Electrochemically Controlled Ion‐exchange Property of Carbon Nanotubes/Polypyrrole Nanocomposite in Various Electrolyte Solutions

Abstract

The electrochemically controlled ion‐exchange properties of multi‐wall carbon nanotube (MWNT)/electronically conductive polypyrrole (PPy) polymer composite in the various electrolyte solutions have been investigated. The ion‐exchange behavior, rate and capacity of the electrochemically deposited polypyrrole with and without carbon nanotube (CNT) were compared and characterized using cyclic voltammetry (CV), chronoamperometry (CA), electrochemical quartz crystal microbalance (EQCM), X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It has been found that the presence of carbon nanotube backbone resulted in improvement in ion‐exchange rate, stability of polypyrrole, and higher anion loading capacity per PPy due to higher surface area, electronic conductivity, porous structure of thin film, and thinner film thickness providing shorter diffusion path. Chronoamperometric studies show that electrically switched anion exchange could be completed more than 10 times faster than pure PPy thin film. The anion selectivity of CNT/PPy film is demonstrated using X‐ray photoelectron spectroscopy (XPS).

Electrically Switched Ion Exchange Based on Carbon-Polypyrrole Composite Smart Materials for the Removal of ReO4– from Aqueous Solutions

“…The ion exchange behavior between the conducting polymer and electrolyte can be verified from CV curves, as the charging and discharging is associated with the redox process. 20 To achieve a stable baseline, the sensor surface was rinsed with Milli-Q (MQ) water for approximately 50 min. An Au electrode was used because it has a 3× faster uptake rate than other electrodes.…”

“…CV (−0.4 to 0.8 V; scan rate = 10 mV/s) measurement with five cycles was used on an EQCMD to reach the equilibrium condition. The ion exchange behavior between the conducting polymer and electrolyte can be verified from CV curves, as the charging and discharging is associated with the redox process . To achieve a stable baseline, the sensor surface was rinsed with Milli-Q (MQ) water for approximately 50 min.…”

Electrically Controlled Anion Exchange Based on a Polypyrrole/Carbon Cloth Composite for the Removal of Perfluorooctanoic Acid

“…Polypyrrole (PPy) has been used as an adsorbent for heavy metals and organic dyes because of its electrical conductivity and excellent redox properties. , Specifically, the backbone of PPy is neutrally charged in the reduced state and positively charged in the oxidized state, making PPy especially suitable for the adsorption of anions through electrically switched ion exchange (ESIX), , an electrochemical technology combining ion exchange and electrochemistry to realize a selective and reversible separation process. ESIX has been widely used for the separation of many metallic and inorganic ions such as Ag + , Li + , Cs + , K + , ClO 4 – , CrO 4 2– , F – , RSO 3 – , ReO 4 – , etc. − In the ESIX system, PPy layers deposited onto conducting carriers act as ion exchangers that are controlled directly by the potential modulation to switch chemical states from oxidation to reduction for anion uptake and elution, respectively.…”

Electrically Switched Ion Exchange Based on Polypyrrole and Carbon Nanotube Nanocomposite for the Removal of Chromium(VI) from Aqueous Solution

“…In addition to its good adsorption property, the ion exchange and redox properties enable PPy to be a suitable matrix for electrically switched ion exchange (ESIX). − In ESIX, the PPy layer is deposited onto a conducting carrier to be an ion-exchanger which can be controlled directly by the potential modulation for ion uptake and elution. During this process, electrical energy can be used efficiently, and the eluted solution can be used repeatedly.…”

“…Inspired by the above analysis and based on our previous work of carbon nanotubes (CNTs), − in this study, nanostructured composites with PPy and multiwalled carbon nanotubes (MWCNTs) on carbon cloth (CC) were synthesized, characterized, and evaluated as an adsorbent for removing Cr­(VI) from aqueous solution by batch adsorption and electrochemical regeneration.…”