Team:SHSBNU China/Description
Inspiration
One of the most ingenious designs in the Tokyo Olympics is the environmentally friendly production of Olympic medals. With all their medals made by precious metals recycling from the e-waste, Japan had saved more that 800,000 dollars, most importantly, the detrimental effects that the waste cause to the environment can also be amended. [1] However, dissolving the metal into solvent is one of the most indispensable processes for separating the desired metal with other undesirable materials. As a result, precious metal ions are very abundant in the effluents of those factories, the heavy metals icons should be subjected to ion extraction treatments. Inspired by the Tokyo Olympics, our project aim to find an feasible method to absorb and recycle the silver ions in the factory effluents.
Current situation of the wasted precious metal
Fig.1 Gold wasted annually from e-waste in comparison of a male adult.
Fig.2 Platinum wasted annually from e-waste in comparison of a male adult.
Fig.3 Silver wasted annually from e-waste in comparison of a male adult.
Fig.4 Money wasted annually from e-waste in comparison of a male adult.
The e-waste dumped every year contain a high amount of precious metal. Those metals are there for their physical properties that are indispensable for electronic devices. Being very rare in the earth’s crust, the prices of the precious metals are very high and are pitiful to be wasted.
Current Approaches
1.Ion exchange resin A low-cost way for water treatment, both cheap and efficient. It can do some degree of ion selection by absorbing only the particles that have a certain charge. However, the resin can only function in relatively extreme pH environments, as a result, after being treated with the resin, the effluents must be processed again to adjust the pH level. Also, since the resin identifies the ions with the charge they have, it cannot specifically capture a certain desired ion so cannot be used for the specific binding of precious metal ions.[2]
2.Precipitation A very effective way of separating the specific pollutant ion from the effluent chemically. However, since it is the chemical reaction that precipitates out the ion, the reactant is rather expensive and cannot be reused. Furthermore, the precipitation is in a compound state so it can be difficult to get pure precious metal with this approach. [3]
3.Ion specific proteins As an important part of biology, proteins have been either found or modified in a variety of research to be able to specifically bind to certain ion in water. However, after the protein is bound to the ion, the only way to separate the desired ion from the protein is to denature the protein, making it both expensive and time consuming to be reused.[4]
Our solution
CAROLINE
We propose an ion capture-recycle platform based on the property of the aptamers-ion binding. For the sake of more efficient experiments, we use Ag+ ion as the target ion in our project. Using all biology-derived components, our cell-free ion capture-release device has no big impact on the environment and has no side effects on the treated effluents. Being not only specific, but also efficient, our device can capture over 95% of silver ions in water solution within 1 hour. By heating the device after it captured the silver ion, the bound ion can be released and be further processed, and the heated device can be reused up to 3 times without experiencing a drastic performance decrease. Because of the huge potential of the aptamers and our fusion protein, we envision our platform to be applied to many other areas in the future: Heavy metal, antibiotics, pheromones, and even nuclear waste treatments.
References:
1.Ortiz, D. (2021). The surprising source of the Tokyo 2020 Olympic medals. Bbc.com. Retrieved 13 October 2021, from https://www.bbc.com/future/article/20181120-the-surprising-source-of-the-tokyo-2020-olympic-medals.
2.The Disadvantages of Ion Exchange. (2021). Retrieved 13 October 2021, from https://sciencing.com/disadvantages-ion-exchange-8092882.
3.Wang L.K., Vaccari D.A., Li Y., Shammas N.K. (2005) Chemical Precipitation. In: Wang L.K., Hung YT., Shammas N.K. (eds) Physicochemical Treatment Processes. Handbook of Environmental Engineering, vol 3. Humana Press. https://doi.org/10.1385/1-59259-820-x:141
4.Hall Sedlak, R., Hnilova, M., Grosh, C., Fong, H., Baneyx, F., & Schwartz, D. et al. (2012). Engineered Escherichia coli Silver-Binding Periplasmic Protein That Promotes Silver Tolerance. Applied And Environmental Microbiology, 78(7), 2289-2296. doi: 10.1128/aem.06823-11
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