Laccase immobilization on nanoporous aluminum oxide for black liquor treatment

Abstract

Nanoporous aluminum oxide coating has been successfully synthesized using different anodic synthesis conditions and self-assembled nanoporous with variable pore diameter, thickness and porosity were obtained. The Anodic Aluminum Oxide (AAO) coatings exhibited appropriate morphological characteristics which were employed for the Phebia brevispora BAFC 633 Laccase immobilization. Principal component analysis demonstrated that pH, contact time and enzyme concentration were the main variables which explain the total variation among the Laccase immobilization in the samples. The highest enzymatic activity was reported in the sample synthesized to 0.3 M of electrolyte concentration, 40°C of temperature and 30 V of anodization voltage. Laccase specific activity of 4.1 Ucm−2 could be obtained using an enzymatic concentration of 3.209 UL−1, pH 4.39 and contact time of 1.18 h according to the proposed regression model. Laccase/AAO bionanocatalyst can be easily collected and reserved 95.6% of initial activity after four cycles tests and immobilization yield of around 18.1%. Application of the immobilized Laccase for Black Liquor removal was also investigated. The bionanocatalyst showed better pH stability, 40% higher BL removal efficiency compared to free laccase after 40 min of reaction, and the ability to be collected and used up to twice for BL treatment. The novelty of this work contemplates the development of a bionanocatalyst from a nanoporous coating and immobilized Laccases that can be successfully applied for the treatment of effluents contaminated with black liquor.