Removal of water pollutants using composite hydrogels comprised of collagen, guar gum, and metal-organic frameworks

Hydrogels are materials with high potential for wastewater treatment. They take out a wide variety of water pollutants being easy their remove after treatment. Currently, there is a growing interest for developing bio-based hydrogels to decrease the use of synthetic polymers. In this work, we prepared bio-based hydrogels from collagen and guar gum (ColGG) for the removal of textile dyes and metal ions. Composite hydrogels were designed incorporating 1 wt% of MgMOF74, CaMOF74, and Zn(Atz)(Py) metal-organic frameworks in the biopolymeric matrix. The hydrogels with MgMOF74 and CaMOF74 increased the storage module of matrix by 324.4 ± 30 and 116.84 ± 10 %, respectively. Further, MOFs decreased the thermal degradation and increased the water uptake capacity of ColGG. MOFs improved the adsorption performance for the removal of mordant brown and direct red from wastewaters. The improvement of the adsorption performance by adding MOFs was more noticeable for the removal of Cu 2+ and Zn 2+ ions. The basicity of the organic linkers played an important role in the improvement of the adsorption performance and physical properties. Interestingly, hydrogels neutralized the pH of wastewaters during the adsorption operation.