Preparation Of Β-cyclodextrin Based Porous Adsorption Material For The Adsorption Performance Of Pollutants From Simulated Printing And Dyeing Wastewater

As an important basic force of livelihood industry and a pillar industry of national economic development,the textile industry of China has achieved remarkable development in the world.However,the environmental problems caused by the discharge of textile printing and dyeing wastewater cannot be ignored.According to incomplete statistics,the water consumption of textiles is 100～200 t for every 1 t of printing and dyeing processing in China,and the large amount of wastewater discharge increases the difficulty of water treatment.Adsorption method can not only effectively decolorize,but also adsorb heavy metal ions and remove organic substances in water that are not easily degraded by chemicals and biodegradation because of its simple operation,low cost,low energy consumption and no secondary pollution,etc.In addition,most of the adsorption process is reversible,which can make the adsorption material can be recycled through the desorption process,especially suitable for the treatment of textile printing and dyeing wastewater with increasingly complex composition,and has broad application prospects.β-cyclodextrin is a cyclic oligosaccharide made of glucose molecules linked byα-1,4glycosidic bonds,which is naturally non-toxic,cheap and easy to obtain,biocompatible,etc.It has a large number of hydroxyl groups on the outside and can be modified by a variety of functional groups to obtainβ-cyclodextrin derivatives,and the special internal cavity structure can encapsulate a variety of organic/inorganic pollutant molecules.In the synthetic application ofβ-cyclodextrin-based adsorbent materials,it is often necessary to modify or graftβ-CD to prepare water-insolubleβ-CD-based adsorbent materials to expand the scope of application,which are currently mainly for two categories ofβ-CD cross-linked polymer adsorbent materials and chemically solidifiedβ-CD-based adsorbent materials.In this study,the cross-linked polymer S-M-β-CD with sulfonic acid group（SO₃H）was prepared by dehydration condensation reaction and carbon-carbon double bond addition reaction withβ-CD as the main body to investigate the adsorption of dyes and heavy metal ions pollutants,to clarify the key factors and laws affecting the adsorption performance,to reveal the mechanism of adsorption-desorption of dyes or heavy metal ions by S-M-β-CD,and to provide a theoretical basis for the development of new adsorbent materials and efficient removal of pollutants from printing and dyeing wastewater.This study will provide theoretical basis and technical reference for the development of new adsorbent materials and the efficient removal of pollutants from printing and dyeing wastewater.The main research contents are as follows:（1）The structural morphology and physicochemical properties of the adsorbent materials were characterized by scanning electron microscopy（SEM）,infrared spectroscopy（FT-IR）,nuclear magnetic（NMR）,specific surface area（BET）,water contact angle（WCA）,etc.The results showed that the surface morphology of S-M-β-CD is characterized by rough and uneven,porous,and the presence of spherical masses of different sizes,which is a porous type of adsorbent material with excellent hydrophilicity.（2）The effects of conditions such as adsorption time,adsorbent content,initial concentration of dyes and p H on the adsorption effect were investigated using the cationic dyes methylene blue and rhodamine B as representatives;In order to study the adsorption mechanism of methylene blue and rhodamine B by adsorbent materials from three aspects,including adsorption kinetics and adsorption isotherms,and adsorption thermos-dynamics;The adsorption process was found to be more consistent with the proposed secondary kinetic adsorption model and the Langmuir isothermal adsorption model,a single-molecule-layer,chemisorption-dominated adsorption process,where adsorption is a spontaneous,heat-absorbing process,increasing temperature promotes the adsorption of the dye;The selective adsorption and cyclic adsorption and desorption experiments were conducted on the adsorbent material,and the results showed that the adsorbent material could achieve selective adsorption of cationic dyes in a mixture of anionic and cationic dyes,thus separating different kinds of dyes well,and the adsorbent material still maintained a high adsorption rate after 7 cycles of adsorption,with excellent cyclic adsorption-desorption performance;The adsorption mechanism was analyzed by using test methods,and the results showed that the adsorption process of organic dyes by adsorbent materials has the electrostatic effect of sulfonic acid groups（SO₃H）,hydrogen bonding between hydroxyl groups,benzene ring inter-action andβ-cyclodextrin host-guest encapsulation.（3）The effects of conditions such as adsorption time,adsorbent content,initial concentration of heavy metal ions and p H on the adsorption effect were investigated with heavy metal ions Cu²⁺and Pb²⁺as representatives.It was found that the strong acidic environment was not favorable for the adsorption of S-M-β-CD on Cu²⁺and Pb²⁺;The adsorption mechanism of Cu²⁺and Pb²⁺by adsorbent materials was investigated from three aspects:adsorption kinetics,adsorption isotherm and adsorption thermodynamics,and it was found that the adsorption process of adsorbent materials was more consistent with the proposed secondary kinetic adsorption model and the Langmuir isotherm adsorption model,the adsorption was unimolecular layer,chemisorption-dominated adsorption,and the adsorption process was a heat absorption process that proceeded spontaneously,increasing the temperature would promote the adsorption;The adsorption of Cu²⁺and Pb²⁺possesses excellent cyclic adsorption-desorption performance,maintaining more than 90%adsorption rate after5 cycles of adsorption;the adsorption material is mainly accomplished by the chelation between hydroxyl group（OH）and heavy metal ions,electrostatic attraction between sulfonic acid group（SO₃H）and heavy metal ions,and host-guest encapsulation betweenβ-cyclodextrin and heavy metal ions.