Photocatalytic efficiency of bentonite-TQD via recycling and photodegradation of organic pollutants and industrial wastewater

The efficient photocatalytic removal of textile dyes from industrial wastewater remains a critical environmental challenge. This study presents the synthesis and characterization of a bentonite-supported TiO₂ quantum dot (BTQD) nanocomposite via co-precipitation methodology for enhanced photodegradation of Brilliant Blue R (BBR) dye. Characterization confirms successful incorporation of uniformly distributed TQDs (5–8 nm average size) within the bentonite matrix, yielding a specific surface area of 212.25 m
2
g
-1
, significantly higher than pristine bentonite. X-ray diffraction (XRD) analysis validates anatase TiO₂ formation with expanded basal spacing of 16.4 Å, indicating effective intercalation within clay interlayers. The composite exhibits a narrowed band gap of 3.18 eV, enhancing visible-light absorption relative to bulk TiO₂. Photocatalytic evaluation demonstrates that BTQD achieves 93% dye degradation within 60 min with a reaction rate constant of 28.01 × 10⁻
3
min⁻
1
, substantially outperforming pristine bentonite (68%) and isolated TiO₂ nanoparticles. The degradation follows pseudo-first-order kinetics, with hydroxyl radicals and superoxide anion radicals identified as principal reactive oxygen species (ROS). Recycling studies confirm exceptional photocatalyst stability over seven consecutive cycles with negligible activity loss. Chemical oxygen demand (COD) analysis demonstrates effective mineralization, reducing COD from 7150 mg L⁻
1
to 610 ± 35 mg L⁻
1
in treated textile effluent. Economic assessment establishes operational cost at $5.63/mm
3
, demonstrating practical scalability. The synergistic integration of abundant clay minerals with quantum-confined semiconductors yields a cost-effective, durable photocatalytic system suitable for sustainable industrial wastewater treatment and environmental remediation.