Aquatic Chemistry 367 Civil and Environmental Engineering

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Aquatic Chemistry 367Civil and Environmental
Engineering

• Meeting time MWF 1100-1150am
• Meeting room Abbott Auditorium in Pancoe
  Pavillion
• Instructor Jean-Francois Gaillard,
  jf-gaillard_at_northwestern.edu
• Grader Amy Dahl, a-dahl_at_northwestern.edu

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Logistics

• Introductions
• http//www.civil.northwestern.edu/ehe/courses/ce-3
  67/ce-367.htm
• Keep on top of the homework!

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Why study Aquatic Chemistry?
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Why study Aquatic Chemistry?

• Required for life
• Pollution transport almost always requires water
• Many environmentally relevant reactions occur in
  water
• Critical for controlling cycling of many elements
• Nutrients
• Toxins
• Oxygen, nitrogen, carbon dioxide atmosphere
  control

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Applications of aquatic chemistry

• Arsenic
• Chromium
• Mercury
• Acid mine drainage
• Global warming

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What is water?

• Universal Solvent
• Required for life
• Molecular structure
• Hydrogen bonding water clustering
• Anomalous behavior compared to other liquids

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What is in water?
Soluble Species
Suspended Particles
Soluble Species
Suspended Particles
Small Complexes
Small Complexes
Particles
Particles

Colloidal, aggregates

Colloidal, aggregates
e.g.,
Inorganic
e.g.,
Inorganic

Oxides (Al, Fe, Mn, Si)

Oxides (Al, Fe, Mn, Si)
Metal Complex
Metal Complex

Adsorption surface

Adsorption surface
Me(CO
)
Me(CO
)
y
-
y
-
complexation
complexation
3
n
3
n

Co
-
entrainment

Co
-
entrainment
Hydrated
Hydrated
Ion
Ion
Me
(H
O)
Me
(H
O)
n
n
2
n
2
n
Living Organisms
Living Organisms

Intra/extra
-
cellular

Intra/extra
-
cellular
Complexes with
Complexes with

Oligoelements

Oligoelements
Macromolecules
Macromolecules

Toxicity

Toxicity
e.g., Fulvic Acid

Defense Mechanisms
e.g., Fulvic Acid

Defense Mechanisms
Sediments
Sediments!
e.g.,
amorphous or crystalline solids
e.g.,
amorphous or crystalline solids (precipitates and
mineral formation)
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What is in water?

• Dissolved ions
• Major Cations (Ca, Na, Mg, K, Fe)
• Trace elements (Zn, Cr, Cu, Cd)
• Anions (F, Cl, nitrate, sulfate)
• Complexes (non-charged)
• Organic molecules (humic substances)
• http//www.ar.wroc.pl/weber/kwasy2.htm
• Particulate
• Organic matter
• Clays
• Oxides

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Chemical Reactions

• Acid-base chemistry
• Coordination chemistry
• Precipitation and dissolution
• Redox reactions

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Kinetic approach

• Does not assume equilibrium has been reached
• Use a rate constant, k, to describe the rate of
  formation of products or consumption of reactants

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Thermodynamic explanation

• Assumes equilibrium of a reaction is reached
• Simplifies solving mathematical expressions of
  chemical systems
• Use an equilibrium constant, K, to describe ratio
  of products to reactants