HomeMy WebLinkAboutClean Water - Bill Cooper PPCEE 162
Environmental Engineering Chemistry
William J. (Bill) Cooper
Engineering Tower 305
wcooper@uci.edu
824-5620
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Do me a favor?
Please put your I-phones and whatever other mobile media ‘thing’ you have away in the silent mode
Really, the only thing I have to offer you is 44+ years of experience – you only have to put up with me for 200 minutes a week – that is if you are on time.
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ME
I get so darn excited about environmental chemistry it is pathetic – but I also have never missed one day of work (except for an appendectomy) since 1970 – and I attribute that to loving
my job – which isn’t a job – but my life
January 20, 2012, 4 PM Environmental Engineering Seminar – hope you show up and you’ll get the answer to why I’m a cross-dresser – or now have seen the light in a spin-forbidden transition!
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Book
Water Chemistry – Pat Brezonik and Bill Arnold
Oxford University Press
2011 – First Edition
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Why are you taking this course?
As Environmental Engineers it is incumbent upon you to have the skill set for understanding the basics of the processes that you will implement in your life
During this course we will learn some chemistry that will directly (whether you believe it or not) benefit you later!
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Why are you taking this course?
Testing the “waters” to see if environmental water chemistry is of interest – not normally taught the chemistry departments
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My Goal
While teaching from the book I will try to provide real-life examples of environmental chemistry
I’ve been doing this since my first publication (and this is the scary part) in 1967!
Official member of the OFC
Last year the students said that more examples of problem solving would be of interest – so we will spend at least 20 minutes of one of the two classes per week doing some problems.
Possibly – one hour at some appointed time – to go over additional problems???
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2012
40th Anniversary of the Clean Water Act
This was enacted on Oct. 18, 1972! President Nixon vetoed it (after he had passed the Clean Air Act in 1970 and established the US Environmental Protection Agency) what was he thinking
or maybe if you are a cynic who was paying him (in the broadest sense) to veto this Act?
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UCI – My Clean Water Act
We are launching a National Celebration of the Clean Water Act here at UCI – April 5 and 6th (first week of the spring semester) for the 40th Anniversary of the first “modern” water
laws passed in the US.
The national bus tour will hit as many campuses as possible and end up in DC Oct 18 – the anniversary of the enactment – for a day-long celebration and conversation at the Capital Visitor
Center
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Assignment
Your first assignment is to ‘like us’ on Facebook - My Clean Water Act just launched a Fan Page. Please "Like" our fan page and be part of our goal to reach 1012 Likes for 2012.
www.facebook.com/MyCleanWaterAct
we are also on Twitter @MyCleanWaterAct
Your second assignment due Tuesday, January 17, is a two to three page essay on the importance of the Clean Water Act and Environmental Engineering and Science.
Your essay – with your permission may end up on our web site and we may also be interviewing you for our You Tube site and Facebook
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Why was this act passed? #!
1962 Rachel Carson’s book “Silent Spring” thought by many to have been one of the most important catalysts for the modern environmental movement – or better yet, the start of people
thinking about sustainability!
Cuyahoga River, Cleveland, Ohio – BURNED
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Cuyahoga River #2
Discharges to Lake Erie
Around Cleveland a fish survey resulted in 9 fish being caught!
Industrial point sources and ‘storm water’ and other non-point sources were being dumped into the river
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Cuyahoga River, Cleveland, Ohio
Cleveland - Plain Dealer file
Former reporter Richard Ellers says he didn't appreciate the thickness of the pollution on Cuyahoga River until he dipped his hand into it. The photo was taken in the 1960s.
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Cuyahoga River
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Orange-brown water from the Cuyahoga River spills out of Cleveland harbor and into Lake Erie, a regular occurrence during the late 1960s when this photo was taken by members of the city's
Bureau of Industrial Wastes.
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Cleveland Ohio
Cuyahoga River Fires of 1868, 1912, 1936, 1952, 1969. Cleveland, Ohio
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Water Pollution Peaked in the 1960s
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Then and Now
Tremendous benefit has come from water regulation in the U.S..
We have come a long way, we have the traditional pollutants under control.
There is a new generation of pollutants.
Pharmaceuticals - New chemical compounds and molecules that didn’t exist a decade ago.
Carcinogens and Endocrine Disruptors.
Nanoparticles and nanomaterials
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Pharmaceuticals in Drinking Water
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Water Milestones by U.S. Congress
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Essay – For Print and Social Media
Who
Why
What
When
Where
How
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Water
The first chapter does a good job of detailing some of the unique characteristics of water and you have all had these before – so I wont’ go over them
Figure 1.2 – what is wrong?
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Units – not exclusively in water but very commonly used in (condensed phase) water
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Concentration Units
Molarity(M) =grams of solute/
g formula wt (g/mol) * vol of sol (L)
mol/L
Normality (N) =grams of solute/
g eq wt of solute * volume of solutions (L)
Normality is used extensively in titration where the fundamental relationship
V1N1 = V2N2
Molality (m) = g of solute/
g formula wt * kg of solvent
used in oceanography and chemical thermodynamics
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Atomic Weights
Carbon 12.011 accounts for the contribution
of 12C and 13C
Chlorine 35.45
35Cl (76 %) and 37Cl (24 %)
Bromine 79.04
79Br (50.69 %) and 81Br (49.31%)
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Avogadro’s Number (NA)
Define based on the 12C isotope
6.02214179 x 1023 atoms per mole
This concept is what levels the ‘playing field’ in chemistry – and the biggest mistake we ever made in the environmental chemistry area was letting engineers and lawyers decide that
regulations are based on weight per unit volume!
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Disinfection By-Products
chemicals that are formed when chlorine or other disinfectants used to control microbial contaminants in drinking water react with naturally occurring organic and inorganic matter in
water.
Cl2 + NOM disinfection byproducts (DBPs)
NOM – natural organic matter – you might have the heard the yellow/brownish color in water referred to a tannins – not quite that simple
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Example – Trihalomethanes (DBPs)
CHCl3 - chloroform or trichloromethane
Mol weight =
CHCl2Br - bromodichloromethane
Mol weight =
CHClBr2 - chlorodibromomethane
Mol weight =
CHBr3 - bromoform or tribromomethane
Mol weight =
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Example - Trihalomethanes
Primary drinking water standards to protect health
The trihalomethanes (THMs) are chloroform, bromodichloromethane, dibromochloromethane, and bromoform. EPA has published the Stage 1 Disinfectants/Disinfection Byproducts Rule to regulate
total trihalomethanes (TTHM) at a maximum allowable annual average level of 80 parts per billion. This standard will replace the current standard of a maximum allowable annual average
level of 100 parts per billion in December 2001 for large surface water public water systems. The standard will become effective for the first time in December 2003 for small surface
water and all ground water systems.
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The Rub – is Toxicity
Now the more you know the more complicated it gets – so lets stay naïve – but recognize that this is not the whole story!!!
Regulations by chemical classes is NOT the real way things should be done
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Plewa 2006
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Summary of 50 DBPs Analyzed with
the CHO Chronic Cytotoxicity Assay
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Plewa 2006
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Comparative DBP Genotoxicity Database
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Haloacetic Acids
CH3-COOH acetic acid – the COOH which is C=O(OH) is the acid part
The –CH3 portion of the molecule can be halogenated (Cl, Br, I) to give haloacetic acids.
HAA5 – mono-, di- and trichloroacetic acids and mono- and dibromoacetic acid
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Plewa 2006
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Summary of 50 DBPs Analyzed with
the CHO Chronic Cytotoxicity Assay
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Plewa 2006
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Comparative DBP Genotoxicity Database
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mg/L as CaCO3
mg/L as CaCO3 is based on the fact that the formula weight of CaCO3 is 100 (40 + 12 + (3 x 16))
the formula is 100 but the equivalent weight is 50 in terms of reactive capacity with H+ (it takes 2 H+ to react with one CaCO3)
Alkalinity – which (for the most part) deals with amount of carbonate/bicarbonate ion in solution is defined as the sum of the bases titratable with strong acid (usually to a predetermine
pH)
Hardness – is the sum of the divalent cations (Ca2+ and Mg2+) in water – there are some cases where Fe2+ and Mn2+ are included.
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mg/L as CaCO3
Alkalinity (mg/L as CaCO3) =
Alkalinity (meq/L) x (50 mg CaCO3/meq of CaCO3)
If we think of this in chemical terms –
1M of CaCO3 = 2N of CaCO3
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Additional Anomalies
NO3- (mg/L as N)
NH4+ (mg/L as N)
PO43- (mg/L as P)
Later in the disinfection lecture we’ll talk about Cl2 - chlorine
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Chemical Reactions in Natural Waters
Chemical equilibrium
𝑎𝐴+𝑏𝐵 ⇌𝑐𝐶+𝑑𝐷
Equilibrium constant (K)
𝐾=[𝐶]𝑐[𝐷]𝑑/[𝐴]𝑎[𝐵]𝑏
Chemical Kinetics – is the study of how fast a reaction proceeds
Although there are various rate expressions – to solve for rate constants in the lab we are forced to reduce equations to 1st order or pseudo 1st order
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Inorganic Reactions
Acid-Base Reactions
Solubility or Precipitation/dissolution
Complexation
Oxidation/reduction (Redox reactions)
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Acid-Base Reactions
𝐻𝐴+𝐻2𝑂 ⇌𝐻3𝑂+ +𝐴-
𝐾𝑎= 𝐻3𝑂+ [A-]/[HA][H2O]
[H2O] is usually taken at 1
𝐾𝑎= 𝐻3𝑂+ [A-]/[HA]
If we multiply the equation by –Log
pKa = pH + [HA]/[A-]
So the pKa is the pH at which the concentration of the acid and it’s conjugate base are equal!
I will often use pKa during certain lectures, e.g. the disinfection lecture – so this is a good concept to remember
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Solubility or Precipitation/dissolution
MA(s) + H2O ⇌ M+(aq) + A- (aq)
This is a hydrolysis (reaction with water) reaction
K = [M+][A-]/[MA][H2O]
K is the equilibrium constant
Ksp = [M+][A-]
Ksp is the solubility product – or the actual analytically measured concentrations in water (f(T), and other variables)
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Complexation
Complexes arise from components capable of independent existence in solution
Central metal ion – electron pair acceptor (Lewis Acid)
One or more ligands – electron-pair donors (Lewis bases)
Ligands can be something as simple as Cl- or NH3
We’ll return to this later
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Oxidation/Reduction (Redox reactions)
OIL – oxidation is loss (of electron)
RIG – reduction is gain (of electron)
Fe3+ + e- Fe2+
When ever you have oxidation you also have reduction, oxidants and reductants, SO when something acts as an oxidant it, itself gets reduced.
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Complexation and Redox
There are many examples of species in solution that should undergo oxidation and don’t because they are complexed and thus stabilized
Exm. Cu1+ in seawater is complexed with Cl- and stabilized (Cl- is 19,000 mg/L in sea water) and in fresh water the chemistry of copper is entirely different because of the lower concentration
of Cl-
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Iron in Rain
Exm. In rain Fe2+ exists, in spite of saturated O2 and the presence of a strong oxidant H2O2.
The significance of this is that Fe2+ is available to organisms and Fe3+ is not as it is essentially insoluble
So when it rains and there is iron in solution it fertilizes the ocean which is nutrient limited in iron in most places
If you add non-rain iron to the surface ocean it is oxidized in seconds, whereas rain-iron may be stable for minutes or longer
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Phase Transfer
(Gas Transfer) Liquid to gas OR gas to liquid
Today the most important is CO2 dissolving into the ocean – causing ocean acidification
Another – acid rain – SOx into water gave acid rain
Aeration stripping – the engineering (low cost) solution to water purification, where water pollutants such as the trihalomethanes or TCE were ‘stripped’ out of water to the air
(Sorption) Solute to sorbents OR adsorbed to dissolved components
The most recognized of these sorts of processes is activated carbon
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