In this work, the effects of temperature, time, and adsorbate initial concentrations were investi- gated on the adsorption efficiency of Cooper oxide (CuO) nanoparticles (NPs) as the adsorbent of boron. In addition, surface properties of CuO were examined using the power X-ray diffraction, specific area by Brunauer–Emmett–Teller method, scanning electron microscopy – energy dispersive X-ray, Fourier transform infrared, and point of zero charge (PZC). Our careful scientific examina- tion action revealed that CuO had very small particles with a mean diameter of 85 nm. Subsequent experiments showed that the adsorption of boron needed neither acidic nor alkaline pH (pH = 7) at temperatures 25°C. Moreover, positive values of ΔH° suggested that the reaction was endothermic whereas negative values for ΔG° showed that adsorption processes were spontaneous. According to the kinetic studies the data better fitted to pseudo-second-order rather than first order. Under the best condition, the CuO adsorption capacity was 3.5 mg/g in a non-competitive solution. However, the amounts of B removal in CuO NPs were 3.0, 3.0, 3.5, and 2.8 mg/g by existing competitive anions, namely humate, phosphate, sulfate, and citrate, respectively. Linear Freundlich among Freundlich, Langmuir, Temkin, and Dubininn and Radushkevich (D–R) models could be considered as the best model in order to explain experimental data with a high average coefficient of determination (R2 = 0.9628). The results indicated that CuO NPs can be considered a promising adsorbent for water purification due to its efficiency in removing boron.
