Study on anionic and cationic dye adsorption behavior and mechanism of biofilm produced by Bacillus amyloliquefaciens DT

Biofilm produced by Bacillus amyloliquefaciens DT was reported to be able to remove crystal violet from water. However, there is no report on the ability of biofilm to remove other dyes. Here, we used methyl blue (MB; anionic) and malachite green (MG; cationic) as model dyes and investigated the behaviors and mechanisms of their adsorption by bacterial biofilm. Biofilm surface morphology, functional groups, and chemical constituents were characterized. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy results demonstrated that the relevant adsorptive functional groups were C-N bond/-NH3- and C-N bond/O=P(C)-O- for MB and MG adsorption, respectively. Isothermic and kinetic models revealed that biofilm adsorbs MB heterogeneously via chemisorption and intraparticle diffusion. In contrast, biofilm adsorbs MG mainly by physical interaction. Biofilm adsorption capacities were substantially higher than those for most other adsorbents. Hence, biofilm is promising as an anionic and cationic dye adsorbent for wastewater treatment.

Automated summary

The biofilm produced by Bacillus amyloliquefaciens DT has been found to effectively remove methyl blue and malachite green from water. The adsorption mechanisms for the two dyes differ, with biofilm showing high adsorption capacities, making it a promising adsorbent for wastewater treatment.