Calcium oxide nanoparticles synthesis from hen eggshells for removal of lead (Pb(II)) from aqueous solution

Abstract

Lead is an important industrial heavy metal used in various production industries. Remediation of Lead poisoned areas has both economical and technological challenges, as conventional and techniques are very expensive to apply for wastewater treatment and its operation is difficult. The adsorption method could solve the problem using sol-gel-based synthesized adsorbent since it is environmentally friendly with high-quality product pro duced. In the present study, the application of synthesized calcium oxide nanoparticles from hen eggshells for the removal of lead ions from aqueous solutions is what was investigated. Characterization of the adsorbent like proximate analysis, particle density, bulk density, porosity, point of zero charges, Fourier transform infrared ra diation spectroscope, X-ray diffraction, specific surface area, thermal gravimetric analysis, and scanning electron microscopy was done before batch adsorption experiments. X-ray diffraction revealed that the size of synthesized calcium oxide nanoparticles was 24.34 nm and the specific surface area was 77.4m2/g. The removal of divalent lead ions from aqueous solutions was optimized by using response surface methodology. The optimum percent removal of lead (99.07) has resulted at initial concentration 75.46 ppm, pH 6.94, adsorbent dose 0.838 g, and contact time 101.97 min. The experimental removal efficiency (98.86%) agreed very well with the predicted one (99.07%), showing the suitability of the model used and the success of response surface methodology in optimizing of removal of Pb (II) ions from aqueous solutions. The lead ions removal was well fitted into the Langmuir isotherm model with correlation coefficients of 0.9963. The adsorption kinetic data were well fitted with the pseudo-second-order model with a correlation coefficient of 0.9982. The pseudo-second-order model was the rate-limiting step in the lead (II) ions adsorption process onto CaO NPs. Based on the obtained results, the calcium oxide nanoparticles prepared from eggshell have a good capacity for the removal of the lead ions from the aqueous solutions