Lignin peroxidase immobilization on Ca-alginate beads and its dye degradation performance in a packed bed reactor system

Abstract

Abstract In this study, lignin peroxidase (LiP) was immobilized by covalent binding onto high-quality Ca-alginate beads using glutaraldehyde as a cross-linking agent. Response surface methodology (RSM) was employed to optimize the operating conditions for optimal immobilization efficiency (IE) and to scrutinize the interactive effects of the processing variables affecting the immobilization efficiency. Influences of various factors such as sodium alginate (0.8, 2.0, and 2.5%), CaCl2 (0.9, 2.2, and 3.4%), and glutaraldehyde concentration (0.1, 0.2, and 0.3 M) on the IE were determined adopting a three-level-three-factor central composite design (CCD). Results indicated that Ca-alginate beads (average 2.0 mm diameter) developed using 2.0% (w/v) Na-alginate in 2.2% (w/v) CaCl2 solution functionalized with 0.2 M glutaraldehyde registered the maximum immobilization efficiency (∼96.31). Sodium alginate, CaCl2, and its combination revealed the most significant effect (p > F less than 0.05) on the IE of LiP. However, glutaraldehyde concentration was recorded to be non-significant with less influence on the LiP immobilization. Moreover, the optimally Ca-alginate immobilized LiP was also applied for the decolorization of a textile dye Remazol Brilliant Blue R (RBBR) in a packed bed reactor system (PBRS). The immobilized biocatalytic system was capable of effective dye decolorization in five consecutive batch operations retaining more than 80% dye removal efficiency after the 5th cycle. Taken together, the results manifest that Ca-alginate immobilized LiP might be an attractive choice as an industrial biocatalyst for bioremediation of textile dyes and effluents.