Soil-Based Microbial Fuel Cells

Ask questions about projects relating to: biology, biochemistry, genomics, microbiology, molecular biology, pharmacology/toxicology, zoology, human behavior, archeology, anthropology, political science, sociology, geology, environmental science, oceanography, seismology, weather, or atmosphere.

Moderators: AmyCowen, kgudger, MadelineB, Moderators

donnahardy2
Former Expert
Posts: 2671
Joined: Mon Nov 14, 2005 12:45 pm

Re: Soil-Based Microbial Fuel Cells

Post by donnahardy2 »

Hi CMS,

I would be happy to write an endorsement for your project, and I will do it on Sunday. Thank-you for asking.

Since Science Buddies is an on-line forum and I don't know you personally, it would not hurt to ask your science teacher for a personal reference, if you think this would help. But I can certainly write an endorsement to support both you and your project.

Donna
Crazy_Mad_Scientist
Posts: 71
Joined: Wed Sep 14, 2016 7:14 pm
Occupation: Student

Re: Soil-Based Microbial Fuel Cells

Post by Crazy_Mad_Scientist »

Hi Donna,

That's great! Thank you so much!

I was thinking that I wanted to begin testing the bacterial bioremediation portion of my experiment first, since it only requires some containers, the lead test kit, and an incubator. Just wondering: if I incubated the soil samples at 25 degrees in an anaerobic environment before adding it to the anode chamber, will it speed up the formation of a biofilm?

Thank you!
CMS
Crazy_Mad_Scientist
Posts: 71
Joined: Wed Sep 14, 2016 7:14 pm
Occupation: Student

Re: Soil-Based Microbial Fuel Cells

Post by Crazy_Mad_Scientist »

I'm also planning to buy this for my incubator: http://www.ebay.ca/itm/182071212734?_tr ... EBIDX%3AIT

It's a temperature controller that I can put in an insulating box.

At first, I wanted to build a whole incubator: http://www.instructables.com/id/Digital ... /?ALLSTEPS
But then I had no idea how/where to start...

Thank you!
CMS
Crazy_Mad_Scientist
Posts: 71
Joined: Wed Sep 14, 2016 7:14 pm
Occupation: Student

Re: Soil-Based Microbial Fuel Cells

Post by Crazy_Mad_Scientist »

I just thought of a problem with bacterial culturing. When I'm transferring bacteria to the dishes, wouldn't the obligate anaerobes be killed? I don't know how long they can survive without oxygen...

Thanks!
CMS
donnahardy2
Former Expert
Posts: 2671
Joined: Mon Nov 14, 2005 12:45 pm

Re: Soil-Based Microbial Fuel Cells

Post by donnahardy2 »

Hi CMS,

Good thinking. You are correct; the culture conditions you will be using are suitable for facultative anaerobes and microaerophilic bacteria, but would not a;;ow obligate anaerobes to grow. Culturing obligate anaerobes requires using an anaerobic chamber for handling the the microbes, and is definitely outside of the scope of your current project.

The 23S RNA analysis would detect obligate anaerobes. You are interested in anaerobes for this project because they do not use oxygen, so might be able to use Pb+2 as an electron acceptor.

Donna
donnahardy2
Former Expert
Posts: 2671
Joined: Mon Nov 14, 2005 12:45 pm

Re: Soil-Based Microbial Fuel Cells

Post by donnahardy2 »

Hi CMS,

I have the endorsement written, but I can't find a place to post it on your project proposal. Did I miss something, or should I post it here for you to copy?

Your plans for an incubator should work. If you have a thermostat and some insulation, and perhaps add a small light bulb, you should be able to maintain a temperature that would support the growth of bacteria.

Donna
Crazy_Mad_Scientist
Posts: 71
Joined: Wed Sep 14, 2016 7:14 pm
Occupation: Student

Re: Soil-Based Microbial Fuel Cells

Post by Crazy_Mad_Scientist »

Hi Donna,

I checked the website. Apparently I would need to send an "invite" to endorse the project through email. Should I send an email to sciencebuddies?

For insulation, I will use cardboard because I don't have styrofoam.

For lead remediation rates, how long should I check lead concentrations? Should I check every 24 hours?

Thank you!
CMS
donnahardy2
Former Expert
Posts: 2671
Joined: Mon Nov 14, 2005 12:45 pm

Re: Soil-Based Microbial Fuel Cells

Post by donnahardy2 »

Hi CMS,

Yes, send the invitation to Science Buddies and reference this topic. Hopefully, I'll be able to forward the endorsement so it can be posted properly.

Cardboard is a good insulator, so I'm sure that will be fine.

I don't remember the incubation times from all of the references we checked. We should go back and check them again to see if the incubation times were included in the methods sections. It seems to me that 24 hours is a little too short; maybe 2 or 3 times a week would be good.

Donna
Crazy_Mad_Scientist
Posts: 71
Joined: Wed Sep 14, 2016 7:14 pm
Occupation: Student

Re: Soil-Based Microbial Fuel Cells

Post by Crazy_Mad_Scientist »

Hi Donna!

I will send the email as soon as my proposal gets approved! The past few days I have just been gathering some more background infomation on my topic :D .

I'm confused about the "electrolyte" used in the paper below. Do I have to dissolve my lead in the acid electrolytes? I'm not too sure that I want to use acid though... Also, what does the hydrolysis mean in this case?

http://www2.bren.ucsb.edu/~dturney/port ... ing/08.pdf

The paper said that lead precipitation rates increase with high ph, especially a ph of 1. Should I consider adding some acid to alter the pH of the solution?

Thank you!
CMS
donnahardy2
Former Expert
Posts: 2671
Joined: Mon Nov 14, 2005 12:45 pm

Re: Soil-Based Microbial Fuel Cells

Post by donnahardy2 »

Hi CMS,

Thanks for the article; this is a good one.

In this paper the electrolyte refers to the acid or base added to the solution used for electroplating Pb out of solution. Electrolytes are atoms or molecules that have a charge when in solution. For example, the perchloric acid is a strong acid with a formula of HCL04. In solution, the molecule dissociates into H+ and CLO4-. The acid or bases described in the article are the electrolytes used for electroplating.

Yes, electrolytes are added to the plating solution containing the lead. The tables in the paper list different combinations of electrolytes that have been used for lead plating. The electrolytes used for lead increase the solubility of the lead, and since electricity is used for electroplating, they increase the conductivity of the solution.

When I suggested trying the electroplate Pb in your MFC, I did not realize that strong acids or bases would be required. Unfortunately, all of the electrolytes listed in the paper are too hazardous for you to use at home. You would need access to a lab or an electroplating facility to use any of these chemicals, so I recommend delaying this part of the experiment until you can devise a safe way to do the experiment. You will still have everything else.

I don’t know if lead can be plated from acetic acid, but this would be much safer to work with.
You should not add acid or base to the anode chamber, as this would inhibit microbial growth. What were you planning to put in the anode chamber besides the mud sample?

Lead ions (Pb+2_ precipitates with many anions, including phosphate, chloride, and sulfate. Lead acetate is fairly soluble.

The hydrolysis described in the paper, for example under the amidosulfonate paragraph, refer to the degradation of the electrolyte and this interferes with the electroplating process. . In hydrolysis, a molecule is split in half by added a water molecule. Amidosulfonic acid is hydrolyzed to ammonia and sulfate.

Donna
Crazy_Mad_Scientist
Posts: 71
Joined: Wed Sep 14, 2016 7:14 pm
Occupation: Student

Re: Soil-Based Microbial Fuel Cells

Post by Crazy_Mad_Scientist »

Hi Donna,

Is it absolutely necessary to use acids in the cathode? My project is trying to be sustainable, so I don't really want to be using these acids...

http://www.explainthatstuff.com/electroplating.html: This paper only mentionned that acids are used to dissolve certain metals.

http://pubs.acs.org/doi/abs/10.1021/j15 ... e=jpchax.2: This paper said that acetic acid can be used. I want to add a small amount of the acid to my cathode.

One more thing: All the papers I have read so far stated that stirring the cathode would speed up the process? Should I try doing this?

Thank you!
CMS
donnahardy2
Former Expert
Posts: 2671
Joined: Mon Nov 14, 2005 12:45 pm

Re: Soil-Based Microbial Fuel Cells

Post by donnahardy2 »

Hi CMS,

These are great references. The first one gives a general description and explanation for electroplating. The second article (did you notice it was published in 1906?) contains the information you needed. It confirms that lead can be electroplated from a solution of lead acetate and acetic acid. So this is good news for your project, I think you could proceed with this idea for your project.

All of the electroplating articles use chemicals that ensure the metal ions are soluble and that are highly conductive to electricity. .

Donna
Crazy_Mad_Scientist
Posts: 71
Joined: Wed Sep 14, 2016 7:14 pm
Occupation: Student

Re: Soil-Based Microbial Fuel Cells

Post by Crazy_Mad_Scientist »

Hi Donna,

I'm so happy that I can use acetic acid now! I'm pretty sure that if I used the acids mentionned in the paper, I would burn a hole in my hand. :lol:

Currently, I'm having trouble finding how much acetic acid to add to the cathode. I can't seem to find any papers on it! :( Should I just drip the acid into the chamber until it reaches a pH of around 4? I know I can't get above 1 (the optimum pH) because I don't have access to strong acids except for HCL, and vinegar has a pH of around 2.4.

Just wondering, for the lead tolerance tests in bacteria, should I use a) varying concentrations of Pb2+ in agar dishes, b) mfcs set up with varying concentrations of lead, or c) several containers with varying concentrations in which I will then conduct OD readings or colony counting? I think we initially agreed on mfcs with varying concentrations, but I realized that setting up that many mfcs would be a lot of work and supply-consuming. Varying concentrations of lead in petri dishes will be tedious without an analytical balance or micropipette. Unless if I use large concentrations as mentionned in this paper: https://www.ncbi.nlm.nih.gov/pubmed/24416938, I would use this method. The paper was actually quite interesting as I didn't know that bacteria could be that tolerant to lead.

I personally like method b) and c) more. b) would lead to quick and accurate results, while c) would give accurate results, although requiring much longer wait-time.

As for the funding, I am still waiting for Experiment to approve my proposal. I got some feedback the last time I submitted the proposal, so I made a lot of changes. Here's the link again: https://experiment.com/projects/cqxypipoiyaswicztosm

Thank you so much for taking the time to write an endoresement! I will send the email to sciencebuddies as soon as my project gets approved.

Thank you!
CMS
Crazy_Mad_Scientist
Posts: 71
Joined: Wed Sep 14, 2016 7:14 pm
Occupation: Student

Re: Soil-Based Microbial Fuel Cells

Post by Crazy_Mad_Scientist »

Hi Donna,

Winter break is approaching, so I will have a lot of time to work on my project. I have been thinking, what if I transfer some of the lead acetate from the cathode after plating to the anode, and let the bacteria "absorb" the lead? This would elimate all of the lead used in the project. I realized that this would be much like an innovation project than an experiment.

Is this a good idea?

Thank you!
CMS
donnahardy2
Former Expert
Posts: 2671
Joined: Mon Nov 14, 2005 12:45 pm

Re: Soil-Based Microbial Fuel Cells

Post by donnahardy2 »

Hi CMS,

Sorry for the delay in responding.

Yes, it’s good news that you can use acetic acid. I have not been able to find any information on the concentration that would be suitable either. Vinegar is about 5% acetic acid. Why don’t you plan on using that and ask your teacher is there if any glacial acetic acid available, just in case it’s needed? This is pure acetic acid, about 17 moles/liter.

If you use Pb in your agar, you will be testing for the lead tolerance of the bacteria that are growing in the MFC. Since I think you can only set up one MFC, I think you should start it with no Pb at first in the MFC, and then if growth and current production is good, add a low concentration (0.5) and measure the effect of adding lead on current production. If current production continues in the MFC, then you could increase it to 1 ppm. If you can set up two MFC's, then do the experiment in duplicate to help verify your results. Most science projects are done with just one MFC.

To start your MFC, use aerobic conditions as a positive control until you know the MFC is working, then switch to lead acetate, acetic acid, and anaerobic conditions all at once in the cathode chamber. It would be good if you could run a trial experiment just on the electroplating on the side, but you may have to try the experiment with your MFC.

So, I agree with you’re a approach. Adding Pb to the agar will measure the lead resistance of the bacteria you have collected from a site that is known to be contaminated with lead. You will actually have a complete project with this experiment. If you add lead to the anode chamber, the mfc will not work if the bacteria are inhibited. So definitely, dothe experiment one small step at a time.

Thanks for the link to your new experimental protocol.

Donna
Locked

Return to “Grades 9-12: Life, Earth, and Social Sciences”