Nur Afifah

Removal of Methylene Blue Dye Contaminant by Combination of Ultrasonic and Visible Light Irradiation Using Perovskite LaMnO3 Nanocatalyst

The applicability of LaMnO3 perovskite as nanocatalyst was investigated for removing of methylene blue as a model compound of organic pollutant under visible light and ultrasonic irradiation simultaneously. The LaMnO3 perovskite was synthesized by co-precipitation method and it was characterized in terms of morphological, structural, compositional, optical and magnetic properties. The detailed characterization confirmed that LaMnO3 perovskite had a single-phase orthorhombic structure with estimated crystallite size of 44 nm. UV-vis diffuse reflectance spectra showed a weak reflection with small band gap energy. The weak ferromagnetic behavior with a saturation magnetization of 3 emu/g was obtained at 1 Tesla. The photosonocatalytic showed significantly higher catalytic activity in decomposing methylene blue compared to that of sonocatalytic or photocatalytic alone. Radical scavenger experiments revealed that holes were the predominant oxidative species involved in the process.

Synthesis, Characterization and Catalytic Properties of Perovskite LaFeO3 Nanoparticles

Orthorhombic structure of rare earth perovskite-type oxide LaFeO3 nanoparticles with light absorption properties in the visible range was prepared by co-precipitation method. The prepared nanoparticles was characterized by several measurements such as X-ray diffraction, energy dispersive X-ray, field emission scanning electron microscope, diffuse reflectance spectroscopy, vibrating sample magnetometer and electron spin resonance spectroscopy. Methylene blue was taken as the model pollutant to evaluate its photocatalytic, sonocatalytic, photosonocatalytic degradation in the presence of LaFeO3 nanoparticles. The degradation of methylene blue followed the pseudo-first order model in all three processes. The observed rate constants indicate that the photosonocatalytic was faster than the respective individual. Radical scavenger experiments revealed that holes were the predominant oxidative species involved in all three processes.

Photocatalytic Activity of Fe-Doped ZnO/Montmorillonite Nanocomposite for Degradation of Malachite Green

In this study, the photocatalytic activity of pure Fe- doped ZnO and Fe- doped ZnO/Montmorillonite nanocomposite has been investigated for the degradation of malachite green under UV light irradiation. Both photocatalysts were synthesized using co-precipitation method and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier-transform infrared absorption, and electron spin resonance. The results showed that the photocatalytic efficiency is better in the presence of montmorillonite compared to pure Fe- doped ZnO. To detect the possible reactive species involved in degradation of organic dyes control experiments with introducing scavengers into the solution of organic dyes were carried out. It is found that electron plays an important role in the degradation of malachite green.

Multifunctional Photocatalytic Degradation of Methylene Blue Using LaMnO3/Fe3O4 Nanocomposite on Different Types of Graphene

This study added different types of graphene (GN-1 and GN-2) in to LaMnO3/Fe3O4 nanocomposite to degrade MB as an organic pollutant. LaMnO3/Fe3O4/GN-1 and LaMnO3/Fe3O4/GN-2 composites were synthesized using the co-precipitation method in a constant 5 wt% of GN. The as-prepared samples were characterized using XRD and TGA. The LaMnO3/Fe3O4/GN-1 and LaMnO3/Fe3O4/GN-2 composites showed the orthorhombic structure of LaMnO3 nanoparticles and the cubic spinel of Fe3O4 nanoparticles, as well as of GN-1 and GN-2. The graphite structure of NGP in LaMnO3/Fe3O4/GN-1 composites was confirmed. However, the peak of graphene in LaMnO3/Fe3O4/GN-2 could not be identified. The photocatalytic efficiency of the LaMnO3/Fe3O4/GN-2 was higher than that of LaMnO3/Fe3O4/GN-1. The enhancement of the photocatalytic light activity can be attributed to the high separation efficiency of electron-hole recombination and to the large surface contact between LaMnO3/Fe3O4 and graphene, which can improve the transfer efficiency of the photocatalytic process. In addition, the effects of catalyst dosage, rate constant, and scavengers were investigated and discussed.

The effect of different graphene surface area on photocatalytic activity of LaFeO3 nanoparticles

LaFeO3 composites with a different surface area of graphene (SA-1 and SA-2) have been prepared using the co-precipitation method. The samples were characterized by some measurements such as X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET) surface area analysis, Fourier-transform infrared absorption (FTIR), and Vibrating Sample Magnetometer (VSM). LaFeO3 nanoparticle and its composites showed orthorhombic structure. The presence of graphene in the composites was also confirmed. The characterized samples were further used to remove methylene blue under visible light irradiation. The obtained results revealed that incorporation of graphene in the composites results a significantly higher photocatalytic activity compared to LaFeO3 nanoparticles. The apparent reaction constant of LaFeO3/SA-2 composite with a highest specific surface area of 123 m2/g showed the fastest degradation in the photocatalytic process. Furthermore, the main factors in the photocatalytic activity were studied and discussed.

Dye adsorption into transition metal-doped zinc oxide nanoparticles supported on natural zeolites to solve wastewater issue

In this work, Fe-doped zinc oxide/natural zeolite (Fe:ZnO/NZ) nanocomposites were prepared using the co-precipitation method with various NZ amounts. The nanocomposites were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis and thermogravimetric analysis (TGA). The nanocomposites were used to remove methylene blue (MB) dye from an aqueous solution. The effect of various NZ amounts and initial MB concentration were tested. The Pseudo-first-order and pseudo-second-order kinetic models were used to explain the adsorption mechanism. The Langmuir and the Freundlich isotherm models were used to fit the adsorption isotherms of the nanocomposites.

Photodegradation of Methylene Blue by LaFeO3/ZnO Nanocomposites under Visible and UV Light Irradiation

In this study, LaFeO3/ZnO nanocomposites with different molar ratios of ZnO (0.1, 0.3, 0.5, and 1) have been prepared using the sol-gel method. The structural and elemental analyses of the samples were measured by X-ray diffraction (XRD) and X-ray fluorescence (XRF) spectroscopy. XRD results showed that the synthesized samples exhibited an orthorhombic structure of LaFeO3 and a hexagonal wurtzite structure of ZnO. However, the ZnO hexagonal wurtzite structure could not be detected below the ZnO molar ratio of 0.5. The presence of ZnO on the nanocomposites was confirmed using XRF measurements. The results revealed that the XRF spectra of the samples consisted of La, Fe, and Zn atoms. The photodegradation of methylene blue (MB) using LaFeO3/ZnO nanocomposites was then monitored under visible and UV light irradiation. The photodegradation results showed that the presence of LaFeO3/ZnO nanocomposites could degrade the MB solution. The highest MB degradation was found in the presence of ZnO at a molar ratio of 0.5. All of the LaFeO3/ZnO nanocomposites showed better photocatalytic performance than did LaFeO3 nanoparticles alone. Furthermore, several parameters, such as the effect of catalyst dose, initial concentration of MB, and various radical scavengers, were also measured to obtain the maximum condition and the main active species involved in the photocatalytic process.

Fe-doped ZnO Supported with Montmorillonite: Synthesis, Characterization, and Photocatalytic Activity

In this study, Fe-doped ZnO/MMT has been prepared by using co-precipitation method with the various amount of MMT (10, 20, 30, and 40 wt%). The samples were characterized by using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy, and (FTIR), Brunauer-Emmett-Teller (BET) surface area analysis. The crystallite structure of ZnO did not change with the additional of dopant and MMT. The presence of MMT could be confirmed by using FTIR, which showed the bending vibration and stretching vibration of Si-O-Al and Si-O-Si. The degradation of methylene blue and methyl orange were examined by using montmorillonite (MMT) modified Fe-doped ZnO catalyst in photocatalytic process under UV light irradiation. The photocatalytic results indicated that certain amount of MMT could increase photocatalytic performance in degrading methylene blue and methyl orange. Methylene blue degradation increased with the increasing of pH value while the opposite trend occurred for methyl orange degradation.