Abstract
In our work, the removal of cationic and anionic dyes from water was estimated both experimentally and computationally. We check the selectivity of the adsorbent, Zn–Fe layered double hydroxide (LDH) toward three dyes. The physical and chemical properties of the synthesis adsorbent before and after the adsorption process were investigated using X-ray photoelectron spectroscopy, energy dispersive X-ray, X-ray diffraction, FT-IR, HRTEM, and FESEM analysis, particle size, zeta potential, optical and electric properties were estimated. The effect of pH on the adsorption process was estimated. The chemical stability was investigated at pH 4. Monte Carlo simulations were achieved to understand the mechanism of the adsorption process and calculate the adsorption energies. Single dye adsorption tests revealed that Zn–Fe LDH effectively takes up anionic methyl orange (MO) more than the cationic dyes methylene blue (MB) and malachite green (MG). From MO/MB/MG mixture experiments, LDH selectively adsorbed in the following order: MO > MB > MG. The adsorption capacity of a single dye solution was 230.68, 133.29, and 57.34 mg/g for MO, MB, and MG, respectively; for the ternary solution, the adsorption capacity was 217.97, 93.122, and 49.57 mg/g for MO, MB, and MG, respectively. Zn–Fe LDH was also used as a photocatalyst, giving 92.2% and 84.7% degradation at concentrations of 10 and 20 mg/L, respectively. For visible radiation, the Zn–Fe LDH showed no activity.
Highlights
In our work, the removal of cationic and anionic dyes from water was estimated both experimentally and computationally
Field Emission Scanning Electron Microscope (FESEM) images were applied to perform the morphology of the synthesis layered double hydroxide (LDH)
The Surface property of synthesized LDH are followed to type II isotherm that matches with H3-type hysteresis loop and that is related to the mesopores/macroporous construction and capillary condensation process
Summary
The removal of cationic and anionic dyes from water was estimated both experimentally and computationally. We check the selectivity of the adsorbent, Zn–Fe layered double hydroxide (LDH) toward three dyes. Single dye adsorption tests revealed that Zn–Fe LDH effectively takes up anionic methyl orange (MO) more than the cationic dyes methylene blue (MB) and malachite green (MG). The effluent discharge of the textile industry leads to environmental pollution owing to the existence of complex mixtures of methylene green (MG), methyl orange (MO), and malachite blue (MB) as cationic and anionic dyes[3] and toxic metal ions in polluted water[4]. The removal of organic pollutants with the use of layered double hydroxide (LDH) has been of great interest to many researchers in recent years. Absorption of visible light from the top of the valence band (which is mainly composed of oxygen (O) 2p orbitals hybridized with Fe or Zn 3d orbitals) to the bottom of the conduction band (which is mainly composed of Fe or Zn 3d orbitals hybridized with O 2p orbitals) is the reason for the electronic band gap transition[19]
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