The Effect of Boric Acid Composition as Additional Cross-Linking Agent in SA-PVA Matrix Immobilized Pseudomonas aeruginosa for Methylene Blue Decolorization

Abstract

Methylene blue (MB) dye is commonly used in the textile industry because of its low cost and abundance properties. Nevertheless, the disposal of MB wastewater can cause environmental pollution and disrupt the ecosystem life. To overcome this problem, biodecolorization by using microorganisms such as Pseudomonas aeruginosa bacteria is one of the best methods for dye removal. P. aeruginosa can be immobilized on sodium alginate-polyvinyl alcohol (SA-PVA) matrix to enhance its capability to decolorize dye. The SA and PVA are well-known as good materials for immobilization. The beads of SA-PVA@P. aeruginosa used in this study were prepared through a cross-linking process with CaCl₂ and boric acid as the cross-linking agents. This study aimed to investigate the effect of boric acid composition as additional cross-linking agent in SA-PVA matrix on Pseudomonas aeruginosa’s ability to degrade MB through immobilization. The peaks of many constituents of the beads existing in FTIR spectra indicated that the cross-linking process in the bead fabrication was successfully done. The result showed that the most optimum percentage of MB decolorization by P. aeruginosa immobilized in SA-PVA matrix was 86.252% which was obtained in the beads cross-linked by using CaCl₂ and boric acid composition of 4:5, followed by 4:7 (83.619%), 4:3 (81.022%), 4:1 (79.212%), and 4:0 (77.140%). In addition, the temperature and time incubation study obtained that the most optimum MB decolorization percentage was reached at 40 °C and 24 hours incubation time.