A review on natural based deep eutectic solvents (NADESs): fundamentals and potential applications in removing heavy metals from soil

Abstract

Natural based deep eutectic solvent (NADES) is a promising green solvent to replace the conventional soil washing solvent due to the environmental benign properties such as low toxicity, high biodegradability, high polarity or hydrophilicity, and low cost of fabrication process. The application of NADES is intensively studied in the extraction of organic compounds or natural products from vegetations or organic matters. Conversely, the use of the solvent in removing heavy metals from soil is severely lacking. This review focuses on the potential application of NADES as a soil washing agent to remove heavy metal contaminants. Hydrophilicity is an important feature of a NADES to be used as a soil washing solvent. In this context, choline chloride is often used as hydrogen bond acceptor (HBA) whereby choline chloride based NADESs showed excellent performance in the extraction of various solutes in the past studies. The nature of NADES along with its chemistry, preparation and designing methods as well as potential applications were comprehensively reviewed. Subsequently, related studies on choline chloride-based NADES in heavy metal polluted soil remediation were also reviewed. Potential applications in removing other soil contaminants as well as the limitations of NADES were discussed based on the current advancements of soil washing and future research directions were also proposed.

Valorization of Sour Cherry Kernels: Extraction of Polyphenols Using Natural Deep Eutectic Solvents (NADESs)

“…The authors concluded that the chosen NADES were non-toxic and safe for further utilization. The detailed mechanism of binding NADES to heavy metals was explained in the paper by Lai et al [ 33 ]. In addition to the proven fact that lactic acid has the ability to bind metals, it is necessary to emphasize the need to establish appropriate conditions, such as the solid–liquid ratio, contact time, and concentration.…”