Green coconut fiber: a novel carrier for the immobilization of commercial laccase by covalent attachment for textile dyes decolourization.
Commercial laccase formulation was immobilized on modified green coconut fiber silanized with 3-glycidoxypropyltrimethoxysilane, aiming to achieve a cheap and effective biocatalyst. Two different strategies were followed: one point (pH 7.0) and multipoint (pH 10.0) covalent attachment. The influence of immobilization time on enzymatic activity and the final reduction with sodium borohydride were evaluated. The highest activities were achieved after 2 h of contact time in all situations. Commercial laccase immobilized at pH 7.0 was found to have higher activity and higher affinity to the substrate. However, the immobilization by multipoint covalent attachment improved the biocatalyst thermal stability at 50 °C, when compared to soluble enzyme and to the immobilized enzyme at pH 7.0. The Schiff's bases reduction by sodium borohydride, in spite of causing a decrease in enzyme activity, showed to contribute to the increase of operational stability through bonds stabilization. Finally, these immobilized enzymes showed high efficiency in the continuous decolourization of reactive textile dyes. In the first cycle, the decolourization is mainly due to dyes adsorption on the support. However, when working in successive cycles, the adsorption capacity of the support decreases (saturation) and the enzymatic action increases, indicating the applicability of this biocatalyst for textile wastewater treatment.
Laboratory of Separation and Reaction Engineering (LSRE), Associate Laboratory LSRE/LCM, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, Rua do Dr. Roberto Frias, 4200-465, Porto, Portugal.
Raquel O
RO
Cristóvão
Sara C
SC
Silvério
Ana P M
AP
Tavares
Ana Iraidy S
AI
Brígida
José M
JM
Loureiro
Rui A R
RA
Boaventura
Eugénia A
EA
Macedo
Maria Alice Z
MA
Coelho
D000327:Adsorption; D001230:Aspergillus / Q000201:enzymology; D001673:Biodegradation, Environmental; D001894:Borohydrides / Q000737:chemistry; D003059:Cocos / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D042845:Laccase / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry; D013784:Textiles; D062065:Wastewater
D001894:Borohydrides; D004396:Coloring Agents; D004800:Enzymes, Immobilized; D042845:Laccase; D012821:Silanes; D062065:Wastewater; C403136:3-glycidoxypropyltrimethoxysilane; C025364:sodium borohydride