Near-neutral bleaching of cotton fabrics at low temperature is of great importance for saving energy and ecological friendliness in textile industry. In this work, glycerol triacetate (GT) was investigated as an activator of hydrogen peroxide (H 2 O 2 ) for low temperature bleaching of cotton knitted fabrics, and satisfactory whiteness was obtained. The bleaching properties of H 2 O 2 /GT system for cotton was assessed by the CIE whiteness index, H 2 O 2 decomposition rate, concentration of generated peracetic acid (PAA) and bursting strength. Possible factors affecting the performance of H 2 O 2 /GT bleaching system were discussed in detail. Adding only 10 mmol/L GT to the hydrogen peroxide solution (60 mmol/L) to bleach cotton knitted fabrics at 60 ℃ for 60 min, the WI was signi cantly increased from 52.09 to 68.92.By using benzenepentacarboxylic acid as a uorescent probe for hydroxyl radical (HO•) detection, it was found that GT could clearly promote HO• generation and the concentration of HO• closely related to the WI of cotton fabric. Furthermore, the bleaching mechanism of H 2 O 2 /GT system to cotton was proposed by exploring the relationship between WI and HO• concentration. As a bleach activator, GT has more economical bene ts and better solubility in water than that of TAED. The H 2 O 2 /GT system may provide a cost-effective and environmentally friendly approach as alternative to conventional alkaline hightemperature bleaching of cotton.
Enzymes as biocatalysts have attracted extensive attention. In addition to immobilizing or encapsulating various enzymes for combating the easy loss of enzymatic activity, strengthening the enzymatic activity upon light irradiation is a challenge. To the best of our knowledge, the work of spatiotemporally modulating the catalytic activity of artificialnatural bienzymes with a near-infrared light irradiation has not been reported. Inspired by immobilized enzymes and nanozymes, herein a platinum nanozyme was synthesized; subsequently, the platinum nanozyme was grafted on the body of laccase, thus successfully obtaining the artificial-natural bienzyme. The threedimensional structure of the artificial-natural bienzyme was greatly different from that of the immobilized enzyme or the encapsulated enzyme. The platinum nanozyme possessed excellent laccase-like activity, which was 3.7 times higher than that of laccase. Meanwhile, the coordination between the platinum nanozyme and laccase was proved. Besides, the cascaded catalysis of artificialnatural bienzyme was verified with hydrogen peroxide as a mediator. The enzymatic activities of artificial-natural bienzyme with and without near-infrared light irradiation were, respectively, 46.2 and 29.5% higher than that of free laccase. Moreover, the reversible catalytic activity of the coupled enzyme could be manipulated with and without a near-infrared light at 808 nm. As a result, the degradation rates of methylene blue catalyzed by the coupled enzyme and the platinum nanozyme were higher than that of laccase. Furthermore, accelerating polymerization of the dopamine was also demonstrated. Briefly, this facile strategy may provide a universal approach to control the catalytic activity of other natural enzymes.
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