Geitu Yirga; H C Ananda Murthy; Eshetu Bekele
Abstract
Humic acid modified magnetite nanoparticles (HA-Fe3O4 NPs) were synthesized by co-precipitation method by varying the precursor magnetite to HA ratio of 10:1 and 20:1. The synthesized NPs were characterized by FTIR, XRD, SEM-EDX and UV-Vis DR Techniques. The appearance of C=O vibration at 1390 cm -1 ...
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Humic acid modified magnetite nanoparticles (HA-Fe3O4 NPs) were synthesized by co-precipitation method by varying the precursor magnetite to HA ratio of 10:1 and 20:1. The synthesized NPs were characterized by FTIR, XRD, SEM-EDX and UV-Vis DR Techniques. The appearance of C=O vibration at 1390 cm -1 confirms positive interaction of carboxylate anion of HA and Fe3O4. The XRD pattern and SEM image shows bare Fe3O4 and HA-Fe3O4 (10:1 and 20:1) exhibit cubic spinel structure and the spherical shape morphology, respectively. The crystallite sizes of NPs were found to be 11.50 nm, 9.17 nm and 12.65 nm for bare, 10:1 and 20:1 Fe3O4-NPs, respectively. The adsorption capacity for the dye was found to increase with increase in contact time, adsorbent dose and initial pH of the solution. The result was best fitted to pseudo 2 nd order kinetics model and Langmuir isotherm model. The methylene blue (MB) removal efficiency of bare, 10:1 and 20:1 Fe3O4-NPs from aqueous solutions was recorded to be 95.8%, 99.4%, and 97.6%, respectively. The study confirms the greater efficiency of HA-Fe3O4 NPs compared to bare Fe3O4 for the removal of MB dye. The MB removal efficiency of HA-Fe3O4 NPs was found to be proportional to amount of adsorbed HA. Copyright © VBRI Press.
G. Robin Wilson;Amit Dubey
Abstract
In order to induce the hydrophobicity and the influence of functional vinyl monomers, vinyl pyridine (VP), vinylpyrolidinone (V2P) and vinylsulphonic acid (VSA) were impregnated into SBA-15 matrix to generate SBA/L nanocomposites and characterized for the adsorption of humic acid (HA) for the first time. ...
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In order to induce the hydrophobicity and the influence of functional vinyl monomers, vinyl pyridine (VP), vinylpyrolidinone (V2P) and vinylsulphonic acid (VSA) were impregnated into SBA-15 matrix to generate SBA/L nanocomposites and characterized for the adsorption of humic acid (HA) for the first time. The structural order of the SBA/L samples was confirmed by standard physicochemical characterizations (powder X-ray diffraction (PXRD), adsorption isotherm, SEM etc). Considerable adsorption (120-140 mg/g) of HA was observed over basic (SBA/VP and SBA/V2P) nanocomposites compared to the acidic ones. Adsorption parameters like effect of temperature, pH, weight of the adsorbent and time were studied. The possible mechanistic pathway for hydrophilic/hydrophobic interactions was also explained.
Y. P. Tsai; J. C. Yang; P. C. Chuang; C. C. Chou; J. W. Lin
Abstract
This study used multi-walled carbon nanotubes (MWCNTs), TiO2 and their mixture (TiO2/CNT) to remove humic acids (HA) in water. The thermodynamic parameters with respect to the adsorption of MWCNTs, including free energy of adsorption (ΔG 0 ), enthalpy (ΔH 0 ), and entropy (ΔS 0 ) changes, ...
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This study used multi-walled carbon nanotubes (MWCNTs), TiO2 and their mixture (TiO2/CNT) to remove humic acids (HA) in water. The thermodynamic parameters with respect to the adsorption of MWCNTs, including free energy of adsorption (ΔG 0 ), enthalpy (ΔH 0 ), and entropy (ΔS 0 ) changes, are further calculated in the study. The ΔH 0 data showed the adsorption of HA onto MWCNTs is an endothermic physisorption. The ΔG 0 data indicates the adsorption of HA onto MWCNTs was spontaneous and thermodynamically favorable. Photocatalytic experiments showed 60 mgl -1 of HAs were completely degraded and mineralized as CO2 after 5 h UV irradiation by 0.8 gl -1 of TiO2, indicating the efficiency of TiO2 for the removal of HA is better than CNTs. The experiments of TiO2/CNT indicated the photocatalytic efficiency of TiO2 in the presence of CNTs was not improved, even worse than TiO2 alone. However, the photocatalytic efficiency of TiO2/CNT mixture became better than TiO2 alone due to the supply of oxygen by aeration, ascribing to the reason that the provided oxygen might be adsorbed on the surface of CNTs and accept e- as well as form •O2 - , which also leads to the formation of •OH - in the system.