Ultrasonic-assisted adsorption of heavy copper and lead metal ions by g-C3N4, application of g-C3N4@MNPs (M: Pb, Cu) in the catalytic photoreduction of organic pollutants

Abstract

In this paper, the prepared g-C3N4 was used firstly as an adsorbent of copper and lead ions by using both ultrasonic and classical methods in order to improve the adsorption of bigger metal amounts in a very good dispersion. This adsorption study was performed in-depth by evaluating the influence of contact time, the metal concentration, and the pH effect. The adsorption mechanism follows the Langmuir isotherm and the pseudo-second-order model which confirm its chemisorption type. The maximal adsorbed quantities obtained were 285.7 mg/g and 238.09 mg/g for Cu2+ and Pb2+ respectively which represent a high performance. Once the adsorption was done, the obtained nanocomposite g-C3N4@CuNPs and g-C3N4@PbNPs were used in the photocatalytic reduction of anionic and cationic dye in a simple and binary system which constitutes a recovery and recycling of heavy metals. All materials were characterized by several analyses in order to investigate the structural, thermal, textural, and morphological properties. Each nanocomposite showed an affinity for a specific material according to its surface charge. Finally, the rate constants towards methylene blue dye reached a high level up to 1.2881 min−1 and 0.6406 min−1 for the g-C3N4@CuNPs and g-C3N4@PbNPs respectively, implying a large efficiency against both organic and inorganic water pollutants.