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<p>Rice husk ash (RHA), a silica-rich byproduct of rice milling, poses environmental and health risks due to the presence of heavy metals and particulate matter. This study presents an optimized biomass gasification method to extract high-purity silica from RHA for industrial applications. Rice husks were gasified at 810–860&#xa0;°C to produce RHA, dissolved in 2 N NaOH at 105&#xa0;°C for 2–3&#xa0;h, followed by carbon removal and sulfuric acid precipitation to yield fine silica powder. The extraction process was optimized for RHA type, gasification duration, and dissolving time, with kinetic analysis using pseudo-first-order and pseudo-second-order models. XRD analysis confirms 96%-99% pure amorphous silica after 4&#xa0;h of dissolving and 1&#xa0;h of gasification. Extraction efficiencies were 73.33% and 86.66% by weight for fly and bottom ash, respectively. FTIR analysis confirmed the presence of Si–O-Si and Si–OH bonds. BET surface area analysis showed fly ash-derived silica with a higher surface area (412.72 m<sup>2</sup>/g) than bottom ash-derived silica (298.98 m<sup>2</sup>/g). Kinetic studies indicated a peak reaction rate at 2&#xa0;h (43.33% yield, k<sub>1</sub> = 0.0179&#xa0;h⁻<sup>1</sup>, k<sub>2</sub> = 0.0088&#xa0;g/(g·h)), with optimal yields between 3 and 4&#xa0;h. This method provides a sustainable solution for RHA disposal. Future research should explore scalability and practical implementation.</p> Graphical Abstract <p></p>

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High-Purity Silica Extraction from Rice Husk Ash via Optimized Biomass Gasification: A Comparative Study of Fly and Bottom Ash

  • 期刊论文

  • 发表日期：

    2025年10月28日

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  • Surya Prakash Molgamudi,
  • Satish Thogaru,
  • Shankarachar M. Sutar

摘要

Rice husk ash (RHA), a silica-rich byproduct of rice milling, poses environmental and health risks due to the presence of heavy metals and particulate matter. This study presents an optimized biomass gasification method to extract high-purity silica from RHA for industrial applications. Rice husks were gasified at 810–860 °C to produce RHA, dissolved in 2 N NaOH at 105 °C for 2–3 h, followed by carbon removal and sulfuric acid precipitation to yield fine silica powder. The extraction process was optimized for RHA type, gasification duration, and dissolving time, with kinetic analysis using pseudo-first-order and pseudo-second-order models. XRD analysis confirms 96%-99% pure amorphous silica after 4 h of dissolving and 1 h of gasification. Extraction efficiencies were 73.33% and 86.66% by weight for fly and bottom ash, respectively. FTIR analysis confirmed the presence of Si–O-Si and Si–OH bonds. BET surface area analysis showed fly ash-derived silica with a higher surface area (412.72 m2/g) than bottom ash-derived silica (298.98 m2/g). Kinetic studies indicated a peak reaction rate at 2 h (43.33% yield, k1 = 0.0179 h⁻1, k2 = 0.0088 g/(g·h)), with optimal yields between 3 and 4 h. This method provides a sustainable solution for RHA disposal. Future research should explore scalability and practical implementation.

Graphical Abstract