Methyl orange adsorption onto simple chemical route synthesized crystalline α-Fe₂O₃nanoparticles: kinetic, equilibrium isotherm, and neural network modeling

Abstract

A B S T R A C TNanoparticles of α-Fe 2 O 3 were synthesized by simple chemical precipitation method and characterized by X-ray diffraction study, scanning electron microscopy, and Fourier transform infrared spectroscopy. Feasibility of as-synthesized nanoparticles was investigated for adsorptive removal of methyl orange (MO) dye from aqueous solution. The effects of various experimental parameters such as solution pH, initial MO concentration, contact time, and α-Fe 2 O 3 nanoparticles dose were studied in batch mode. More than 90% removal was reported at pH 2.0 with 30 mg L −1 initial MO concentration treated with 1.00 g L −1 adsorbent dose. Isotherm study reveals that Langmuir isotherm model is the most efficient one in explaining the process and maximum adsorption capacity as much as 28.90 mg g −1 is reported. Kinetic study shows that the adsorption process is best explained by second-order kinetic model confirming the dominancy of chemisorption in the process. Subsequently, the experimental data were modeled by artificial neural network to predict the removal efficiency of MO by α-Fe 2 O 3 nanoparticles following conduction of 95 experimental data points. A three-layer feed-forward back-propagation model with Levenberg-Marquardt algorithm was developed which show that the optimal network topology is 4-10-1. Model predicted data shows very good agreement with experimental data set with mean squared error and coefficient of determination (R 2 ) as 0.00152 and 0.9916, respectively.

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“…Human toxicities of dyes include several skin and eye related problems, carcinogenicity, and mutagenicity. Methyl orange (MO) [Sodium 4‐((4‐dimethylamino) phenyldiazenyl) benzenesulfonate] is an azo dye which is known for its carcinogenicity and mutagenicity towards human being . Likewise MO dye, eosin yellow (EY) is another toxic anionic dye which is known for its severe toxicities like carcinogenicity, liver and kidney related problems, skin and eye problems as well as genotoxicity in several human organs .…”

“…MO and EY dyes are mainly originating from effluents generated from industries like textiles, printing, paper manufacturing, pharmaceutical and food processing industries. Moreover, MO dye also has extensive use in research laboratories as acid base indicator . So, huge quantities of these dyes are being entering in to the aquatic environment through the disposal from dyeing units of above mentioned industries.…”

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