Accelerated Cr (VI) removal by a three‐dimensional electro‐Fenton system using green iron nanoparticles

• Published in: Water environment research 2024-01, Vol.96 (1), p.e10981-n/a
• Main Authors: López‐Campos, Brian, Paniagua, Sergio A., Vega‐Baudrit, José Roberto, Muñoz‐Arrieta, Rodrigo, Guerrero‐Gutiérrez, Edward M. A.
• Format: Article
• Language: English
• Subjects: Chromium; cyclic voltammetry; Electrodes; electro‐Fenton process; green synthesis; Hexavalent chromium; Iron; iron nanoparticles; Nanoparticles; pH effects; Removal; Response surface methodology
• ISSN: 1061-4303; 1554-7531
• DOI: 10.1002/wer.10981

Green‐synthesized iron nanoparticles (GAP‐FeNP) were used as particle electrodes in a three‐dimensional electro‐Fenton (3DEF) process to accelerate the removal of hexavalent chromium [Cr (VI)]. Removal was evaluated by varying the pH (3.0, 6.0, and 9.0) and initial Cr (VI) concentrations (10, 30, and 50 mg/L) at 5 and 25 min. These results demonstrated that GAP‐FeNP/3DEF treatment achieved more than 94% Cr (VI) removal under all tested conditions. Furthermore, it was observed that Cr (VI) removal exceeded 98% under pH 9.0 in all experimental parameters tested. The results of the response surface methodology (RSM) determined two optimal conditions: the first, characterized by a pH of 3.0, Cr (VI) concentration at 50 mg/L, and 25 min, yielded a Cr (VI) removal of 99.7%. The second optimal condition emerged at pH 9.0, with Cr (VI) concentrations of 10 mg/L and 5 min, achieving a Cr (VI) removal of 99.5%. This study highlights the potential of the GAP‐FeNP to synergistically accelerate Cr (VI) removal by the 3DEF process, allowing faster elimination and expansion of the alkaline (pH 9.0) applicability. Practitioner Points The required time for >99% of Cr (VI) removal by the GAP‐FeNP/3DEF process was shortened from 25 to 5 min. EF process with GAP‐FeNP reduces the time necessary for Cr (VI) removal, which is 67% faster than conventional methods. EF process using GAP‐FeNP removed >94% of Cr (VI) after 25 min for all initial Cr (VI) concentrations and pH treatments. Cr (VI) removal by the GAP‐FeNP/3DEF process was >98% at a pH of 9.0, widening the solution pH applicability. Hexavalent chromium (Cr (VI)) is a water‐soluble heavy metal with high toxicity. The incorporation of GAP‐FeNP in the EF process accelerated the Cr (VI) removal from 25 to 5 min for >98% of Cr (VI) removal at pH 9.0, which is 20%–50% higher than conventional treatments at similar pH.