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Adsorption and Release of Surfactant into and from Multifunctional Zwitterionic Poly(NIPAm-co-DMAPMA-co-AAc) Microgel Particles

Description
Monodispersed zwitterionic microgel (ZI-MG) particles that undergo an extensive, reversible change in volume in response to environmental stimuli such as pH and temperature were synthesized. These aqueous ZI-MG dispersions exhibited a minimum hydrodynamic diameter value at an adjustable isoelectric point(IEP). In addition, the study elucidates the controlled uptake and release…

Monodispersed zwitterionic microgel (ZI-MG) particles that undergo an extensive, reversible change in volume in response to environmental stimuli such as pH and temperature were synthesized. These aqueous ZI-MG dispersions exhibited a minimum hydrodynamic diameter value at an adjustable isoelectric point(IEP). In addition, the study elucidates the controlled uptake and release of ionic and nonionic surfactants from these particle systems. The extent of surfactant loading and the ensuing relative swelling/deswelling behaviors within the colloidal polymer networks are explained in terms of their binding interactions.
ContributorsKelley, Morgan Taylor (Author) / Dai, Lenore L. (Thesis director) / Chen, Haobo (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
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Biodegradation of Surfactants in the O2-based MBfR and the Impacts on the Microbial Community and Antimicrobial-resistance Genes

Description
While most household surfactants are biodegradable in aerobic conditions, their presence in a microbiological treatment process can lead to the proliferation of antimicrobial-resistance genes (ARG) in bacteria, such as Pseudomonas aeruginosa. Surfactants can be cationic, anionic, or zwitterionic, and these different classes may have different effects on the proliferation…

While most household surfactants are biodegradable in aerobic conditions, their presence in a microbiological treatment process can lead to the proliferation of antimicrobial-resistance genes (ARG) in bacteria, such as Pseudomonas aeruginosa. Surfactants can be cationic, anionic, or zwitterionic, and these different classes may have different effects on the proliferation of ARG. This study evaluated how the three classes of surfactants affected the microbial community’s structure and ARG in O2-based membrane biofilm reactors (O2-MBfRs) that provided at least 98% surfactant removal. Cationic cetrimonium bromide (CTAB) had by far the strongest impact with highest ARG abundance in the biofilm. In particular, Pseudomonas and Stenotrophomonas, the two main genera in the biofilm treating CTAB, were highly correlated to the abundance of ARG for efflux pumps and antibiotic inactivation. CTAB also promoted potential of horizontal gene transfer (HGT) of ARG. Combining results from the metabolome and metagenome identified four possible pathways for CTAB biodegradation. Of special important is a new pathway: β-carbon oxidation of CTAB to produce betaine. An insufficient nitrogen source could lead to irreversible ARB and ARG enrichment in the MBfR biofilm. Finally, a two-stage O2-MBfR successfully removed a high concentration (730 mg/L) of CTAB: Partial CTAB removal in the Lead reactor relieved inhibition in the Lag reactor. Metagenomic analysis also revealed that the Lag reactor was enriched in genes for CTAB and metabolite oxygenation.
ContributorsZheng, Chenwei (Author) / Rittmann, Bruce (Thesis advisor) / Delgado, Anca (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Lai, Yen-Jung (Committee member) / Arizona State University (Publisher)
Created2023