figure 4 and Table 1) showed that the plasma treatment significantly increased the oxygen content from 3.65 wt% to 6.27 wt% for the carbon treated at power of 50 W and but the oxygen content slightly increased with the plasma power from 50 W to 100 W

Summary

Introduction

With increasing worldwide demands for fresh water, brackish water is considered a potential source especially in those areas with limited renewable water resources [1,2,3]. It is well known that the ion adsorption capacity of an electrode is directly related to its surface area and bulk conductivity. Porous carbon materials with high surface area and good conductivity, such as active carbon (AC) [10,11,12,13], carbon aerogels [14, 15], carbon nanofiber [16, 17], carbon nanotubes [18, 19], and mesoporous carbon [20, 21] have been widely used as the CDI electrodes. AC from abundant natural sources is currently considered the most promising material for the CDI electrodes; the electrosorption of commercial ACs is limited. This work first demonstrates that capacitively coupled RF plasma is a potentially efficient approach to activating biochar

Materials and Experimental

Results and Discussion

75 W 100 W

Conclusion