Inorganic–organic hybrid quantum dots for AOP-mediated photodegradation of ofloxacin and para-nitrophenol in diverse water matrices

Abstract

Due to concerns about the accessibility of clean water and the quality of treated wastewater, developing a suitable solution to enhance the water quality is critical. Thus, the current study focused on the synthesis of cadmium-doped CdIn2S4 incorporated in chitosan, forming Cd/CdIn2S4@Ch quantum dots using a solvothermal technique for the efficient photodegradation of hazardous pollutants like ofloxacin and para-nitrophenol through H2O2-mediated AOP. Cd/CdIn2S4@Ch quantum dots were characterized by several advanced methods, including XRD, PL, UV-DRS, FTIR, SEM, HR-TEM, XPS, DSC, TGA, EDX, and Elemental mapping analysis. The influence of varying reaction parameters, such as the effect of organic compounds, inorganic ions, and water matrices, was also investigated. The prepared composite showed outstanding photodegradation efficiency of 85.51 ± 1.35% and 96.70 ± 1.31%, with a rate constant of 0.02334 and 0.15134 min−1, which is about 1.24 and 2.07 times higher than pristine CdIn2S4 for ofloxacin and para-nitrophenol, respectively. The COD values were reduced to 80.67 ± 1.67% for ofloxacin and 88.36 ± 1.43% for para-nitrophenol, whereas the TOC values reduced to 73.49% and 86.34%, respectively, from their initial values. The improved performance is ascribed to the encapsulation of CdIn2S4 by chitosan, leading to the self-doping of cadmium into the photocatalyst, as the incorporated cadmium doping site can generate a local electron accumulation point, improving the charge separation efficacy and surface charge mitigation capability of chitosan nanosheets even further. The scavenger experiments showed that hydroxyl and superoxide radicals played a significant part in the photodegradation of contaminants. Additionally, the quantum dots showed excellent constancy and were recyclable up to six times, suggesting exceptional stability and reusability of the manufactured photocatalyst. The fabricated Cd/CdIn2S4@Ch quantum dots could be an excellent photocatalyst for removing organic pollutants from wastewater in the near future.