Abstract
Amorphous silica, a specialised silicate adsorbent is extensively extracted from agricultural residues for application in various
environmental domains. Wheat straws are a rich source of silica that have earlier been overlooked however demand for value
addition. The study presents an innovative approach to extracting silica from wheat straw and standardising the extraction process
to produce clean product. The sodium silicate solution and the amorphous silica synthesis were obtained by modifying the template mediated sol–gel method. Optimum temperature, concentration and pH were identifed for the cleaner production of silica
with maximum yield and favourable adsorbent characteristics. The crystallographic properties analysed by the X-Ray Difraction
revealed the amorphous nature of silica extracted from ash at 650 °C for 4 h. The structure of phytolith present in the wheat straw
was observed in the form of articulated elongate undulate epidermal phytolith under scanning electron microscopy. The Energy
Dispersive X-ray spectrum exhibited higher amount of silica (Si %) of 70.10% with a minimal percentage of potassium (9.96%).
The sharp bend at 1025 cm−1 is attributed to the siloxane (Si–O-Si) vibrations in Fourier transform infrared spectroscopic graph
of amorphous silica. The specifc surface area measurements of amorphous silica showed type II isotherm curve with a hysteresis
of H3 type. The optimum conditions derived to produce amorphous silica were 3 M NaOH and 3 M H2SO4 at pH 9.
environmental domains. Wheat straws are a rich source of silica that have earlier been overlooked however demand for value
addition. The study presents an innovative approach to extracting silica from wheat straw and standardising the extraction process
to produce clean product. The sodium silicate solution and the amorphous silica synthesis were obtained by modifying the template mediated sol–gel method. Optimum temperature, concentration and pH were identifed for the cleaner production of silica
with maximum yield and favourable adsorbent characteristics. The crystallographic properties analysed by the X-Ray Difraction
revealed the amorphous nature of silica extracted from ash at 650 °C for 4 h. The structure of phytolith present in the wheat straw
was observed in the form of articulated elongate undulate epidermal phytolith under scanning electron microscopy. The Energy
Dispersive X-ray spectrum exhibited higher amount of silica (Si %) of 70.10% with a minimal percentage of potassium (9.96%).
The sharp bend at 1025 cm−1 is attributed to the siloxane (Si–O-Si) vibrations in Fourier transform infrared spectroscopic graph
of amorphous silica. The specifc surface area measurements of amorphous silica showed type II isotherm curve with a hysteresis
of H3 type. The optimum conditions derived to produce amorphous silica were 3 M NaOH and 3 M H2SO4 at pH 9.
| Original language | English |
|---|---|
| Pages (from-to) | 5049–5063 |
| Number of pages | 15 |
| Journal | Silicon |
| Volume | 15 |
| DOIs | |
| Publication status | Published - 22 Mar 2023 |