Experimental investigation of novel Trabulsiella odontotermitis derived glycolipid biosurfactant stabilized emulsion liquid membrane for methylene blue extraction from simulated wastewater

Abstract In this investigation, a biosurfactant‐stabilized emulsion liquid membrane (BS‐ELM) was developed for the extraction of methylene blue (MB) from aqueous solution. Biosurfactant (BS) producing microbial isolates were isolated from soil and characterized using Cetyltrimethylammonium bromide (CTAB) agar, hydrocarbon overlay assay (HOA), drop collapse, and emulsification index (E24) techniques. Among five candidates, strain BS‐5 demonstrated superior emulsification capacity and was taxonomically resolved as Trabulsiella odontotermitis (Accession no. PV450623) via 16S rRNA sequencing. Proton nuclear magnetic resonance ( 1 H NMR), Fourier transform infrared (FTIR) spectroscopy, and High‐resolution mass spectrometry (HRMS) elucidated structural features analogous to those of low‐molecular‐weight glycolipids. The formulated BS‐ELM leveraged waste cooking oil (WCO) as an eco‐friendly diluent, Aliquat 336 as an effective carrier, 0.8 M NaOH as the stripping phase, and biosurfactant‐enriched cell‐free supernatant (CFS) as an emulsifier. The zeta potential analysis revealed BS‐5 has good emulsion stability with a magnitude of +40 ± 3 mV. Furthermore, Dynamic light scattering (DLS) analysis indicates BS‐5 has a mean size of 1.7 μm. The MB extraction efficiency using BS‐ELM was recorded as 85% ± 1.8% under the optimum parameters, including feed pH 8, stirring speed 300 rpm, treat ratio 2:1, internal phase concentration 0.8 M, and 20% v/v biosurfactant. Kinetic analysis shows that the MB extraction by BS‐ELM follows a first‐order reaction. Overall, the findings of this study demonstrate the potential of the microbial glycolipid biosurfactant‐derived BS‐ELM as a promising technique for extracting MB from aqueous solutions.