Methylene blue removal using alginate-PVA-Pseudomonas aeruginosa biocomposite: Kinetics and biodegradation studies

Abstract

• Alg-PVA immobilized P. aeruginosa removed more MB compared to free cells. • MB removal followed pseudo-second-order kinetics and Langmuir isotherm model. • LC-QTOF/MS identified MB metabolites, confirming a successful biodegradation. Methylene blue (MB) is a common synthetic dye used in various industries due to its abundance and cost-effectiveness. However, the presence of this synthetic dye in industrial wastewater has the potential to cause significant effects on the environment and public health when released into soil or water bodies. According to results, biological wastewater treatment has emerged as a promising approach due to its economic feasibility, efficiency, and environmental compatibility. Therefore, this study aims to evaluate the MB removal by Pseudomonas aeruginosa immobilized within alginate–polyvinyl alcohol (Alg-PVA) matrix and compare removal performance to that of free (non-immobilized) cells. The results showed that the immobilized P. aeruginosa (Alg-PVA-PA beads) exhibited higher MB removal efficiency (72.52 %) compared to free cells (55.52 %) and Alg-PVA beads alone (43.12 %). Adsorption analysis showed that the removal process followed a pseudo-second-order kinetic model, suggesting chemisorption, and was best described by the Langmuir isotherm, showing monolayer adsorption. Additionally, reusability tests showed that the immobilized biocomposite beads retained over 35 % MB removal efficiency after five consecutive cycles, suggesting the sustainability of the beads. XRD, FTIR, and SEM-EDX analysis confirmed the successful entrapment of P. aeruginosa within the Alg-PVA matrix and showed structural changes in the beads following the MB removal process. The results were also supported by LC-QTOF/MS outcomes, which showed metabolites with retention times of 1.17, 1.52, 8.35, and 9.36 min, suggesting the successful degradation of MB.

Topics & Concepts