关键词: β-环糊精, 多孔材料, 印染废水, 吸附, 循环

Abstract: As an important basic force of people's livelihood industry and a pillar industry of national economic development, China's textile industry has made remarkable development achievements. However, the environmental problems caused by the discharge of printing and dyeing wastewater cannot be ignored. According to incomplete statistics, the water consumption of one ton of textiles in China is 100～200 tons, and the large amount of wastewater discharge increases the difficulty of water treatment. In order to remove the pollutants with complex composition in printing and dyeing wastewater, the common printing and dyeing wastewater treatment methods including the physical method, the chemical method and the biological method are adopted. Among them, the adsorption method in the physical method is simple in operation, low in cost and energy consumption, and causes no secondary pollution. It can not only effectively decolorize, but can also adsorb heavy metal ions, remove substances that are not easily degraded chemically and biologically in water. In addition, most of the adsorption process is reversible, which can make the adsorption material be recycled through the desorption process. It is especially suitable for the treatment of printing and dyeing wastewater with increasingly complex components and has broad application prospects.
However, the pollutant removal performance of traditional adsorption materials is difficult to meet the requirements of printing and dyeing wastewater treatment, and the recycling performance is poor and the energy consumption is large. β-cyclodextrin is a cyclic oligosaccharide composed of glucose molecules linked by α-1,4 glycosidic bonds and is naturally non-toxic, cheap and easy to obtain, and biocompatible. It has a large number of hydroxyl groups on the outside, which can be modified by a variety of functional groups to obtain β -cyclodextrin derivatives. The internal special cavity structure can envelope a variety of organic/inorganic pollutant molecules. In the synthesis and application of β-cyclodextrin-based adsorption materials, it is often necessary to modify or graft β-CD to prepare water-insoluble β-CD-based adsorption materials and enhance their application effect. At present, there are mainly two types of β-CD crosslinked polymer adsorption materials and chemically immobilized β-CD-based adsorption materials.
In this paper, β-cyclodextrin (β-CD), methacrylic anhydride (MA) and sodium p-styrene sulfonate (SS) were used as raw materials to prepare the crosslinked polymer S-M-β-CD containing sulfonic acid group (SO3H) by dehydration condensation reaction and carbon-carbon double bond addition reaction. The microstructure characteristics of S-M-β-CD were studied. The adsorption mechanism of S-M-β-CD for methylene blue (MB) was analyzed. It is concluded that S-M-β-CD is a spherical block structure with rough, porous and uneven surface, and contains a large number of mesopores and trace micropores, which are helpful for the adsorption of pollutant MB. S-M-β-CD can still maintain 98.15 % adsorption rate for MB after seven cycles of desorption-adsorption, indicating that it has excellent adsorption-desorption properties. When the pH of MB solution is 9, the adsorption effect of S-M-β-CD on MB is the best, and the adsorption rate is close to 99.00 %. The adsorption process of MB by S-M-β-CD is more in line with the pseudo-second-order kinetic model and Langmuir isothermal adsorption model, that is, the adsorption process is monolayer adsorption dominated by chemical adsorption and synergistic effect of physical adsorption.
It has been more than 120 years since Villiers discovered cyclodextrin. β-CD has been widely sought after by researchers for its special spatial structure. Nowadays, the synthesis and development of adsorption materials based on β-cyclodextrin have attracted more and more researchers' attention. Based on the systematic study of S-M-β-CD adsorption materials, we hope to provide feasible research ideas and methods for the development and application of new adsorption materials with low cost and high efficiency.

Key words: β-cyclodextrin, porous material, dyeing wastewater, adsorption-desorption, recyclability