Doped Ti-glutamate MOFs@TiO2 and biochar into starch-hydrogel as a sustainable and innovative multi-capturing nanobiosorbent for tetracycline antibiotic and Hg(II) pollutants

Metal organic frameworks (MOFs), biodegradable polymers, and biochar have been regarded as promising materials for the adsorptive capture of a wide variety of hazardous pollutants. In the current investigation, a green synthesis strategy was developed to fabricate a multifunctional bionanocomposite for the sustainable capture of Hg(II) ions and tetracycline (TC) antibiotic pollutants from water effluent. Initially, titanium–glutamate MOFs (TGMOFs) were synthesized and subsequently induced with TiO 2 -nanoparticles to form TGMOFs(TiO₂). This hybrid was then combined with banana stalk nanobiochar (BSNB) via microwave-assisted incorporation in the presence of a starch hydrogel (SH), yielding the target TGMOFs(TiO₂)@BSNB@SH bionanocomposite. Comprehensive characterization techniques confirmed the successful fabrication of the bionanocomposite, revealing a crystalline and porous network structure with 26–29 nm average particle size. FT-IR and EDX analyses further verified the chemical structure and elemental composition. The TGMOFs(TiO₂)@BSNB@SH bionanocomposite exhibited excellent adsorption performance toward Hg(II) and TC, achieving maximum removal efficiencies at pH 6 and 3, respectively. Both non-linear and linear kinetic models and isotherm were applied, with the non-linear versions of Langmuir isotherm and the pseudo-second order kinetic model providing the optimal fit. Thermodynamic Investigations demonstrated that the adsorptive capture processes for both Hg(II) and TC were spontaneous and endothermic. Moreover, the developed bionanocomposite showed excellent reusability over five consecutive cycles, retaining removal efficiencies of 92.5% for Hg(II) and 88.6% for TC. Application to real wastewater samples demonstrated high Hg(II) and TC capture (91.7–100.0%), highlighting the potential of TGMOFs(TiO₂)@BSNB@SH as a sustainable and effective material for future environmental remediation applications.