Adsorption of Acid Yellow 42 dye on calcined layered double hydroxide: Effect of time, concentration, pH and temperature

Abstract

The adsorption of textile dyes onto Layered Double Hydroxides (LDH) and their thermally decomposed products is a promising strategy for the treatment of contaminated effluents-combining high removal efficiency with reasonable cost. The main purpose of this paper was to investigate the adsorption of textile azo dye Acid Yellow 42 (AY) onto calcined and uncalcined Mg-Al-CO 3-LDH. A set of analytical techniques was used to characterize the materials, namely X-ray diffraction (XRD), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), thermogravimetric analyses (TGA), N 2 adsorption-desorption isotherms and Scanning Electron Microscopy (SEM). In the study of azo dye adsorption, the following factors were assessed: kinetics, adsorption capacity, effect of temperature, initial pH value, and recyclability of the adsorbent material. The adsorption capacity of calcined LDH (CLDH) was almost four times greater than that of the LDH precursor: 1266 mg•g −1 (1.669 mmol•g −1) and 330.0 mg•g −1 (0.4350 mmol•g −1), respectively, at pH equal to 7.0 and 25°C. The greater adsorption capacity for CLDH is related to the recovery property of these materials in light of the so called "memory effect", which allows an intercalation process of the anionic dye, as demonstrated by XRD data.

Organic-Inorganic Hybrid Materials: Layered Double Hydroxides and Cellulose Acetate Films as Phosphate Recovery

“…2b. For this material, it is possible to observe the presence of two bands located at 850/cm and 670/cm, which are attributed to vibration modes of Al-O and Mg-O of Mg(Al)O [21,22,35]. The CAF, CAF-LDH and CAF-LDH-c spectra are shown in Figs.…”

“…The LDH sample obtained via the coprecipitation method as described above was subjected to the calcination process as follows: the powder was heated in a tubular furnace for 4 h at 550 °C, under O 2 atmosphere with a constant flow of 50 mL/min and a heating rate of 10 °C/min. These conditions of calcination process were chosen to optimize the adsorption capacity of the calcined LDH by the strutural recovery property of this material [21,22]. The calcined material (abbreviated LDH-c) was stored under reduced pressure in a desiccator containing silica gel.…”

“…1b) shows peaks referring to the presence of MgO, as indicated in the figure. For this material, the calcination process at suitable temperature and atmosphere may give rise to the MgO crystalline phase and other amorphous phases, such as oxides and mixed oxihydroxides [21,22]. The diffractrogram of CAF (Fig.…”

A new magnetic bio-sorbent for arsenate removal from the contaminated water: Characterization, isotherms, and kinetics

“…Then, the obtained slurry was refluxed in a round-bottom flask at 70°C under vigorous stirring for 1 h. The obtained slurry was aged at 70°C for 24 h. Finally, the obtained precipitate (Co/Fe/ Al LDH) was centrifuged and washed with the deionized water until pH of the solution reached 7. The synthesized LDH was dried at 50°C for 12 h and calcination was performed at 500°C for 3 h by furnace in air atmosphere, leading to an increase in the porosity of the Co/Fe/Al LDH (35). The calcined material was signed as CLDH.…”

Potassium hydroxide-treated palm kernel shell sorbents for the efficient removal of methyl violet dye

“…Dyes in water are originated from textiles, paper-making, printing, colouring, food processing and cosmetic industries. Over 700,000 tons of wastewater produced every year is due to dyes [6,7]. Methyl violet is an example of the commonly used basic dyes with high colour intensity.…”