Recyclable Saccharomyces cerevisiae loaded nanofibrous mats with sandwich structure constructing via bio-electrospraying for heavy metal removal.

Biosorbents, such as algae and yeast, have been applied in heavy metal adsorption due to their low cost and efficacy. However, they cannot be recycled and reused after direct application, which may cause a secondary pollution. In this study, we used bio-electrospraying technique to immobilize Saccharomyces cerevisiae (a byproduct from food fermentation) onto the surface of poly(ε-caprolactone)/chitosan/rectorite ternary composites based nanofibrous mats. This technique not only combined the advantages of both S. cerevisiae (cheap) and nanofibers (large surface area) in heavy metal removal, but also made biosorbents easy to recollect and reuse. Layer-by-layer structured nanofibrous mats were also fabricated by alternating electrospinning and bio-electrospraying for a couple of times and loaded more S. cerevisiae for enhancing heavy metal biosorption. The morphology of S. cerevisiae loaded nanofibrous mats with different numbers of layers was observed. Biosorption assay was performed on PbNO3 solution under different pH values, contact time, initial concentrations of Pb2+ and biosorbents weights, at last the elemental composition was measured before and after biosorption. The results showed that S. cerevisiae loaded nanofibrous mats had a biosorption capacity of Pb2+ up to 238mg/g. Desorption assay indicated that these mats were reusable and maintained high biosorption capacity after three biosorption-desorption cycles.