Abstract:Competitive adsorption of three anionic orange-type dyes (i.e., methyl orange, orange II, orange G) and three inorganic anions (HPO 4 2− , SO 4 2− , CrO 4 2− ) onto Mg−Al layered double hydroxide (LDH) from bisolute aqueous solutions has been studied in view of potential application of the sorption-based technology in dye removal from textile wastewater effluents. The individual solute affinities for the LDH sample were inferred from the calorimetry measurements of the cumulative enthalpy of displacement in si… Show more
“…Notably, the hydrated environment around the A − anions affects their interactions with the anilinium cations. According to the simple empirical model, inorganic anions are much smaller and more hydrated than the MO − dye, with the radius r of the bare anion, average number n of water molecules in the hydration shell, and enthalpy of hydration Δ H hyd of r =0.240 nm, n= 3, Δ H hyd =−1035 kJ mol −1 for SO 4 2− , and r =0.181 nm, n= 2, Δ H hyd =−365 kJ mol −1 for Cl − …”
The composite anion‐exchange material MOR‐1–HA (metal–organic resin‐1–alginic acid) was investigated as sorbent for the capture of the methyl orange anion (MO−) from aqueous solutions. MOR‐1–HA shows a remarkably high sorption capacity (up to 859 mg g−1) and rapid sorption kinetics, the fastest among the reported metal–organic sorbents. It is capable of absorbing MO− over a wide pH range (1–8) and, in addition, it exhibits significant MO− sorption affinity even in the presence of large excesses of competing anions (e.g., Cl−, NO3−, SO42−). The exceptional MO−‐sorption properties of MOR‐1–HA arise not only from its highly porous structure and easily exchangeable Cl− anions, but also from a multitude of interaction effects, such as electrostatic interactions between MO− and the NH3+ groups of the material, hydration/dehydration, hydrophobicity/hydrophilicity, size and capacity of generating lateral interactions, and intercalation as revealed by theoretical studies. An ion‐exchange column with a stationary phase containing MOR‐1–HA and silica sand showed high efficiency for the removal of MO− from various types of aqueous samples. The column can be readily regenerated and reused for many runs with minimal loss (2.3–9.3 %) of its exchange capacity. The simplicity of the MOR‐1–HA/sand column and its high regeneration capability and reusability make it particularly attractive for application in the remediation of MO−‐contaminated industrial wastewater.
“…Notably, the hydrated environment around the A − anions affects their interactions with the anilinium cations. According to the simple empirical model, inorganic anions are much smaller and more hydrated than the MO − dye, with the radius r of the bare anion, average number n of water molecules in the hydration shell, and enthalpy of hydration Δ H hyd of r =0.240 nm, n= 3, Δ H hyd =−1035 kJ mol −1 for SO 4 2− , and r =0.181 nm, n= 2, Δ H hyd =−365 kJ mol −1 for Cl − …”
The composite anion‐exchange material MOR‐1–HA (metal–organic resin‐1–alginic acid) was investigated as sorbent for the capture of the methyl orange anion (MO−) from aqueous solutions. MOR‐1–HA shows a remarkably high sorption capacity (up to 859 mg g−1) and rapid sorption kinetics, the fastest among the reported metal–organic sorbents. It is capable of absorbing MO− over a wide pH range (1–8) and, in addition, it exhibits significant MO− sorption affinity even in the presence of large excesses of competing anions (e.g., Cl−, NO3−, SO42−). The exceptional MO−‐sorption properties of MOR‐1–HA arise not only from its highly porous structure and easily exchangeable Cl− anions, but also from a multitude of interaction effects, such as electrostatic interactions between MO− and the NH3+ groups of the material, hydration/dehydration, hydrophobicity/hydrophilicity, size and capacity of generating lateral interactions, and intercalation as revealed by theoretical studies. An ion‐exchange column with a stationary phase containing MOR‐1–HA and silica sand showed high efficiency for the removal of MO− from various types of aqueous samples. The column can be readily regenerated and reused for many runs with minimal loss (2.3–9.3 %) of its exchange capacity. The simplicity of the MOR‐1–HA/sand column and its high regeneration capability and reusability make it particularly attractive for application in the remediation of MO−‐contaminated industrial wastewater.
“…Table 3 presents the calculation results of the coefficient correlation, which identifies that the Langmuir model better fitted than the Freundlich model for composite material. A good fit of the Langmuir model indicates the adsorption process of the composite is monolayer with uniform energy distribution [34]. According to Meili et al [19], the Langmuir process assumed that no significant interaction between adsorbate molecules.…”
Section: Effect Of Temperature and Isotherm Adsorptionmentioning
“…The interplanar distance of LDHs increases from 1.099 nm to 2.552 nm aer MO adsorption, which was ascribed to the intercalated MO anions. 39 This nding meant that anion exchange existed between the interlayer anions and MO anions during adsorption process. Meanwhile the adsorption also could occur on the external surface of LDHs through the electrostatic attraction and hydrogen bonds, because it exhibited positive charge and contained a lot of hydroxyl groups.…”
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