期刊
JOURNAL OF COLLOID AND INTERFACE SCIENCE
卷 504, 期 -, 页码 538-548出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcis.2017.06.005
关键词
Cation adsorption enthalpy; Flow microcalorimetry; Energetics; Thermodynamics; Cation exchange; Cation adsorption; Quartz
资金
- U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division [211267]
- separate project - Division of Chemical Sciences, Geoscience and Biosciences, Office of Basic Energy Sciences, U.S. Department of Energy
- Virginia Tech National Center for Earth and Environmental Nanotechnology Infrastructure (NanoEarth), a member of the National Nanotechnology Coordinated Infrastructure (NNCI)
- NSF [ECCS 1542100]
Cations in natural solutions significantly impact interfacial processes, particularly dissolution and surface charge measurements for quartz and silica, which are amongst the most naturally abundant and technologically important solids. Thermodynamic parameters for cation-specific interfacial reactions have heretofore been mostly derived instead of directly measured experimentally. This work investigates the energetics of adsorption and exchange reactions of alkali metal (M+) and alkaline earth (M2+) cations with the quartz surface by flow adsorption microcalorimetry, in tandem with in-situ pH measurements. The magnitudes of the heats of adsorption and exchange were found to increase along the Hofmeister series i.e., Li2+ < Na2+ < K2+ < Rb2+ < Cs2+ and Mg2+ < Ca2+ < Sr2+ < Ba2+, and exhibited strong correlations to bulk cation hydration enthalpies (Delta H-hyd). These results suggest inner-sphere adsorption for all studied cations and highlight the role Delta H-hyd plays in rationalizing these reactions and controlling their net overall enthalpy. pH measurements demonstrate that quartz surface charge will vary depending on the cation present, as is well known for amorphous forms of silica. Along with calorimetric signals, pH data revealed kinetic differences between the adsorption and desorption reactions of M+ and Ms2+, and individual cations within each group. (C) 2017 Elsevier Inc. All rights reserved.
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