Synergistic cavitation and photocatalysis over layered Bi₂SiO₅ anchored MXene/g-C₃N₄ nanocomposites for accelerated sonophotocatalytic degradation of bisphenolic contaminants from aqueous environment

Bisphenols (BPs) are persistent endocrine-disrupting contaminants widely detected in aquatic environments due to their extensive use in polycarbonate plastics and epoxy resins. In this work, a ternary heterostructured nanocatalyst composed of Bi₂SiO₅, Ti₃C₂T_x MXene, and g-C₃N₄ was synthesized through a sonochemical-assisted hydrothermal approach and employed for the degradation of bisphenol A (BPA) under multi-frequency ultrasound-assisted sonophotocatalytic (MFUSP) conditions. The ternary nanocomposites were characterized using advanced analytical characterization techniques such as XRD, XPS, and TEM analyses. Consequently, Structural and microscopic observations confirmed intimate interfacial contact between Bi₂SiO₅ nanoparticles and layered Ti₃C₂T_x and g-C₃N₄ nanosheets which forms an efficient heterojunction nanoarchitecture. Optical analysis revealed that the incorporation of Ti₃C₂T_x and g-C₃N₄ extended the optical response of Bi₂SiO₅ into the visible region which led to the optical band gap to 2.8 eV. Systematic optimization of MFUSP parameters such as nanocomposite's dosage, influence of ultrasound frequency and nanocatalyst variation was performed. Under optimized conditions, Bi₂SiO₅/Ti₃C₂/g-C₃N₄ nanocomposites achieved 93% BPA degradation within 60 min under (20 + 40 + 80 kHz) ultrasound and blue LED irradiation. The degradation rate constant reached 4.51 × 10⁻² min⁻¹ which is ∼7.6-fold higher than commercial P25 TiO₂. The enhanced degradation efficiency is attributed to synergistic cavitation effects, improved mass transfer, and efficient interfacial electron transfer between Bi₂SiO₅ and g-C₃N₄. The nanocatalysts also demonstrated effective simultaneous degradation of bisphenol A and bisphenol F in mixed systems. Mechanistic analysis indicates the Z-scheme heterojunction promotes efficient generation of reactive oxygen species which are responsible for the oxidative degradation of BPs.