Phenyl-functionalized silica gels comprised of hydrophobic microspherical patches with adhered biodegrading bacteria were developed. The resulting bio-gels showed enhanced chemical adsorption and biodegradation properties. Silica gels with increasing phenyl alkoxide content were characterized using fluorescence measurements, confocal and scanning electron microscopy. Efficiency of adsorption and biodegradation was assessed using a model hydrophobic pollutant, the herbicide atrazine, and an <i>E. coli</i> strain expressing atrazine chlorohydrolase. The phenyl doped silica gels contained spherical hydrophobic patches increasing in size and abundance as a function of phenyl content introduced. These materials exhibited a 6-fold enhancement of atrazine adsorption over a non- functionalized silica gel and a 4-fold selectivity of the substrate (atrazine) over the product (hydroxylatrazine). Moreover, biodegradation rates of atrazine increased almost five-fold at 75% phenyl alkoxide content. Similar trends were observed for other triazines, such as fluoroatrazine and additional pesticides, such as parathion. SEM and confocal images suggest that the increase in activity is due to increasing bacterial adherence to the phenyl-silica gel; this creates a unique configuration where the hydrophobic microspheres act to sequester hydrophobic chemicals from water and allow facile transfer of the desired chemicals to the adhering non-viable bacteria.

Enhancing chemical adsorption and biodegradation using bioreactive phenyl-functionalized silica gels

251st National Meeting (2016)

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