Abstract

This current study reviews the utilization of the traditional extraction methods and latest findings in extraction of silica from agricultural wastes, in particular, sugarcane bagasse, using inorganic acids to produce nano-silicon. The three key processes discussed in detail include electrochemical, ball milling, and sol–gel processes. The sugarcane bagasse has been identified as the cheapest source of producing silica from the potential raw material for the preparation of nano-silicon. The acid-base extraction and precipitation methodology involves the use of bases like sodium hydroxide (NaOH) and potassium hydroxide (KOH), and acids such as hydrofluoric acid (HF), sulphuric acid (H2SO4), nitric acid (HNO3), and hydrochloric acid (HCl) for the treatment of the ash. Sugarcane bagasse has notably emerged as an excellent and sustainable source of both tailored silica particles and bioenergy production. The ability to manipulate the engineered silica particles at the nano-level from sugarcane bagasse-based silica is explained in detail. Silica is a significant raw material with various industrial applications, with much research underway to extract it efficiently from industrial agro-waste, such as sugarcane bagasse. The production of highly pure silicon nanoparticles from sugarcane bagasse ash will serve as an important synthetic route in lowering the manufacturing costs and providing a low-cost polycrystalline silicon semiconductor for niche application in thin film solar technology.

Highlights

  • Valorization of sugarcane bagasse has been studied extensively over the years, with its niche applications in the sugar industry and bioenergy production

  • Sugarcane roots play a key role in absorbing silicic acid from the soil and delivering it to the shoots, where it is stored as amorphous silica

  • Amorphous silica predominates in sugarcane bagasse ash with other metallic contaminants [2,3]

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Summary

Introduction

Valorization of sugarcane bagasse has been studied extensively over the years, with its niche applications in the sugar industry and bioenergy production. The sugarcane bagasse ash is rich with silica of about 73%, and it is economically feasible due to the conversion of raw material to the production of silica gels and powders [4,5]. Silica is produced by reaction of sodium carbonate powder and quartz sand at higher temperatures to form sodium silicate, which will react with sulfuric acid to precipitate silica [10]. This method is considered hazardous to the ecosystem since most of its by-products (sodium sulphate, carbon dioxide, and lots of wastewater) are detrimental to the environment. Biomass is in abundance and serves as the future source of renewable energy reservoirs [11]

Extraction of Silica
Electrochemical Process
Ball Milling Process
Sol–Gel Process
Carbothermic Reduction of Silica to Silicon
Magnesiothermic Reduction of Silica to Silicon
Purification of Silicon
Findings
Conclusions
Full Text
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