Comparison of cutinases in enzymic deinking of old newsprint

In this study, the impact of cutinases from Thermobifida fusca and Fusarium solani pisi on the deinking of old newsprint were evaluated for the first time. When repulped old newsprint was treated with 8 U/g of T. fusca cutinase at pH 8 and 60 ∘\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{\circ }$$\end{document}C for 30 min, the brightness of the deinked papers reached 42.01%. With 8 U/g F. solani cutinase at pH 8.5 and 35 ∘\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{\circ }$$\end{document}C for 30 min, the brightness reached 41.62%. These brightness values are higher than that achieved using chemical deinking by 5.13 and 4.38%, respectively. These brightness values were also superior to that achieved using commercial lipase in this study and those previously reported using cellulases, hemicellulases, and laccase, which were higher than that achieved using chemical deinking by 2–4%. The mechanical properties of the deinked paper, including tensile index, tear index, and burst index, were also measured. The results showed that the two cutinases had different effects on the paper fibers. In summary, both T. fusca and F. solani pisi cutinases were able to remove ink from old newsprint more efficiently than alkaline chemistry or other enzymes. This study provides a potential strategy to deink efficiently old newsprint using cutinase.