Waste remediation: Low-temperature synthesis of hybrid Cu(OH)/CuO and CuO nanostructures from spent printed circuit boards and their dye degradation studies.

The demand for environmentally friendly and sustainable resource utilization techniques for recycling waste printed circuit boards is significant due to their status as valuable secondary resources, containing high-purity copper and precious metals. In this context, Cu(OH)/CuO and CuO nanostructures were fabricated using alkaline precipitation and low-temperature aging methods using the strip solution originated from laboratory-scale spent mobile phone printed circuit board recovery process. XRD, FTIR, FESEM-EDX, and TEM were utilized to characterize the as-recovered nanoproducts. A hybrid structure of Cu(OH)/CuO was formed at 70°, and monoclinic CuO phase was formed at 80 °C aging time. The results show that Cu(OH)/CuO nanoflakes have an average crystallite size of 24.06 nm and a particle width of 22 ± 3 nm. Cu(OH)/CuO nanoflakes formed at 70 °C aging temperature and 24-h residence time have finer crystallite and particle sizes than CuO-ridged nanospheres formed at 80 °C aging temperature. The optical band gap energy of Cu(OH)/CuO and CuO nanostructures formed was found to be 2.28 eV and 2.22 eV, respectively. The hybrid Cu(OH)/CuO nanostructure photocatalyzed the decomposed 97.28% rhodamine blue using a visible light source, whereas the CuO nanostructure degraded only 14.64% rhodamine blue dye under similar conditions. A surfactant-less hybrid structure is developed without the use of any chemical precursor. Thus, a high value-added product is produced using one waste material to remove another waste in wastewater treatment.