Adsorption properties of Silica gel (commercial silica), rice husk ash (RHA) silica, and their hydrothermally treated products towards water molecules were studied in this work. RHA silica was prepared by heating rice husk to 650°C for 4 h after pretreatment with hydrochloric acid. Portions of the samples of silica were evacuated at 200℃ and then allowed to adsorb water molecules from the surrounding air at either 42 or 50% humidity. The near infrared spectra of these samples were measured at different time intervals during their adsorption of water molecules. The evolved near infrared spectra were analyzed using second derivative techniques. Adsorption properties of these samples were further studied by gravimetric analysis. Surface functionalities and adsorption evolution of water molecules on silica samples studied showed that the adsorption of water molecules on commercial silica gel sample and RHA silica Samples takes place readily with hydrogen-bonded silanol groups on the surfaces of the samples. This adsorption arising from the OH stretching and bending vibrations of these water molecules gives rise to a band at 5,270 cm −1 in the near infrared region. The adsorbed water molecules then continue at the free silanol groups which is indicated by the absorption around 5,314 cm −1 . The results clearly show that the silica made from rice husk adsorb water in the same manner as the commercial silica, but the quantity of water molecules adsorbed is less compared to commercial silica used in this experiment. However, the study clearly shows that the rice husk silica can replace the commercial silica as a substitute for desiccant purposes in industry.

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商业二氧化硅和稻壳灰（RHA）二氧化硅的吸附性能比较：近红外光谱研究

在这项工作中，研究了硅胶（商业二氧化硅），稻壳灰（RHA）二氧化硅及其水热处理产品对水分子的吸附性能。在用盐酸预处理后，将稻壳加热至650°C 4小时，即可制得RHA二氧化硅。在200℃下抽空一部分二氧化硅样品，然后在42％或50％的湿度下从周围的空气中吸收水分子。这些样品在吸收水分子的过程中，在不同的时间间隔测量了近红外光谱。使用二阶导数技术分析了所产生的近红外光谱。通过重量分析进一步研究了这些样品的吸附性能。所研究的二氧化硅样品的表面功能和水分子的吸附演变表明，水分子在市售硅胶样品和RHA二氧化硅样品上的吸附很容易在样品表面上带有氢键合的硅烷醇基团。由这些水分子的OH拉伸和弯曲振动引起的这种吸附在近红外区域中产生了5270 cm -1的能带。然后，被吸附的水分子在游离的硅烷醇基团处继续，这由5,314 cm -1附近的吸收指示。结果清楚地表明，由稻壳制成的二氧化硅以与商用二氧化硅相同的方式吸附水，但是与该实验中使用的商用二氧化硅相比，所吸收的水分子的数量更少。然而，