Abstract

A controlled co-precipitation method was used to prepare nanoparticles of zinc sulfide doped with Ni and/or Cu in the presence of mercaptoethanol as capping agent. The nanoparticles characterize via UV-visible spectra, atomic absorption spectrophotometer (AAS), X-ray powder diffraction (XRD) patterns and transmission electron microscope (TEM) image. The doping of Ni²⁺ and/or Cu²⁺ ions did not altered the phase of zinc sulfide nanoparticles. Congo red photodegradation kinetic catalyzed by synthesized nanoparticles was studied under UV-visible irradiation. The effect of dopant mole fraction, the dosage of photocatalysts and the samples pH were investigated on the decolorization rate of dye. More degradation of dye was achieved in neutral samples versus acidic or alkaline pH. The Congo red was degraded more than 95 and 98% in the presence of 800 mg/L of Zn_0.94Ni_0.06S and Zn_0.90Cu_0.10S nanoparticles, respectively, within 120 min. The effect of hydrogen peroxide and several anions were investigated on the catalytic activity of proposed photocatalysts. Also, the reproducibility of nanoparticles behavior as photocatalyst showed at least a four-cycle of photodegradation process.

Key words: Nanoparticles, zinc sulfide, Congo red, photocatalyst, photodegradation.

Abbreviation

AOTs, Advanced oxidation techniques; AAS, atomic absorption spectrophotometer; XRD, X-ray powder diffraction; TEM, transmission electron microscope; CR, Congo red; IEP, isoelectric points.