Mineral
Weathering and Mineral Surface Processes - III Sorption and Ion Exchange
Overview
As
seen in previous lectures, solubility may control the
concentrations of some elements in natural waters,
especially major elements. However, the concentrations of
many trace elements and organic compounds are controlled by
sorption processes, in which they are removed from solution
onto the surface of a foreign mineral. These processes can
be very important in limiting the mobility of contaminants.
Objectives
Learn about sorption; distinguish among
adsorption, absorption and ion exchange.
Understand why minerals acquire surface
charge and what the implications are.
Learn about sorption isotherms.
Learn to deal quantitatively with ion
exchange.
Investigate the role of ion exchange in
natural and contaminated waters.
Learning
Resources
Read:
Chapter 4 (pp.
107-128) in Kehew (2001)
Additional Questions to consider:
Here are some study guide questions to
contemplate as you read pages 107-128. You need not turn these
in, but after reading the text, you should be able to answer
these.
Distinguish between adsorption,
absorption and ion exchange.
Distinguish between inner- and
outer-sphere surface complexes.
What is a siloxane cavity?
Describe the diffuse double layer
model of a mineral surface in contact with an aqueous
solution.
What are the two types of surface
charge and how are they acquired?
Describe the individual components of
net surface charge.
Summarize examples from the
literature of ion exchange in uncontaminated and
contaminated aquifers.
Compare and contrast the expressions
for Freundlich and Langmuir isotherms.
For each of the Lectures
choose the option(s) that best fits your needs
