Hydrophobic magnetic deep eutectic solvents: An all-in-one platform for fast visualization, removal, recycle and...

With the wide use of dyes, the issues they caused in food safety and environmental pollution have become increasingly serious. Endeavors for dyes detection, removal, recycling and degradation are of great significances. However, existing methods for dyes detection are highly relied on instrumental tools. High instrumentation cost and poor portability prevent them being used for on-site rapid detection. For separation, recycling and degradation of dyes, well-designed materials featured with fine-tunable pore size, good permeability and large specific surface area are often indispensable. Robust and user-friendly multi-function platforms are highly practical but still rather limited.

An all-in-one platform for fast visualization, removal, recycle and degradation of anionic dyes was developed using hydrophobic magnetic deep eutectic solvents (HMDESs) as an all-rounder. Anionic dyes could be efficiently extracted by HMDESs through electrostatic interaction and hydrophobic effect, giving extraction rates over 99.0 % within 3 min. Colorimetric assays were adopted for fast visualization of dyes, of which the colorimetric LODs reached 10^-7 g/mL level. The extracted dyes could be facilely desorbed and recycled via adjusting system pH, showing recycling rates surpassed 99.5 %. By combining with H₂O₂, Fenton reactions constructed by Fe³⁺-doped HMDES achieved nearly complete degradation of the extracted dyes. As proof-of-concept assays, the multi functions of HMDESs were experimentally proved using commercial drinks and simulated dye effluents (viz., dyes-spiked purified water, tap water, river water, aquaculture pond water and industrial sewage) as real samples, and the results were double-verified with instrumental tools and smartphone-derived digital image analysis.

A HMDESs-based multi-purpose platform has been constructed herein, and its applications for fast visualization, removal, recycle and degradation of anionic dyes in both food and environmental samples have also been demonstrated. As far as we know, this is the first case to report such an all-in-one platform constructed by HMDESs for multi-dimension analysis of dyes. Since HMDESs are of many merits such as fine transplantability, easy-to-prepare, low cost, handy magnetic separation, etc., this work will find its more potentials in other areas like environmental analysis and biochemical separation and offer a reference for design other platforms for multi-use applications.