Preparation and properties of a biomass cellulose-based colorimetric sensor for Ag+ and Cu2+

A biomass cellulose-based colorimetric sensor for Ag + and Cu 2+ was prepared by grafting 2,5-dithiourea (DTu) onto biomass-pulp cellulose. The as-prepared sensor (cellulose-DTu) showed excellent selectivity and sensitivity towards Cu 2+ over other common metal ions (Pb 2+ , Mn 2+ , Mg 2+ , Zn 2+ , Hg 2+ , K + , Al 3+ , Ca 2+ , Na + , Cd 2+ , Ni 2+ , Ba 2+ , and Li + ), exhibiting a color change from white to light grey. However, the sensor exhibited a remarkable color change from white to yellow-red upon the addition of Ag + . The naked-eye-detection concentration limits for Ag + and Cu 2+ were 10 −3 and 10 -4 mol/L, respectively. Furthermore, cellulose-DTu responded to both Ag + and Cu 2+ within 5 s. A mechanism for the selective identification of Ag + and Cu 2+ by cellulose-DTu was proposed based on 13 C solid NMR, XPS, and TEM analyses. In addition, the application of cellulose-DTu in real water confirmed that it exhibits the advantages of simplicity, rapidity, and high selectivity for in-situ identification of Ag + and Cu 2+ .