Glutaraldehyde-crosslinked chitosan bimetallic organic framework composite with tailored surface functionality for...

The persistence of hexavalent chromium (Cr(VI)) in aquatic environments poses a serious threat to both the environment and human health. Addressing this significant issue requires innovative and effective removal strategies. In this study, a copper‑iron bimetallic assisted succinic acid supported metal organic framework (CuFe-MOF) was synthesized using a hydrothermal technique and integrated with a chitosan network (CuFe-MOF@Chi) to effectively eliminate Cr(VI) ions from water. The structural integrity of all rigid materials and polymeric composites was comprehensively analyzed using various analytical techniques. The significant batch parameters were systematically optimized. The synergistic combination of the CuFe-MOF@Chi composite demonstrated a prominent adsorption capacity of 163.93 mg/g at pH 4.0 with a minimum contact period of 90 min. Studies on isotherm and kinetic models revealed that the Langmuir isotherm and pseudo-second-order (PSO) models were well fitted to the experimental results. Therefore, the adsorption characteristics of Cr(VI) over the prepared CuFe-MOF@Chi composite can be established as monolayer adsorption via chemisorption. Moreover, the Cr(VI) ions adsorbed on the surface of the CuFe-MOF@Chi composite formed a network via electrostatic attraction and surface complexation. XPS results confirmed that the CuFe-MOF@Chi composite effectively removed Cr(VI) and converted into Cr(III). The material showed stable performance for up to five cycles, indicating good reusability. The adsorption process is spontaneous and improves at higher temperatures. Overall, the composite exhibited high selectivity and environmental friendliness, and it was successfully tested for real water applications, demonstrating its effectiveness in removing chromium from contaminated water.