Preparation of Bletilla striata polysaccharide composite aerogel and its application in adsorption of dyes and oils from water

In this study, Bletilla striata polysaccharide/powdered activated carbon (BSP/PAC) aerogels were prepared by freeze-drying of homogeneous mixture of BSP and PAC. Solvent replacement method, mechanical analysis, scanning electron microscope and Fourier transform infrared spectroscopy were used to characterize the morphology and performance of the aerogels. Dyes including anionic methylene orange (MO), cationic methylene blue (MB) and oil red O (ORO) and oils including trichloromethane, n-hexane, edible oil and engine oil in aqueous solution were used to study the adsorption properties of aerogels. The results showed that the prepared aerogels had porous structure and good adsorption capacity. The results of dye adsorption showed that BSP/PAC aerogel had stronger adsorption capacity for MB compared with MO and ORO, and the adsorption data for MB were more consistent with the Langmuir model with maximum experimental capacity of 166.295 mg center dot g(- 1), indicating the efficiency in absorption. In addition, according to the results of adsorption kinetics, the adsorption of MB on BSP/PAC aerogels could be described by a quasi-second-order model. The results of oil adsorption showed that BSP/PAC had the highest adsorption rate of edible oil compared with the other oils, which was nearly 52 times of its own weight. Overall, BSP/PAC is a porous material with three-dimensional structure, which can effectively remove MB dye and oil from water, and may have potential application prospects in sewage purification.