Nano-zerovalent manganese/biochar composite for the adsorptive and oxidative removal of Congo-red dye from aqueous solutions

• Published in: Journal of hazardous materials 2021-02, Vol.403, p.123854, Article 123854
• Main Authors: Iqbal, Jibran, Shah, Noor S., Sayed, Murtaza, Niazi, Nabeel Khan, Imran, Muhammad, Khan, Javed Ali, Khan, Zia Ul Haq, Hussien, Aseel Gamal Suliman, Polychronopoulou, Kyriaki, Howari, Fares
• Format: Article
• Language: English
• Subjects: Adsorption; Adsorption and oxidation; Biowaste; Charcoal; Congo; Congo Red; Congo-red dye; Hydrogen Peroxide; Hydrogen-Ion Concentration; Kinetics; Manganese; Oxidative Stress; Phoenix dactylifera; Solutions; Water; Water Pollutants, Chemical - analysis; Water treatment
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.123854

[Display omitted] •The nZVMn/PBC showed high activity in adsorptive and oxidative removal of Congo-red.•The physical properties of biochar were improved with the coupling of nZVMn.•The nZVMn/PBC-catalyzed H2O2 into ●OH that caused oxidative removal of Congo-red.•Congo-red removal was promoted with the high dose of adsorbent and H2O2.•Degradation pathways of Congo-red in ●OH-mediated oxidative system were proposed. Congo-red (CR), a precursor of textile products and a contaminant of great concern, has contaminated aquatic environments. Here, we explored the synthesis of mesoporous nano-zerovalent manganese (nZVMn) and Phoenix dactylifera leaves biochar (PBC) composite for the removal of CR from water. The nZVMn/PBC adsorbed 117.647 mg/g of CR versus 25.316 mg/g by PBC at [CR]0 = 20 mg/L and [PBC]0 = [nZVMn/PBC]0 = 500 mg/L. Variation of [nZVMn/PBC]0, [CR]0 and pH influenced the adsorption of CR. Freundlich adsorption isotherm and pseudo-first-order kinetic models best fitted CR adsorption. The H2O2 coupling with nZVMn/PBC promoted removal of CR possibly due to the formation of hydroxyl radical (●OH) and caused 95 % removal of CR versus 77 % by nZVMn/PBC alone. The ●OH scavengers inhibited the removal of CR. The nZVMn/PBC showed a good reusability and efficient removal of CR up to the seventh cycle of treatment. Results reveal that nZVMn improved performance, thermal stability and reusability of biochar. Degradation products from ●OH-mediated degradation of CR were studied by ultraperformance liquid chromatography with mass spectrometric detector to establish degradation pathways. The ion-chromatographic analysis showed the formation of non-toxic inorganic acetate product, which suggests high potential of the newly fabricated adsorbent in the removal of CR.