The Functionalization of Activated Carbon by Oxidation

Abstract

Activated carbon is one of the most widely used adsorbents, but it shows low removal efficiency for polar molecules such as ammonia or ions due to the low content of oxygen containing groups. To increase the amount of oxygen containg groups, activated carbon was modified by the oxidation of activated carbon using the HNO3/H3PO4-NaNO2. The results showed that the carboxyl content of the modified activated carbon (MAC) increased with an increase in reaction time and temperature. The condition at 50°C for 60 hours yielded the MAC with a carboxyl content 1.07 mmol/g. The oxygen content of MAC also increased, suggesting the formation of carboxyl or carbonyl groups in the products after the oxidation. Brunauer-Emmett-Teller (BET) analysis and scanning electron microscopy (SEM) images demonstrated an increase in porosity of the MAC. The maximum capacity of ammonia adsorption was 5.81 mg/g for MAC.