In-situ modification of porous juncus with polyethyleneimine for efficient capture of Cr(Ⅵ) from wastewater

An adsorbent with the advantages such as high utilization of amino group, stable structure and easy-to-handle operation was prepared to efficiently capture aquatic Cr(Ⅵ) by using the polyethyleneimine (PEI) as the modification reagent and the juncus (JC), a natural biomass with sponge-like structure, as the structure support. The PEI solution containing epichlorohydrin was firstly introduced into the JC and then the PEI was in-situ attached to JC fibers by the grafting reaction, resulting in a porous adsorbent (PEI-JC). The elemental analysis, SEM, FT-IR and XPS were employed to characterize the composition and structure of PEI-JC, as well as the adsorption mechanism of Cr(Ⅵ). The effects of PEI concentration, solution pH, initial concentration of Cr(Ⅵ) and coexisting compounds on the adsorption were studied. The results show that the maximum adsorption capacity of the Langmuir model of PEI10.0-JC prepared from PEI with concentration of 10.0%(mass) is 474.6 mg•g-1 at 30℃ and a pH of 2.0; PEI10.0-JC could decrease the Cr(Ⅵ) in the solutions with different coexisting compounds from 10.0 mg•L-1 to the value that is less than the emission standard of industrial wastewater of China (0.5 mg•L-1); PEI10.0-JC can be reused, and its structure has not changed significantly during the adsorption process; adsorption and reduction are the main mechanisms for PEI-JC to remove Cr (Ⅵ) from aqueous solutions. © 2021, Editorial Board of CIESC Journal. All right reserved.