New And Improved Project
What is this?
This was a project that allowed us to use our acquired information on physical and chemical properties along with our knowledge of ionic bonding to improve a product, or create a new product all together. After we had found the product, we had to alter it (for the better) in someway, with most of the focus on the chemical makeup of the product. The final part of the project was to form a letter containing our results in laymen terms, but also an enclosure with the extremely scientific information on it, and send these in a business letter to the company who’s product we improved.
Letter
3026 Main Avenue
The Effects of
Biochar on Leachate pH of Mine Site Soils
. Introduction
Another aspect that should be looked into is the points where the 0% biochar mix had lower rate of change and was more basic than even the 30% mix.
What is this?
This was a project that allowed us to use our acquired information on physical and chemical properties along with our knowledge of ionic bonding to improve a product, or create a new product all together. After we had found the product, we had to alter it (for the better) in someway, with most of the focus on the chemical makeup of the product. The final part of the project was to form a letter containing our results in laymen terms, but also an enclosure with the extremely scientific information on it, and send these in a business letter to the company who’s product we improved.
Letter
3026 Main Avenue
Durango, CO 81326
(970)-247-2474
October 30, 2011
Public Relations
2200 Richmond Ave,
Staten Island, NY 10314
Dear Public Realations,
In my chemistry class we have been given the challenge to find an everyday product and chemically change
the composition in some way, with the goal of improving the product. The product that came to my mind is the containers you sell your tic tacs in, and how so many are sold, but then just thrown away. There is a bio-friendly polymer out there that could replace the polypropylene plastic that you use now, that polymer being polylactide (polylactic acid).
the composition in some way, with the goal of improving the product. The product that came to my mind is the containers you sell your tic tacs in, and how so many are sold, but then just thrown away. There is a bio-friendly polymer out there that could replace the polypropylene plastic that you use now, that polymer being polylactide (polylactic acid).
Polylactide is a thermoplastic aliphatic polyester that is derived from renewable resources, like corn starch and sugar cane. This is a plastic that is already used in the food service industry in cups, utensils, and serving dishes, so it has been proven to perform well under active use. Due to PLA’s chirality, you can achieve very strong bonds because of the “criss-cross” bonding that occurs, and this is what gives PLA a higher impact strength than PP. However, this may not result in a polymer that can act as a living hinge as well, like PP, but it would still do a good job. Also, PLA has a higher density than PP, by just a little bit, so the containers would be heavier, but the difference isn’t enough that it would really alter the product. Lastly, PP has a higher tensile strength than PLA, but in the context these polymers are being used, differences in tensile strength aren’t as important.
The cost to start using polylactide instead of polypropylene is also something that is important to you, but I believe it wouldn’t be a sharp increase. There are multiple companies around the world that produce polylctide, so there is the opportunity to get the companies to compete for a chance at you buying their product. To compensate for the small rise in cost you would see in production, you may be able to sell the candy for a little bit more since you would be able to market it as a “green” candy (and people would pay more to help the environment).
The use of bio-plastics is increasing everyday as companies try to make their products as environmentally friendly as possible, to preserve the earth we live on. Using polylactide in your containers would give you the opportunity to be on the leading edge of the “green movement”, while still retaining the quality of your product containers, and allow you to market to a whole new faction of people who are very environmentally aware, and buy as “friendly” as possible. There are the costs of changing to this compound, but the benefits will out way them as you look into the future.
Thank you for your time,
Caleb Darland
Enclosures: 1
Polylactide (PLA) Properties
· Impact Strength: 0.16-1.35 J/cm
· Melting temperature: 150-160 degrees Celsius
· Density: 1210-1430 kg/m3
· Tensile Strength: 10-60 MPa
· PLA has a chiral nature to it, so when bonding occurs between PLA molecules, it is strong because of the “criss-cross” structure to the bond.
· Covalently bonded.
· A little bit more expensive than PP because it is a newer polymer and mass production doesn’t exist yet.
Polypropylene (PP) Properties
· Impact Strength: 25-30 MPa
· Melting Temperature: 160-165 degrees Celsius
· Density: 902/907 kg/m3
· Tensile Strength: 25-30 MPa
· Thermal conductivity: 0.22 W/m.K
· Covalently bonded.
· Relatively cheap to use in production due to the mass production that already exists.
Reflection
Overall I am proud of the work I did with this project, but it did have some flaws. I feel that I produced a good alternative plastic for my product, and I provided good reasons for this change. Also, I wrote a very clear, business style letter, which clearly shared the information intended. If I was to do this product again I would research all of the angles of my product, so that I could provide an abundance of evidence to back up my claims. Furthermore I would employ the help of my chemistry teacher more, so that I undoubtedly understood all of the information I was reading about. Finally, I would find the actual public relations address for Tic Tac, due to the fact that my letter came back a couple days ago, saying it was undeliverable.
Biochar Reasearch Project
The final result of this project was the scientific paper below and a scientific poster. Please excuse the missing charts and graphs, as blogger would not allow them to be shown.
The Effects of
Biochar on Leachate pH of Mine Site Soils
Caleb
Darland*, Chad Brickey*, Duke Millett*
*Students of Animas High School, Durango, Colorado
*Students of Animas High School, Durango, Colorado
ABSTRACT
Areas with a strong mining history are beginning to encounter the unforeseen effects brought about by heavy mining in the mountains. Acid mine drainage has begun to pollute the streams and rivers below these sites with harmful levels of metals because of the extremely low pH of the drainage. A possible solution is adding biochar, a pyrolyzed organic material, into the mine sites to raise the pH, in turn reducing the amount of metals in solution, and create a better ecological environment. This study conducted experiments using mine site soil combined with varying amounts of biochar in an attempt to determine how biochar concentrations affect pH. The goal of the study is whether or not the percent of biochar present in the soil relates to the change of the pH of the leachate from that soil.
Areas with a strong mining history are beginning to encounter the unforeseen effects brought about by heavy mining in the mountains. Acid mine drainage has begun to pollute the streams and rivers below these sites with harmful levels of metals because of the extremely low pH of the drainage. A possible solution is adding biochar, a pyrolyzed organic material, into the mine sites to raise the pH, in turn reducing the amount of metals in solution, and create a better ecological environment. This study conducted experiments using mine site soil combined with varying amounts of biochar in an attempt to determine how biochar concentrations affect pH. The goal of the study is whether or not the percent of biochar present in the soil relates to the change of the pH of the leachate from that soil.
The study found that biochar
tended to decrease fluctuations in the pH of the leachate and raise the pH of
leachates in all cases. However, the results of the study showed that the
effect the biochar had on the leachate varied greatly depending on the location
of the site and the type of mining that happened there. This supports the idea
that any solution to this problem would have to be done on a case by case
basis, and that there is not a fix all solution.
. Introduction
Acid mine drainage has become a problem
in areas that have a strong mining history. The tailing piles that were left
behind contain high amounts of metals, metals that are being washed into the
creeks and rivers by runoff water. In April of 1997, tests on Cement Creek (a
creek flowing down from the mine sites) showed the pH of the water to be 7.64
(Colorado DOW web). Recently, on April 26, 2012, a pH test on the river yielded
a pH of 3.90. The decline shown over the past fifteen years has been so drastic
that the creek can no longer harbor life, and if left unchecked will become
worse as time goes on (Rodebaugh, D. 2012).
The study is concentrating on mine
sites in the San Juan Mountains, to see how harmful metals running off into the
creeks and streams can be prevented. Bringing vegetation back to these
locations will significantly lower the amount of harmful runoff. Attempts at revegetation
are difficult because the extreme pH values, the very low fertility, and
minimum water holding capacity of the tailings piles create a hostile
environment for native plants. (Fellet et al. 2011). This study is looking at a
rehabilitative approach, where the site is chemically and physically improved
(Johnson, M., Tanner, P. 2005). To rehabilitate these piles, biochar is being
incorporated into the soil in attempt to provide a better ecological
environment.
Biochar is a low density, organic mass
that has been pyrolyzed to maximize the carbon contained in the product.
Pyrolysis is decomposition brought about by high temperatures, in an oxygen
poor environment. Once pyrolyzed, biochar becomes a porous charcoal-like
material that has a very high surface area to volume ratio (Amonette and Joseph, 2009). It is
technically charcoal, but not intended for fuel. The high carbon contained in
biochar optimizes it for agricultural uses. It is considered to be an excellent
treatment for nutrient depleted and contaminated soils, like those found around
abandoned mine sites (Amonette and Joseph, 2009).
More specifically, this study is
concentrated on finding whether or not the percent of biochar present in the
soil relates to the change of the pH of the leachate from that soil. The study
focused on whether there was a change in pH as the
concentrations of biochar were increased. The study will also investigate if
there was an effect on this change due to the initial pH or composition of the
site. The results are expected to show that having biochar present in the soil
will raise the pH of the leachate, meaning the metals will not dissolve into
solution. The biochar that is mixed into the tailings acts as a buffer to
increase the pH of the leachate of the soil. The addition of biochar also adds
carbon and biomass to depleted soil, allowing improved vegetation growth. These
two factor work in tandem to reduce the amount of metals that enter solution
and flow downstream. Ecosystems downstream should see eventual long term
improvement because they will no longer be contaminated by the acidic runoff (Rodebaugh,
D. 2012).
2. Materials and
Methods
2.1 Introduction to Experiment:
These experiments were conducted at some mine
site just outside of Silverton, CO. As a class, we went up to the mines sites,
plotted the coordinates, and then began taking samples if the soil. The overall
goal for this project was to determine the amount of biochar in the first 15 cm
of soil at a few different mine sites.
2.2 Preparing Containers
After
the sample preparation is done, the next step is to prepare the containers.
First thing is to label the containers with site, treatment, sample ID, and the
start date. Then sieve the soils and
separate the seeds into 1 gram mix (no Lupine)+ 4 Lupine seeds per sample. In grams, weigh 200ml of each soil sample and
add to labeled container. Next measure biochar volumes, (0 ml = 0%, 20 ml = 10%, 40 ml = 20%, 60 ml = 30). Weigh each biochar volume and record on data sheet.
Mix soil and biochar together in mixing container as completely as possible.
Then add soil and biochar mix back to labeled containers. Water until saturated
then let drain overnight. Now gently remix biochar and soil combinations. Mix
in 1 gram seed mix and 4 lupine seeds. Then water, drain, and weigh in grams.
Next cover and allow to grow for 72 hours (keep warm). Once seeds have
germinated watering should be every Monday (100 ml tap water – measure pH of
water prior to irrigation).
2.3 Taking Measurements
Every
Monday measurements will need to be taken. The first is photo documentation, (dry
erase board to note plots, treatment, date, and team). Take the mass of the
container prior to watering it. Then measure the average height of the
vegetation in mm. After that, record the pH of the irrigation water. Now water
with 100ml of the irrigation water, let the container drain and measure the pH
of the collected leachate. The first thing that you have to do before taking
the pH is calibrate the pH probe. You do this by placing the probe in the pH 4
buffer and taking the reading, and then doing the same thing but with the pH 7
buffer. Next find the mass of the container after watering. Collect the
leachate from the first and last watering for metals analysis. At the end of
the 55 days, the measurements will slightly differ. You will first take the
mass of the container then the height of the green vegetation. Next separate
the green vegetation from the brown and find the mass of each. After this, you
will find the leachate of the soil.
3. Results
3.1 Change in pH
Figure 1: The average pH of the leachate on each day of
sampling for all biochar concentrations
Biochar showed some improvement over untreated soils. This change is
represented in Figure 1 and Table 1. The samples that contained 30% biochar by
mass, shown in purple, tended to remain more basic than those that were
untreated. It must be noted that these and all other pH values are already
averages because the leachate of all of the containers for one mine site and
biochar concentration are collected together. These results seem to correspond
closely to the change in pH per trial (Table 2, Figure 2).
The
average change in pH data gives a more accurate and important measurement of
the relationship between biochar’s concentration and the pH of the leachate because
it removes some of the variances that is caused by changes in the pH of the
irrigation water. The irrigation water had a very large span of values that
varied constantly.
Figure 2: The average change in the pH of the leachate on each
day of sampling for all biochar concentrations
Table 1: The Average pH of All Samples on Each Day
of Sampling
Average pH of drained irrigation
water
|
|||||||
1/27/2012
|
2/1/2012
|
2/6/2012
|
2/13/2012
|
2/22/2012
|
2/27/2012
|
3/5/2012
|
|
0
|
6.32
|
7.19
|
6.94
|
7.33
|
7.25
|
7.27
|
6.8
|
10
|
6.32
|
6.94
|
7.06
|
7.1
|
7.08
|
7.13
|
6.45
|
20
|
6.56
|
7.48
|
7.07
|
7.24
|
7.33
|
7.28
|
6.9
|
30
|
6.67
|
7.45
|
7.13
|
7.26
|
7.25
|
7.26
|
7.3
|
Daily Average
|
6.46
|
7.25
|
7.05
|
7.25
|
7.23
|
7.23
|
6.83
|
Table 2: The Average Change in pH of All Leachate
Samples on Each Day of Sampling
Average pH of drained irrigation
water
|
|||||||
1/27/2012
|
2/1/2012
|
2/6/2012
|
2/13/2012
|
2/22/2012
|
2/27/2012
|
3/5/2012
|
|
0
|
6.32
|
7.19
|
6.94
|
7.33
|
7.25
|
7.27
|
6.8
|
10
|
6.32
|
6.94
|
7.06
|
7.1
|
7.08
|
7.13
|
6.45
|
20
|
6.56
|
7.48
|
7.07
|
7.24
|
7.33
|
7.28
|
6.9
|
30
|
6.67
|
7.45
|
7.13
|
7.26
|
7.25
|
7.26
|
7.3
|
Daily Average
|
6.46
|
7.25
|
7.05
|
7.25
|
7.23
|
7.23
|
6.83
|
This data
shows several things. The first is
that the pH of the 30% biochar
soils fluctuated less than that of the soils with no biochar. The data also
shows that there are some very consistent trends throughout the trial. The
first test showed a large change in all samples. The changes in the next five
tests are all very linear and also are similar between samples. The final test
has an elevated level of change, but not as extreme as the first.
Because
of the fact that pH is a logarithmic scale the data above may not deliver an
extremely accurate representation of what changes are occurring. Looking at the
number of moles of H3O+ that
were subtracted gives the most accurate representation. Because the changes
were fairly small and close to each other there does not seem to be a great
difference in the patterns shown in these two data sets. This new data set
decreased differences and spikes in the data even more than the change alone.
This data set is the most useful for analysis. Several aspects will be
important to look at. The first of these is the fact that the soil with the 10%
biochar mixture was more acidic and had a larger change than all of the other
soils.
Another aspect that should be looked into is the points where the 0% biochar mix had lower rate of change and was more basic than even the 30% mix.
Figure 3: The average change in moles of H3O+ on each day of sampling
3.2 Environment Specific Effects
Figure 4: The pH of each sample on each day of sampling for
all 30% mixes
Figure 5: The pH of each sample on each day of sampling for
all 30% mixes
Biochar showed different effects when mixed with soils with different
properties. The Bonner site had a very low initial pH. The addition of biochar
showed quick effects on pH. Once the pH had risen, the level of change
flattened out at around 7.25-7.5. The
Joe John site had a relatively high initial pH as compared the other sites. It
had a pH of around 6.5 or so. The addition of a 30% mixture of biochar caused
the leachate to become much more basic, with a pH of 7.25-7.5 through the rest
of the trial. Without the addition of biochar the leachate pH leveled off at
around 7 (Figure 4, Figure 5). Road Cut was a unique site. It was not a
tailings pile, but instead was the area that had been carved into the slope of
the Rocky Mountains to allow for a road to be built. The depth from the surface
was much different than from mine tailings. This site had a usual initial pH of
about 6.5. The addition of biochar seemed to have some effect, but this is
difficult to determine because of the large fluctuations in pH throughout the
trial.
3.3 Data Consistency
Figure 6: The minimum and maximum values of the percent change
in pH for all different concentrations of biochar.
Table 3: The minimum, maximum, and 25th -75th
percentile for the percent change in pH
Biochar %
|
Minimum Value
(% change)
|
25th
Percentile
|
75th
Percentile
|
Maximum Value
(% change)
|
0
|
1.16
|
3.88
|
10.65
|
26.01
|
10
|
0.90
|
4.91
|
14.00
|
23.54
|
20
|
0.96
|
4.07
|
9.68
|
19.64
|
30
|
0.26
|
2.87
|
9.89
|
18.47
|
The data fluctuated throughout the trials. Table 3 and Figure 6 show
this fluctuation. The minimum and maximum values cover a massive range. The 30%
biochar mix showed a change of only .26% at one point and the soil without
biochar showed a change of over 26%. As the concentration of biochar was
increased the range of the data decreased. The minimum values and the values
for the 25th percentile generally decreased. This indicates that the
leachate was being affected less and was being affected less more often.
4.
Conclusion
4.1 Reduction of Change in pH
Biochar
was expected to raise the pH of the leachate in the contaminated soils. It
showed some promise in this respect. In its highest concentration, 30% by
volume, there was an effect at some parts of the test. In other areas there was
no effect at all. This may be due to the fluctuation of the data. Figure 3
shows these effects. On the first sampling date the pH of all the leachate was
organized in the order that was expected by the original hypothesis. The soil
without biochar had a larger change in pH than those with biochar. This
indicated that he biochar was acting as a buffer to prevent some of the change
in the pH. This buffering was occurring either as the biochar contacted the
leachate or because it was altering the soil chemistry in some way. One week
later when the next pH sample was taken the data had become much more compact.
The mix containing 10% biochar had moved to the bottom of the graph, indicating
that it had changed the most. It would remain there for the remainder of the
experiment. It is difficult to say why the 10% mix consistently changed the
most and, as can be seen in Figure 1, was the most acidic. On the final day of
sampling the biochar in the 30% mix appeared to have prevented an increase in
pH, because all of the other samples experienced much more acidic runoff than
they had previously. This was likely accused by biochar’s ability to act as a
buffer and prevent large decreases in pH.
4.2 Prevention of pH Fluctuation
The
addition of biochar appeared to be fairly effective at preventing large
fluctuations in pH. Figure 1 showed that
on the first sampling date the R² value for the 0% biochar mix is only 0.1732.
The R² value for the 30% biochar mix is a slight improvement at 0.225. These
values are derived from linear equation of best fit. Because the value for the
30% is higher it indicates that the biochar has prevented the pH from
fluctuating. This is likely due to biochar’s buffering capability. Biochar obviously
acts to neutralize the leachate that it comes in contact with. This is what
likely caused biochar to have a capacity to buffer, but only to a limit. This
limit can be seen in section 4.3.
4.3 Affects under different conditions
Figures
4-5 show biochar’s effects on each site individually. Bonner had a very low
initial pH. Figure 4 showed that when Bonner soils were mixed with 30% biochar
the pH of the leachate rose over a period of 1-2 weeks to a much more average
level. When this data is compared with the data from Figure 5 there is an
obvious difference. The untreated soil took much longer to have a basic
leachate. It took almost 4 weeks for the untreated soil, as compared to the one
week with biochar. The leachate from Bonner’s untreated soils was not as basic
once a neutral pH was reached.
The Joe
John site, or JJ, was much more basic. Biochar increased the leachate pH after
the first test, just as it did with BON. But, because the initial pH was higher
the pH leveled off at a higher level. This indicates that biochar has a limited
ability to raise the pH of a leachate.
Road cut
was a unique site. Because the soil was not mined from deep in the earth it had
different properties. The pH fluctuated much more than the other samples. This
made any changes much harder to judge. It is very difficult to say whether the
soil was responsible for these fluctuations or whether it was some other
variable.
4.4 Data Fluctuation
The data
in this experiment fluctuated over a decent range, but not one that is large
enough to invalidate the data. Figure 6 shows the minimum and the maximum of
this range. This figure shows that there is a fairly wide range for the
extremes of the data set. It also shows that the addition of biochar reduces
fluctuation within these extremes. The soil that had no biochar showed a much
larger range between the minimum and the maximum than the mixtures that
contained biochar. As the amount of biochar was increased the range decreased.
This coincides with all of the other data that has been observed. Data from
another team operating in Silverton showed very similar results in all areas as
well. Their data shows the same trends as the data from this study. These
trends include biochar’s ability to increase pH of acidic leachate and its
ability to buffer and prevent large drops in the pH of this leachate (Peltz,
Livensperger, et al, 2012).
Table 3 shows that the grouping
of the data was fairly densely packed, but there were still a number of
outliers, especially in the direction of a larger change in pH. The level of
compactness shown by the data is decent enough to consider it reliable. The
outliers were likely caused by one of two things. The first may have been
inaccurate or poorly calibrated pH measuring equipment. Different pH probes
were found to show different readings from the same sample. A remedy to this
problem would have been to use more accurate equipment or insure that the pH
probes accurately calibrated using a multi point calibration method. The other
source of error that may have occurred would have been caused by differences in
the soils. The growth of vegetation may have altered the pH. Containers that
grew more vegetation may have had different pH readings than those which grew
very little. Soil density may have played a role. Some soil samples compacted
and shrunk in their containers. This caused their irrigation water to run
through quite quickly. This would have meant that there was less contact
between the soil and the water. Less contact may have resulted in less change
in the pH of the leachate.
4.5 The Next Step
Although
this experiment yielded some results, it is only a start. The results should be
confirmed with another experiment conducted under stricter standards. Soils
used to test plant growth should not be the same soils used to test pH.
Measuring equipment, such as pH meters, should be well calibrated. PH readings
should be taken more often and, unlike in this experiment, the pH should be
taken from the leachate of each of the three samples from each site. This would
yield more data points and allow for more certain conclusions. Once this
experiment was completed the data from it could be used to determine whether
biochar was actually a viable option. If this proves to be the case action
should be taken to incorporate biochar into the hundreds of tailings piles that
are scattered across the Rocky Mountains.
References
Amonette, J.E. and Joseph, S., 2009. Physical properties of biochar. In:
Lehmann, J., Joseph, S. (Eds.), Biochar for Environmental Management. London
Sterling, VA, pp. 13–29.
Fellet, G., L. Marchiol, G. Delle Vedove, and Peressotti, A. 2011.
Application of Biochar on Mine Tailings. Effects and Perspectives for Land
Reclamation. Environmental Pollution 83, 1262-1267.
Johnson, M. and Tanner, P. (2005, June 27). Mine Site Rehabilitation and
Ecosystem Reconstruction for Biodiversity Gain. In IDRC Archive. Retrieved May
2, 2012, from http://web.idrc.ca/en/ev-84055-201-1-DO_TOPIC.html
Rodebaugh, Dale. "No Superfund: Feds Back off in Silverton."
Duango Herald. 20 Apr. 2012. Web.
<http://durangoherald.com/article/20120421/NEWS01/704219948/0/SEARCH/No-Superfund:-Feds-back-off-in-Silverton>.
Riverwatch Volunteers . (1997, September 11). Riverwatch Data Summary .
In Colorado Division of Wildlife . Retrieved May 2, 2012, from
http://wildlife.state.co.us/LandWater/Riverwatch/Data/Pages/DataSummaryStations.aspx
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