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The physical and optical studies of crystalline silica derived from the green synthesis of coconut husk ash


Anuar, Muhammad Fahmi and Yap, Wing Fen and Mohd Zaid, Mohd Hafiz and Matori, Khamirul Amin and Mohamed Khaidir, Rahayu Emilia (2020) The physical and optical studies of crystalline silica derived from the green synthesis of coconut husk ash. Applied Sciences, 10 (6). art. no. 2128. pp. 1-11. ISSN 2076-3417


The green synthesis of silica has been extensively explored over the last few decades, as silica compounds found in commercial products can cause negative effects on human health. This calls for alternative ways to produce silica that are safer, cheaper and more environmentally friendly. Some of the agricultural wastes proven to contain silica include rice husk, sugarcane bagasse, coconut shells and coconut husk. This paper describes the synthesis of silica from coconut husk waste, and its physical and optical properties for potential utilization in optical applications. Coconut husk was subjected to fire at 500–700 °C so as to form coconut husk ash (CHA), and was then treated with sulfuric acid to extract silica from the ash. Most of the weight degradation subsequently occurred at temperatures from 221 to 360 °C. X-ray fluorescence (XRF) analysis proved that 91.76% of the silica was obtained, while major peaks on the X-ray diffraction (XRD) spectrum were observed after the acid treatment. Chemical bonds such as Si-O-Si, CH2, -OH and Si-OH were found in the spectrum of the Fourier transform infrared spectroscopy (FTIR). Furthermore, the particles displayed rod-like shapes and irregular sizes, but the particle with sizes ranging from 200–750 nm decreased after the acid treatment. The relationship between the absorption coefficient and photon energy was obtained by finding the optical energy gap, which was found to be 4.3 eV. These data points provide critical information when used in optical applications. The overall studies show that synthesized silica has great potential for use in optical field applications.

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Official URL or Download Paper: https://www.mdpi.com/2076-3417/10/6/2128

Additional Metadata

Item Type: Article
Divisions: Faculty of Science
Institute of Advanced Technology
DOI Number: https://doi.org/10.3390/app10062128
Publisher: MDPI
Keywords: Silica; Coconut husk ash; Green synthesis; Agriculture waste; XRD
Depositing User: Nabilah Mustapa
Date Deposited: 14 Apr 2020 13:55
Last Modified: 14 Apr 2020 13:55
Altmetrics: http://www.altmetric.com/details.php?domain=psasir.upm.edu.my&doi=10.3390/app10062128
URI: http://psasir.upm.edu.my/id/eprint/38116
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