Sonocatalytic degradation of methylene blue by a novel sno2-fe3o4@mwcnt hybrid nanocatalyst under ultrasonic irradiation

Abstract

In the present work, SnO2-Fe3O4@MWCNT nanocatalyst was fabricated according to a sonochemical-hydrothermal procedure. The surface morphology and structure analyses of the synthesized SnO2-Fe3O4@MWCNT were investigated by transmission electron microscope (TEM), X-ray diffraction (XRD), Raman spectroscopy, EDS, FTIR and BET analyses. The degradation efficiency of SnO2-Fe3O4@MWCNT nanocatalyst in MB solution was tested by several experimental conditions such as SnO2-Fe3O4@MWCNT dosage (8-20 mg/L), initial MB concentration (20-50 mg/L), initial solution pH (5-9), and ultrasonic output power (37-60 kHz). SnO2-Fe3O4@MWCNT nanocatalyst retained its efficiency as 85% at common experimental conditions of 16 mg/L of SnO2-Fe3O4@MWCNTs, 45 mg/L of MB, pH of 8, H2O2 of 15 mM, and 60 kHz in 60 min under ultrasonic irradiation. In addition, the optimum experiment conditions for SnO2-Fe3O4@MWCNTs in MB degradation were investigated. The experiment result showed that the degradation efficiency of MB was increased by adding H2O2 to the reaction medium due to forming more free radicals. Further, it was detected that OH center dot radicals were determined to be the dominant oxidative species in MB degradation using SnO2-Fe3O4@MWCNT catalyst. The reuse tests showed that SnO2-Fe3O4@MWCNT sonocatalyst preserved its very stable structure after using the same catalyst 5 times. The intermediates and by-products after MB degradation using the catalyst were indicated by GC-MS analysis. Overall the results showed that the SnO2-Fe3O4@MWCNT sonocatalyst has excellent potential for treating organic pollutants in wastewater.