Study of Adsorption and Intercalation of Orange-Type Dyes into Mg–Al Layered Double Hydroxide

Abstract

In the context of depollution and textile wastewater treatment, the sorption-based processes are good candidates to achieve the efficient removal of such toxics substances as dyes. In the present study, the exchange−adsorption from aqueous solutions of three azoic dyes, Methyl Orange (MO), Orange II (OII), and Orange G (OG), onto Mg−Al−LDH−NO 3 layered double hydroxides (LDH, molar Mg:Al ratio of 2) was investigated through monitoring all retained and removed species in combination with direct calorimetry and X-ray diffraction measurements. Kinetic curves, determined for several initial concentrations of the three dyes, indicated that the process was fast (between 60 and 100 min) and followed the pseudo-second order model in line with the passage of the removed dye through a chemisorption stage, thus constituting the ratelimiting step. Dye adsorption isotherms (H2-type) showed some differences in the maximum adsorption quantity (5.5 mmol g −1 , MO; 2.7 mmol g −1 , OII; 1.7 mmol g −1 , OG), consistent with anionic exchange capacity and adsorption on the external surface, depending on the cross-sectional area of the dye species and with their hydrophobic− hydrophilic character. The uptake of sodium cations as a function of the dye type and the surface coverage ratio pointed that the counterions can either stay in solution or be adsorbed to neutralize the free −SO 3 − moieties or other anionic species in the interlayer space. The cumulative enthalpy of displacement was negative in conformity with the exothermic character of the overall process. The intercalation of dye anions into the interlayer space of LDH materials led to its expansion with various distances being dependent both on the dye type and on the overall exchange balance. The latter included also the desorption of nitrates as well as the presence of carbonate species within the interlayer space, due to exchange in open systems exposed to the ambient atmosphere.

Synthesis of imidazolium-crosslinked chitosan aerogel and its prospect as a dye removing adsorbent

“…32 An adsorption maximum of 1800 mg g À1 was reported for methyl orange using inorganic Mg-Al layered double hydroxide. 33 Due to the high variety of studied dyes and adsorption experimental setups found in the literature, a direct comparison between the different adsorbents might not be meaningful (e.g., no correlation was found between the amount of charged groups in dyes and the adsorption maximum of glutaraldehyde crosslinked chitosan). 29 However, it can be concluded that the anionic dye adsorption capacity of ICC1 is among the highest reported for organic and inorganic materials.…”

Adsorption Study of Malachite Green Removal from Aqueous Solution Using Cu/M3+ (M3+=Al, Cr) Layered Double Hydroxide

“…Ln qe = ln kF + 1 ln Ce (4) Where, qmax and kL are Langmuir constants, kF and n are Freundlich constants with n giving an indication of favorable the adsorption process and verify the type of adsorption process. The isotherm adsorption parameters were shown in Table 3.…”

“…Textile wastewater is a complex mixture and contains a highly polluting substance, i.e., heavy metal cations, and dye 3 . Most of dyes substance contained aromatic structure, which makes them toxic 4 , non-biodegradable, and also carcinogenic for humans and the environment 5,6 . In the environment, these colored effluent's was covering the surface of waters and reduced the oxygen 7 .…”

Synthesis and characterisation of dye­intercalated nickel­aluminium layered­double hydroxide as a cosmetic pigment

“…In particular, it is proposed to extract Evans Blue using Zn-Al LDH [20], Orange-type dyes -using Zn-Al LDH [21], Perylenediimide -using Zn-Al, Co-Al, Ni-Al LDH [22]. Various azo-dyes [23], including Remazol Brilliant Violet [24], had been extracted using Ni-Al LDH, blue dyes (including Maya Blue) [ [20,26] and intercalation [24]. However, the pigment preparation was not the aim of the study.…”

“…1) synthesis of LDH with inorganic anions, using coprecipitation at high supersaturation [11,16,17], coprecipitation at constant рН [9,24], homogeneous coprecipitation [37], etc. ;…”