The required treatment and monitoring of contaminants in wastewater reinforces the development of low-cost adsorbents/ chemosensors, introducing advantages relative to the detection/removal of toxic metals and dyes. Herein, it is reported a two-step process of fabrication of fluorescent carbon dots via the hydrothermal treatment of amino acids for the following encapsulation in electrospun fibers. The prominent anionic behavior of electrospun fibers of Eudragit L100 was explored for adsorption of cationic dyes (methylene blue and crystal violet)-with the prevailing electrostatic interaction of parts being favored by the formation of monolayers on the surface of adsorbents. On the other hand, the controlled release of carbon dots (CDs) from fibers to the reactor can be explored for a second application: the nitrogen ligands from released glycinebased carbon dots can be explored to indicate the presence of metal ions in aqueous solution. Our experiment resulted in a quenching in the fluorescence of the CDs in order of 90% in the emission of particles in the response of the presence of Fe 3+ ions, characterizing a promising perspective for this experimental system.

The use of unmodified and chemically treated natural fibers for water remediation (removal of chemical residues/oil spills and organic wastewater from water) is a significant and low-cost strategy to reduce the contamination of aquifers with metal ions, as well as marine environments with oil spills and water bodies with organic dyes. Furthermore, synthetic fibers exhibit a superior performance owing to their tunable surface area and superhydrophobic/swelling properties. This review summarizes the most recent advances in natural fiber-based biosorbents and synthetic fiber mats since the efficient removal of toxic compounds depend on adequate incorporation of functional groups on the fiber surface for mutual electrostatic and diffusion of contaminants into the fibrils. The most relevant results in the removal of oil, trace metal ions, and organic dyes are presented and evaluated. The evaluation is done according to the strategies for chemical modification of raw materials by the reuse of plastics or conventional electrospinning techniques to support the hierarchical growth of more complex chemical structures.

No abstract