Adsorptive Removal of Iron Using SiO₂ Nanoparticles Extracted from Rice Husk Ash

Abstract

In this work, SiO2 nanoparticles were prepared by the sol-gel method after sodium silicate was extracted from rice husk ash (RHA) under various experimental conditions such as types of acids, NaOH concentration, dissolved time, and temperature and used for removal of Fe2+ ions from aqueous solutions. The extracted SiO2 was morphologically and chemically characterized and showed a surface area of 78 m2/g and uniform pores of 2.71 nm, offering high adsorption capacity for Fe2+ ions. The influence of pH, contact time, and amount of adsorbent was studied in order to establish the best conditions for the Fe2+ adsorption and removal. Furthermore, the adsorption data were fitted with an exponential shape curve for all the three variable parameters that affect the adsorption process. The best results were obtained for pH 5, 20 min contact time, and 0.5 g adsorbent dose. The loading adsorption capacity was 9 mg of Fe2+ ions/g SiO2 in the concentration range 0.1–1.0 mgL−1. In addition, the synthesized SiO2 with the size of around 50 nm can be used for specific heavy metal removal and drug delivery, after modification of the SiO2 surface with various functional groups.

Nitrate Removal from Waste-Water Using Silica Nanoparticles

“…SiNPs were generated from rice husk ash, and physicochemical properties were characterized by the Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). e results showed that the absorption bands were obtained at 1069 and 794 cm −1 , which corresponded to the symmetric and asymmetric components of Si-O-Si variation as shown in Figure 1(a) [28]. e irregular shapes of SiNPs with a diameter of around 50 nm were achieved by SEM as depicted in Figure 1(b).…”

“…e gel obtained was then dispersed in ethanol, washed with distilled water (three times), and dried at 110°C for 2 h to remove remaining surfactants. e SNPs synthesized were stored in desiccator for further characterizations [28].…”

“…Removal. In this study, SiNPs were generated from the rice husk ash based on the sol-gel method [28] and utilized for nitrate removal. An adsorption capability of nitrate was investigated based on the controllable parameters including contact time, pH, adsorbent's mass, and concentration at room temperature.…”

“…erefore, it is worth to consider that silica nanoparticles (SiNPs) are promising material for removal of heavy metals [26][27][28] with high adsorption capability. In addition, the rice husk ash (RHA), which contains high amount of silica (approximately 90%), is the by-product of a brick-kiln industry.…”

Removal of phosphate from wastewater using coal slag

“…However, they have several drawbacks such as high costs, time-consuming to perform, complicated in operation, and low efficiency in processing [8]. Therefore, adsorption-based methods are the most useful and economical among the various techniques mentioned above due to benefits such as high adsorption capacity, low cost and an environmentally friendly approach [9,10].…”