A Study of Preconcentration Using Ion Selectivity Membranes with Graphene Oxide

  • 張 鈞皓

Student thesis: Master's Thesis

Abstract

In this thesis we utilized the micro-electromechanical technique using Nafion instead of a nanochannel in microfludic chips for use in sample preconcentration When an electric field is applied to the micro-nano chip the cation selective membrane (Nafion) has the characteristic of cation and anion flux difference due to the overlapped double layer effect in the nanochannel which results in the concentration polarization phenomenon at the micro- and nano-interface The concentration polarization phenomenon causes a concentration gradient to occur near the membrane On the anodic side the ion depletion zone can be induced by applying a voltage The ion accumulation is the result of the difference in electro-migration at the boundary between the depletion zone and electroosmotic flow Therefore it creates a high concentration interface in the channel to achieve ion concentration The aim of this study was to explore a modified cation selective membrane by adding graphene oxide (GO) to a traditional Nafion membrane used in preconcentration chips It was found that the GO functional group enhanced our preconcentration phenomenon We also discuss how to enhance the feasibility after which we optimize the preconcentration effect in this modified membrane To this end we respectively mix GO and Nafion with different volume ratios and GO content (%) to find the optimal volume ratio and concentrations Then we compare GO/Nafion with Nafion alone Based on the experimental result we applied a voltage of 30 V in a straight microchannel In using 0 5 wt % GO to mix with Nafion the GO volume was three times more than that of the Nafion These kinds of GO/Nafion ion selectivity membranes can achieve a 60-fold increase in preconcentration factor within 30 min which is superior Nafion membranes that offer a 40-fold increase
Date of Award2016 Aug 24
Original languageEnglish
SupervisorRuey-Jen Yang (Supervisor)

Cite this

A Study of Preconcentration Using Ion Selectivity Membranes with Graphene Oxide
鈞皓, 張. (Author). 2016 Aug 24

Student thesis: Master's Thesis