Fabrication of α-MnO2/Fe-Mn binary oxide nanocomposite as an efficient adsorbent for the removal of methylene blue from wastewater

The development of the safe and cost-effective technologies for treating the dye-polluted wastewater has been a significant focus of researchers. In the light of this, alpha-MnO2/Fe-Mn binary oxide (alpha-MnO2/Fe-Mn BO) nanocomposite has been synthesized by a co-precipitation method. It was characterized by the FT-IR, XRD, BET, SEM, EDX, and TEM. The results indicated that the nanocomposite has a spheroid-like surface, a surface area of 92.954 m2/g and an average pore diameter of 2.39 nm. It was used as an adsorbent for the removal of methylene blue (MB) dye from an aqueous medium. The batch experiment revealed that 0.013 g of the nanocomposite can remove 98 % of MB (12.71 mg/L) in 30 min. The pH of the medium was the dominant factor in MB adsorption, where the highest removal efficiency was obtained at pH 4. Incorporation of sodium dodecyl sulfate (SDS) and NaCl decreased the MB adsorption. The adsorption process followed the pseudo-second-order and Elovich kinetic models. The results also fitted well with the Langmuir and Dubinin-Radushkevich (D-R) adsorption models. The maximum adsorption capacity was 89.63 mg/g at 30 degrees C and the nanocomposite showed good separation and regeneration properties. The removal efficiency decreased by about 20 % through five cycles. The alpha-MnO2/Fe-Mn BO is therefore considered a promising adsorbent for dyes owing to its high adsorption capacity, high chemical stability, good reusability, and simple synthesis procedure.(c) 2022 Elsevier B.V. All rights reserved.