Organic-inorganic nanocomposites fabricated via functional ionic liquid as the bridging agent for Laccase immobilization and its application in 2,4-dichlorophenol removal

In this study, organic-inorganic nanocomposite including mesoporous silica SBA-15 and chitosan was combined using carboxyl-functionalized ionic liquid as the bridging agent (SBA-CIL-CS), and which was characterized by scanning electron microscope, Fourier transform infrared spectroscopy, thermogravimetric analysis, and nitrogen adsorption-desorption isotherms. Thus prepared nanocomposite was applied to laccase immobilization via physical adsorption (SBA-CIL-CS-Lac) and utilized in 2,4-dichlorophenol (2,4-DCP) removal for the first time. SBA-CIL-CS-Lac showed relatively high immobilization efficiency, activity retention (75.3%), pH stability and storage stability. Kinetic experiment showed SBA-CIL-CS-Lac had the eminent affinity to the substrate. Circular dichroism and fluorescence analysis verified the active conformation of SBA-CIL-CS-Lac was maintained well to keep its enzymatic activity. Compared with the previous methods, SBA-CIL-CS-Lac exhibited prominent catalytic efficiency and reusability as well as pH and temperature stability for 2,4-DCP removal. The removal rate of SBA-CIL-CS-Lac for 2,4-DCP could be up to "90% after 35 h. Moreover, 58.8% removal rate could be retained after five operation runs. These results indicated that organic-inorganic nanocomposite SBA-CIL-CS was an ideal support for enzyme immobilization.