两种含氨基β-环糊精衍生物对萘和蒽的光催化降解作用

Effects of Two Amino Acids Derived from β-Cyclodextrinson on the Photodegradation of Naphthalene and Anthracene

为进一步探讨含氨基β-CD（β-环糊精）衍生物对PAHs（多环芳烃）的光催化降解机理,合成了两种含氨基β-CD衍生物——ACD（氨基-β-CD）和EDCD（乙二胺-β-CD）,并研究了其对溶液中萘和蒽的包合作用及光催化降解作用.结果表明：β-CD、ACD、EDCD对萘和蒽的包合能力分别为76.3和251 L/mol、111和394 L/mol、191和427 L/mol,由于β-CD亲水外缘极性基团的引入,使得其疏水空腔内部的水分子具有更高的能量,易移出,易被PAHs分子取代,因此ACD和EDCD的包合能力有所增强;对萘和蒽光敏化作用的大小表现为ACD〉EDCD〉β-CD,在溶液中分别加入3 g/L的β-CD、ACD和EDCD后,萘和蒽的光解率分别提高了40.0%-50.9%和44.3%-104%.研究显示：由于光解过程中含氨基β-CD疏水空腔对三重态PAHs起到了包合保护作用,导致三重态PAHs与三重态氧分子碰撞及产生高活性单重态氧的几率增加,包合作用越大光催化降解能力越强;但是ACD和EDCD的氨基会对三重态氧分子进攻三重态PAHs产生阻碍作用,导致光催化降解效率降低.

Two amino acids derived from β-cyclodextrins,amino-β-cyclodextrin（ ACD） and ethanediamine-β-cyclodextrin（ EDCD）,were synthesized and examined for their inclusion and photodegradation for PAHs,naphthalene and anthracene in aqueous solution. The results showed that the inclusion capacity of β-CD,ACD and EDCD for naphthalene and anthracene were 76. 3 and 251 L/mo L,111 and 394L/mo L,191 and 427 L/mo L,respectively. ACD and EDCD have inclusion capacities higher than β-CD because water molecules in their hydrophobic cavums have more energy and can be easily replaced by naphthalene or anthracene molecules. Among the three cyclodextrins,the photosensitization on naphthalene or anthracene decreased as follow： ACD 〉EDCD 〉β-CD. In the presence of 3 g/L β-CD,ACD or EDCD,the photolysis rates of naphthalene and anthracene were increased up to 40. 0%-50. 9% and 44. 3%-104% due to the fact that self-quenching of triplet PAH molecules in cyclodextrin hydrophobic cavum was decreased,which increased the chances of triplet PAH molecules colliding with tripletoxygen molecules and producing more oxygen molecules and more highly reactive singlet oxygen molecules.As a result,more inclusion capacity for PAH molecules in cyclodextrins and greater photodegradation was achieved. However,amino in ACD or EDCD could impede collision detection between triplet PAH molecules and triplet oxygen molecules,and EDCD with more amino group could result in lower photodegradation ability for PAHs than ACD.