title: Comprehensive study on enhanced photocatalytic activity of heterojunction ZnS-NiS/zeolite nanoparticles: Experimental design based on response surface methodology (RSM), impedance spectroscopy and GC-MASS studies.
abstract: In the present work, coupled and supported NiS and ZnS onto the mechanically prepared clinoptilolite nanoparticles (NC) was prepared and characterized by XRD, FTIR, SEM-EDX, X-ray mapping, DRS, BET, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The obtained catalysts were used in photodegradation of metronidazole (MZ). The mole ratio of NiS/ZnS affects the degradation activity of the obtained catalysts so the best activity was obtained for the NZ4-NC (NiS1.0-ZnS5.2/NC, containing 1.0 and 5.2W% of NiS and ZnS, respectively and mole ratio of ZnS/NiS about 4) catalyst. The simultaneous effects of the experimental parameters were studied using central composite design combined with response surface methodology (RSM). Results of CV and EIS have good agreement with photodegradation results, so the coupled NiS-ZnS-NC system with significant enhancement in charge transfer with respect to the monocomponent systems showed the best photodegradation activity. The best degradation extent of MZ was obtained at a run including pH 2, catalyst dose of 3gL-1, 4mgL-1of MZ at irradiation time of 150min. The high correlation coefficient (R2=0.9883) for the second-order polynomial model, showed that the data predicted using RSM were in good agreement with the experimental results. Change of initial pH of MZ solution from 5.5 to 4.1 during 150min, confirms formation of acidic degradation intermediates.
authors.affiliation: Department of Chemistry, Shahreza Branch, Islamic Azad University, P.O. Box 311-86145, Shahreza, Isfahan, Iran; Young Researchers and Elite Club, Shahreza Branch, Islamic Azad University, Shahreza, Iran.
authors.forename: Hadis
authors.initials: H
authors.lastname: Derikvandi
authors.affiliation: Department of Chemistry, Shahreza Branch, Islamic Azad University, P.O. Box 311-86145, Shahreza, Isfahan, Iran; Young Researchers and Elite Club, Shahreza Branch, Islamic Azad University, Shahreza, Iran; Razi Chemistry Research Center (RCRC), Shahreza Branch, Islamic Azad University, Isfahan, Iran. Electronic address: arnezamzadeh@iaush.ac.ir.
authors.forename: Alireza
authors.initials: A
authors.lastname: Nezamzadeh-Ejhieh
keywords: Clinoptilolite nanoparticles; Heterogeneous photocatalysis; Response surface methodology; ZnS-NiS heterostructure