Modeling and optimization of cadmium (II) ion adsorption from aqueous solutions using mixed macroalgal biomass: kinetics and ANN insights

The research focuses on examining the biosorption capability of raw mixed seaweed biosorbent (RMSB) for the removal of the hazardous metal cadmium (II) under controlled environmental conditions. Using techniques such as elemental dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR), biosorbent was characterized. The impacts of adsorbent dosage, contact time, initial Cd concentration, pH, and temperature have been assessed for the removal of Cd (II) and its adsorption. Optimum levels-pH, biosorbent mass, contact duration, and temperature were 5, 2 g/L, 50 min, and 303 K, resulting in a maximum Cd (II) removal efficiency (%R) of 99.256%. The optimum intake of metals Cd (II) has been evaluated with isotherm modeling. Single-layer sorption was confirmed by the Freundlich isotherm, which proved to be an excellent fit. Maximum potential adsorption of Cd (II) was 146.2 mg/g. The biosorption kinetics of Cd (II) onto RMSB exhibit pseudo-first-order behaviour. The feasibility of the sorption process was established, and the thermodynamic parameters were determined. The Cd (II) sorption onto RMSB biomass has been estimated through the use of artificial neural networks (ANNs). With the high cross-correlation coefficient (R) value, the ANN models predicted the Cd (II) adsorption onto RMSB with remarkable accuracy. Additionally, regeneration studies showed that RMSB retained 65.3% of its initial adsorption efficiency after eight cycles, demonstrating potential for repeated use. The outcomes showed that Cd (II) may be effectively removed from the aqueous solution using RMSB.