Fabrication and Catalytic Characterization of Laccase-Loaded Calcium-Alginate Beads for Enhanced Degradation of Dye-Contaminated Aqueous Solutions

Abstract

Engineered laccases represent an eco-friendlier and robust biocatalytic tool for the treatment of dye-harboring textile wastewater. This study investigates the immobilization of purified laccase from Pleurotus sapidus onto firm-quality spherical Caalginate beads by a cross-linking approach. Sodium alginate at an optimal concentration of 4% (w/v) furnished the highest immobilization efficiency (69%). EDX analysis confirmed the detection of copper in the laccase-incorporated alginate beads. The optimum pH for free laccase was 3.0, while the Ca-alginate-Lac showed the maximum enzyme activity (440.2 U/mL) at pH 5.0. In contrast to a free enzyme (40 °C), immobilized laccase performed best at an elevated temperature of 65 °C. The Km and V max values in the case of free and Ca-alginate immobilized enzymes were 114 µM, 370 U/mL, and 123 µM, 548 U/ mL, respectively. Immobilized laccase catalyzed a highly efficient decolorization of various reactive and disperse dye pollutants and recorded in the range of 86.19-91.01%. The COD and TOC levels were substantially reduced to 91.90-94.94 and 77.01-93.29%, respectively, in the maximally degraded dye solutions. Therefore, immobilization of laccase on Ca-alginate beads offers a cost-effective and facile method for environmental remediation applications.

Ecotoxicological impacts of industrial effluents on irrigation water quality, animal health and the role of calcium alginate in effluents treatment

“…These functional groups could gravitate positively charged metals found in a solution through the adsorption process (Chen et al, 2021 ). Moreover, Refaay et al ( 2022 ) attributed the adsorption capacity of alginate to the richness with carboxyl groups, where calcium ions could be replaced by hydrogen ions on the carboxylic acid groups of the adjacent chains, forming a polymetric matrix of Ca-alginate distinguished by excellent pollutant capability through passive adsorption between metal ions and binding sites on the molecular structure (Tiwari & Kathane, 2013 ; Bilal & Iqbal, 2019 ; Aslam et al, 2021 ).…”

“…On the other hand, different techniques have been applied for treatment of effluents polluted with heavy metals, including chemical precipitation, coagulation-flocculation, and ion exchange (Renu et al, 2017 ; Silva et al, 2008 ; Türkmen et al, 2022 ). However, usage of metal biosorbents derived from living organisms has been developed for this purpose, especially those derived from seaweeds (macroscopic algae) and alginate derivatives that are widely abundant and less expensive than industrial synthetic adsorbents (Aslam et al, 2021 ; Hamdy et al, 2018 ; Qamar et al, 2022 ). Algins are salts of alginic acid, a natural polymer found in brown algae ( Phaeophyceae) .…”

“…Several studies revealed that sodium alginate is an efficient candidate for heavy metals adsorption such as Cu 2+ , Cd 2+ , and Pb 2+ (Gao et al, 2020 ; Qamar et al, 2022 ; Refaay et al, 2022 ). However, others used alginate in the form of calcium alginate beads because the dry beads have higher sorption capacity per unit mass and are more suitable for practical handling (Aslam et al, 2021 ; Bilal & Iqbal, 2019 ; Silva et al, 2008 ). Therefore, this study aims to evaluate the quality of MRI effluents for irrigation and watering animals through analyzing physicochemical characteristics and heavy metals concentration and comparing them to world health organization (WHO) limits for drinking water and food and agricultural organization (FAO) limits for irrigation water.…”

Prevention of Swelling Phenomenon of Alginate Beads To Improve the Stability and Recyclability of Encapsulated Horse Liver Alcohol Dehydrogenase

“…Enzyme trapping within alginate beads is a widely used procedure as it is simple, fast, inexpensive, and environmentally sustainable. [6,7] However, some disadvantages are often associated with this support, including low mechanical strength and significant loss of the encapsulated biomolecules due to the swelling behavior caused by the open structure, large pore size, and high hydrophilicity. [8] These disadvantages, therefore, significantly reduce the stability of the biocatalysts, preventing their large-scale application.…”

“…However, if the enzyme is to be used in large‐scale processes, it is extremely important to reduce both the economic and ecological costs of the immobilized catalyst. Enzyme trapping within alginate beads is a widely used procedure as it is simple, fast, inexpensive, and environmentally sustainable [6,7] . However, some disadvantages are often associated with this support, including low mechanical strength and significant loss of the encapsulated biomolecules due to the swelling behavior caused by the open structure, large pore size, and high hydrophilicity [8] .…”