Production and characterization of silica nanoparticles from fly ash: conversion of agro-waste into resource

Abstract

A chemical method to synthesize amorphous silica nanoparticles from the incinerated paddy straw has been introduced. The synthesis was conducted through the hydrolysis by alkaline-acidic treatments. As a result, silica particles produced with the sizes were ranging at 60–90 nm, determined by high-resolution microscopy. The crystallinity was confirmed by surface area electron diffraction. Apart from that, chemical and diffraction analyses for both rice straw ash and synthesized silica nanoparticles were conducted by X-ray diffraction and Fourier-transform infrared spectroscopy. The percentage of silica from the incinerated straw was calculated to be 28.3. The prominent surface chemical bonding on the generated silica nanoparticles was with Si–O–Si, stretch of Si–O and symmetric Si–O bonds at peaks of 1090, 471, and 780 cm⁻¹, respectively. To confirm the impurities of the elements in the produced silica, were analyzed using X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The stability of silica nanoparticles was investigated using thermogravimetric analysis and zeta potential. The measured size from zeta potential analysis was 411.3–493 nm and the stability of mass reduction was located at 200 °C with final amount of mass reduced ∼88% and an average polydispersity Index was 0.195–0.224.

Keywords:

• Element and chemical bondings
• incineration
• rice straw ash
• silica nanoparticles