Abundance of CO (solid lines) and CO ice (dashed lines) along the disk mid-plane for the α = 10^-3 model, with CO binding energy of 855 K (blue lines) and 1100 K (brown lines). The vertical dashed-dotted black line shows the location of the CO snowline as determined by Qi et al. (2015). The parametrisation of the model is by de Gregorio-Monsalvo et al. (2013). To reproduce the observed snowline location, the CO binding energy needs to be higher than that of pure CO ice, with E_b = 1100 K leading to a much better agreement than E_b = 855 K.