  The adsorption of single colloidal microparticles (0.5--1 $\mu$m radius) at a
water-oil interface has been recently studied experimentally using digital
holographic microscopy [Kaz \textit{et al., Nat. Mater.}, 2012, \textbf{11},
138--142]. An initially fast adsorption dynamics driven by capillary forces is
followed by an unexpectedly slow relaxation to equilibrium that is logarithmic
in time and can span hours or days. The slow relaxation kinetics has been
attributed to the presence of surface "defects" with nanoscale dimensions
(1--5\,nm) that induce multiple metastable configurations of the contact line
perimeter. A kinetic model considering thermally activated transitions between
such metastable configurations has been proposed [Colosqui \textit{et al.,
Phys. Rev. Lett.}, 2013, \textbf{111}, 028302] to predict both the relaxation
rate and the crossover point to the slow logarithmic regime. However, the
adsorption dynamics observed experimentally before the crossover point has
remained unstudied. In this work, we propose a Langevin model that is able to
describe the entire adsorption process of single colloidal particles by
considering metastable states produced by surface defects and thermal motion of
the particle and liquid interface. Invoking the fluctuation dissipation
theorem, we introduce a drag term that considers significant dissipative forces
induced by thermal fluctuations of the liquid interface. Langevin dynamics
simulations based on the proposed adsorption model yield close agreement with
experimental observations for different microparticles, capturing the crossover
from (fast) capillary driven dynamics to (slow) thermally activated kinetics.
