Modification of coal fly ash for high capacity adsorption of methylene blue

Coal fly ash (FA) waste from local thermal power plant has been modified by acid activation and SiO2 enrichment using hydrochloric and acetic acids. The modified FA with acid activation (FAA_HAc and FAA_HCl) and SiO2 enrichment (SiO2_HCl and SiO2_HAc) were applied in the adsorption of methylene blue...

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Main Authors: Mardiyah Kurniasih, Nurul Hidayat Aprilita, Roto Roto, Mudasir Mudasir
Format: Article
Language:English
Published: Elsevier 2025-06-01
Series:Case Studies in Chemical and Environmental Engineering
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Online Access:http://www.sciencedirect.com/science/article/pii/S2666016425000088
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author Mardiyah Kurniasih
Nurul Hidayat Aprilita
Roto Roto
Mudasir Mudasir
author_facet Mardiyah Kurniasih
Nurul Hidayat Aprilita
Roto Roto
Mudasir Mudasir
author_sort Mardiyah Kurniasih
collection DOAJ
description Coal fly ash (FA) waste from local thermal power plant has been modified by acid activation and SiO2 enrichment using hydrochloric and acetic acids. The modified FA with acid activation (FAA_HAc and FAA_HCl) and SiO2 enrichment (SiO2_HCl and SiO2_HAc) were applied in the adsorption of methylene blue (MB) from aqueous solution. The physicochemical and morphological characteristics of the modified FA were characterized by XRF, SEM-EDX, XRD, BET, and TGA. The adsorption study was carried out in a batch system by optimizing pH, adsorbent dosage, contact time, initial dye concentration and temperature. The optimum adsorption is achieved at pH 8.0, adsorbent dosage of 1.5 g/L and contact time of 75 min. The experimental data fits the pseudo-second-order models and the activation energies (Ea) are 48.71, 48.95, 32.26, and 30.61 kJ mol−1 for FAA_HAc, FAA_HCl, SiO2_HAc, and SiO2_HCl, respectively. Langmuir, Freundlich, or Temkin isotherm models described well the experimental data. The maximum adsorption capacities (qm) of FAA_HAc, FAA_HCl, SiO2_HAc, and SiO2_HCl with Lamgmuir model at 318 K are 151.33, 146.18, 100.78, and 95.81 mg/g, respectively. The qm values increase with temperature, indicating endothermic adsorption process. Themodynamic study gives the positive value of enthalpy (ΔH°) and entropy (ΔS°), and the negative value of free energy (ΔG°) changes, suggesting an endothermic and spontaneous process. The lower activation energy and higher adsorption capacity of modified FA with a simple, low-cost and eco-friendly technique provide a prospective application of the adsorbents for the removal of dye waste from aqueous solution.
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spelling doaj-art-52f6f406329649c1b1d4e1edd9d74d402025-01-13T04:19:10ZengElsevierCase Studies in Chemical and Environmental Engineering2666-01642025-06-0111101101Modification of coal fly ash for high capacity adsorption of methylene blueMardiyah Kurniasih0Nurul Hidayat Aprilita1Roto Roto2Mudasir Mudasir3Chemistry Department, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara P.O. Box Bls. 21, Yogyakarta, 55281, Indonesia; Chemistry Department, Faculty of Mathematics and Natural Sciences, Universitas Jenderal Soedirman, Jl. Dr. Soeparno, Purwokerto, 53123, IndonesiaChemistry Department, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara P.O. Box Bls. 21, Yogyakarta, 55281, IndonesiaChemistry Department, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara P.O. Box Bls. 21, Yogyakarta, 55281, IndonesiaChemistry Department, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara P.O. Box Bls. 21, Yogyakarta, 55281, Indonesia; Corresponding author.Coal fly ash (FA) waste from local thermal power plant has been modified by acid activation and SiO2 enrichment using hydrochloric and acetic acids. The modified FA with acid activation (FAA_HAc and FAA_HCl) and SiO2 enrichment (SiO2_HCl and SiO2_HAc) were applied in the adsorption of methylene blue (MB) from aqueous solution. The physicochemical and morphological characteristics of the modified FA were characterized by XRF, SEM-EDX, XRD, BET, and TGA. The adsorption study was carried out in a batch system by optimizing pH, adsorbent dosage, contact time, initial dye concentration and temperature. The optimum adsorption is achieved at pH 8.0, adsorbent dosage of 1.5 g/L and contact time of 75 min. The experimental data fits the pseudo-second-order models and the activation energies (Ea) are 48.71, 48.95, 32.26, and 30.61 kJ mol−1 for FAA_HAc, FAA_HCl, SiO2_HAc, and SiO2_HCl, respectively. Langmuir, Freundlich, or Temkin isotherm models described well the experimental data. The maximum adsorption capacities (qm) of FAA_HAc, FAA_HCl, SiO2_HAc, and SiO2_HCl with Lamgmuir model at 318 K are 151.33, 146.18, 100.78, and 95.81 mg/g, respectively. The qm values increase with temperature, indicating endothermic adsorption process. Themodynamic study gives the positive value of enthalpy (ΔH°) and entropy (ΔS°), and the negative value of free energy (ΔG°) changes, suggesting an endothermic and spontaneous process. The lower activation energy and higher adsorption capacity of modified FA with a simple, low-cost and eco-friendly technique provide a prospective application of the adsorbents for the removal of dye waste from aqueous solution.http://www.sciencedirect.com/science/article/pii/S2666016425000088AdsorptionCoal fly ashSiO2 enrichmentMethylene blueKineticsThermodynamics
spellingShingle Mardiyah Kurniasih
Nurul Hidayat Aprilita
Roto Roto
Mudasir Mudasir
Modification of coal fly ash for high capacity adsorption of methylene blue
Case Studies in Chemical and Environmental Engineering
Adsorption
Coal fly ash
SiO2 enrichment
Methylene blue
Kinetics
Thermodynamics
title Modification of coal fly ash for high capacity adsorption of methylene blue
title_full Modification of coal fly ash for high capacity adsorption of methylene blue
title_fullStr Modification of coal fly ash for high capacity adsorption of methylene blue
title_full_unstemmed Modification of coal fly ash for high capacity adsorption of methylene blue
title_short Modification of coal fly ash for high capacity adsorption of methylene blue
title_sort modification of coal fly ash for high capacity adsorption of methylene blue
topic Adsorption
Coal fly ash
SiO2 enrichment
Methylene blue
Kinetics
Thermodynamics
url http://www.sciencedirect.com/science/article/pii/S2666016425000088
work_keys_str_mv AT mardiyahkurniasih modificationofcoalflyashforhighcapacityadsorptionofmethyleneblue
AT nurulhidayataprilita modificationofcoalflyashforhighcapacityadsorptionofmethyleneblue
AT rotoroto modificationofcoalflyashforhighcapacityadsorptionofmethyleneblue
AT mudasirmudasir modificationofcoalflyashforhighcapacityadsorptionofmethyleneblue