LAUSR

A novel biomass pulp fibre (PF)-based colorimetric sensor was prepared by grafting l-lysine (l-lys) onto the surface of PFs via a Schiff base reaction. The grafted l-lys contained two specific synergistic recognition groups (–COOH and –NH2), which only recognize Ag+. The as-prepared sensor (DAPF-l-lys) showed excellent selective recognition of Ag+ and an obvious visual colour change from light-yellow to brown in aqueous solutions containing other ions (Cu2+, Pb2+, Mn2+, Mg2+, Cd2+, Ca2+, H2O, Al3+, Hg2+, Cr6+, K+, Na+ and Zn2+). The visual limit of detection for Ag+ was 10–7 mol/L. Furthermore, DAPF-l-lys responded to Ag+ within 30 s based on the dynamic conditions of the detection method. The biomass PF matrix possessed the excellent properties, including a large external surface area, a short transit distance and good flexibility. When specific synergistic recognition groups were grafted onto the PF of the prepared PF-based colorimetric sensor, Ag+ could be rapidly absorbed and enriched on the surface of DAPF-l-lys through only bi-dentate ligand chelation between Ag+ and the synergistic recognition groups (–COOH and –NH2) of DAPF-l-lys. Thus, the DAPF-l-lys colorimetric sensor exhibited promising prospects for on-site identification of Ag+ (the level of ppb) due to its high selectivity and sensitivity.