Efficient Hg²⁺ adsorption using a silk fibroin/MOF-2/alginate composite: Kinetics and thermodynamics

The effective adsorption of (mercuric ions) Hg²⁺ onto synthesized and characterized composite materials based on calcium alginate (CG), zinc metal-organic farmwork (MOF-2), and silk fibroin powder (SF) has been reported in this study. Under various application conditions, the adsorption capacities of silk fibroin powder/zinc metal organic framework/alginate composite (ZSG) were compared with those of the other individual solid materials. These solid adsorbents materials were characterized by various physicochemical techniques. Characterization tools proved the well-advanced physiochemical properties of the formed composite with 298.6 m²/g as surface area, pore radius of 35.91 Å, 0.10 % swelling ratio, 6.50 as pH_PZC, and the presence of various surface chemical functional groups. The maximum Hg²⁺adsorption capacity was found to be 453.67 mg/g for ZSG as calculated from nonlinear Langmuir adsorption model. Studies on kinetics and thermodynamics revealed that the pseudo-second-order model, Elovich, and Van 't Hoff models fit the adsorption process. It was discovered that the adsorption process was endothermic, physical, and spontaneous. Total dissolved solids (TDS) were found to have an adverse effect on the adsorption capacity. According to findings, the developed composite shows promise as a reusable solid adsorbent for metal cations.