Preparation Of Molecularly Imprinted Adsorbent Materials And Study On The Properties Of Separation/Enrichment Antibiotics

Recently, with the advances of science and medical, antibiotics have been widely used in medical treatment, livestock production, aquaculture and other fields. The resulted problems such as drug-resistant organisms, and antibiotic residues existed in organism, humans and environment, lead to problems of water security, ecological security and other public safety, therefore, how to eliminate antibiotic pollution becomes one of the research focuses. Adsorption separation is one of the effective methods to remove antibiotic residues due to such characteristics as simple and low cost. Development of novel and efficient separating/enriching materials is not only one of the keypoints of adsorption research, but also plays an important role to detect antibiotics residues, reduce or eliminate antibiotics pollution from water, and protect human health and public safety.In this study, with combination the advantages of biomass material, Pickering emulsion polymerization and molecular imprinting technology, different molecular imprinted adsorbent materials with magnetic or temperature sensing properties were synthesized, and applied to absorption and selective recognition of antibiotics in solutions. The physical and chemical properties of the synthesized molecular-imprinted adsorbents were characterized using different methods. Also, different antibiotic molecules were used as target pollutants to study the selective adsorption behavior and mechanism by the aboved adsorption materials. The main contents are as followed:(1) Hydrophobic magnetic nanoparticles were prepared with such methods as co-precipitation and oleic acid modification, with erythromycin as a template molecule and chitosan nanoparticles as stable particles, the oil-in-water (O/W) Pickering emulsion was built. Then the magnetic molecularly imprinted polymers (MMIPs) were prepared by high temperature initiated polymerization. Various methods were applied to characterize the prepared polymers. Results indicated that:MMIPs were microspheres which stabilized by chitosan nanoparticles on the surface, and MMIPs possessed good thermal stability and super para-magnetic (Ms=0.32 emu/g). Data of isotherm experiments were better fitted by Freundlich model (R2>0.99). The maximum adsorption amount at 15℃ was 52.32 μmol/g for heterogeneous solid surface. Pesudo-first-order kinetics were more consistent with kinetic data (R2>0.98). Dynamic bed adsorption studies confirmed that the adsorbent had a good dynamic adsorption performance, and Thomas model better fitted with the dynamic bed breakthrough curve.(2) Hollow temperature-sensitive molecularly imprinted polymers (HTMIPs) were prepared by precipitation polymerization, using yeasts as a sacrifice template, temperature-sensitive monomer N-isopropyl acrylamide (PNIPAM), and tetracycline (TC) as a template molecule. The prepared HTMIPs had a hollow porous structure and good thermal stability. At pH 5.0, HTMIPs had the maximum adsorption capacity to the template molecule TC at 35℃, which was about 78.89 μmol/g. HTMIPs also showed good affinity and selectivity to TC. The adsorption isotherm data fitted better with Freundlich model. The kinetic data fitted to pseudo-second-order model more suitable, which indicated that the adsorption of TC molecules for HTMIPs was mainly by covalent and ionic bonding interactions. HTMIPs had good regeneration properties, since after five cycles of adsorption the adsorption efficiency loss of HTMIPs was only about 6.64%.(3) Porous temperature-sensitive molecularly imprinted polymers (PTMIPs) prepared by high internal phase Pickering emulsion polymerization and amoxicillin as the template molecule, NIPAM as temperature-sensitive monomer, while the Pickering emulsion were co-stabilized by both chitosan nanoparticles and surfactant alkyl phenol ethoxylates (OP-10). The results indicated that chitosan and OP-10 could be well stabled in the O/W surface of high internal phase emulsion. PTMIPs were applied to adsorb amoxicillin. The isotherm data well fitted by Langmuir monolayer adsorption, and the maximum adsorption capacity was 17.04μmol/g at 35℃. The adsorption kinetics data could be better described by pseudo-second-order equation. The adsorbent had good recognition of template molecule. After five cycles of adsorption-desorption, the adsorption capacity of PTMIPs were lost about 8.07%, indicating that the sorbent could be used repeatedly.