Colorimetric determination of Cu2+ in simulated wastewater using naphthalimide-based Schiff base

A new Cu2+-selective colorimetric sensor was developed by combining the chromophore 3-hydroxynaphthalimide with diaminomaleonitrile. The sensor showed Cu2+-selective colorimetric signaling behavior in dimethylsulfoxide, indicated by a solution color change from yellow to pink, which was readily discernible without any external devices. Practical application of the sensor to the detection of Cu2+ in an aqueous solution containing other environmentally relevant metal ions by selective two-phase liquid-liquid extraction with ethyl acetate was possible. Particularly, extractive signaling of Cu2+ in simulated semiconductor wastewater with a readily-usable smartphone as a colorimetric data capture and analysis tool was successfully conducted. (C) 2016 Elsevier Ltd. All rights reserved.