A nano CoFe2O4 entangled CMC/psyllium/RGO (CPRHG/CF)-based hydrogel composite for the adsorption & photocatalytic removal of pharmaceutical effluent: tramadol

Abstract

The fabrication of environmentally friendly materials for wastewater remediation represents a promising approach. Thus, we present the fabrication of nanostructured CoFe₂O₄ (CF) particles entangled within a hydrogel-based matrix composed of carboxy methyl cellulose–psyllium–RGO (CPR_HG/CF). The functionality, composition, and nature of the fabricated composite were characterized using FTIR, XRD, and XPS techniques. Furthermore, the internal and surface morphology was analyzed through FE-SEM and HR-TEM imaging. To assess the photo activity, UV-Vis and photoluminescence (PL) spectroscopy were employed, confirming that CPR_HG/CF exhibits significant potential for light absorption in the visible spectrum while minimizing the charge recombination rate. The fabricated CPR/CF_HG composite hydrogel was employed for the removal of pharmaceutical effluent, tramadol (TMD), via both adsorption and photocatalysis processes. In batch adsorption experiments lasting 2 hours, the composite hydrogel demonstrated impressive adsorption efficiency of 92.93% and a maximum adsorption capacity of 89.97 mg g⁻¹. Subsequently, during photocatalytic treatment under 1 h of solar illumination, approximately 90.36% of the TMD was successfully degraded. The degradation process followed a pseudo-first-order kinetics model with a rate constant (k₁) of 0.0380 min⁻¹. Furthermore, the investigation of reactive oxygen species (ROS) has identified superoxide radicals (O₂˙⁻) as the major species responsible for the degradation process, which was confirmed through radical scavenging experiments.