Sonochemical synthesis of Sm-doped ZnS nanoparticles for photocatalytic degradation of Direct Blue 14: Experimental design by response surface methodology and development of a kinetics model

In this research, a facile and swift method was presented to synthesize pure and samarium (Sm)-doped zinc sulfide (ZnS) nanoparticles by ultrasonic probe. The synthesized samples were characterized by XRF, DRS, XRD, and FE-SEM. The prepared samples have a cubic zinc blende ZnS phase with nanoscale particles and uniform morphology. The photocatalytic activity of the synthesized samples was evaluated through the degradation of Direct Blue 14 (DB14) under UV light irradiation. The 5% Sm-doped ZnS nanoparticles revealed a higher photocatalytic performance than the pure ZnS and other Sm-doped ZnS nanoparticles. The impact of operational factors on the removal efficiency of dye was investigated by response surface methodology (RSM). The optimum conditions for photocatalytic degradation of DB14 (86.36%) were found to be 10 mg L-1 of DB14, 0.8 g L-1 of 5% Sm-doped ZnS, at pH = 3.5, and an irradiation time of 48 min. A kineticsmodeling of the process was also proposed, based on the Langmuir Hinshelwood mechanism, and an empirical equation was obtained for the estimation of apparent pseudo first -order rate constant (k(ap)) as a function of operational factors. Finally, byproducts resulting from the photocatalytic degradation of DB14 were identified using the GC-MS technique. (C) 2017 Published by Elsevier B.V.