Abstract
A unique iron/carbon aerogel (Fe/CA) was prepared via pyrolysis using ferric nitrate and bamboo cellulose fibers as the precursors, which could be used for high-efficiency removal of toxic Cr(VI) from wastewaters. Its composition and crystalline structures were characterized by FTIR, XPS, and XRD. In SEM images, the aerogel was highly porous with abundant interconnected pores, and its carbon-fiber skeleton was evenly covered by iron particles. Such structures greatly promoted both adsorption and redox reaction of Cr(VI) and endowed Fe/CA with a superb adsorption capacity of Cr(VI) (182 mg/g) with a fast adsorption rate (only 8 min to reach adsorption equilibrium), which outperformed many other adsorbents. Furthermore, the adsorption kinetics and isotherms were also investigated. The experiment data could be much better fitted by the pseudo-second-order kinetics model with a high correlating coefficient, suggesting that the Cr(VI) adsorption of Fe/CA was a chemical adsorption process. Meanwhile, the Langmuir model was found to better describe the isotherm curves, which implied the possible monolayer adsorption mechanism. It is noteworthy that the aerogel adsorbent as a bulk material could be easily separated from the water after adsorption, showing high potential in real-world water treatment.
Highlights
IntroductionHeavy metal ions have become an emerging threat to the ecosystem because of high toxicity [1,2,3]
Accepted: 6 December 2021In modern society, heavy metal ions have become an emerging threat to the ecosystem because of high toxicity [1,2,3]
Fe/CA was prepared from cellulose and ferric nitrate via pyrolysis, which could be used as an effective adsorbent for Cr(VI) removal
Summary
Heavy metal ions have become an emerging threat to the ecosystem because of high toxicity [1,2,3]. Hexavalent chromium (Cr(VI)) is classified as one of the most harmful pollutants in wastewater due to its acute toxicity to skin and living organisms and even potential carcinogenicity for human beings. It can migrate freely in the aqueous environment and is more likely to expand water pollution. The removal of Cr(VI) from contaminated water before discharge is of critical importance for the safety of our ecosystem [4,5,6]. During the past few decades, scientists have attempted to develop a variety of strategies to remove Cr(VI)
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