ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Green synthesis, characterization, and adsorption of Co(II) and Cu(II) ions from aqueous solution by mesoporous silica MCM-41

Raghad S. Hatem, Alaa F. Hussain, and Hayder H. Mihsen

Department of Chemistry, College of Science, University of Kerbala, Kerbala, Iraq

E-mail: Raghad.saad@uokerbala.edu.iq

Received: 27 February 2024  Accepted: 26 May 2024

Abstract:

Rice husk (RH) is regarded as one of the most common agricultural residues worldwide. MCM-41 (Mobil Composition of Matter No. 41) is prepared from RH. RH can itself be transformed to sodium silicate through a reaction with NaOH solution. This study includes three steps, the first of which involves extraction of silica from RH using a leaching process in the presence of HNO₃; the second and third involve generation of RH-SiO₂ and MCM-41 from the extracted silica. Characterization of the synthesized compounds can be successfully achieved, via the use of various techniques including FT-IR, FESEM-EDX, TEM, N₂-adsorption–desorption, XRD, and thermogravimetric analysis represented by TGA/DSC. The XRD and TEM investigation demonstrated that MCM-41 with an extremely ordered hexagonal arrangement was generated. The findings of the N₂-adsorption–desorption analysis revealed that the average pore diameter, total pore volume, and MCM-41 specific surface area were 6.80 nm, 126.12 cm³ g⁻¹ and 548.92 m² g⁻¹, respectively. Thermogravimetric analysis (TGA/DSC) of silica materials represented by both RH-SiO₂ and MCM-41 revealed two mass reduction steps, where the initial step involved elimination of water adsorbed in physical/chemical processes on the silica surface, and the second involving the breakdown of Si–OH groups. The RH-SiO₂ and MCM-41 were utilized for the adsorption of heavy pollutants like Cu(II) and Co(II) ions from aqueous solution.

Keywords: Adsorption; Mesoporouse materials; MCM-41; Rice husks; Surface area; Uptake metal

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-024-03538-8

Chemical Papers 78 (11) 6331–6342 (2024)