Stability of iron chelates during photo-Fenton process: The role of pH, hydroxyl radical attack and temperature

Ahile, Ungwanen J.; Wuana, R. A.; Itodo, A. U.; Sha’Ato, Rufus; Dantas, Renato F.

doi:10.1016/j.jwpe.2020.101320

Cited by 34 publications

(14 citation statements)

References 38 publications

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“…It was found that the higher temperature accelerated the removal percentage of RhB, especially when the temperature was increased from 40°C to 60°C (from 41.9% to ∼100%). The highly efficient catalytic performance was ascribed to the increased generation of •OH that were possibly produced at an elevated temperature, and the diffusion rate of RhB and H 2 O 2 molecules was accelerated by the clay self‐motion 46–48 . Several different processes of the RhB removal at 60°C and 80°C were compared, and the results were given in Figure S4.…”

Section: Resultsmentioning

confidence: 99%

“…The highly efficient catalytic performance was ascribed to the increased generation of •OH that were possibly produced at an elevated temperature, and the diffusion rate of RhB and H 2 O 2 molecules was accelerated by the clay self-motion. [46][47][48] Several different processes of the RhB removal at 60 • C and 80 • C were compared, and the results were given in Figure S4. The blank experiment (curves a) was carried out to elucidate decomposition at pH 2.0 without pelagic clays or H 2 O 2 .…”

Section: Removal Of Rhb By Raw Pelagic Claysmentioning

confidence: 99%

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Deep‐sea clays using as active Fenton catalysts for self‐propelled motors

et al. 2022

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Raw deep-sea clays (i.e., pelagic clays) collected from the Indian Ocean were able to function as Fenton catalysts and self-propelled micromotors due to the high content of Fe-and Mn-. The pelagic clays were for the first time observed to be automatic in the H 2 O 2 solution. The pelagic clays existed in the form of poorly crystallized marine sedimentation. The major minerals were found as illite/montmorillonite (I/M) and amorphous ferromanganese nodules, and the minor minerals included kaolinite, quartz, feldspar, and calcite. Significant amounts of oxygen bubbles were generated when the clay particles were dispersed into the H 2 O 2 solution (0.1-10.0 wt.%), and the average velocity of the motors was observed as high as 183.0 μm s -1 in 10.0 wt.% H 2 O 2 . The selfpropulsion would induce vigorous mixing in local areas of the solution and was confirmed to benefit the catalytic performance. The clays were employed to remove Rhodamine B (RhB) for a proof-of-concept study. In the acid solution (pH = 1.0-5.0), the removal of RhB was controlled by the Fenton process accompanied by the adsorption of clay particles. In the alkaline solution (pH = 9.0), the removal of RhB was found to follow an adsorptive bubble separation pathway. Both processes were greatly influenced by the self-motion of MnO x motors contained in the pelagic clays.

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Section: Resultsmentioning

confidence: 99%

Section: Removal Of Rhb By Raw Pelagic Claysmentioning

confidence: 99%

Deep‐sea clays using as active Fenton catalysts for self‐propelled motors

et al. 2022

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“…Photo-Fenton degradation of MB in the presence of nanocatalysts at different application temperatures enables the calculation of activation energy (E a , kJ/mol) using Arrhenius equation, enthalpy change (ΔH*, kJ/mol), entropy change (ΔS*, kJ mol −1 K −1 ), and Gibbs free energy change (ΔG * , kJ/mol) by applying Eqs. 25-27 [36,37]:…”

Section: Thermodynamic Studies Of Methylene Blue Photo-fenton Degrada...mentioning

confidence: 99%

“…(iv) The change in entropy for the process was calculated to be negative 0.191 and 0.190 in the presence of NM and NC, respectively, and that is related to the decrease in the randomness of MB at the surface of catalysts with an irreversible tendency for the process. (v) The change in free energy is positive and proves that the degradation process is nonspontaneous and requires external energy such as radiation and/or heat [36,37].…”

Section: Effect Of Temperature On Methylene Blue Degradation By Photo...mentioning

confidence: 99%

Adsorption and Photo-Fenton Degradation of Methylene Blue Using Nanomagnetite/Potassium Carrageenan Bio-Composite Beads

et al. 2022

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The present study deals with the preparation of nanomagnetite (NM), potassium carrageenan (KC), and nanomagnetite/potassium carrageenan bio-composite beads (NC). Characterization of the prepared solid materials using different physicochemical techniques such as X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscope (TEM), energy-disperse X-ray spectroscopy (EDX), diffuse reflectance spectrophotometer (DRS), swelling ratio (SR%), N2 adsorption, pH of point of zero charges (pHPZC), and Fourier transform infrared spectroscopy (FTIR). Comparing between adsorption and photo-Fenton degradation process for methylene blue (MB) on the surface of the prepared solid materials. Nanomagnetite/potassium carrageenan bio-composite (NC) exhibited high specific surface area (406 m2/g), mesoporosity (pore radius, 3.64 nm), point of zero charge around pH6.0, and the occurrence of abundant oxygen-containing functional groups. Comparison between adsorption and photo-Fenton oxidation process for methylene blue (MB) was carried out under different application conditions. NC exhibited the maximum adsorption capacity with 374.50 mg/g at 40 °C after 24 h of shaking time while 96.9% of MB was completely degraded after 20 min of photo-Fenton process. Langmuir's adsorption model for MB onto the investigated solid materials is the best-fitted adsorption model based on the higher correlation coefficient values (0.9771–0.9999). Kinetic and thermodynamic measurements prove that adsorption follows PSO, endothermic, and spontaneous process, while photo-Fenton degradation of MB achieves PFO, nonspontaneous, and endothermic process. Photo-Fenton degradation is a fast and simple technique at a lower concentration of dye (< 40 mg/L) while at higher dye concentration, the adsorption process is preferred in the removal of that dye.

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“…[9][10][11] This big hurdle is mainly attributed to three factors: (1) the oxidation potential of OH radicals under neutral conditions is dramatically reduced, thereby undermining its oxidation capacity to react with organic contaminants; (2) increasing pH of the solution would promote the disproportionation of H 2 O 2 into O 2 and H 2 O, greatly diminishing generation efficiency of OH radicals; (3) at pH 7.0, Fe 2+ will precipitate out as iron hydroxides, greatly decreasing its catalytic activity and thus the decomposition efficiency of H 2 O 2 to OH radicals. 12 As a result, it is of great significance to develop a more efficient, convenient, and extensive method to promote the heterogeneous Fenton reaction at pH 7.0.…”

Section: Introductionmentioning

confidence: 99%