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Ionic polymer-coated laccase with high activity and enhanced stability: application in the decolourisation of water containing AO7.

Zhang X, Hua M, Lv L, Pan B - Sci Rep (2015)

Bottom Line: The stability of the resulting LacPG was highly enhanced against pH variations, thermal treatments and provided better long-term storage with a negligible loss in enzymatic activity.Compared to Lac, LacPG exhibited significantly higher decolourisation efficiency in the degradation of a representative azo dye, acid orange 7 (AO7), which resulted from the electrostatic attraction between the coating and AO7.The increased size and modified surface chemistry of LacPG facilitated ultrafiltration and reduced membrane fouling.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, P.R. China.

ABSTRACT
Eliminating dyes in environmental water purification remains a formidable challenge. Laccase is a unique, environmentally friendly and efficient biocatalyst that can degrade pollutants. However, the use of laccase for the degradation of pollutants is considerably limited by its susceptibility to environmental changes and its poor reusability. We fabricated a novel biocatalyst (LacPG) by coating polyethylenimine onto the native laccase (Lac) followed by crosslinking with glutaraldehyde. The stability of the resulting LacPG was highly enhanced against pH variations, thermal treatments and provided better long-term storage with a negligible loss in enzymatic activity. Compared to Lac, LacPG exhibited significantly higher decolourisation efficiency in the degradation of a representative azo dye, acid orange 7 (AO7), which resulted from the electrostatic attraction between the coating and AO7. LacPG was separated from the AO7 solution using an ultrafiltration unit. The increased size and modified surface chemistry of LacPG facilitated ultrafiltration and reduced membrane fouling. LacPG exhibited enhanced stability, high catalytic activity and favourable properties for membrane separation; therefore, LacPG could be continuously reused in an enzymatic membrane reactor with a high efficiency for decolourising water containing AO7. The developed strategy appears to be promising for enhancing the applicability of laccase in practical water treatment.

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(a) Effect of pH variation (25°C, incubation for 96 h) and (b) thermal treatment (pH 7.0, 60°C) on the residual activity of Lac and LacPG; error bars show standard deviations for triplicate measurements.
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f3: (a) Effect of pH variation (25°C, incubation for 96 h) and (b) thermal treatment (pH 7.0, 60°C) on the residual activity of Lac and LacPG; error bars show standard deviations for triplicate measurements.

Mentions: In general, enzymatic biocatalysts are susceptible to variations in pH and temperature during the catalytic degradation of organic pollutants, which greatly limits their practical application to water treatment. Thus, we examined the performance of LacPG under variations in pH and temperature. Figure 3(a) shows that a negligible loss in the activity of LacPG was observed after incubating the system over a pH range between 3 and 8 for 96 h at 25°C, whereas Lac lost ca. 50–90% of its initial activity. A slower deactivation rate was observed in the thermal study for LacPG than for Lac when the systems were incubated at 60°C (Fig. 3(b)). The thermal stability was quantitatively evaluated by determining the thermal parameters using the following simplified deactivation model40.


Ionic polymer-coated laccase with high activity and enhanced stability: application in the decolourisation of water containing AO7.

Zhang X, Hua M, Lv L, Pan B - Sci Rep (2015)

(a) Effect of pH variation (25°C, incubation for 96 h) and (b) thermal treatment (pH 7.0, 60°C) on the residual activity of Lac and LacPG; error bars show standard deviations for triplicate measurements.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4317704&req=5

f3: (a) Effect of pH variation (25°C, incubation for 96 h) and (b) thermal treatment (pH 7.0, 60°C) on the residual activity of Lac and LacPG; error bars show standard deviations for triplicate measurements.
Mentions: In general, enzymatic biocatalysts are susceptible to variations in pH and temperature during the catalytic degradation of organic pollutants, which greatly limits their practical application to water treatment. Thus, we examined the performance of LacPG under variations in pH and temperature. Figure 3(a) shows that a negligible loss in the activity of LacPG was observed after incubating the system over a pH range between 3 and 8 for 96 h at 25°C, whereas Lac lost ca. 50–90% of its initial activity. A slower deactivation rate was observed in the thermal study for LacPG than for Lac when the systems were incubated at 60°C (Fig. 3(b)). The thermal stability was quantitatively evaluated by determining the thermal parameters using the following simplified deactivation model40.

Bottom Line: The stability of the resulting LacPG was highly enhanced against pH variations, thermal treatments and provided better long-term storage with a negligible loss in enzymatic activity.Compared to Lac, LacPG exhibited significantly higher decolourisation efficiency in the degradation of a representative azo dye, acid orange 7 (AO7), which resulted from the electrostatic attraction between the coating and AO7.The increased size and modified surface chemistry of LacPG facilitated ultrafiltration and reduced membrane fouling.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, P.R. China.

ABSTRACT
Eliminating dyes in environmental water purification remains a formidable challenge. Laccase is a unique, environmentally friendly and efficient biocatalyst that can degrade pollutants. However, the use of laccase for the degradation of pollutants is considerably limited by its susceptibility to environmental changes and its poor reusability. We fabricated a novel biocatalyst (LacPG) by coating polyethylenimine onto the native laccase (Lac) followed by crosslinking with glutaraldehyde. The stability of the resulting LacPG was highly enhanced against pH variations, thermal treatments and provided better long-term storage with a negligible loss in enzymatic activity. Compared to Lac, LacPG exhibited significantly higher decolourisation efficiency in the degradation of a representative azo dye, acid orange 7 (AO7), which resulted from the electrostatic attraction between the coating and AO7. LacPG was separated from the AO7 solution using an ultrafiltration unit. The increased size and modified surface chemistry of LacPG facilitated ultrafiltration and reduced membrane fouling. LacPG exhibited enhanced stability, high catalytic activity and favourable properties for membrane separation; therefore, LacPG could be continuously reused in an enzymatic membrane reactor with a high efficiency for decolourising water containing AO7. The developed strategy appears to be promising for enhancing the applicability of laccase in practical water treatment.

Show MeSH
Related in: MedlinePlus