Removal of methylene blue dye from aqueous solutions by adsorption onto new 1,3-dibromopropane crosslinked Schiff base chitosan/CoFe2O4/SiO2 nanocomposite.

In this study, a novel modified Schiff base chitosan/1,3-dibromopropane/4-hydroxybenzaldehyde/CoFe2O4/SiO2 (Cs-DBP-HBA-CoFe2O4-SiO2) nanocomposite was synthesized. The synthesized nanocomposite was analyzed using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometry (VSM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) techniques. The synthesized nanocomposite was utilized as an efficient adsorbent for removing methylene blue (MB) from aqueous solutions via the batch adsorption method. Various parameters, including pH, contact time, adsorbent dosage, and initial dye concentration, were investigated. The optimized adsorption parameters were determined to be an adsorbent dose of 40 mg L-1, an initial dye concentration of 100 mg L-1, pH = 3, and a contact time of 30 min. Adsorption studies revealed that the methylene blue uptake by the synthesized nanocomposite is a highly favorable process (R L and n values within the favorable range) occurring on a heterogeneous surface (R 2 = 0.9729). The mechanism is primarily governed by physisorption involving non-covalent interactions, such as hydrogen bonding and pi-pi stacking, rather than chemisorption. Additionally, the divergence in maximum adsorption capacities (q m) calculated via Langmuir model. Kinetic studies demonstrated that the adsorption followed the pseudo-first-order model, suggesting that the rate-limiting step is physisorption mechanism. Thermodynamic analysis indicated that the adsorption of MB onto the nanocomposite was an endothermic and spontaneous process.