A Stable, Reliable, Cost-Effective Technique Route for Ni Detection in Industrial Wastewater via a Microfluidic Paper-Based Platform

Nickel (II) as one of the primary categories of heavy metals can lead to serious health problems if achieving the critical levels in the water. Thus, it is vital to propose a stable, reliable, and economical approach for detecting Ni ions. The microfluidic paper-based analytical devices (µPADs) are potential candidates for the detection of water quality parameters including pH, heavy ions, nitrite and so on. However, it suffers from a huge error caused by the environment and artificial mistakes. In this study, we proposed an improved technique route to increase the stability and reliability of microfluidic paper-based analytical devices. The main technique points include a stable light source, a matched camera, improved reliability of the devices, and effective calculated methods. Finally, we established 15 standard curves that could be used to detect nickel ions and obtained uniform colorimetric results with reliability and repeatability. With those improvements, the relative errors for the five types of real water samples from the Zhongshan industrial parks were reduced to 0.26%, 14.78%, 24.20%, 50.29% and 3.53%, respectively. These results were conducive to exploring this technique for the detection of nickel ions in wastewater from the Zhongshan industrial parks. The results demonstrated that the above technique route is promising for the detection of other heavy metal ions in industrial effluent.