“…A Box-Cox procedure (Fig. 4 e) was used to determine the normality of the data and establish the model significance of the sonophotocatalytic process 42 . Figure 4 The diagnostics plots for validation of quadratic model: ( a) predicted values vs. factual values, ( b ) normal probability distribution of residuals, ( c) internally studentized residuals vs. predicted values plot, ( d ) internally studentized residuals vs. run numbers, and ( e) Box-Cox plot.…”
Section: Resultsmentioning
confidence: 99%
“…This trend can be attributed to the following elements: (a) A test apparatus operating under identical conditions will produce analogous results (equal production of hydroxyl radicals at each initial R195 concentration) 44 ; (b) the generation of hydroxyl radicals is proportional to the initial concentration of R195 40 . Therefore, an increase in the number of dye molecules can lead to the saturation of active sites on the surface of the photocatalyst and inadequate production of hydroxyl radicals 42 . (c) Produced intermediates of R195 during sonophotocatalytic degradation (at high concentrations of R195) reduce removal efficiency due to a competition reaction between the dye and intermediate with free radicals 5 .…”
In this study, the magnetic photocatalyst Scendesmus/Fe3O4/TiO2 was synthesized, and its sonophotocatalytic properties in relation to the degradation of the Red195 dye were evaluated. Particles were characterized using a scanning electron microscope (SEM), Fourier's transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and a vibrating-sample magnetometer (VSM). At a pH of 5, a photocatalyst dosage of 100 mg, an initial R195 concentration of 100 mg/l, an ultrasound power of 38W, and an exposure time of 20 min, the maximum Red195 removal efficiency (100%) was achieved. After five cycles of recycling, the composite's sonophotocatalytic degradation stability for R195 remains above 95%. Experiments on scavenging indicate that electrons (h+) and hydroxyls (OH-) are indispensable decomposition agents. The removal of R195 by Scendesmus/Fe3O4/TiO2 is consistent with the pseudo-first-order kinetic, Freundlich, and Henderson's isotherm models, as determined by kinetic and isotherm investigations. The negative activation enthalpy of the standard (ΔH°) illuminates the exothermic adsorption mechanism. The increase in standard Gibbs activation free energy (ΔG°) with increasing temperature reveals the process is not spontaneous. As indicated by the negative value of the standard entropy of activation (ΔS°), activation of the reactants resulted in a loss of freedom.
“…A Box-Cox procedure (Fig. 4 e) was used to determine the normality of the data and establish the model significance of the sonophotocatalytic process 42 . Figure 4 The diagnostics plots for validation of quadratic model: ( a) predicted values vs. factual values, ( b ) normal probability distribution of residuals, ( c) internally studentized residuals vs. predicted values plot, ( d ) internally studentized residuals vs. run numbers, and ( e) Box-Cox plot.…”
Section: Resultsmentioning
confidence: 99%
“…This trend can be attributed to the following elements: (a) A test apparatus operating under identical conditions will produce analogous results (equal production of hydroxyl radicals at each initial R195 concentration) 44 ; (b) the generation of hydroxyl radicals is proportional to the initial concentration of R195 40 . Therefore, an increase in the number of dye molecules can lead to the saturation of active sites on the surface of the photocatalyst and inadequate production of hydroxyl radicals 42 . (c) Produced intermediates of R195 during sonophotocatalytic degradation (at high concentrations of R195) reduce removal efficiency due to a competition reaction between the dye and intermediate with free radicals 5 .…”
In this study, the magnetic photocatalyst Scendesmus/Fe3O4/TiO2 was synthesized, and its sonophotocatalytic properties in relation to the degradation of the Red195 dye were evaluated. Particles were characterized using a scanning electron microscope (SEM), Fourier's transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and a vibrating-sample magnetometer (VSM). At a pH of 5, a photocatalyst dosage of 100 mg, an initial R195 concentration of 100 mg/l, an ultrasound power of 38W, and an exposure time of 20 min, the maximum Red195 removal efficiency (100%) was achieved. After five cycles of recycling, the composite's sonophotocatalytic degradation stability for R195 remains above 95%. Experiments on scavenging indicate that electrons (h+) and hydroxyls (OH-) are indispensable decomposition agents. The removal of R195 by Scendesmus/Fe3O4/TiO2 is consistent with the pseudo-first-order kinetic, Freundlich, and Henderson's isotherm models, as determined by kinetic and isotherm investigations. The negative activation enthalpy of the standard (ΔH°) illuminates the exothermic adsorption mechanism. The increase in standard Gibbs activation free energy (ΔG°) with increasing temperature reveals the process is not spontaneous. As indicated by the negative value of the standard entropy of activation (ΔS°), activation of the reactants resulted in a loss of freedom.
“…Selectivity in dye adsorption can be induced in a polymer chain by introducing different functional groups, which can be tuned by varying pH. 29 Some reports pertaining to the removal of MB dye by polymer-based adsorbents include poly(acrylic acid- co -vinylsulfonic acid) hydrogel, 30 polyaniline–magnetite composites, 31 polyaniline–sodium alginate, 29 polyaniline nanotubes, 32 pyrrole-based materials, 33,34 polydopamine, 35 polyaniline-based silica composite, 36 and dextrin- g -poly m -phenylenediamine. 37 Similarly, poly(2-(dimethylamino)ethyl methacrylate)/nanocrystalline cellulose hydrogels 38 and polyaniline–chitosan composites 39 have also been reported for the adsorptive removal of MO dye.…”
Polyaniline grafted maleic acid was synthesized via the ring opening reaction of maleic anhydride using polyaniline as a nucleophile. The polymer was used for selective removal of cationic (pH > 6.8) and anionic (pH < 6.8) dyes at different pH values.
The potential of pyrolyzed Mytella falcata shells as an adsorbent for removing thiazine dye from aqueous solutions was investigated. The study found that the adsorbent produced at 600°C of pyrolysis temperature, with an adsorbent mass of 0.5 g, particle diameter 0.297-0.149 mm, and pH 12.0, demonstrated the highest dye removal efficiency of 82.41%. The material's porosity was observed through scanning electron microscopy (SEM), which is favorable for adsorption, while FTIR and XRD analyses confirmed the presence of calcium carbonate (CaCO3) in the crystalline phases. The pseudo-second order model was found to be the best fit for the data, suggesting that the adsorption mechanism involves two steps: external diffusion and diffusion via the solid pores. The Redlich-Peterson isotherm model better represented the equilibrium data, and the methylene blue adsorption was found to be spontaneous, favorable, and endothermic. The hydrogen peroxide with UV oxidation was found to be the most efficient method of regeneration, with a regeneration percentage of 63% achieved using 600 mmol.L -1 of oxidizing agents. The results suggest that pyrolyzed Mytella falcata shells could serve as an economically viable alternative adsorbent, reducing the amount of waste produced in the local environment while removing pollutants from water. The material's adsorption capacity remained almost constant in the first adsorption-oxidation cycles, indicating its potential for repeated use.
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