Biodegradation of crystal violet using Burkholderia vietnamiensis C09V immobilized on PVA–sodium alginate–kaolin gel beads

The strain, Burkholderia vietnamiensis C09V was immobilized on PVA–alginate–kaolin gel beads as a biomaterial to improve the degradation of crystal violet from aqueous solution. The results show that 98.6% (30 mg L−1) crystal violet was removed from aqueous solution using immobilized cells on PVA–alginate–kaolin gel beads, while 94.0% crystal violet was removed by free cells after degradation at the pH 5 and 30 °C for 30 h. Kinetics studies show that the pseudo-second-order kinetics well described the adsorption of crystal violet on the PVA–alginate–kaolin beads. Biodegradation of crystal violet on immobilized cells was fitted well by first-order reaction kinetics, indicating that CV was adsorbed onto kaolin and followed their degradation by immobilized cells onto the the PVA–alginate–kaolin beads. Characterization with SEM shows that cells attached well to the surface of PVA–alginate–kaolin beads, leading to improved crystal violet transfer from aqueous solution to immobilized cells. In addition, UV–vis show that the absorption peak at 588 nm was reduced by the degraded N-bond linkages, as well as the formation of degrading products were observed by Fourier transform infrared (FTIR). These results suggest that crystal violet was biodegraded to N,N-dimethylaminophenol and Michler's Ketone prior to these intermediates being further degraded.

► Burkholderia vietnamiensis C09V immobilized on PVA–alginate–kaolin beads.
► 98.6% crystal violet was removed using immobilized cell beads.
► The adsorption and biodegradation of crystal violet on immobilized beads.
► Characterization with SEM, UV and FTIR.
► The mechanism for adsorption and degradation was proposed.