This week was a great week in the N.E.W.T. lab at ASU! I ran my final test on my mini column system with the 2 SIAC GAC media, my impregnated F400 GAC, Clemson’s CU #2, GAC blank, and zeolite blank. If you have been following my posts, you will remember that Clemson’s CU #2 is my nemesis and was very difficult to get water to flow threw it. Well, this week I tested with 90% diluted tap water spiked with 250 ppb bromide and the CU#2 worked! I could get water to flow through all six of my columns for the first time this summer! It was so beautiful. I will be very curious to see the bromide results from this run.
Now that I am done running my tests, I have focused my time on creating my poster and the presentation I had to do for my PI on my research. It was a little intimidating getting up and talking in from of these professors, doctoral students, and graduate students. My mentor said I did very well and I didn’t get many questions at the end so I call that a success! My poster was actually a lot of fun to make. I have been teaching my students for years how to make a scientific poster, but I have never made on myself until now. I was worried because I was only able to get one of my tests analyzed because we are waiting on a silver guard and we were short on people who were properly trained and had time to run samples for me. A shout out to Choa Zeng for helping me out and analyzing at least 27 samples for me so I had something to talk about on my poster. The results showed that the SIAC 4% GAC and the CU#1 media could remove bromide, but only for a small bed volume (400 BV and 100BV). What was surprising about the data was that the GAC blank also removed bromide from the samples. I am looking forward to getting the characterization information back about that media to see if there is something that could help explain that result better.
I am glad to be done with my poster though and can’t wait to share it with everyone next week at Rice University!
Have a good weekend!
This week in the N.E.W.T. lab at ASU we shifted our focus from small columns with crushed media to large columns with larger media to see if it worked as well, or better, than the small columns at removing bromide from water. I test some of the same media that I have been using (GCU blank, Clemsen GAC with silver, Silver impregnated activated carbon) and a new media that is commonly used in water filtration called Purolite. The large columns were so much easier to pack and they all could run water through them with no pressure. It was so nice! Unfortunately, the columns did not work very well at removing organics. They reach a 50% breakthrough of organic compounds almost instantly. I hypothesized that the crushed worked better because there was more surface area for the organics to come in contact with and less space between the media. I will be interested to see if it removed bromide at all.
I was able to learned 2 new skills this week: sieving and silver impregnation. The silver impregnation procedure came from Clemsen and we wanted to replicate what they have done to see if we got the same results. What was different about this procedure is that they use Nitric acid to oxidize the carbon. That part was a little scary because when I was heating it to 90 degrees Celsius, the solution started bubbling and fuming. I survived though. We added to Silver Nitrate to the GAC and Zeolite media. I forgot how Silver Nitrate can stain your hands so I still have little black spots on my hand. The last step was to crush the media to 90 microns. This takes forever! I was covered in black carbon after.
We tested the media I made today along with a commercial Zeolite that was impregnated with silver. I couldn’t get the commercial Zeolite or the GAC with silver that I made to work, but I am very interested to see how my Zeolite with silver works at removing bromide.
I should finally get my bromide results back next Monday. Wish me luck!
(Unfortunately, my server wont let me attach pictures. I will try again when I get home. Sorry!)
Good morning everyone!
This week in the N.EW.T. lab at ASU was about problem solving and not giving up. My research consist of determining what type of media that is impregnated with silver nanoparticles works the best at removing silver in a column. If you have been following along, I have not had much success with the media that was sent to me from Clemsen University. Although it failed most of my test so far, we were determined to make it work. I set up columns with the 2 types of Granular Activated Carbon (GAC) at .25 in. height, .5 in height, and 1 in. height to see if the media would work at all.
Finally, we had success! Both of the Clemsen GACs worked at .25 inch, and .5 inch height, but only the CU GAC #1 worked at 1 inch. Since Clemsen is trying to get publish for their new method of impregnating silver, we do not know what exactly is different from that GAC compared to the commercial GAC we are using. We will be in contact with Clemsen next week to see if we can get any more information about the GAC they created so that we can design a test that works best with that GAC.
This week I was able to spend some time in the N.E.W.T. lab that Richard is in this summer. Richard is also working with silver nanoparticles, but instead of applying them to columns to remove bromide, he is using them on filters to prevent fouling. The problem is that the silver nanoparticles don’t stay on the filter very long. To solve this, his lab is adding sulfur to the filters with silver nanoparticles to help the silver stay on longer. Richard’s role is to figure out what is the right amount of sulfur to add to the filter so that it doesn’t loose to much of its antimicrobial ability. I thought it was very interesting how they were collecting data and was able to get some ideas of how I can apply using nanoparticles in my Biotechnology classes.
Next week, I will be impregnating silver into GAC I crushed and testing it see if it works as well as the GAC they sent from Clemsen. I will also be learning how to use an ICP machine to measure the amount of bromide that is in my samples. Wish me luck!
P.S. Sorry for no photos this week. I am in Dallas for my students competition and the Wifi is horrible here. I will try to add some when I get back to Arizona.
One of the things I try to always remind my students of when they are working on their research project is that you don’t always get the results you want and that’s okay. You often learn better from a failure than a success and I was reminded of that this week.
In my journey to learn about how silver nanoparticles remove bromide from water, I have also learned a lot about what it is like to be an engineer. This week we tried to run the column with the Granular Activated Carbon (GAC) that we are testing to see which GAC that was impregnated with silver nanoparticles worked the best. After loading all of my mini column with the GAC to our desired 8 in. mark, I tried running water through, but I could not get water to run through any columns. This is where the engineering came in and we had to figure out why.
We loaded our control GAC that didn’t have nanoparticles in the column one pipet (1 mL) full at a time and run the water. We repeated this until we could not get sufficient flow of water. We determined that it took 3 pipets full of GAC to a height of 2 inches to get 5 mL of flow at a low pressure. I loaded the other 5 columns with the silver impregnanted GAC the exact same way as our control and tried to get water to flow. We tested 2 commercial GAC, 2 GACs that were made by Clemsen University, and Zeolte (no silver nanoparticles were on the Zeolite). The two new GACs from Clemsen would not work during my runs and the rest of the columns did.
I decided to pipet the GACs into a 15mL conical tube to see if the amount laded was the same for each. I noticd that the GAC from Clemsen was lower than the rest of the GACs. Based off of this, my goal for the beginning of nest week will be to try and figure out why the Clemsen GAC is acting differently from the rest and figure out what it’s flow capacity is.
My lesson is coming along with great ideas about what materials the students could add to their column to try to remove glucose from water.
Have a good week everyone!
My name is Taylor Miller and I am a RET intern in the NEWT lab at ASU. I am working in Dr. Westerhoff’s lab with my mentor Shahnawaz Sihna. The focus of my internship is removing harmful bromides that are created through the process of chlorinating water. Disinfectant By Products (DBPs) such as brominated DBPs are extremely hard to get out of our water and my lab is trying to remove them by adding silver nanoparticles to a common cleaning media and new medias that were created by Clemsen. We are putting the media with the silver nanoparticles in a column and adding water contaminated with bromide. If everything works correctly, the silver will attach to the bromide and we will be able to have DBP free water!
The first step in this process was testing to see if the column system Shahnawaz built actually works. I don’t have much engineering experience, but I feel like an engineer after this week. The system was one leak after another. Once I would get it to stop leaking, I had to make sure the flow was the same for the 6 different columns all the while keeping the PSI as close to zero. Sounds difficult, but it was actually pretty easy once I figured out how to control the motor and flow valve.
Next step was packing the column. This hasn’t been done before and the column are only .4 centimeters in diameter so I didn’t have much area to work with. I loaded the columns with 2 in. of glass wool to make sure that the media would not go through the column. The columns had great flow when I tested them with the glass wool. I can’t say the same for when I added the media. The media we were practicing with this week was Granular Activated Carbon (GAC). The GAC was tricky to figure out how to get into the column. The first problem we ran into was how to get the GAC all the way down the tube. Dry loading the GAC didn’t work because it would stick to sides of the tube and there were a lot of air bubbles. I decided to add some water and then add the GAC. The wet load worked and the GAC loaded with hardly any bubbles.
The moment of truth came when I had to test the columns with water. It worked the first day with 3 columns, but not the next day. I could get a single column to get water to flow through it. back to the drawing board. I realized that the downward flow of the water into the column was causing bubbles and the media was being compressed from the pressure. After talking to another scientist, Paul, we were able to reverse the flow so the water would go up the column and I could control the flow before it entered the column, not after. Success! Well sort of…
One of my columns didn’t work after a while and will be remaking it again next week. Also, there were more leaks. On a brighter note, I just found out from my PI that I can use some pumps that another lab was using. Hopefully by having each column have its own pump I will be able to see water flow easily through each column.
I am having a great time in my lab and am putting together a great lesson for students to learn about this process!
Until next week,