Preparation Of DA-β-CD-EP Polymer And Study On Its Selective Adsorption Of Malachite Gree

Malachite green（MG）has excellent dyeing function,is widely used in silk,wool and biological tissue dyeing,can also be used as a sterilizer and insecticide,and be used for the prevention and treatment of aquatic animals such as water mildew disease.MG is a triphenyl-methane substance.After entering the water environment,it will hinder the incidence of sunlight,affects the growth and reproduction of aquatic organisms,causing the ecological imbalance of water environment.It has very high toxicity that will damage liver,kidney and other organ tissues after entering the human body,but also makes DNA mutation,and then lead to cancer.Therefore,it is urgent to take measures to treat malachite green wastewater.In this paper,a new type of renewable and degradable adsorption material was developed usingβ-cyclodextrin（β-CD）and dopamine（DA）for the selective treatment of malachite green wastewater.The specific work and conclusions are as follows:（1）β-cyclodextrin crosslinked dopamine polymers（DA-β-CD-EP）were prepared with three different molar ratios ofβ-CD and DA with an appropriate amount of epichlorohydrin.The results of Fourier transform infrared spectroscopy（FT-IR）and X-ray diffraction（XRD）indicate thatβ-CD and DA are successfully cross-linked.Scanning electron microscopy（SEM）showed that the surface morphology of DA-β-CD-EP polymer was porous.Energy dispersive X-ray analysis（EDS）showed that the polymers were composed of three elements of C,N and O,with the highest content of O.The analysis of specific surface area and pore structure（BET）showed the pore structure of DA-β-CD-EP polymer was mainly micropores,and the surface area,average pore size and pore volume of DA-β-CD-EP(n _DA:nβ_-CD=2:1)polymer was larger than those of the other two polymers.（2）The adsorption results of single dye system and mixed dye system based on eight different types of dyes showed that DA-β-CD-EP(n_DA:nβ_-CD=2:1)polymer had selective adsorption property for MG.（3）The static adsorption results of DA-β-CD-EP polymers on MG under different adsorption conditions showed that:DA-β-CD-EP polymers has good adsorption property for MG.Under the optimal adsorption conditions（p H 8,polymer dosage 1g/L,initial dye concentration 50mg/L,adsorption time and adsorption temperature 20 minutes and 318 K respectively）:The adsorption efficiency of DA-β-CD-EP(n_DA:nβ_-CD=2:1)polymer for MG reach maximum,was 99.07%.（4）The adsorption kinetics model,isotherm and thermodynamic parameters fitted according to the existing experimental data showed that the pseudo-second-order kinetics model and Langmuir isotherm can better describe the adsorption behavior of DA-β-CD-EP polymers on MG,and the maximum adsorption capacity of DA-β-CD-EP(n_DA:nβ_-CD=2:1)polymer is 652.025 mg/g.At the same time,the adsorption of MG by DA-β-CD-EP polymers was a spontaneous endothermic process.（5）Using anhydrous ethanol as desorption reagent,the adsorption efficiency of MG remained 81.06%after five times of regeneration.The SEM and XRD images of DA-β-CD-EP(n_DA:nβ_-CD=2:1)adsorbent after regeneration showed that the adsorbent basically maintained the original morphology and structure after regeneration for five times.These results show that DA-β-CD-EP(n_DA:nβ_-CD=2:1)adsorbent has good regeneration performance.（6）DA-β-CD-EP(n_DA:nβ_-CD=2:1)adsorbent waste of the degradation efficiency was 86.97%after 12 months of natural degradation,and,which proved that it had good degradation performance.（7）Through the characterization results of FT-IR and XPS,as well as the analysis of BET,it was found that groups such as C=O,C=N and so on participated in the adsorption process,and MG molecules can just enter the pore size of the adsorbent.Therefore,the selective adsorption mechanism of DA-β-CD-EP(n _DA:nβ_-CD=2:1)for MG is mainly the interaction between host and guest and the effect of pore size.