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Catalysis in Green Chemistry and Engineering

ISSN 打印: 2572-9896
ISSN 在线: 2572-990X

Catalysis in Green Chemistry and Engineering

DOI: 10.1615/CatalGreenChemEng.2018028634
pages 307-323

EFFICIENT REMOVAL OF ANIONIC DYE POLLUTANT BY NIMGAL LAYERED DOUBLE HYDROXIDES OF VARIABLE COMPOSITION

Dipshikha Bharali
Department of Chemical Sciences, Tezpur University, Napaam 784028, India
Pankaj Bharali
Department of Chemical Sciences, Tezpur University, Napaam 784028, India
Ramesh Ch. Deka
Department of Chemical Sciences, Tezpur University, Napaam-784028, Assam, India

ABSTRACT

NiMgAl layered double hydroxides (LDHs) with various Ni/Mg molar ratios have been synthesized using a simple coprecipitation route and used as an adsorbent for the removal of anionic organic dye pollutants from aqueous solution. The resulting ternary LDHs were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), Raman spectroscopy, UV-visible diffuse reflectance spectroscopy (UV-DRS), scanning electron microscopy (SEM), N2 physisorption by the Brunauer-Emmett-Teller method (BET), and transmission electron microscopy (TEM) techniques. The PXRD patterns showed the formation of LDH-like compound with characteristic peaks for all the samples. The relative intensity, crystallinity (%), and cell parameter values were calculated for all the samples. The high BET surface area and pore volume of LDH with a Ni/Mg molar ratio of 1:1 supports its high adsorption capacity for the removal of methyl orange (MO) from aqueous solution with a dye uptake percentage of 97%. The adsorption process was studied by optimizing different parameters, such as contact time, adsorbent dosage, initial dye concentration, and solution pH. The kinetic study showed that the adsorption process followed a pseudo-second-order kinetic model. The adsorption data fit better with the Langmuir isotherm model than the Freundlich isotherm model with a maximum adsorption capacity (qm) of 127.9 mg/g at 25°C and pH 6. Adsorption interactions of MO dye onto the ternary LDH from aqueous solution were investigated using XRD, SEM, and FTIR spectroscopy. Moreover, the reused adsorbents retained their adsorption capacity up to three successful cycles.