Abstract
Water pollution by heavy metals has significant effects on aquatic ecosystems. Copper is one of the heavy metals that can cause environmental pollution and toxic effects in natural waters. This encourages the development of better technological alternatives for the removal of this pollutant. This work explores the application of ZnO nanoparticles (ZnO-NPs) for the removal of Cu(II) ions from acidic waters. ZnO NPs were characterized and adsorption experiments were performed under different acidic pHs to evaluate the removal of Cu(II) ions with ZnO NPs. The ZnO NPs were chemically stable under acidic conditions. The adsorption capacity of ZnO NPs for Cu(II) was up to 47.5 and 40.2 mg·g−1 at pH 4.8 and pH 4.0, respectively. The results revealed that qmax (47.5 mg·g−1) and maximum removal efficiency of Cu(II) (98.4%) are achieved at pH = 4.8. In addition, the surface roughness of ZnO NPs decreases approximately 70% after adsorption of Cu(II) at pH 4. The Cu(II) adsorption behavior was more adequately explained by Temkin isotherm model. Additionally, adsorption kinetics were efficiently explained with the pseudo-second-order kinetic model. These results show that ZnO NPs can be an efficient alternative for the removal of Cu(II) from acidic waters and the adsorption process was more efficient under pH = 4.8. This study provides new information about the potential application of ZnO NPs as an effective adsorbent for the remediation and treatment of acidic waters contaminated with Cu(II).
Highlights
Surface and groundwater contamination by heavy metals is a growing concern
The results show that Zinc oxide (ZnO) NPs have a great affinity for Cu(II) ions, getting adsorption capacities even higher than previous studies
Raman confirmed the presence of ZnO NPs and scanning electron microscope (SEM)-EDX and is based on the NanoAdsorbent qe
Summary
Surface and groundwater contamination by heavy metals is a growing concern. One of the major sources of heavy metals is the contamination derived from acid mine drainage (AMD) release [1,2,3]. ZnO nanoparticles (NPs) have a high potential to be used as nano-adsorbents since they have a large specific surface area and various functional groups that favor their interaction and removal of heavy metals from aqueous solutions [45]. It has other advantages, such as high resistance to chemical and optical corrosion, high chemical stabilization, biocompatibility, environmentally friendly and is non-toxic in nature [46,47]. Knowing the removal effectiveness in AMD waters allows determining its chemical and functional stability under more aggressive conditions, which can give it a comparative advantage compared with other commercial adsorbents and can promote effective scaling in real conditions
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