Study of the properties and mechanism of deep reduction and efficient adsorption of Cr(VI) by low-cost Fe3O4-modified ceramsite.

To efficiently treat low-concentration chromium wastewater at low cost, adsorbent iron-modified ceramsite (FCM) was successfully prepared. The adsorbent was characterized by SEM, XRD, FT-IR, XPS, ζ potential and VSM. From the experimental results, the optimum adsorption pH, adsorbent dosage and adsorption time were 4, 1 g/L and 120 min, respectively. The percentage removal of Cr(VI) was 93% and the reduction efficiency of Cr(VI) was 74.3% when the concentration was 2 mg/L. After 5 cycles, using 0.1 mol/L NaOH as the regeneration agent, the removal rate of Cr(VI) did not decrease significantly. Furthermore, the mechanism of deep reduction and adsorption, the process of regeneration, the kinetics and adsorption isotherms were also explored. This paper can provide theoretical and technical support for reducing the toxicity and the advanced treatment of hexavalent chromium. Unlabelled Image • FCM can realize deep reduction and adsorption of Cr(VI) at low-cost. • The adsorption and regeneration mechanisms were studied in-depth. • The pseudo second-order kinetic model was found to correlate the experimental data well. • The adsorption isotherm conformed to Langmuir Model. [ABSTRACT FROM AUTHOR]