Abstract

ABSTRACTManganese oxide nanocomposite (Mn2O3/Mn3O4) was prepared by sol-gel technique and used as an adsorbent. Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and Field Emission Scanning Electron Microscopy (FE-SEM) were used to characterize the adsorbent. The response surface methodology (RSM) was employed to evaluate the effects of solution pH, initial Fe (III) ions concentration, adsorbent weight, and contact time on the removal ratio of the Fe (III) ions. A total of 27 adsorption experimental runs were carried out employing the detailed conditions designed based on the Box-Behnken design (BBD). Results showed that the pH of the solution and initial Fe (III) ions concentration were the most significant parameters for Fe (III) ions removal. In process optimization, the maximal value of the removal ratio of Fe (III) was achieved as 95.80%. Moreover, the corresponding optimal parameters of adsorption process were as: contact time = 62.5 min, initial Fe (III) concentration = 50 mg/L, adsorbent weight = 0.5 g, and pH = 5. The experimental confirmation tests showed a strong correlation between the predicted and experimental responses (R2 = 0.9803). The fitness of equilibrium data to common isotherm equations such as Langmuir, Freundlich, and Temkin were also tested. The sorption isotherm of adsorbent was best described by the Langmuir model. The kinetic data were analyzed using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich kinetic models. The adsorption kinetics of Fe (III) ions were well fitted with the pseudo-second-order kinetic model.

Highlights

  • Today, adsorption is used as one of the most promising methods in removal process of heavy metal ions because of its high efficiency, easy handling, and the effectiveness of various adsorbents [1, 2]

  • These results suggest that the relationship between adsorbent weight and removal ratio was related to the increase in the number of adsorption sites and that increasing this number had no effect after equilibrium was reached

  • The analysis of variance (ANOVA) results showed that the pH of the solution and initial Fe (III) concentration were the most significant parameters for Fe (III) ions removal

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Summary

Introduction

Adsorption is used as one of the most promising methods in removal process of heavy metal ions because of its high efficiency, easy handling, and the effectiveness of various adsorbents [1, 2]. Often characterized by a significant amount of surfaces and high capacity, are among the promising adsorbents for heavy metals removal because of their unique properties and potential applications [3–5]. It is well known that heavy metals have toxic or harmful effects on many forms of life. Iron toxicity can cause anorexia, shock, and oliguria. Iron overdose known as hemochromatosis is caused by a gene that enhances iron absorption in the body [8]. Iron accumulates over time in the liver, bone marrow, pancreas, skin, and testicles. Accumulation of iron in these organs causes them to functions poorly [9, 10]

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