Potassium and cyano co-modified carbon nitride as a highly efficient adsorbent for selective removal of Pb(II) from wastewater

The selective removal of highly toxic heavy metal ion Pb(II) from wastewater is of significant importance to the ecological environment and human health, while the development of high performance adsorbents for selective Pb(II) adsorption remains a big challenge. Herein, a cleverly designed heavy metal adsorbent over potassium and cyano modified carbon nitride (KCCN) is proposed, exhibiting excellent performance toward Pb(II) selective removal. The amino and cyano groups in KCCN are found high affinity to that of Pb(II) in such a potassium doped system, as a result showing an excellent Pb(II) selective adsorption performance in the presence of various ions without obviously changing the distribution coefficient K d value. In addition, the adsorption process is found to follow the Langmuir isotherm model and pseudo-second-order kinetic, with a maximum adsorption capacity for Pb(Ⅱ) of 293.26 mg/g. Furthermore, no obvious adsorption capacity drop is found after five cycles of Pb(II) adsorption processes, demonstrating the high reusability on Pb(II) removal.