Biochar rich in amino ligand for copper selective recollection in wastewater

The coexistence with other similar valence counterparts greatly hinders the selective recovery of metals, resulting in serious resource waste and environmental pollution. Herein, biochar with numerous surface –NO 2 and –COOH groups was prepared, and in-situ ammonization reaction was catalyzed by electricity to transform those attached –NO 2 into –NH 2 . The as-obtained biochar with stable ligand of –NH 2 (BC-NH 2 ) exhibited an excellent selective adsorption efficiency for copper. Among six bi-valence ions of copper, lead, cadmium, zinc, magnesium and calcium, the above adsorbent could selective recollect 88.76 % and 73.61 % of copper from aqueous and soil respectively. More importantly, the other existent bi-valence ions can be effectively substituted by Cu(II) with a high efficiency up to 91.92 %, even they were saturated on the BC-NH 2 . The Linear sweep voltammetry curves (LSV) and density functional theory (DFT) demonstrate the strongest affinity between Cu(II) and BC-NH 2 than that of other heavy metals, indicating the keynote of the selective mechanism should be the formation of ultra-stable complex between –NH 2 and copper ions. Besides, –COOH group participate the pathway for the transformation from –NO 2 to –NH 2 . This study provides a new concept, and an ideal material as well as novel preparing stratagem, for selective recollecting copper through chelating.