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Synthesis and Characterization of ZnO/MnFe2O4 Nanocomposites for Degrading Cationic Dyes

Yuniar, Agustina Tuty Emilia, Faizal Muhammad, Hariani Poedji Loekitowati

Journal of Ecological Engineering

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2023

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Vol. 24, nr 4

252--263

EN

By breaking down harmful dye waste into harmless components under the right irradiation sources, photocatalysis is an unorthodox but promising technique that can reduce industrial wastewater pollution, particularly in the textile industry. Synthetic textile dyes called cationic dyes must be handled carefully because they are poisonous and challenging to breakdown. Photocatalytic oxidation is a useful technique for eliminating hazardous organic pigments. This investigation aims to synthesize and characterize ZnO/MnFe2O4 nanocomposites as well as investigate the effects of varying ZnO:MnFe2O4 ratios, pH levels, doses, and irradiation times on band gap reduction and photocatalytic applications tested with cationic dyes, specifically methylene blue, under the illumination of sunlight. the co-precipitation approach for the manufacture of nanocomposites with different mole ratios of ZnO:MnFe2O4 (1:0.1; 2:0.1; 3:0.1). The component comprising the nanocomposite is ZnO/MnFe2O4, according to the results of the characterisation using XRD, SEM-EDX, FTIR, and BET. UV-DRS measurements of the band gap revealed that as ZnO was reduced, the band gap of the nanocomposite likewise decreased, from 3.35 eV to 2.78 eV. The greatest degradation of 93.2% was achieved for the degradation of 50 mg/L methylene blue (MB) dye with a catalyst dosage of 20 mg at a ratio of 1:0.2 for 50 minutes of irradiation. Since the point of zero charges (pzc) was reached at a pH of 7.8, a photodegradation adsorption-friendly solution pH of 8 was created.

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Magnetic Composite for Efficient Adsorption of Iron and Manganese Ions from Aqueous Solution

Purwaningrum Widia, Hasanudin, Rachmat Addy, Riyanti Fahma, Hariani Poedji Loekitowati

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 8

143--154

EN

Iron Fe(III) and Manganese Mn(II) ions were effectively removed from aqueous solutions using a magnetic composite of Fe3O4/CaO/PDA, with CaO sourced from green mussel. The composite material was comprehensively characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive – X-ray Spectroscopy (SEM-EDS), Brunauer, Emmett and Teller (BET) surface area analysis, Vibrating Sample Magnetometer (VSM). The impact of physicochemical adsorption parameters, such as solution pH, contact time, and concentration, were investigated. The Fe3O4/CaO/PDA composite displayed a value of 51.47 emu/g in saturation magnetization, enabling rapid separation through the use of an external magnet without the need for filtration. Optimal conditions for adsorbing Fe(III) ions were achieved at pH 3 and initial concentration of 400 mg/L with maximum efficiency reach after 60 minutes. Similarly, optimal conditions for Mn(II) ion adsorption were observed at pH 4 with the same contact time and initial concentration. The adsorption efficiencies were found to be 88.56% for Fe(III) and 75.65% for Mn(II). The pseudo-second-order model aptly depicted the kinetics associated with the adsorption of both types of ions while the Langmuir isotherm model indicated that monolayer adsorption takes place on the composite’s surface. The maximum capacities for adsorption is 322.58 mg/g for Fe(III) ions and 208.33 mg/g for Mn(II) ions. A negative Gibbs free energy value affirmed that the process occurs spontaneously under natural conditions. These results underscored the potential use of this Fe3O4/CaO/PDA composite in treating wastewater to remove heavy metal ions.

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Modification of Calcium Oxide from Green Mussel Shell with Iron Oxide as a Potential Adsorbent for the Removal of Iron and Manganese Ions from Acid Mine Drainage

Purwaningrum Widia, Hasanudin Hasanudin, Rachmat Addy, Riyanti Fahma, Hariani Poedji Loekitowati

Journal of Ecological Engineering

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2022

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Vol. 23, nr 11

188--201

EN

Acid mine drainage (AMD) has the characteristics of high heavy metal ion content and low pH. This study aimed to synthesize the CaO/Fe3O4 composite for the adsorption of iron and manganese ions from acid mine drainage. CaO was synthesized from the shells of green mussels (Perna viridis). The CaO/ Fe3O4 composites were characterized using XRD, BET surface area, SEM-EDS, and VSM. The functional groups of the composite before and after adsorption were analyzed using FTIR. The adsorption of Fe(II), Fe(III), and Mn(II) ions was carried out with the batch method to determine the effect of pH, contact time, and initial concentration of metal ions. The CaO/ Fe3O4 composite has magnetic properties, as indicated by the saturation magnetization value of 65.49 emu/g. The Langmuir and Freundlich isotherm models were used to describe the adsorption isotherm of the composite for Fe(II), Fe(III), and Mn(II) ions. Investigations were also conducted on adsorption kinetics, including pseudo-first-order and pseudo-second-order, as well as adsorption thermodynamics comprising free energy, enthalpy, and entropy. Pseudo-first-order and Langmuir isotherms are suitable to describe the adsorption of Fe(II), Fe(III), and Mn(II) ions with adsorption capacities of Fe(III) > Fe(II) > Mn(II). Moreover, the adsorption of all ions using the composite occurred spontaneously. The removal effectiveness for Fe and Mn ions from AMD using CaO/ Fe3O4 composite, reached 90.41 and 97.59%, respectively, in volume 100 mL AMD, composite mass 0.4 g, and a contact time of 60 minutes.

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High Efficient Photocatalytic Degradation of Methyl Orange Dye in an Aqueous Solution by CoFe2O4-SiO2-TiO2 Magnetic Catalyst

Hariani Poedji Loekitowati, Said Muhammad, Salni, Aprianti Nabila, Naibaho Yohanna Asina Lasma Rohana

Journal of Ecological Engineering

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2022

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Vol. 23, nr 1

118--128

EN

This study successfully synthesized a core-shell-shell in the form of CoFe2O4-SiO2-TiO2 catalyst magnetic and recyclable. The catalyst was employed for the photocatalytic degradation of methyl orange (MO) dye. Subsequently, the catalyst was subjected to XRD, FTIR, SEM-EDS, VSM, as well as UV-DRS characterizations. The photocatalytic degradation was studied as a function of the solution pH, MO concentration, and irradiation time, while the kinetics of photocatalytic degradation and the catalyst reusability were also evaluated. On the basis of the XRD, FTIR, and SEM-EDS characterizations, the CoFe2O4 coating was successfully carried out using SiO2 and TiO2. CoFe2O4-SiO2-TiO2 was discovered to possess magnetic properties with a saturation magnetization of 17.59 emu/g and a bandgap value of 2.4 eV. The photocatalytic degradation of MO followed the Langmuir-Hishelwood model. The optimum degradation was obtained at the MO concentration of 25 mg/L, solution pH of 4, catalyst dose of 0.05 g/L, irradiation time of 160 minutes, MO removal efficiency achieved 93.46%. The regeneration study showed CoFe2O4-SiO2-TiO2 after 5 cycles were able to catalyze the photocatalytic degradation with an MO removal efficiency of 89.96%.