Adsorption behavior and XPS analysis of nonylphenol ethoxylate on low rank coal
More details
Hide details
1
Shandong University of Science and Technology
Publication date: 2019-04-24
Corresponding author
Lin Li
Shandong University of Science and Technology, No. 579, Qianwangang Road, Economics and Technology Development Zone, 266590 Qingdao, China
Physicochem. Probl. Miner. Process. 2019;55(3):721-731
KEYWORDS
TOPICS
ABSTRACT
In this work, low rank coal was used for the removal of nonylphenol ethoxylate with fifteen ethylene oxide groups (NPEO15) from aqueous solutions at different contact times, temperatures, and initial adsorbent concentrations. The adsorption isotherms showed good fit with the Langmuir equation. Maximum adsorption capacities calculated at 308, 318, and 328 K were 23.64, 29.41, and 35.71 mg g–1, respectively. The changes in the free energy of adsorption (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were calculated in order to predict the nature of adsorption. The results of the thermodynamic analysis indicated that a spontaneous process took place, driven synergistically by both enthalpy and entropy. The adsorption kinetics of NPEO15 were consistent with a pseudo-second order reaction model. XPS results showed that the oxygen functional groups on the low rank coal surface were significantly covered by NPEO15. Furthermore, while the content of C–C/C–H functional groups increased significantly, that of C–O functional groups decreased after absorption. These results clearly indicate that low rank coal is more hydrophobic and displays better floatability.