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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

2023

Vol. 24, iss. 8

143--154

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.

Biodiesel Production of Palm Oil Mill Effluent by Using Hydrotalcite Catalyst

Agustina Tuty Emilia, Heraldy Eddy, Hadiah Fitri, Hasanudin, Arita Susila, Prakoso Tirto, Sari Tuti Indah, Suprapto Bhakti Yudho, Putra Muhammad Firdaus Kusuma, Ramadhani Dimas Luthfi

Journal of Ecological Engineering

2022

Vol. 23, nr 6

172--181

Biodiesel is currently preferred for consumption and has been widely used as a substitute for diesel. This study aimed to determine the effect of various methanol-to-oil ratios in the esterification process and also the effect of hydrotalcite catalyst weight on the transesterification product. The catalyst was characterized with SEM, XRD, FTIR, and TG-DTG-DTA. The esterification process was operated at various oil-to-methanol ratios, i.e., 1:12–1:36 and the transesterification was performed using several catalyst weights, 0.5%–2.5%. The results showed that the optimum conditions of esterification were at the 1:30 molar ratio of oil-to-methanol, which decreased the amount of acid number by 95.75%, while the optimum condition of transesterification was at 1.5% catalyst weight. The characteristics of biodiesel using 0.5–2% hydrotalcite catalyst (acid number, total glycerol, free glycerol, ester levels, viscosity, density, oxidation stability) have met the Indonesian biodiesel standard of SNI-04-7182-2012.