Accelerated photoelectron transmission by carboxymethyl β-cyclodextrin for organic contaminants removal: An alternative to noble metal catalyst

Applications of noble metal decorated photocatalytic nanomaterials are restricted by its high cost. In this study, carboxymethyl beta-cyclodextrin (CM-beta-CD), as an alternative to gold nanoparticle, was used to modified titanium dioxide (CM-beta-CD-P25) to accelerate photoelectron transmission and enhance the organic contaminants removal from water. Several of emerging organic contaminants, such as bisphenol A (BPA), phenol and sulphanilamide (SA), were used to evaluate their photocatalytic activities. Carboxymethyl-beta-cyclodextrin not only provide hydrophobic sites to entrap organic contaminants but also provide a bridge for accelerated transmission of photogenerated charges without introducing the recombination interface. Consequently, 91.6 % of BPA, 71.9 % of phenol and 97.1 % of SA could be removed by CM-beta-CD-P25(2:1) under 1 h UV light irradiation. The photooxidation rate constant of BPA, phenol and SA by CM-beta-CD-P25(2:1) were 0.039 min(-1), 0.021 min(-1) and 0.062 min(-1), respectively, which are much higher than that of pristine P25 and Au-P25. Moreover, the photocatalytic activity of CM-beta-CD-P25(2:1) remains almost unchanged in repeated cycle test owing to its high stability. The reasonable mechanism of CM-beta-CD-P25 were investigated. CM-beta-CD-P25 hybrid nanoparticles completely surpasses Au-P25 in organic contaminants removal, and shows great potential to replace noble metal as mediator.