Calcined Layered Double Hydroxides for Decolorization of Azo Dye Solutions: Equilibrium, Kinetics, and Recycling Studies

Teixeira, Thaisa P.F.; Pereira, S. I.; Aquino, Sérgio Francisco de; Dias, Anderson

doi:10.1089/ees.2011.0293

Cited by 30 publications

(18 citation statements)

References 31 publications

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“…anionic surfactant) since there were no significant changes in the lattice parameters (d 003 = 6.1 Å; a = 2.4 Å, and c = 18.4 Å -see Equations (2) and (3)). These results are in agreement with our previous results, (Teixeira et al, 2012;Vieira et al, 2009) which showed that the decolorization of azo dye (Remazol Golden Yellow RNL) solutions by LDH was due to adsorption rather than intercalation of the organic molecule. Figure 5 shows that a high dose of LDH (20 g/L) is necessary to place the raw effluent samples (RTE) within the discharge limits for the parameter of COD, which is 250 mg/L for textile effluents, as defined in the Minas Gerais State Environmental Legislation (COPAM /CERH 01/2008).…”

Section: Resultssupporting

confidence: 94%

“…The loss of COD removal efficiency was steeper and higher with the raw effluent, indicating a larger amount of adsorbed/intercalated compounds that could not be decomposed by the thermal treatment (500 °C for 4h). Examples of such compounds include azo dyes, which do not decompose completely at 500 °C, (Teixeira et al, 2012;Vieira et al, 2009) and chloride and hydroxide ions, which are present in high concentrations in the textile effluent. Although anions like chloride and hydroxide do not themselves contribute to the COD result, their adsorption/intercalation would obviously preclude the removal of oxidizable organics in the COD test, thereby reducing the COD removal efficiency.…”

Section: Resultsmentioning

confidence: 99%

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Use of calcined layered double hydroxides for the removal of color and organic matter from textile effluents: kinetic, equilibrium and recycling studies

Teixeira

Aquino

Pereira

et al. 2014

Braz. J. Chem. Eng.

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-This paper presents data for the synthesis and characterization of layer double hydroxides (LDH) and their use for color and chemical oxygen demand (COD) removal from effluents generated by a textile industry. Adsorption studies with raw and biologically treated (activated sludge) textile effluent showed that the pseudo-second order model best fitted the experimental data, leading to adsorption coefficients of 39.1 and 102.9 mgCOD/gLDH for raw and treated effluents, respectively. The best conditions for color and COD removal were obtained at lower values of temperature and pH (25 °C and pH 7) and, in these conditions, an LDH dose of 10 g/L resulted in color removal efficiencies of 56% for samples of raw and 66% for samples of treated effluent. Recycling studies indicated that the reuse of thermally treated LDH led to a progressive loss in the removal efficiencies of COD and color. The reduction was more pronounced with samples of the raw textile effluent. LDH characterization performed before and after each adsorption and regeneration experiment showed that there was no intercalation of dye molecules in the interlayer region of the LDH, indicating that COD and color removal might be due to the adsorption of organic molecules onto the LDH surface.

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Section: Resultssupporting

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Use of calcined layered double hydroxides for the removal of color and organic matter from textile effluents: kinetic, equilibrium and recycling studies

Teixeira

Aquino

Pereira

et al. 2014

Braz. J. Chem. Eng.

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“…On the other hand, according to literature data the RNL azo dye has three pK a Figure 6: UV-vis spectra of RNL azo-dye, after adsorption and after photocatalytic test at pH 6 (a) and pH 3 (b) Raman shift (cm -1 ) Intensity values: 3, 3.5 and 6 -the sulphonic group is deprotonated at pH 3, the sulphate group is deprotonated at pH 3.5 and the amido group is deprotonated at pH 6, which results in a large negative charge, as displayed in Fig. 7 [42,43]. Therefore, an attractive force between the positive surface charge of the perovskite and the negative charge of the azo dye occurs at pH 3 favoring the dye adsorption and the highest solution discoloration.…”

Section: Photocatalytic Efficiencymentioning

confidence: 99%

CaSnO 3 obtained by modified Pechini method applied in the photocatalytic degradation of an azo dye

et al. 2017

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Pure forms of alkaline-earth stannates with perovskite structure (ASnO 3 , A= Ca ) have been used as photocatalysts. In this work, CaSnO 3 perovskite sample was synthesized by a modified Pechini method at 800 ºC and characterized by X-ray diffraction (XRD), UV-visible spectroscopy, infrared spectroscopy and Raman spectroscopy. The photocatalytic degradation of remazol golden yellow (RNL) dye under UV radiation was evaluated. The XRD pattern showed that the synthesis method favored the orthorhombic CaSnO 3 crystallization. According to the Raman spectrum, a material with high short-range order was obtained despite of the relatively low synthesis temperature, compared to the solid-state reaction one. The highest photocatalytic activity was attained at pH 3, which presented 51% discoloration and improved activity of 35% compared to discoloration solely due to adsorption (absence of radiation). The point of zero charge (PZC) and the photocatalytic results indicated that a direct mechanism prevailed at pH 3, whereas an indirect mechanism prevailed at pH 6.

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“…Layered double hydroxides (LDH), also known as hydrotalcite-like compounds (HTlc), are a class of synthetic two-dimensional anionic clays which can be described as containing brucite-like layers in which partial substitution of trivalent for divalent cations results in a positive charge on the sheet balanced by anions within interlayer galleries [23,24]. The possible mechanism of growth of LDH has been discussed elsewhere [25,26].…”

Section: Introductionmentioning

confidence: 99%

Preparation of biomorphic Ni–Al LDHs using cotton from discarded T–shirt as a template and the adsorption capability for Congo red

Wang

Duan

et al. 2014

Res Chem Intermed

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Biomorphic Ni-Al layered double-hydroxide (LDH) nanosheets with 3D hierarchical structures were synthesized with cotton from discarded T-shirt as templates. The as-prepared samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetry-differential thermal analysis, scanning electron microscopy, and energy-dispersive X-ray diffraction. Adsorption of Congo red (CR) by calcined Ni-Al layered double hydroxides (CLDH) from aqueous solution was investigated in detail. Different conditions were evaluated, including solution pH, amount of adsorbent, initial CR concentration, contact time, and temperature. The adsorption kinetics and equilibrium isotherms of the CLDH were studied by use of pseudo-first-order and pseudo-second-order kinetic models, and the Langmuir, Freundlich, and Dubinin-Radushkevich isotherms. Equilibrium isotherms of uptake of CR by CLDH were a good fit to the Freundlich equation, and the adsorption kinetics of CR followed a pseudo-secondorder kinetic model. These results suggest that CLDH may be effective adsorbents for the removal of anionic dyes from wastewater.

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Calcined Layered Double Hydroxides for Decolorization of Azo Dye Solutions: Equilibrium, Kinetics, and Recycling Studies

Cited by 30 publications

References 31 publications

Use of calcined layered double hydroxides for the removal of color and organic matter from textile effluents: kinetic, equilibrium and recycling studies

Use of calcined layered double hydroxides for the removal of color and organic matter from textile effluents: kinetic, equilibrium and recycling studies

CaSnO 3 obtained by modified Pechini method applied in the photocatalytic degradation of an azo dye

Preparation of biomorphic Ni–Al LDHs using cotton from discarded T–shirt as a template and the adsorption capability for Congo red

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