Synthesis, characterization and catalytic applications of CaO-Cu decorated PANI/SA nanocomposites for wastewater treatment

The development of an innovative and efficient catalyst has led to the synthesis of calcium oxide-copper bimetallic nanoparticles (CaO-Cu BNPs) through the chemical reduction of copper nitrate Cu(NO₃)₂ and calcium oxide (CaO) using sodium borohydride (NaBH₄) as a reducing agent. Polyaniline (PANI) and sodium alginate (SA) were incorporated via in-situ oxidative polymerization. Characterization techniques including X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and Fourier-transform infrared (FTIR) spectroscopy confirmed the structure, morphology and elemental composition identifying Ca, Cu, and O of the BNPs and nanocomposites (NCs). The catalytic performance of the CaO-Cu BNPs and their NCs CaO-Cu/SA, CaO-Cu/PANI, and CaO-Cu/SA/PANI were evaluated for the reduction of methyl red (MR), crystal violet (CV), methyl blue (MB), and eriochrome black T (EBT). CaO-Cu/SA/PANI NC showed superior performance achieving a 97 % reduction of MB in 18 min with an apparent rate constant of 0.2096 min⁻¹ and a half-life of 3 min. The reduction time for organic dyes achieved by CaO- Cu/SA/PANI NC is 18 min for MB, 20 min for EBT, 30 min for MR, and 16 min for CV, and half-life values for these dyes were 3, 4, 5, and 3 min, respectively. These findings highlight the potential of CaO-Cu/SA/PANI as an effective catalyst for dye reduction in wastewater treatment.