In this work, four poly(glycidyl
methacrylate-co-ethylene glycol methacrylate) [PGMA-co-EDGMA] functionalized
particles were synthesized and characterized, and tested in gas oil
adsorption. Particles consisted of identical polymer support (PGMA-co-EDGMA, henceforth referred to as PGMA) and π-acceptor
moiety (2,4,5,7-tetranitroflorenone, TENF), while the linkers (linear
diamines) were varied from a two- (diaminoethane, DAE (2)), a three- (diaminopropane, DAP(3)) to a four-carbon
(diaminobutane, DAB(4)) containing compounds. The particles
notation takes the form: PGMA-DAE(2)-TENF, PGMA-DAP(3)-TENF, PGMA-DAB(4)-TENF and PGMA-DAB(4)5-TENF, where 5 denotes the synthesis in 5% (vol./vol.)
linker and 95% (vol./vol.) toluene solution, while for other three,
100% (vol./vol.) linker was used. Particles were characterized by,
among others, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric
analysis (TGA), elemental carbon, hydrogen, nitrogen and sulfur analysis
(CHNS) and scanning electron microscopy (SEM). The change in linker
length did not result in a significant effect on loading as similar
amounts of TENF were immobilized on the polymeric particles regardless
of the linker length. From the adsorption studies of light gas oil
(LGO), results showed that diaminopropane (PGMA-DAP(3)-TENF) substituted particles gave the highest % adsorption of nitrogen
compounds, followed by the diaminobutane (PGMA-DAB(4)-TENF)-based
particles, while no significant differences between the particles
with diaminoethane (PGMA-DAE(2)-TENF) and PGMA-DAB(4)5-TENF were observed. The results further showed that all
the four types of particles selectively adsorbed nitrogen compounds,
while the sulfur concentration in LGO remained unchanged under the
following adsorption process conditions: ambient temperature (24 °C),
time (24 h), particles to oil loading ratio (1:4 wt./wt.) and stirring
speed (400 rpm). Generally, steric hindrance around the TENF molecules,
on the surface of the particles, had a major role to play in the adsorption
process than the length of the linker.
