Efficient performance of copper oxide nanoparticles synthesized with pomegranate leaf extract for neutral red dye adsorption

Abstract The adsorption of dyes in water and wastewater using metallic nanoparticles stands out due to its high removal capacity and low environmental impact. The present study proposed the use of copper oxide nanoparticles (CuO_NP), synthesized with pomegranate leaves extract ( Punica granatum ) to remove the neutral red (NR) dye from the aqueous medium. The characterization confirmed the efficiency of the redox process and the formation of nanoparticles. The adsorption results were promising, wherein the maximum adsorption capacity was 283 mg/g (298 K), with 0.4 g/L of adsorbent concentration, equilibrium time at 120 min, and removal rate of 96%. The pseudo‐second‐order and Langmuir models had a better fit concerning the kinetic and isothermal data, respectively. Thermodynamic parameters revealed an exothermic, spontaneous, and reversible process. The mechanisms that described the adsorptive process were hydrogen bonds, π‐interactions, and electrostatic attraction. CuO_NP showed good regeneration performance up to four reuse cycles (98–52 mg/g). In addition, not pronounced changes were verified in its adsorption capacity with dissociated ions (90–102 mg/g, in relation to the adsorption with no salts 104 mg/g). This secures the material versatility and cost‐effectiveness, justifying its high potential for industrial application to remove NR from water and wastewater.