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

Adsorption is one of the most commonly used methods for the remediation of heavy metals. Generally, the spent adsorbent is regenerated using chemicals. Although chemical regeneration is efficient, it often leads to secondary wastes. To overcome such a problem, a novel remediation protocol for Cr(VI) featured with high capacity adsorption and electrochemical regeneration was carried out in this study. Experimental results showed that multiwalled carbon nanotube (MWCNT) modified carbon cloth (CC) can be used as an excellent carrier for electrodepositing polypyrrole (PPy) film, and the resultant nanocomposite termed as CC-MWCNT-PPy could be used as an adsorbent with high adsorption capacity and stability. Moreover, CC-MWCNT-PPy could be electrically regenerated to reduce secondary wastes. Desorption of Cr(VI) can be enhanced greatly by applying a reduction potential on spent CC-MWCNT-PPy. It was also observed that the Cr(VI) removal efficiency of CC-MWCNT-PPy remains almost unchanged after at least 7 cycles.