Study On Potassium Resource Extraction And Sulfadiazine Removal Based On Imprinting Technology

Imprinting technology,also known as template technology,is a new technology based on multi-disciplinary developments such as polymer chemistry,biochemistry,chemical engineering and materials science.It belongs to the research field of supramolecular chemistry.The polymer prepared by molecular imprinting technique is called molecular(ionic)imprinted polymer,which has memory effect on specific molecules(ions)and can realize the selective recognition and enrichment of targets.Therefore,imprinted polymers are widely used in the fields of separation and purification,catalytic degradation,biomimetic sensing and so on.Potassium is one of the essential nutrients for crop growth.The distribution of potassium resources in the world is uneven,and many countries need to rely on imports of potassium fertilizer.However,there are abundant potassium resources in seawater,so it is urgent to develop an efficient and green technology to extract potassium resources from seawater.The pollution of sulfonamides has attracted the attention of many scholars because of its complex structure and easy enrichment in river sediment,which seriously threatens human health.At present,the removal of sulfonamides in water is complicated and costly,and may even lead to secondary pollution.It is of great significance to prepare an adsorbent for effectively removing sulfadiazine antibiotics.It is an effective strategy to apply imprinting technique to the extraction of potassium ions from seawater and the removal of sulfonamides in water.In this paper,potassium ions imprinted polymers(E-IIPs)with activated carbon derived from enteromorpha as carrier,sulfadiazine molecular imprinted polymer(L-MIP)with porous carbon derived from lotus shell as carrier and sulfadiazine molecular imprinted polymer(M-MIP)with MCM-41 were prepared based on surface imprinting technique.The adsorption materials were characterized by FT-IR,SEM,TEM and BET.The adsorption properties and mechanisms were also investigated.Finally,the selectivity and regeneration properties of the materials were investigated.The main contents of the study are as follows:(1)The adsorption performance of potassium ions imprinted polymers to potassium ions in solution was investigated.The results showed that the pH,contact time,initial concentration and temperature of potassium ion affected the adsorption capacity.The optimum adsorption conditions for potassium ions were as follows:pH is 9;contact time is 30min;the temperature is 25 C.At the optimum conditions,the maximum saturated adsorption capacity is 971.87?mol/g.Langmuir isothermal adsorption model indicated that the adsorption site of the material was uniformly dispersed.The pseudo second order dynamics fitting experiment confirmed that the rate of'adsorption was dominated by chemisorption.The thermodynamic fitting results showed that the adsorption process was a spontaneous endothermic process.The relative selectivity coefficients for K+/Na+,K+/Li+,K+/Mg+ were 3.58,1.91 and 1.35,respectively.After eight adsorption-desorption experiments under the same conditions,the K+ adsorption capacity of E-IIPs decreased only 6.35%.Thus it can be concluded that E-IIPs had excellent selectivity and regeneration.(2)The adsorption performance of sulfadiazine imprinted polymer in aqueous solution was investigated.The influence of coupling agent KH-540 loading on the adsorption capacity was discussed.The results showed that the amount of loading afrected the for,,mation of imprinting sites and therefore the adsorption capacity.In addition,the effects of solution pH,contact time,initial concentration of sulfadiazine and temperature on adsorption capacity were discussed.Under the optimum adsorption conditions(pH is 6;contact time is 30min;temperature is 25 C),the maximum saturated adsorption capacity is 55.25mg/g.The fitting results of kinetics and isothermal adsorption model showed that the adsorption process of sulfadiazine by L-MIP was consistent with the kinetic second-order model and the Langmuir isothermal adsorption model,respectively.The selective experiment showed that L-MIP had high selectivity to sulfonamides.After five cycles of adsorption and regeneration,the adsorption capacity of L-MIP remained almost maximum value.It showed that the material had good reuse performance.(3)An imprinted polymer of sulfadiazine based on silanized MCM-41 molecular sieves was prepared.The adsorption mechanism of materials toward sulfadimidines was studied by using kinetic model and isotherm adsorption model.The adsorbents were characterized by SEM with spherical structure and rough surface.The adsorption saturation of sulfanilamide was realized by M-MIP within lOmin.The adsorption capacity of M-MIP toward sulfadiazines was higher than that of M-NIP toward sulfadiazines.The adsorption capacity of M-MIP toward sulfadiazines was more than three times that of tetracyclines.M-MIP had excellent selectivity and affinity.