(544b) Material Property Targets for Emerging Adsorptive Water Treatment and Resource Recovery Systems

There is a critical need to develop sustainable separations technologies to meet current and emerging challenges, for example, i) the removal of trace metals such as lead from water to ensure acceptable contaminant levels^[1] and ii) the recovery of lithium from brines to keep up with the raw material demand due to vehicle electrification^[2]. Yet, the synthesis of numerous advanced materials in the past three decades have failed to produce a corresponding revolution in separation applications^[3]. In this talk, we present a mathematical modeling framework for material property targets in general adsorption separation systems; using the framework, we benchmark existing materials and identify theoretical limits for the lead removal and lithium recovery applications ^[4].

In the paradigm of process targeting^[5], feasible high-level goals such as solute recovery targets are fixed before detailed process optimization. Once targets are fixed, fundamental thermodynamics and material and energy balances are used to find alternate, often non-trivial pathways to achieve the targets. Process targeting is commonly applied to flowsheet optimization wherein the individual unit operations are optimized after setting a feasible overall production (or utility consumption) target^[6]. Traditionally, design is carried out using sequential techniques in which unit operations are optimized in a logical order which is most often the sequence based on the process flowsheet. Sequential design techniques often place a huge demand on the downstream processes which makes them very difficult to design efficiently. Process targeting overcomes the limitations of sequential design by explicitly accounting for inter-unit interactions early in the design process.

We extend process targeting to study adsorptive separation systems from a multiscale perspective: we set process targets at the device-scale to study the feasibility of using existing adsorbent materials as the separating medium. We use material balances and isotherms to set process targets. At the materials scale, we use structure-property relationships to define the theoretical limits of adsorptive membranes and packed-bed adsorbers. We demonstrate that while there is still scope for improvement, the sorbents for next-generations separations such as the lead removal from water and lithium extraction from brine already exist and are limited by engineering at the device-scales or higher. In other words, our framework helps illuminate if specific applications are process- or materials-limited. We highlight our belief that adsorption-based devices will play a key role in realizing the fit-for-purpose paradigm of water treatment which places emphasis on treating water to meet the varied specifications of its end users^[7].

References

[1] Hanna-Attisha, M., LaChance, J., Sadler, R., & Schnepp, A. (2016). Elevated Blood Lead Levels in Children Associated With the Flint Drinking Water Crisis: A Spatial Analysis of Risk and Public Health Response. American Journal of Public Health, 106(2), 283–290. https://doi.org/10.2105/AJPH.2015.303003

[2] Li, H., Eksteen, J., & Kuang, G. (2019). Recovery of lithium from mineral resources: State-of-the-art and perspectives – A review. Hydrometallurgy, 189. https://doi.org/10.1016/j.hydromet.2019.105129

[3] Luo, J., & Crittenden, J. (2019). Nanomaterial Adsorbent Design: From Bench Scale Tests to Engineering Design. Environmental Science & Technology, 53(18), 10537–10538. https://doi.org/10.1021/acs.est.9b04371

[4] Eugene, E. A., Phillip, W. A., Dowling, A. W., (2020). Material Property Targets for Emerging Nanomaterials to Enable Point-of-Use and Point-of-Entry Water Treatment Systems. Preprint submitted to ACS ES & T Engineering https://chemrxiv.org/articles/preprint/Material_Property_Targets_for_Eme...

[5] Fox, J. A., & Stacey, N. T. (2019). Process targeting: An energy based comparison of waste plastic processing technologies. Energy (Oxford), 170, 273–283. https://doi.org/10.1016/j.energy.2018.12.160

[6] Hildebrandt, D., Glasser, D., Patel, B., Sempuga, B. C., & Fox, J. A. (2015). Making processes work. Computers & Chemical Engineering, 81, 22–31. https://doi.org/10.1016/j.compchemeng.2015.03.022

[7] Zodrow, K., Li, Q., Buono, R., Chen, W., Daigger, G., Dueñas-Osorio, L., Elimelech, M., Huang, X., Jiang, G., Kim, J.-H., Logan, B., Sedlak, D., Westerhoff, P., & Alvarez, P. (2017). Advanced Materials, Technologies, and Complex Systems Analyses: Emerging Opportunities to Enhance Urban Water Security. Environmental Science & Technology, 51(18), 10274–10281. https://doi.org/10.1021/acs.est.7b01679