Preparation of transition metal ions (Fe2+, Co2+ and Ni2+) doped carbon nanoparticles from biowaste for cystine and Cr(VI) detection and fluorescence ink

Recently, hydrothermal carbonization of naturally available precursors has been proved that it can produce unique physicochemical properties of carbon nanoparticles. The aim of this paper was to study the carbonization products of tea scraps as carbon source by doping Fe2+, Co2+ and Ni2+ ions. The obtained Fe-C-NPs, Co-C-NPs and Ni-C-NPs expanded the scope of concentration detection of CrO(4)(2-)ions (0 similar to 45 mu g.mL(-1)), and the minimum detection limit was 0.168 mu M. And a novel detection method for cystine was carried out, the minimum limit of detection was 5.2382 mu M. In addition, they could be applied to invisible inks. The paper provides valuable reference for comprehensive utilization of waste tea and reduces environmental pollution.