The
floatability of lignite is usually known to be very poor. Generally,
surfactants are applied to improve its hydrophobicity in the flotation
process. This research focuses on the adsorption performance of a
nonionic surfactant, sorbitan monooleate, on the lignite particles
with different densities, including −1.45 g/cm3,
−1.80+1.45 g/cm3, and +1.80 g/cm3. From
Fourier transform infrared spectroscopy results, it was obvious that
organic oxygen functional groups determined the surface properties
of lower density lignite, whereas inorganic Si-O determined the surface
properties of higher density sample. Qualitative similarities are
found in the curves of the surface electrokinetic potentials versus
pH values. Points of zero charge of the samples were measured to be
at pH values of 2.3, 3.0, and 3.0, respectively. Hence, organic oxygen
functional groups are similar to Si-O on the coal surface in adsorbing
OH– and H+ in electrolyte solution. The
X-ray photoelectron spectroscopy results show that the lower density
lignite particle has stronger adsorptions of sorbitan monooleate.
In other words, organic oxygen functional groups have the priority
over inorganic Si-O in adsorbing sorbitan monooleate. In addition,
polar groups of the surfactant have different adsorbing abilities
with organic oxygen functional groups. Interestingly, the oxygen content
of +1.8 g/cm3 lignite nearly does not change after the
pretreatment by sorbitan monooleate solutions. Therefore, the sorbitan
monooleate
molecule almost cannot adsorb on the mineral surface.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.