天然磁铁矿光催化转化水中头孢菌素类抗生素研究:共存离子的影响

Studies on the Photocatalytic Conversion of Cephalosporin Antibiotics in Aqueous Environment by Natural Magnetite:Effect of Coexisting Ions

头孢菌素类抗生素(CEPs)在环境水体中普遍存在,但目前水环境中含量较高的无机离子对天然磁铁矿光催化转化CEPs的影响研究尚不全面.本研究发现可见光(λ≥420 nm)/天然磁铁矿体系对水中CEPs有一定去除能力,确定活性物种有空穴、电子及羟基自由基.以头孢哌酮钠(CFP)为代表性CEPs,重点考察了多种无机离子对可见光/天然磁铁矿体系催化降解水中CFP的影响.研究表明:共存的SO_(4)^(2-)、NO_(3)^(-)、HCO_(3)^(-)、Cl^(-)、Br^(-)及I^(-)通过改变体系中的活性物种影响降解,SO_(4)^(2-)、NO_(3)^(-)、Br^(-)及高浓度I^(-)均有较好的促进作用,而HCO_(3)^(-)反应前期、Cl^(-)及低浓度I^(-)抑制降解.另外,高浓度HCO_(3)^(-)在反应后期会引起CFP发生碱水解而表现出促进.F^(-)、Ca^(2+)及Mn^(2+)通过改变磁铁矿活性而影响CFP降解,其中Ca^(2+)、Mn^(2+)及低浓度F^(-)不利于降解,但高浓度F^(-)有利于降解.共存的Mg^(2+)、Zn^(2+)及Cu^(2+)通过与CFP相互作用促进降解.各无机离子存在下的CFP降解中间产物相同,并分析了其在可见光/天然磁铁矿体系下的主要降解产物及降解途径.

Cephalosporin antibiotics(CEPs)are prevalent in environmental waters,but the effects of relatively high content of inorganic ions on the photocatalytic conversion of CEPs in the aqueous environment by natural magnetite have not been comprehensively studied.In this study,the visible light(λ≥420 nm)/natural magnetite system was found to have a certain capacity of CEPs removal from water,and the active species were determined to be hole,electron and hydroxyl radical.Using cefoperazone sodium(CFP)as the representative CEPs,the effects of various inorganic ions on the catalytic degradation of CFP in water by visible light/natural magnetite system were mainly investigated.It was shown that coexisting SO_(4)^(2-),NO_(3)^(-),HCO_(3)^(-),Cl^(-),Br^(-),and I^(-)affected the degradation by changing the reactive species in the system,while SO_(4)^(2-),NO_(3)^(-),Br^(-)and high concentration of I^(-)all promoted the degradation well.However,HCO_(3)^(-) in the early stage of reaction,Cl^(-)and low concentration of I^(-)inhibited the degradation.In addition,high concentration of HCO_(3)^(-) in the later stage of reaction can cause alkali hydrolysis of CFP and thus exhibited promotion.The presence of F^(-),Ca^(2+),and Mn^(2+)affected CFP degradation by altering magnetite activity,in which Ca^(2+),Mn^(2+),and low concentration of F^(-)were detrimental but high concentration of F^(-)was beneficial to CFP degradation;Coexisting Mg^(2+),Zn^(2+),and Cu^(2+)enhanced degradation by interacting with CFP.Moreover,the degradation intermediates in the presence of various inorganic ions were same,and the main degradation products and degradation pathways of CFP in the visible light/natural magnetite system were analyzed.