Enhanced adsorption of Cr(VI) from wastewater by utilizing sludge and reed to prepare ceramsite modified with Fe ₃ O ₄

Abstract A large amount of wastewater containing Cr(VI) is highly toxic and harmful to the environment, which requires effective treatment. In this study, an adsorbed ceramsite was prepared from dredged sludge (DS) and reed powder (RP). Then the prepared ceramsite was introduced Fe 3 O 4 magnetic functional groups by a simple hydrothermal method to enhance the adsorption of Cr(VI) from wastewater. Batch adsorption experiments of Fe 3 O 4 ‐modified ceramsite (FCS) to remove Cr(VI) were studied systematically. Effects of different contact time, adsorbent mass and initial Cr(VI) concentration on Cr(VI) removal efficiency were investigated and optimized by a response surface methodology. The results show that when the loading content of Fe 3 O 4 is 30% (FCS‐0.3), the highest removal efficiency of Cr(VI) reached 88.48%, and the Cr(VI) adsorbed process can be well described by pseudo‐second‐order kinetics and Langmuir model, indicating that adsorption process is a chemisorption and monolayer adsorption. Moreover, the FTIR, XPS and Zeta potential analysis further revealed the mechanism of efficient removal of Cr(VI) by Fe 3 O 4 loaded onto the ceramsite to increase the specific surface area and functional groups to adsorb Cr(VI). This study provides an effective method to convert solid waste such as DS and RP into a highly efficient magnetic adsorbent to adsorb and remove Cr(VI) from wastewater.