Biological synthesis of copper nanoparticles, using Nerium oleander leaves extract: Characterization and study of their interaction with organic dyes

Metal oxide nano-materials have been proved to be highly developed materials. In this current work, copper sulfate was reduced into copper oxide nanoparticles using biological Nerium oleander leaves extract. The prepared particles were used as valuable nano-adsorbents of methylene blue and crystal violet from aqueous solution. FT-IR spectroscopy analysis indicated that the studied extract contained carbonyl groups, phenolics, and other reducing agents. SEM analysis showed that the nanoparticles varied in size and shape distribution. The purity of the particles was proved by EDX analysis, showing the presence of elemental copper oxide. The crystalline nature of the nanoparticles was confirmed using XRD patterns and the crystallite size was calculated as 21 nm. The effect of dye concentration, adsorbent dosage, pH, time, and temperature on the sorption behavior was discussed. The sorption equilibrium of methylene blue and crystal violet was reached, only, at about 30 and 40 min, respectively. The sorption process was correlated with kinetics and common isotherm models. The pseudo second-order equation exhibited the optimal fitting results. Langmuir monolayer adsorption was 81.2 mg/g for methylene blue and 67 mg/g for crystal violet which was a level comparable to some other common bio-sorbents. In summary, we have highlighted effective and eco-friendly nano-adsorbent for the treatment of colored waters and it will be, also, interesting for multipurpose applications.