Deep Removal and Photodegradation of Methylene Blue Dye Using Superabsorbent Polymer Hydrogel Composite with Activated Charcoal and TiO₂ Nanoparticles

The low-cost and effective interaction of hydrogels with pollutants has drawn significant interest in the wastewater treatment domain. This study aims to explore a novel, biodegradable superabsorbent polymer (SAP) hydrogel composite incorporated with activated charcoal (AC) and TiO₂ nanoparticles to efficiently remove and subsequently photodegrade methylene blue (MB) dye. The addition of activated charcoal boosted the adsorption capacity of the composite hydrogel, while the integration of TiO₂ nanoparticles increased its photocatalytic activity. The adsorption reaction was allowed to proceed over 24 h, during which small sample aliquots (5 mL) were collected at specific time intervals. After the 24-h period, the MB adsorption capacity was found to be 198.99 mg g^-1 for SAP-TiO₂ and 203.97 mg g^-1 for SAP-AC/TiO₂, respectively. After a 24-h time interval of maximum MB adsorption, MB degradation was conducted by exposing the solution to a UV-A source positioned at a distance of 15 cm. The maximum MB degradation percentages under UV-A irradiation were found to be 77.11 ± 1.9 using SAP-TiO₂ and 87.77 ± 2.9 using SAP-AC/TiO₂, respectively. This study demonstrates the potential of a SAP composite hydrogel, incorporating AC and TiO₂ nanoparticles, as a promising material for efficiently removing and degrading MB dye from wastewater.