L-Aspartic Acid with Dual Functions: An Eco-Friendly and Affordable Choice to Accelerate High Salinity Brine Utilization

Abstract

L-Aspartic acid (L-Asp) poses a dual function, which can affect the evaporation and crystallization process of the high-salinity brine by altering the physical or chemical properties of the salts. MSWI (municipal solid waste incineration) fly ash washing leachate, as a typical high-salinity brine, is utilized here to validate this hypothesis under the simulation guidance. Since L-Asp has stronger adsorption energy on the (110) crystal face of CaCO3, L-Asp can facilitate the preferential growth of more valuable vaterite during the softening process (pretreatment before crystallization). Subsequently, the resulting solution undergoes a stable interfacial solar-driven crystallization process under the L-Asp, with a high salt recovery ratio of 0.14 kg m−2 h−1 within 40 h under 1 sun. Finally, to harness the “cradle to grave” full life cycle utilization of washing leachate, the extracted mixed salts are utilized for moisture-enabled electricity generation. L-Asp can significantly enhance this process by reducing the critical relative humidity of mixed salts, thereby exhibiting a stable open circuit potential and short-cut current of ≈ 0.51 V and 10.6 µA within continuous 800 min. In conclusion, this work not only provides innovative approaches for upcycling high-salinity wastewater but also explores novel applications for L-Asp.