Design of polyamidoamine dendrimer grafted zeolite to remove malachite green from aqueous media

The present study describes a novel, non-toxic, and cost-effective composite of zeolite/graphitic carbon nitride modified with highly branched polyamidoamine dendrimer (ZMPA). Graphitic carbon nitride, an affordable and non-toxic compound featuring various C-N bonds, was utilized to grow highly branched polyamidoamine dendrimer on the zeolite/graphitic carbon nitride composite. Fourier transform infrared spectroscopy, X-ray diffraction analysis, field emission scanning electron microscopy, and energy-dispersive X-ray analysis were employed to confirm and characterize the material. The adsorption properties of the adsorbent for the removal of malachite green were examined using the batch method. Consequently, the key parameters affecting the adsorbent's performance in removing malachite green (MG), such as pH, contact time, initial concentration, and adsorbent dosage, were investigated and optimized. The maximum adsorption capacity and removal efficiency of the adsorbent were found to be 1111 mg g^-1 and 99%, respectively, at a pH of 10, a low ZMPA/MG ratio of 6:10 mg mL^-1, and a dye concentration of 200 mg L^-1 over a duration of 30 min. Various adsorption isotherms were analyzed, and the results were fitted to the Langmuir isotherm, which exhibited a high R² value of 0.987. The adsorption capacity (385-1170 mg g^-1) increased with rising dye concentrations from 200 to 1200 mg L^-1 under equilibrium conditions. These findings can be attributed to the strong electrostatic interactions and/or trapped dye molecules within the cavities between the adsorbent and the absorbed. The innovative zeolite composite may be considered a promising adsorbent for malachite green removal in diverse wastewater samples (from paint and textile industries) due to its high adsorption capacity and removal rate.