Electrochemical nanocomposite sensor based on carbon nanotubes and modified polyketone for rapid detection of copper ions in acidic copper solutions

The hydrometallurgical production route of copper in Chile, contributing 15–30 % of total production in the last 15 years, generates solutions with high copper concentrations. However, rapid and reliable instruments are lacking in quantifying its copper content in solution. Furthermore, actual acid samples contain chemical species that act as interferents, limiting the measurement's accuracy and reliability. Therefore, developing sensors with high precision and reliability for acidic solutions obtained from copper ores is one of the main challenges to advancing these operations. Electrochemical nanocomposite sensors were developed based on carbon nanotubes (CNT) mixed with polyketones modified with 1,2-diaminopropane (PKDAP) via Paal-Knorr reaction. The nanocomposite CNT-PKDAP has primary amino groups with high affinity to Cu⁺², which enhances Cu²⁺ detection. The sensor was characterized by the presence of a redox mediator, evaluating the effect of the content of amino groups in the polymer and the CNT-PKDAP ratio in the composite's response. The effect of pH, the counterion, and the potential application before measuring was evaluated, obtaining the best response at pH 1.0 and applying a potential of −0.5 V for 30 s before each measurement. It showed a linear response from 50 to 500 mg/L with a detection limit of 7.2 mg/L. Finally, the sensor successfully detects Cu⁺² in water samples derived from heap leachate. Tests in heap leachates achieved low relative standard deviation, offering a faster alternative to atomic absorption spectroscopy.