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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• 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. [ABSTRACT FROM AUTHOR]

In this study, Fe3O4/Mn3O4/CuO nanoparticles were synthesized, characterized, and used as a nanocatalyst in methylene blue (MB) degradation under ultrasonic conditions. The synthesis of Fe3O4/Mn3O4/CuO nanoparticles was carried out according to a facile method and characterized using some analytical techniques such as FTIR, scanning electron microscopy (SEM) with transmission electron microscopy (TEM), EDS, and X-ray diffraction (XRD). The obtained Fe3O4/Mn3O4/CuO nanoparticles showed a very homogeneous structure, and the average particle size was determined as 1.87 nm. XRD analyses revealed that Fe3O4/Mn3O4/CuO nanoparticles have a 2.27 nm crystalline particle size. The chemical composition of Fe3O4/Mn3O4/CuO nanoparticles was well detected by FTIR and SEM–EDS analyses. The products formed after the degradation of MB were detected by gas chromatography–mass spectrometry (GC–MS). The degradation of MB was investigated with several experimental conditions using Fe3O4/Mn3O4/CuO nanoparticles, and optimum experiment conditions were detected to be [T] = 301 K, [MB] = 0.03 g/L, [Cat.] = 1.0 g/L, [H2O2] = 5 mM, [Ult.] = 60 kHz. A maximum of 95.04% MB degradation using Fe3O4/Mn3O4/CuO nanoparticles was achieved in 150 min. To detect the radical effectiveness, t-butanol, ethanol, and t-butanol scavenger solvents were tested, and it was detected that these scavenger solvents prevent the formation of radicals that are effective in MB degradation. As a result, the present work paves the way to prepare excellent and highly efficient sonocatalysts for the degradation of organic dyes. [ABSTRACT FROM AUTHOR]

In this study, AgCu@MWCNT nanocatalyst was synthesized by following a series of physicochemical hydrothermal processes. The obtained catalysts of AgCu@MWCNT were characterized by advanced spectroscopic methods. AgCu@ MWCNT nanocatalyst used for degradation of MB was investigated under ultrasonic irradiation, and AgCu@MWCNT nanocatalyst exhibited an excellent sonocatalytic activity function. The effects on sonocatalytic activity were investigated with various experimental parameters. Percent degradation of MB after sonocatalytic activity was found to be 90.2% for 60 min. Findings showed that in the presence of AgCu@MWCNT nanocatalysts, OH and O2% - radicals were determined to be the main molecules in the degradation of MB under sonocatalytic conditions. The intermediate by-products of the paint formed in the degradation process were characterized by GC-MS technique. Overall, based on the results, AgCu@MWCNT nanocatalysts were detected as an effective nanocatalyst for degradation of MB using the ultrasonic process method. [ABSTRACT FROM AUTHOR]

AgFe 2 O 4 @MWCNT nanocatalysts were successfully synthesized by following a series of physicochemical hydrothermal processes and characterized by various instruments such as XRD, TEM, Raman, UV-Vis spectroscopy, and XPS techniques. The activity of the nanocatalyst was assessed by examining the degradation of methylene blue (MB) through combined adsorption and heterogeneous sonocatalysis. AgFe 2 O 4 @MWCNT nanocatalysts exhibited better removal efficiency in the case of pre-adsorption followed by sonocatalytic reaction as compared to the simultaneous adsorption and sonocatalysis system. The effects the AgFe 2 O 4 @MWCNT nanocatalysts on the sonocatalytic activity were investigated in details by various experimental parameters such as solution pH (5.5–10), catalyst dosage (8–20 mg L−1), hydrogen peroxide (H 2 O 2) dosage (5–20 mM), temperature (298–328 K), and dye concentration (12–40 mg L−1). The results revealed that the efficiency of AgFe 2 O 4 @MWCNT in MB degradation after sonocatalytic activity under optimum conditions was found to be about 98.5% in 75 min. Furthermore, OH• and O 2 • radicals exhibited the crucial molecular functions in the degradation of MB under sonocatalytic conditions in the presence of AgFe 2 O 4 @MWCNT nanocatalysts.The intermediate products after the degradation of MB were characterized by the GC-MS technique Based on the results, the adsorption followed by sonocatalytic degradation in the presence of AgFe 2 O 4 @MWCNT nanocatalysts showed great potential for the efficient treatment of wastewater. [Display omitted] • AgFe 2 O 4 @MWCNT nanocatalysts were synthesized by following a series of physicochemical hydrothermal processes. • AgFe 2 O 4 @MWCNT nanocatalysts were successfully applied for the degradation of methylene blue. • The OH• radicals were found to be very effective in the MB degradation. [ABSTRACT FROM AUTHOR]