Pelargonium as a cost-effective Additive in Bio-composite Adsorbent in Removing dyes from Wastewater: Equilibrium, Kinetic, and Thermodynamic studies

In this study, pelargonium (Plg) was used as a biosorbent to remove Methylene blue (MB), Methyl orange (MO), Congo red (CR), Malachite green (MG), Safranine (SA), and Fuchsine (FU) from water. Due to its high availability, biocompatibility, and economic efficiency, salep was used as a substrate in producing of hydrogel-based semi-IPN biosorbent with entrapped Plg to remove dyes from water. To produce a hydrogel-based composite, salep biopolymer was used in the presence of acrylamide monomer, ammonium persulfate (APS) as an initiator, N,N’-Methylenebisacrylamide (MBA) as a crosslinker, and powdered Plg leaves as an additive in the polymer matrix. The Plg biosorbent was characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), and thermo thermal gravimetric analysis (TGA). The studied parameters are swelling measurements, contact time, biosorbent dosage effect, and the reusability potential of the prepared biosorbent. Equilibrium data were analyzed using the Langmuir, Freundlich, and Temkin isotherm models. The equilibrium data were best represented by the Langmuir isotherm, with a prediction R 2 of 0.9916. Adsorption kinetic data were fitted using pseudo-first-order, pseudo-second-order, and intraparticle diffusion. The adsorption kinetics for the dye on the Plg biosorbent was best described by the second-order kinetic equation. In addition, the biosorption process was exothermic and spontaneous. The results obtained proved that the Plg biosorbent, including 3 wt% bio-additive at optimal conditions, at room temperature, the dosage of 0.5 g for biosorbent pretreated, pH of 7, and 20 ppm of initial dye concentration with 120 min of contact time demonstrated the best performance of the dye removal: 93.19% for MB, 82.25% for MO, 73.3% for MG, 96.9% for CR, 90% for FU, and 65.1% for SA after 2 h contact time, and great recoverability was achieved after three cycles of recovering.