Deep-eutectic solvent coated paper: A reusable multi-purpose device for rapid visualization, adulteration identification, efficient removal and recycling of dyes in both food and environmental samples

[Display omitted] •A multi-purpose paper device was handily prepared by coating HDES onto printing paper.•Visual detection of dyes could be achieved as fast as 10 s by HDES-coated paper.•HDES-coated paper-based dye extraction was of fine anti-interference.•HDES-coated paper could be used for adulteration identification of natural/artificial dyes.•Dyes extracted by HDES-coated paper could be efficiently recycled by adjusting system pH. Herein, a multi-use strategy was initiated for visual point-of-care tests, adulteration identification, removal and recycling of dyes in both environmental and food samples using hydrophobic deep-eutectic solvent (HDES)-coated paper as an all-in-one device. HDES, which composed by decylic acid and tetraoctylammonium bromide, was prepared as a sorbent for dyes, then paper devices were facilely fabricated by coating HDES onto printing papers. Due to the coexistence of carbon chains, carboxyl and quaternary ammonium groups, HDES-mediated dyes extraction was of fine versatility through electrostatic interaction and hydrophobic effect, by which the recycling rate of dyes reached 96.5 % at only 5 min of extraction time. Colorimetry of dyes in simulated dye effluents and drinks could be ended as fast as 10 s with LODs at 10−3 mg/mL level, and the colorimetric results were highly agreed with those generated by instrumental techniques and smartphone-based image analysis. Identifications of fruit/vegetable juices and chili oil adulterated with the same-color artificial dyes were also realized in a single paper strip, giving an identification capacity low as to 1.5 × 10−3 mg/mL. The success of these cases enlightens a new direction for HDES-based multi-purpose application.