Collaborative strategy for elevated reduction of Cr(VI) through pyrolyzed graphite-based biosynthetic Schwertmannite composite catalyzed by oxalic acid

Abstract

Graphite has the potential to mediate the reduction process of Cr(VI) by oxalic acid (OA), but a reasonable modification is required to enhance the mediation of electron transfer. In this study, biosynthetic Schwertmannite (Sch) modified graphite (Sch@G) was pyrolyzed at 700°C for Cr(VI) remediation. Biosynthetic Sch particles were successfully loaded on the graphite, providing high specific surface area and abundant O-containing functional groups. The removal efficiency of Cr(VI) reached 90.42% within 60 min, facilitated by the synergistic between 1 g/L Sch@G and 1 mmol/L OA. Additionally, the comparative experiments exhibited a significant capacity of Sch@G in a wide pH range (pH 2–10), the removal efficiency was 97.9% within 60 min even at pH 10. Furthermore, the catalyst presented superior environmental adaptability in solutions containing various types of anions (Cl⁻, SO₄²⁻, NO₃⁻, H₂PO₄⁻). Mechanism analysis revealed that the catalyst greatly promotes the transfer of electrons from OA to Cr-contaminants, along with the release of low-valent Fe from Sch, enabling efficient electrons transfer to the Cr-contaminant. Meanwhile, the addition of OA could complex OA-Cr(VI) compound, lowering the activity of Cr(VI) and facilitating the subsequent Cr(VI) removal. Generally, the synergistic effect of the catalyst and OA can form an efficient system that enables rapid and effective remediation of Cr(VI) contamination across a wide pH range. Thus, the catalyst presents as a promising graphite-based biomaterial for the rapid and effective remediation of Cr(VI) contaminants from wastewater.

Keywords

graphite / biosynthetic Schwertmannite / Cr(VI) remediation / oxalic acid activation / electron transfer

References

[1] Lu Y, Cai Y-w, Zhang S, et al.. Application of biochar-based photocatalysts for adsorption- (photo) degradation/reduction of environmental contaminants: Mechanism, challenges and perspective [J]. Biochar, 2022, 4(1): 45.

[2] Rahman Z, Thomas L, Chetri S P K, et al.. A comprehensive review on chromium (Cr) contamination and Cr(VI) -resistant extremophiles in diverse extreme environments [J]. Environmental Science and Pollution Research, 2023, 30(21): 59163-59193.

[3] Liang H-x, Zhang H-w, Zhao P-y, et al.. Synthesis of a novel three-dimensional porous carbon material and its highly selective Cr(VI) removal in wastewater [J]. Journal of Cleaner Production, 2021, 306: 127204.

[4] Fang J, Gu Z-m, Gang D-c, et al.. Cr(VI) removal from aqueous solution by activated carbon coated with quaternized poly(4-vinylpyridine) [J]. Environmental Science & Technology, 2007, 41(13): 4748-4753.

[5] Zou Y-d, Wang X-x, Khan A, et al.. Environmental remediation and application of nanoscale zero-valent iron and its composites for the removal of heavy metal ions: A review [J]. Environmental Science & Technology, 2016, 50(14): 7290-7304.

[6] Xu Y-l, Chen J-y, Chen R, et al.. Adsorption and reduction of chromium(VI) from aqueous solution using polypyrrole/calcium rectorite composite adsorbent [J]. Water Research, 2019, 160: 148-157.

[7] Qu J-h, Bi F-x, Hu Q, et al.. A novel PEI-grafted N-doping magnetic hydrochar for enhanced scavenging of BPA and Cr(VI) from aqueous phase [J]. Environmental Pollution, 2023, 321: 121142.

[8] Wang Q, Wang L-y, Zheng S-z, et al.. The strong interaction and confinement effect of Ag@NH₂-MIL-88B for improving the conversion and durability of photocatalytic Cr(VI) reduction in the presence of a hole scavenger [J]. Journal of Hazardous Materials, 2023, 451: 131149.

[9] Azeez N A, Dash S S, Gummadi S N, et al.. Nanoremediation of toxic heavy metal contamination: Hexavalent chromium [Cr(VI)] [J]. Chemosphere, 2021, 266: 129204.

[10] Liu Y, Shen L-g, Huang Z-y, et al.. A novel in situ micro-aeration functional membrane with excellent decoloration efficiency and antifouling performance [J]. Journal of Membrane Science, 2022, 641: 119925.

[11] ZHANG Da-peng, WANG Ye-hong, YI Ming, et al. The peroxisome proliferator-activated receptor γ agonist pioglitazone protects vascular endothelial function in hypercholesterolemic rats by inhibiting myeloperoxidase [J]. Cardiology Research and Practice, 2020: 1845969. DOI: https://doi.org/10.1155/2020/1845969.

[12] Wang Y, Gong Y-s, Lin N-p, et al.. Cellulose hydrogel coated nanometer zero-valent iron intercalated montmorillonite (CH-MMT-nFe₀) for enhanced reductive removal of Cr(VI): Characterization, performance, and mechanisms [J]. Journal of Molecular Liquids, 2022, 347: 118355.

[13] Jung K W, Choi B H, Hwang M J, et al.. Adsorptive removal of anionic azo dye from aqueous solution using activated carbon derived from extracted coffee residues [J]. Journal of Cleaner Production, 2017, 166: 360-368.

[14] Luo Y-p, Zeng L-s, Zhao Y-h, et al.. Roles of ZnCl₂ and FeCl₃ in preparing high performance corn stover-based carbon materials for efficient removal of Cr(VI) from wastewater [J]. Journal of Water Process Engineering, 2022, 47: 102743.

[15] Zhu J-y, Gan M, Zhang D, et al.. The nature of Schwertmannite and Jarosite mediated by two strains of Acidithiobacillus ferrooxidans with different ferrous oxidation ability [J]. Materials Science and Engineering C, 2013, 33(5): 2679-2685.

[16] Boily J F, Gassman P L, Peretyazhko T, et al.. FTIR spectral components of schwertmannite [J]. Environmental Science & Technology, 2010, 44(4): 1185-1190.

[17] Bigham J M, Schwertmann U, Traina S J, et al.. Schwertmannite and the chemical modeling of iron in acid sulfate waters [J]. Geochimica et Cosmochimica Acta, 1996, 60(12): 2111-2121.

[18] Studenroth S, Huber S G, Kotte K, et al.. Natural abiotic formation of oxalic acid in soils: Results from aromatic model compounds and soil samples [J]. Environmental Science & Technology, 2013, 47(3): 1323-1329

[19] Li M-x, Dai H-l, Zhan P, et al.. Rapid reduction of aqueous Cr(VI) by oxalic acid on N-doped lignin charcoal: A significant contribution of structural defects and electronic shuttle effect [J]. Journal of Cleaner Production, 2023, 415: 137883.

[20] Jiang B, Wang X-l, Hu P, et al.. Dual enhancement-inhibition roles of polycarboxylates in Cr(VI) reduction and organic pollutant oxidation in electrical plasma system [J]. Chemosphere, 2016, 144: 1611-1617.

[21] Mu Y, Jiang X, Ai Z-h, et al.. Mn²⁺ promoted Cr(VI) reduction with oxalic acid: The indispensable role of in situ generated Mn³⁺ [J]. Journal of Hazardous Materials, 2018, 343: 356-363.

[22] Gan M, Sun S-j, Zheng Z-h, et al.. Adsorption of Cr(VI) and Cu(II) by AlPO₄ modified biosynthetic Schwertmannite [J]. Applied Surface Science, 2015, 356: 986-997.

[23] Tian Y-s, Fu W-y, Wang Q, et al.. High electron transfer rate and efficiency on Fe⁰ modified by sulfidation and pre-magnetization for carbamazepine degradation by heterogeneous electro-Fenton in wide pH ranges [J]. Chemical Engineering Journal, 2022, 427: 131694.

[24] Huang M, Mi K, Zhang J-h, et al.. MOF-derived bi-metal embedded N-doped carbon polyhedral nanocages with enhanced lithium storage [J]. Journal of Materials Chemistry A, 2017, 5(1): 266-274.

[25] Zhou M, Zhang C-g, Yuan Y-f, et al.. Pinewood outperformed bamboo as feedstock to prepare biochar-supported zero-valent iron for Cr⁶⁺ reduction [J]. Environmental Research, 2020, 187: 109695.

[26] Behera M, Alqahtani F O, Chakrabortty S, et al.. CuO/TiO₂/ZnO NPs anchored hydrogen exfoliated graphene: To comprehend the role of graphene in catalytic reduction of p-nitrophenol [J]. ACS Omega, 2023, 8(45): 42164-42176.

[27] Lascovich J C, Scaglione S. Comparison among XAES, PELS and XPS techniques for evaluation of Sp2 percentage in a-C: H [J]. Applied Surface Science, 1994, 78(1): 17-23.

[28] BELMONTE T, THIÉBAUT J M, MÉZERETTE D. Role of active species in surface cleaning by an Ar-N₂ atmospheric pressure post-discharge [J]. Journal of Physics D: Applied Physics, 35(16): 1919–1926. DOI: https://doi.org/10.1088/0022-3727/35/16/304.

[29] Idriss H. On the wrong assignment of the XPS O1s signal at 531 - 532 eV attributed to oxygen vacancies in photo- and electro-catalysts for water splitting and other materials applications [J]. Surface Science, 2021, 712: 121894.

[30] Zhang P, Zheng S-l, Liu J, et al.. Surface properties of activated sludge-derived biochar determine the facilitating effects on Geobacter co-cultures [J]. Water Research, 2018, 142: 441-451.

[31] Xu Z-b, Xu X-y, Tao X-y, et al.. Interaction with low molecular weight organic acids affects the electron shuttling of biochar for Cr(VI) reduction [J]. Journal of Hazardous Materials, 2019, 378: 120705.

[32] Chen R-h, Cheng Y-y, Wang P, et al.. High efficient removal and mineralization of Cr(VI) from water by functionalized magnetic fungus nanocomposites [J]. Journal of Central South University, 2020, 27(5): 1503-1514.

[33] Pozdnyakov I, Sherin P, Bazhin N, et al.. Fe(Ox)₃]₃-complex as a photodegradation agent at neutral pH: Advances and limitations [J]. Chemosphere, 2018, 195: 839-846.

[34] Lin Z-y, Natoli J M, Picuri J C, et al.. Replication of the conversion of goethite to hematite to make pigments in both furnace and campfire [J]. Journal of Archaeological Science: Reports, 2021, 39: 103134

[35] Sun T-r, Levin B D A, Guzman J J L, et al.. Rapid electron transfer by the carbon matrix in natural pyrogenic carbon [J]. Nature Communications, 2017, 8: 14873.

[36] Liu Y, Cheng J, Qi S-s, et al.. Experimental study on contaminant suppression method for thermal vacuum test of electric conduction link [J]. Environmental Technology, 2020, 38(4): 58-61

[37] Liu W-f, Zhang J, Zhang C-l, et al.. Preparation and evaluation of activated carbon-based iron-containing adsorbents for enhanced Cr(VI) removal: Mechanism study [J]. Chemical Engineering Journal, 2012, 189: 295-302.

[38] Ting L, Ma R-g, Ke K, et al.. Synthesis of gallic acid functionalized magnetic hydrogel beads for enhanced synergistic reduction and adsorption of aqueous chromium [J]. Chemical Engineering Journal, 2021, 408: 127327.

[39] Sun X-f, Ma Y, Liu X-w, et al.. Sorption and detoxification of chromium(VI) by aerobic granules functionalized with polyethylenimine [J]. Water Research, 2010, 44(8): 2517-2524.

[40] Xiang L, Niu C-g, Tang N, et al.. Polypyrrole coated molybdenum disulfide composites as adsorbent for enhanced removal of Cr(VI) in aqueous solutions by adsorption combined with reduction [J]. Chemical Engineering Journal, 2021, 408: 127281.

[41] Wang J, Wang X-x, Zhao G-x, et al.. Polyvinylpyrrolidone and polyacrylamide intercalated molybdenum disulfide as adsorbents for enhanced removal of chromium(VI) from aqueous solutions [J]. Chemical Engineering Journal, 2018, 334: 569-578.

[42] Zhang L-x, He F-x, Mao W, et al.. Fast and efficient removal of Cr(VI) to ppb level together with Cr(III) sequestration in water using layered double hydroxide interclated with diethyldithiocarbamate [J]. Science of the Total Environment, 2020, 727: 138701.

[43] Gu C-y, Cai M, He P, et al.. Biogenic carbon encapsulated iron oxides mediated oxalic acid for Cr(VI) reduction in aqueous: Efficient performance, electron transfer and radical mechanisms [J]. Chemosphere, 2023, 313: 137557.

[44] Nie X, Li G-y, Wang Y, et al.. Highly efficient removal of Cr(VI) by hexapod-like pyrite nanosheet clusters [J]. Journal of Hazardous Materials, 2022, 424: 127504.

[45] Zhang J, Yang X-n, Shi J, et al.. Carbon matrix of biochar from biomass modeling components facilitates electron transfer from zero-valent iron to Cr(VI) [J]. Environmental Science and Pollution Research International, 2022, 29(16): 24309-24321.

[46] Qiu C-j, Jiang L-l, Gao Y-g, et al.. Effects of oxygen-containing functional groups on carbon materials in supercapacitors: A review [J]. Materials & Design, 2023, 230: 111952.

[47] Chen Y-z, He P, Zhang K, et al.. Enhanced Cr(VI) reduction using highly conductive material synthesized by modified chitosan coated with natural iron-manganese minerals [J]. Applied Surface Science, 2023, 611: 155635.

[48] Yang D-x, Deng R-y, Chen M-l, et al.. Biochar-based microporous nanosheets-mediated nanoconfinement for high-efficiency reduction of Cr(VI) [J]. Journal of Hazardous Materials, 2023, 459: 132283.

[49] Wang M-q, Yang S-y, Liu J-q, et al.. Enteromorpha prolifera biochar as a novel ball milling aid for enhancing the interfacial reaction activity of microscale zero-valent iron (mZVI) for Cr(VI) removal from water [J]. Journal of Water Process Engineering, 2022, 48: 102844.

[50] Xie L-h, Chen Q-j, Liu Y-y, et al.. Enhanced remediation of Cr(VI) -contaminated soil by modified zero-valent iron with oxalic acid on biochar [J]. Science of The Total Environment, 2023, 905: 167399.

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