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Abstract
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In this study, removal of Cd
2+ from aqueous solutions using ZnO- graphene quantum dots nanocomposite embedded in chitosan biopolymer (ZnO-GQDs/Chit) adsorbent was reported. The prepared materials were studied with fluorescence spectroscopy, scanning electron microscopy and Fourier-transform infrared spectroscopy thoroughly in details. Using a batch removal system, the important parameters affecting the adsorption efficiency including adsorbent amount, initial Cd
2+ concentration, solution pH and contact time were optimised. Various adsorption models were used to study the equilibrium isotherm and calculate the isotherm constants. Consequently, the ZnO-GQDs/Chit was effective in Cd
2+ removal up to 149.25 mg g
−1 from aqueous solutions, with good agreement to Langmuir isotherm model (R
2 = 0.9956). Accordingly, chemical adsorption was the rate-limiting step in adsorption (R
2 = 0.9996) with a pseudo-second-order model. Consequently, ZnO-GQDs/Chit demonstrated a high degree of stability and reproducibility, indicating that it is a suitable adsorbent for treatment of water samples.
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