Photocatalytic degradation of catechol using ZnO nanoparticles as catalyst: Optimizing the experimental parameters using the Box-Behnken statistical methodology and kinetic studies

Abstract A catalyst of ZnO nanoparticles was used in the photocatalytic process of treatment for potential use towards catechol degradation in an aqueous solution. The investigation of the characterization was carried out using TEM, SEM, XRD, and FT-IR techniques, which indicated that the catalyst of ZnO nanoparticles possesses unique catalytical features related to the surface morphology, structure, and functional groups. The efficiency of degradation was put to the test in relation to the variation of several experimental parameters including: pH (3–11); dose nanoparticles (0.2–0.25 g/L); reaction time (15–120 min); initial concentration (10–200 mg/L), and intensity of UV radiation (8–40 W). These aforementioned parameters were optimized and examined for the influence that they exerted on the efficiency of degradation which involved the usage of the Box-Behnken design methodology. According to the ANOVA results that yielded a confidence level of 95%, a high regression along with fitting values were obtained between the results of the experimental degradation of catechol and the predicted quadratic model. The kinetic study revealed that the data on experimental degradation could be described by using the Langmuir-Hinshelwood expression, which showed high precision values of the coefficient of regression. The optimum efficiency of degradation of 69.8% was achieved at optimized experimental conditions of pH = 3, a dosage of ZnO nanoparticles equal to 0.24 g/L, a reaction time of 98 min, with an initial concentration of catechol of 74 mg/L, and with the intensity of UV radiation equal to 40 W. Thus, the present study indicated that a catalyst of ZnO nanoparticles has a high practical utility, and exhibits good performance as a catalyst for degradation of catechol in a photocatalytic process.