Preparation of modified humic acid/TiO2/P(AA-co-AM) nanocomposite hydrogels with enhanced dye adsorption and photocatalysis

Abstract

A novel composite hydrogel with exceptional adsorption and photocatalytic properties was synthesized using modified coal-based humic acid (HA-C), modified titanium dioxide (TiO₂) nanoparticles, acrylic acid (AA), and acrylamide (AM) as precursors. The modification of HA-C and TiO₂ significantly enhances the structural support provided by the hydrogel for photocatalytic components. Moreover, we investigated the effects of monomer ratio, dye concentration, temperature, and pH on the material properties. Additionally, we tested the mechanical strength, swelling behavior, and reusability of the hydrogels. The composite hydrogel's adsorption performance and synergistic adsorption-photocatalytic performance were evaluated based on its removal rate for both absorbed and degraded methylene blue (MB). Remarkably, incorporating HA-C greatly improved the adsorption efficiency of the composite hydrogel for methylene blue to a maximum capacity of 1490 mg g⁻¹. Furthermore, TiO₂ nanoparticles in the structure promoted MB degradation with an efficiency exceeding 96.5%. The hydrogel exhibited excellent recoverability and reusability through nine cycles of adsorption/desorption as well as six cycles of degradation.