Comparison of malachite green adsorption by two yeast strains using Raman microspectroscopy.

Malachite green (MG), as a triarylmethane compound, poses a health hazard and causes considerable environmental concern. In this work, batch biosorption experiments were conducted under different operational conditions such as pH, contact time and adsorption dose to assess the optimal parameters of MG dye removal by yeast biomass from aqueous solutions. Then, the conventional biochemical assay was used to evaluate MG removal efficiency (75.18 and 95.85%) by Saccharomyces cerevisiae and Candida utilis. In addition, Fourier-transform infrared spectroscopy in combination with Raman microspectroscopy was employed to scrutinize the differences of dye removal between two types of yeast strains. This study demonstrates that Raman microspectroscopy may serve as a useful and powerful tool to quantitatively measure the content of MG dye on yeast cell surfaces in situ, and even offer an alternative new technique to seek potentially proper adsorbents for the removal of toxic dyes from industrial effluents.