Innovative hybrid poppy oil-alginate bigel material for neodymium recovery

The recovery of rare earth elements like neodymium (Nd(III)) has gained significant attention due to their critical industrial role and potential environmental impact when released into ecosystems. In this study, a novel biosorbent system combining poppy oil and alginate was developed as a bigel matrix for the efficient uptake of neodymium ions from aqueous solutions. The bigel was synthesized using a hydrogel (alginate) and an oleogel (poppy oil and beeswax) structure, combining the advantages of both materials for enhanced biosorption performance. The biosorption process was optimized by varying pH, temperature, and contact time. The maximum biosorption capacity was determined as 91.40 mg/g at pH 4.0, with an equilibrium time of 120 min and a temperature of 25°C, according to the linearized Dubinin–Radushkevich isotherm model. The biosorption yield increased from 64.45% to 81.23% with increasing temperature from 25 to 55°C. Thermodynamic analysis confirmed that the process is endothermic and spontaneous, with an enthalpy of 24.69 kJ/mol, an entropy of 139.7 J/mol · K, and a Gibbs free energy ranging from −16.95 to −21.14 kJ/mol. Linear and non-linear isotherm models evaluated the system. The Freundlich model best described the biosorption, suggesting surface heterogeneity and multilayer adsorption. scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR) analyses confirmed the structural integrity of the bigel and the successful adsorption of Nd(III), with EDS revealing 21.65 wt.% Nd(III) on the biosorbent. These findings demonstrate that the poppy oil–alginate bigel is a promising and environmentally friendly biosorbent for neodymium recovery, with potential applications in sustainable resource recovery and waste management.