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Efficient removal of atrazine from aqueous solutions using magnetic Saccharomyces cerevisiae bionanomaterial

Wu, Xin, He, Huijun, Yang, William L., Yu, Jiaping, Yang, Chunping
Applied microbiology and biotechnology 2018 v.102 no.17 pp. 7597-7610
Fourier transform infrared spectroscopy, Saccharomyces cerevisiae, X-ray diffraction, aqueous solutions, atrazine, biodegradation, bioremediation, carbon, deamination, dechlorination, energy-dispersive X-ray analysis, gas chromatography-mass spectrometry, glucose, hysteresis, iron, iron oxides, isomerization, magnetism, mineralization, nanoparticles, nitrogen, pH, polyvinyl alcohol, scanning electron microscopy, sodium alginate, transmission electron microscopy
A novel bionanomaterial comprising Saccharomyces cerevisiae (S. cerevisiae) and Fe₃O₄ nanoparticles encapsulated in a sodium alginate-polyvinyl alcohol (SA-PVA) matrix was synthesized for the efficient removal of atrazine from aqueous solutions. The effects of the operating parameters, nitrogen source, and glucose and Fe³⁺ contents on atrazine removal were investigated, and the intermediates were detected by gas chromatography-mass spectrometry (GC-MS). In addition, the synthesized Fe₃O₄ particles were characterized by XRD, EDX, HR-TEM, FTIR, and hysteresis loops, and the bionanomaterial was characterized by SEM. The results showed that the maximum removal efficiency of 100% was achieved at 28 °C, a pH of 7.0, and 150 rpm with an initial atrazine concentration of 2.0 mg L⁻¹ and that the removal efficiency was still higher than 95.53% even when the initial atrazine concentration was 50 mg L⁻¹. Biodegradation was demonstrated to be the dominant removal mechanism for atrazine because atrazine was consumed as the sole carbon source for S. cerevisiae. The results of GC-MS showed that dechlorination, dealkylation, deamination, isomerization, and mineralization occurred in the process of atrazine degradation, and thus, a new degradation pathway was proposed. These results indicated that this bionanomaterial has great potential for the bioremediation of atrazine-contaminated water.