Preparation and properties of CA/ATP--CDs gel fibers for simultaneous detection and adsorption of methylene blue.

To detect and adsorb methylene blue (MB) from wastewater simultaneously, a solid fluorescent and absorbent material was designed by immobilizing attapulgite (ATP) on calcium alginate (CA) and reacting with carbon dots (CDs) which were modified by the activation of γ-(2,3-epoxypropoxy) propyltrimethoxysilane (KH-560), then the CA/ATP--CDs gel fibers were prepared. The problem of CDs easily falling out of materials was solved. The structures of the gel fibers were characterized by field emission scanning electron microscopy (FE-SEM), specific surface area (BET) and X-ray photoelectron spectroscopy (XPS). The thermal properties were analyzed by thermogravimetry (TG). The adsorption capacity was measured and the effect of initial pH was investigated. The results showed that ATP was successfully reacted with CA and the adsorption capacity was enhanced with the increase of the pH value. CA/ATP--CDs gel fibers were favorable materials to detect and adsorb MB simultaneously, and MB could be adsorbed by gel fibers and also the fluorescence of CA/ATP--CDs was weakened. At low concentrations of MB (1 μg L), the removal efficiency could even be as high as 100%.