Adsorption Removal Of Antibiotics By Sodium Alginate-based Materials From Aqueous Solution

Fluoroquinolones(FQs),powerful broad-spectrum synthetic antibiotics,are widely used in human and veterinary medicine.However,the presence of FQs at lower concentrations in the environment could threaten to human health and agricultural production by stimulating bacterial resistance owing to the remarkably stability of its chemical properties.Thus the development of efficient and environmentally friendly adsorbents is of great importance.FQs could bind metal ions forming complexes,as a result,the new type adsorbent based on chelation would be capable of removal efficiently,selective recognition and adsoption to FQs.Besides,there are rarely reported in related literatures.In this paper,the adsorption membranes and adsorption gel beads were prepared based on biodegradablity and crosslinking with multivalent metal ions of sodium alginate(SA),respectively.The SA membranes and gel beads could play its role effectively with its metal ions on the surface,and the combination of SA adsorbing materials and other treatment technologies may degrade FQs pollutants completely.Besides,the SA adsorbing materials can be degraded environmentally to avoid secondary pollution after loss of its adsorption capacity.Firstly,the preparation and adsoprion of adsorption membranes,named SA-Al/Ca membranes and SA-Ca membrane crosslinking by CaCl2 and AlCl3/CaCl2 solutions respectively,were studied.The adsorption results shown that the presence of Al3+ in crosslinking agent could produce a large number of adsorption sites on the surface of SA-Al/Ca membrane and improve the adsorption performance remarkably.The thermodynamics of the adsorption of CIP and S-OFX were well fitted with the Tempkin adsorption isotherm model(R2=0.9455)and D-R adsorption isotherm model(R2=0.9822)respectively.The maximum amount of S-OFX adsorbed on SA-Al/Ca membrane reached 836.31 mg·g-1.The adsorption process could approach chemical equilibrium in 120 min when initial concentration was 100 mg·L-1.The SA-Al/Ca membranes had a certain degree of tolerance in temperature,pH,ionic strength change,and also demonstrated an efficient and selective in FQs.Then,the prepration and adsoprion performance of adsorption beads,named GA(SA-Al/Ca)gel beads and SA-Al/Ca gel beads,were studied to improve reusability and simplify the preparation process of SA adsorbents.It was found that GA(SA-Al/Ca)gel beads crosslinked with glutaraldehyde(GA)were capable of good reusability and excellent adsorption performance.The equilibrium absorption capacity of GA(SA-Al/Ca)gel beads could reach to 145.70 mg·g-1,when initial concentration of S-OFX was 100 mg·L-1.The maximum removal rate of S-OFX with GA(SA-Al/Ca)gel beads could reach 88.45%.Besides,The GA(SA-Al/Ca)gel beads also had a certain degree of tolerance in temperature,pH,ionic strength change.The kinetics of the adsorption of S-OFX could reach the equilibrium states within 10 min.