TITLE:
Addition of Thiourea Host Monomer to Polymer Flocculants to Improve Selectivity of Phosphate Sorption
AUTHORS:
Timothy S. Goebel, Kevin J. McInnes, Scott A. Senseman, Robert J. Lascano, Alex M. Cullen, Timothy J. Fuhrer, Sarah Pickle, Netochi O. Adeolokun, Todd A. Davis
KEYWORDS:
Molecular Recognition, Thiourea, Polymers, Flocculants, Phosphate
JOURNAL NAME:
Journal of Agricultural Chemistry and Environment,
Vol.9 No.3,
August
24,
2020
ABSTRACT: Inorganic phosphate is a common nutrient that is applied as a fertilizer
to both agricultural fields as well as urban settings such as private yards,
public parks and other urban landscaping. While phosphate typically binds
tightly to soil, movement of phosphate off of application sites can occur
through soil erosion. The soil and its bound phosphate can then end up in
surface waters such as rivers and lakes. Phosphate found in surface water
bodies exists both as bound to the suspended clay as well as that free in
solution. Elevated phosphate concentration in surface waters can lead to algal
blooms and eutrophication. While the phosphate bound to clay in suspension in
surface water bodies can be removed by commercially available polymer
flocculants, the phosphate that is free in solution is more challenging as it
is usually found in low concentrations and other anionic salts are generally
present in higher concentrations. To remove phosphate from contaminated water
systems, where other anions exist at higher concentrations, it is favorable to
have a method of removal that is selective for phosphate. As a proof of
principle, thiourea derivatized polymer flocculants were examined for the
selective removal of phosphate in the presence of competing anions. The polymer
flocculants exhibited selectivity for phosphate through hydrogen bonding and
were effective at removing up to 43% of phosphate from simulated wastewater.
Computational studies and 1H NMR were used to investigate the
selectivity of the thiourea monomer for phosphate over competing anions such as
chloride and sulfate.