Sodium Chloride is used to clean roads, but harms plants and the environment.
Could either take a preventive or reactive environmental solutions -- either come up with an alternative or mitigate a system's effects.
Alternative solutions that exist:
- Reducing use
- Enhancing performance
- Alternative deicers
Team decided to look at a reactive solution: desalinating run-off while it is in the drain.
Existing desalination processes:
- Reverse osmosis
- electrodialysis
These focused on drinking water, too intensive and expensive.
Ion exchange resins - rubbery mass of caviar-like balls that have free ions on their surface that can be traded for undesirable ions in the water. Currently, this is used as a substep in water purification and water softening. Have not been researched as a standalone.
Resin beads are either positive (trade H+) or negative (trade OH-), with an end result of Na+ and Cl- being removed in exchange for H_2O.
Want to determine resin desalination capability, quantify ion exchange.
Had unusual result for Anion, fewer cumulative moles removed for higher NaCl concentration. Anion resins reached exhaustion point faster than cation resins. Removal efficiency generally decreased for both an and cat as concentration of salt was increased.
Salt can be extracted from the used resins via a strong acid, and could be collected and reused for deicing. Need to check if reactions work the same near 0 degrees C, as this is when such systems are needed, not at the 20 degrees C of a lab. Would need 257 ft^3, with more anion than cation, due to relative efficiencies to desalinate flow from a typical storm in a typical american storm drain.
My Questions: If positive and negative resins are put together, will they react with each other? Do Na+ and Cl- react at the same rate? If not, doesn't that mean you're producing an acid/base? Won't you need to change these resins in every storm drain constantly?
all adressed
sodium affects plants more, chloride affects aquatic and infrastructure more
- Would need to consider how large particulate or sticks could disable water flow? a film of some sort that is cleaned
- How often would you need to regenerate these/what is your goal? needs future testing
- How did you choose these resins/how do they work in attracting sodium? some orgo stuff
- What would you improve if you had one more month to do experiments?
- Would putting the pos and neg resins together change effects? No, they are strong acid/strong base, should not be affected by pH.
- How would other byproducts from the desalination procedure affect the environment? Don't know, need to test.
- How does the production of these resins affect the environment? "they're polymers, we don't know, chemistry happens"