Variation in surface energy heterogeneity of graphite due to adsorption of polyoxyethylene sorbitan monooleate.
The heterogeneity of surface energy of graphite before and after adsorption of polyoxyethylene sorbitan monooleate (Tween80) was investigated by the nitrogen adsorption technique. The nitrogen adsorption energy distributions (AEDs) were calculated from the low-pressure isotherm data (i.e., the data of submonolayer adsorption) according to the regularization method. Based on the AED of pristine graphite, two types of dominant energetic surface are identified and assigned respectively to the basal surface and the irregular surface, including the stepped edges and defect sites. When the adsorption amount of Tween80 is raised, both the surface energy and the energy heterogeneity of graphite gradually decline. It is thus demonstrated that Tween80 prefers interacting with and screening higher energetic surfaces to lower ones.
Research Center of Surface and Interface Chemical Engineering Technology, Nanjing University, Nanjing 210093, People's Republic of China.
Qingfeng
Q
Hou
Xiancai
X
Lu
Xiandong
X
Liu
Baixing
B
Hu
Jiang
J
Yuan
Jian
J
Shen