Abstract
Abstract Hydrophobic silica aerogels (SiO2(AG)) was prepared via sol-gel and solvent exchange method under ambient pressure, which could be transformed to hydrophilic after heated under 500∘C. Heat treatment cannot change its structure. SiO2(AG) samples were the micro-porous structure formed by numerous fine particles and had high specific surface area, pore size and pore volume. The absorption performance of hydrophobic/hydrophilic SiO2(AG) on nitrobenzene, phenol and methylene blue (MB) showed that hydrophobic SiO2(AG) exhibited strong adsorption capacity on slightly soluble organic compounds, while hydrophilic SiO2(AG) was much more effective on adsorbing soluble compounds, which could be analyzed by the hydrophobic and hydrophilic interaction theory between the adsorbent and adsorbate.Hydrophobic/hydrophilic SiO2(AG) adsorption performance for MB is superior to that for phenol, which could be explained via the electrostatic interaction theory.
Highlights
In the last decades, with the rapid development of industry, large amounts organic compounds were widely used in different field, such as pesticides, dyes, synthetic rubber, plastics
SiO2(AG) samples were the micro-porous structure formed by numerous fine particles and had high specific surface area, pore size and pore volume
The results showed that hydrophobic/hydrophilic SiO2(AG) samples had high specific surface area, pore size and pore volume
Summary
With the rapid development of industry, large amounts organic compounds were widely used in different field, such as pesticides, dyes, synthetic rubber, plastics. The method of supercritical drying can avoid capillary stress and associated drying shrinkage This process is energy intensive and can be dangerous, which leads to high costs and results in limited practical applications [21, 22]. APD technique could overcome the disadvantages of supercritical aerogel process, and made the manufacture and application of SiO2(AG) in large scale possible [23,24,25]. Hrubesh et al [28] prepared hydrophobic SiO2(AG) via the supercritical drying method, and proceeded the adsorption experiments of decomposing different organic compounds in water. Hydrophobic/hydrophilic SiO2(AG) were prepared via the APD route, and to compare different adsorption performance for nitrobenzene, phenol and methylene blue (MB) with different physicochemical properties, which were common pollutants in industrial wastewater. The adsorption isotherm were evaluated, and the adsorption mechanisms were discussed
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