Capacitive deionization of seawater effected by nano Ag and Ag@C on graphene

  • 蔡 佩芳

Student thesis: Master's Thesis


Drinking water is becoming scarce Seawater is an abundant source for drinking water; therefore development of the capacitive deionization (CDI) method for desalination is merit CDI has the advantages of low energy consumption (only 0 1-0 6 kWh/m3) reduced secondary pollution simple operation and low-cost CDI can be applied not only in desalination but also water softening removal of metals from groundwater and wastewater Characteristics of electrode materials (e g conductivity specific surface area and hydrophilicity (wetting ability)) have a great impact on the CDI process In this study graphene (rGO) nano Ag /rGO and Ag@C/rGO were prepared and characterized by scanning electron microscopy (SEM) transmission electron microscopy (TEM) X-ray diffraction (XRD) Fourier transform infrared spectroscopy (FTIR) Raman spectra and cyclic voltammetry After reduction rGO possesses the wrinkle surface and becomes porous The hydrophilic function groups of GO was also removed which lead to the hydrophobic rGO The specific capacitance of rGO can be high as 140 46 F/g In addition the removal efficiency of NaCl can reach up to 15% in a NaCl solution The particles size of the Ag@C is in the range of 70-110 nm determined by small angle X-ray scattering (SAXS) spectroscopy Ag and a small amount of Ag2O are found in the Ag@C nanoparticles which was obtained by component-fitted X-ray adsorption near edge structure (XANES) spectroscopy To enhance antimicrobial activity and electrical conductivity nano Ag and Ag@C were added to promote the performance of graphene electrodes The conductivity of the porous structure of the electrodes are enhanced in the presence the dispersed nano Ag and Ag@C The NaCl removal efficiency from seawater can be as high as 45% with the nano Ag and Ag@C/rGO electrodes Notably the regeneration can reach 90% in the very short contact time (5 mins) In summary a very effective method for CDI with an ability of de-infection has been developed in the present work
Date of Award2014 Aug 1
Original languageEnglish
SupervisorHong-Paul Wang (Supervisor)

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