Document Type : Research Paper
Authors
1
School of Chemical and Metallurgical Engineering, Faculty of Engineering and Built Environment, University of the Witwatersrand, Johannesburg, Private Bag 3, Wits 2050, South Africa
2
Department of Chemical Engineering, Faculty of Engineering, Built Environment and Information Technology, University of Pretoria, Hatfield 0028, Pretoria, South Africa
Abstract
Silica Sodalite (SSOD) was synthesized by topotactic conversion and hydroxy sodalite (HSOD) by hydrothermal synthesis in this study for comparison in membrane performance during acid mine drainage (AMD) treatment. Consequently, two membranes, SSOD/PSf and HSOD/PSf membranes at different nanoparticles loading (5wt. % and 10wt. %) were prepared. The morphology, textural property, crystallinity, surface chemistry, and thermal stability of the synthesized nanoparticles were checked using Scanning Electron Microscopy (SEM), N2 physisorption at 77 K, X-Ray Diffraction (XRD), Fourier Transform Infra-red (FTIR), and Thermogravimetry analyser (TGA), respectively. The hydrophilicity and the mechanical strength of the as-prepared membranes were obtained using contact angle measurement and a nano-tensile analyser, respectively. The RUB-15 conversion to SSOD was confirmed with the preserved sheet-like shape of the nanoparticles, and the absence of CH3 deformation vibrations at 1488 cm-1. The absence of the –OH bond in the 2900-3600 cm-1 region of the FTIR spectra further confirmed the formation of SSOD. The SEM images showed a successful infusion of nanoparticles. Loading the membranes with SSOD enhanced the membrane permeability from 0.02 g.h-1.cm-2 for PSf to 0.21 g.h-1.cm-2 for 10%SSOD/PSf at 5 bar. The 10%HSOD/PSf membrane had good metal ion rejection with 75 %, 66 %, 61 %, 57 %, 52 %, and 38 % for Mg2+, Fe3+, Mn2+, Ca2+, Al3+ and Na2+, respectively, while Al3+ had the highest rejection (89%) in the 10%SSOD/PSf membrane. This study provides a platform for further study on the improvement of SSOD usage in AMD treatment as it shows enhanced permeability with promising rejection.
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