Nitrate removal for drinking water by FeCl3-oxidated polypyrrole- grafted activated carbon: Adsorption property and mechanism
Yanan Zhao, Jixiu Jia, Chunlu Li, Chuanping Feng, Zonglu Yao, Nan Chen
Abstract
Developing efficient nitrate removal technologies is crucial for ensuring the safety of drinking water, a polypyrrole-grafted activated carbon (PPy-AC) was synthesized via in situ chemical oxidative polymerization to enhance nitrate adsorption from water. It was showed that the PPy-AC composite featured a maximum adsorption capacity of 13.36 mg NO3−-N/g and exhibited high selectivity toward nitrate in the presence of co-existing anions. The PPy-AC composite exhibited a considerable capacity for adsorbing nitrate over a wide pH range of 3.0-9.0. The absorption performances were well-fitted by the Redlich-Peterson isotherm model, and the adsorption kinetics were well-described by the pseudo-second-order equation. Furthermore, the mass and charge balance calculations showed that 8.4% of the nitrogen atoms in the PPy-AC facilitated the adsorption of nitrate. The mechanisms of nitrate removal by the PPy-AC composite were determined through the electrostatic attraction and ion-exchange process, in which the nitrate ions are replaced by doped chloride ions, and the other N+ sites in PPy were occupied by nitrate ions. The PPy-AC is a promising material for the nitrate removal from wastewater.