Photocatalytic removal of Cefixime using ZnO/BiOBr/Bi2S3: Suspended and immobilized on Graphite

The ZnO/BiOBr/Bi 2 S 3 dual Z-scheme heterojunction was synthesized via the solvothermal method, and the photocatalytic removal of cefixime (CFX) was investigated using the nanocomposite. Structural and morphological studies were conducted using XRD, FTIR, Raman spectroscopy, XRF, FE-SEM, TEM, UV-Vis DRS, PL, and BET. The results indicated that the ZnO/BiOBr/Bi 2 S 3 exhibited a synergistic effect, reducing the band gap energy to 2.70 eV and enhancing charge separation in comparison with individual and binary components. The Raman peak shifts confirmed the formation of heterojunction among the components. Optimization of the mass ratio through screening experiments resulted in an optimum composition of 30 wt% ZnO to BiOBr/Bi 2 S 3 , achieving a 75% removal efficiency. CFX adsorption on the nanocomposite followed a monolayer mechanism, with a maximum adsorption capacity of 15.32 mg.g -1 . In addition, approximately 96% CFX removal was achieved using the immobilized ternary ZnO/BiOBr/Bi 2 S 3 heterojunction on graphite under optimal operating conditions. The <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="M1"> <mml:mrow> <mml:msup> <mml:mrow> <mml:msub> <mml:mrow> <mml:mtext>O</mml:mtext> </mml:mrow> <mml:mrow> <mml:mrow> <mml:mtext>2</mml:mtext> </mml:mrow> </mml:mrow> </mml:msub> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mrow> <mml:mi>•</mml:mi> </mml:mrow> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> and h + for the suspended and the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="M2"> <mml:mrow> <mml:msup> <mml:mrow> <mml:msub> <mml:mrow> <mml:mtext>O</mml:mtext> </mml:mrow> <mml:mrow> <mml:mrow> <mml:mtext>2</mml:mtext> </mml:mrow> </mml:mrow> </mml:msub> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mrow> <mml:mi>•</mml:mi> </mml:mrow> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> and OH <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="M3"> <mml:mrow> <mml:mrow> <mml:mi>•</mml:mi> </mml:mrow> </mml:mrow> </mml:math> for the immobilized system play the major role in CFX degradation.