Revista de Engenharia Química e Tecnologia de Processos
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Chemical, Structural and Elemental Characterization of Biosorbents Using FE-SEM, SEM-EDX, XRD/XRPD and ATR-FTIR Techniques

Sohan Shrestha

The chemical, structural, and elemental composition of any adsorbents plays undoubtedly crucial role and has paramount significance in adsorption process. The present study of chemical, structural, and elemental characterization of powdered Pinus densiflora pine cones, lignite and coconut shell-based activated carbon fiber (ACF), and powdered oyster shell prior employed for anionic surfactant sodium dodecyl sulfate (SDS) adsorption was undertaken using field emission scanning electron microscope (FE-SEM), scanning electron microscope coupled with energy dispersive x-ray (SEM-EDX), X-ray diffraction/X-ray powder diffraction (XRD/XRPD), and multiple internal reflectance (MIR) or attenuated transform reflectance – fourier transform infrared spectroscopy (ATR-FTIR) techniques. The FESEM imaging observed at three different magnifications depicted the change in surface texture of aforementioned biosorbents before and after SDS adsorption. SEM-EDX analysis indicated alteration in the concentration and distribution of different compositional elements. The XRD analysis suggested the amorphous character in lignite and coconut shell-based ACF and powdered Pinus densiflora cones, whilst indicating the sample of powdered oyster shell to be crystalline in nature and entirely composed of CaCO₃ with the very trivial amount of impurities. Further, infrared (IR) spectroscopy demonstrated variation in IR spectra of the samples prior to and after surfactant adsorption and also further suggested occurrence of complexing or (complexation) process between ionizable functional groups and DS― or Na+ ions of SDS. In addition, iodine number of the lignite and coconut shell-based ACF, powdered Pinus densiflora cones, and powdered oyster shell were found to be 285.86 mg/g, 25.01 mg/g, and 28.48 mg/g, respectively.