BIORESOURCE TECHNOLOGY
·
2025
·
IF 9
Chengyu Yang,Jie Wei,Yixuan Li,Yuanhao Peng,Xuan Wu,Xianrui Zhang,Yingxin Ding,Shumi Lu,Chongling Feng,Chao Huang
Aging-induced surface passivation of nano zero-valent iron (nZVI) significantly diminishes its reactivity for Cr(VI) reduction, thereby impeding its practical application in environmental remediation. Herein, we propose a novel system integrating aged nZVI (AnZVI), Shewanella oneidensis MR-1, and the endogenous electron shuttle riboflavin (RF) to overcome the passivation limitations and enhance Cr(VI) removal. Remarkably, the AnZVI/MR-1/RF system achieved complete removal of 20 mg L − 1 Cr(VI) within 3 h, outperforming AnZVI/MR-1 and AnZVI alone by 23.8 % and 36.6 %, respectively. Mechanistic investigations revealed that RF mediated direct interfacial contact between AnZVI and MR-1, promoting microbial reduction of the AnZVI passivation layer. Electrochemical analyses confirmed RF’s critical role as an electron mediator in accelerating charge transfer between AnZVI and MR-1. Three-dimensional fluorescence mapping (3D-EEM) analysis revealed microbial extracellular polymeric substances (EPS) contributions to chromium immobilization processes. The immobilization of chromium is primarily attributed to the reduction of Cr(VI) to insoluble Cr(III) species, in conjunction with adsorption and surface complexation mechanisms. TEM validated a significant reduction in the thickness of the iron passivation layer, resulting in the exposure of the underlying Fe⁰ core and a resultant enhancement in reductive capacity. This work provides a robust strategy to overcome AnZVI’s limitations by coupling microbial activity with electron shuttling, offering new insights into sustainable remediation via biotic-abiotic synergies.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Liwen Zhang,Shaohua Chen,Shanyi Tan,Huizi Wen,Shuyu He,Fen Zhang,Xiangru Zuo,Ling Xiong
The inherent limitations of nano zero-valent iron (nZVI) severely limit its widespread application in heavy metal pollution remediation. To address this, Shewanella oneidenis MR-1 (MR-1) was utilized to counteract the iron oxide passivation layer on nZVI surface, however, this approach suffered from low electron transfer rate between MR-1 and the passivation layer. In this research, a novel PDA-modified nZVI composite (PDA-nZVI) was synthesized. Compared to unmodified nZVI, the proportions of Fe 0 and Fe(II) on the PDA-nZVI surface increased 2.06 % and 21.63 %, respectively. The electrochemical tests (e.g., a more negative corrosion potential, a lower charge-transfer resistance, a higher current density, and a 3.4-times larger electrochemical active surface area for PDA-nZVI compared to nZVI) confirm that PDA enhances electron transfer from iron core to the outside, thereby promoting Fe 0 availability and Fe(II) generation on the PDA-nZVI surface. Meanwhile, PDA modification successfully enhanced the material's dispersibility and hydrophilicity in aqueous solutions. Results demonstrate that the Cr(VI) elimination capacity of the PDA-nZVI and MR-1 combined system (PDA-nZVI/MR-1) was markedly superior to that of the nZVI/MR-1 system. Mechanism analyses demonstrate that PDA can act as an electron shuttle to accelerate electron transfer between MR-1 and the passivation layer, thereby promoting more Fe(III) transformation to Fe(II). This process enables more Cr(VI) to be reduced to Cr(III), which is subsequently adsorbed or complexed on the material surface as Cr 2 O 3 /FeCr 2 O 4 and Cr x Fe 1-x (OH) 3 , ultimately being removed from the solution via co-precipitation. The PDA-nZVI/MR-1 system successfully overcomes the inherent limitations and exhibits an exceptional Cr(VI) elimination capability
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WATER RESEARCH
·
2019
·
IF 7.913
Meng Jiang,Xiong Zheng,Yinguang Chen
Bio-denitrification (i.e., microbial reduction of nitrate to gaseous nitrogen) is usually reported to be affected by operating and environmental parameters, such as carbon source type, pH value, and temperature. In this paper, the enhancement of denitrification performance with the elimination of nitrite accumulation and nitrous oxide emission by Shewanella oneidensis MR-1 were investigated and the mechanisms were explored. It was found that S. oneidensis MR-1 itself had marginal nitrate removal capacity, but its presence in the denitrification system of a well-studied denitrifier (Paracoccus denitrificans ) obviously enhanced nitrate removal efficiency (from 65.3% to 97.8%) and reduced nitrite accumulation (0.67 against none-detectable) and N 2 O generation (from 8.87 μm/mM-TN to none-detectable). The mechanism study showed that S. oneidensis MR-1 promoted electrons transfer activity via the formation of nanotube between cells, which resulted in the increase of denitrification enzymes activity , carbon source metabolism, ATP level and cell viability. As the generation, transfer and consumption of electrons were enhanced by S. oneidensis MR-1, the improvement of denitrification performance with reduction of nitrite accumulation and N 2 O emission was therefore achieved. Finally, the performance of denitrification enhanced by S. oneidensis MR-1 was testified by laboratory groundwater treatment experiment. This study suggested the potential role of S. oneidensis MR-1 in accelerating nitrate bio-transformation in nitrogen geochemical cycle and increasing bio-treatment of nitrate contamination with negligible harmful intermediates (nitrite and N 2 O) accumulation.
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CHEMICAL ENGINEERING JOURNAL
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2025
·
IF 13.2
Lv Xi,Xu Xincheng,Peng Yang,Li Bolin,Yang Lie,He Xiaoman
This study introduces a novel modification method for micron-sized zero-valent iron, utilizing Shewanella oneidensis MR-1 to simultaneously colonize its surface, disrupt the passivation layer, and alter the crystal structure of the core. This process yields a composite that retains its reducing activity even in high concentrations of pollutants (500 ppm Cr(VI)) and under neutral to slightly acidic conditions. Our findings indicate that the modified system induces the Kirkendall effect in zero-valent iron, leading to the formation of amorphous zero-valent iron with a non-spherical core structure, in contrast to conventional direct mixing approaches. The modified system achieves complete reduction of 100 ppm Cr(VI) to Cr(III) within 8 h. Notably, within the first 4 h of reaction, the reduction rate is approximately three times higher than that of the conventional direct mixing system. XPS, XRD, SEM, EEM and TEM analyses reveal that the surface passivation layer of the biochemically modified zero-valent iron is disrupted, leading to changes in its crystal structure, the formation of hollow spherical structures, and the development of a biological protective film on its surface. Interestingly, electrochemical and ETSA analyses indicate that the electron transfer rate of the biochemically modified composite is significantly enhanced. This study provides fundamental insights into the removal of Cr(VI) from groundwater using biochemically modified micron-sized zero-valent iron (mZVI).
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Journal of Environmental Chemical Engineering
·
2026
·Vol. 14
·期 3
·122797
·
IF 7.5
Huanlong Liu,Jie Zhao,Shen Tang,Wanxin Cheng,Yanhong Li,Dunqiu Wang,Jie Zhang
The co-contamination of hexavalent chromium Cr(VI) and chlorpyrifos (CPF) poses a severe challenge to traditional remediation technologies due to synergistic toxicity. This study constructed a bio-material synergistic system (FeO/C@ S. oneidensis MR-1) for their simultaneous removal. Results demonstrated that under optimal conditions (0.08 g/L FeO/C, 10% amount of inoculation, pH 7.0), the removal rates of Cr(VI) and CPF reached 75.5% and 93.7%, respectively, maintaining robust degradation efficiency even under a severe organic shock load of 50 mg/L CPF. Importantly, comprehensive multi-scale characterizations (SEM, CLSM, EDS, XRD, FTIR, XPS, 3D-EEM), revealed a bidirectional bio-material synergy: FeO/C acted as an electron shuttle and play a role of bio-driven electron allocation, preferentially driving the Fe(III)/Fe(II) cycle to detoxify Cr(VI), while dynamically secreted extracellular polymeric substances (EPS) acted as an active interface to enrich CPF ensuring the efficient biomineralization of CPF and complex heavy metals. This dual action effectively alleviated acute oxidative stress, enabling cell viability to recover to 80%. For real-world applications, a clear takeaway is that this self-sustaining system entirely eliminates the need for external chemical electron donors. It offers a scalable, bio-driven electron allocation green engineering strategy for the in-situ bioremediation of complex heavy metal-organic wastewater.
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CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Cholnam Ri,Fengxiang Li,Hyokchol Mun,Linan Liu,Jingchun Tang
The technology of integrating sulfidated zero-valent iron and functional anaerobic bacteria has been extensively explored to improve the removal efficiency of pollutants and enhance the performance of anaerobic microbial system. In this study, the simultaneous DCNB(2,4-dichloronitrobenzene) reduction and methane production by ball-milled 1:1 Fe 0 /FeS 2 (briefly, 1:1 Fe 0 /FeS 2 ), Shewanella oneidensis MR-1 and microbial consortium (MC) were firstly investigated. The result showed that the DCNB reduction was increased by 2.6 and 1.7 times in 1:1 Fe 0 /FeS 2 + MR-1 group compared to 1:1 Fe 0 /FeS 2 and MR-1, respectively, while it further increased by almost 2 times in 1:1 Fe 0 /FeS 2 + MC + MR-1 group as compared to that of 1:1 Fe 0 /FeS 2 + MR-1 group. Moreover, the methane production was drastically facilitated via the reciprocal interaction among FeS as the reaction product, MR-1 and MC. Dechlorination was not found, mainly due to the inability of 1:1 Fe 0 /FeS 2 and the inexistence of dechlorinating bacteria in original inoculum. Meanwhile, the microbial community was also changed, with genera like Eubacterium capable of reducing nitroaromatic compound and Methanosarcina as acetoclastic methanogen enriched by 1:1 Fe 0 /FeS 2 and MR-1. Therefore, fast DCNB reduction and methane production using 1:1 Fe 0 /FeS 2 in anaerobic microbial system, gives useful reference for both establishment of pollutant removal and biogas production. In conclusion, Fe 0 /FeS 2 , as a kind of sulfidated ZVI, is a good candidate for enhancing both pollutant degradation and CH 4 production in anaerobic wastewater treatment.
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Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Jie Zhang,Ting Hu,Shen Tang,Yanhong Li,Huanlong Liu
This study elucidates the mechanism by which hexavalent chromium [Cr(VI)] synergistically promotes malathion biodegradation in Shewanella oneidensis MR-1. Exposure to 5 mg/L Cr(VI) significantly enhanced the malathion degradation rate by 2.3-fold, achieving 96.79 % removal within 72 h under optimized conditions (5 % inoculum, pH 6). Analysis of cell membrane parameters combined with microscopic observation techniques indicated that Cr(VI) induced biofilm densification and membrane lipid peroxidation. Metabolomic profiling identified three critical Cr(VI)-activated pathways: (1)tryptophan-mediated redox homeostasis, (2)sulfur assimilation for antioxidant substances biosynthesis, and (3)cofactor biosynthesis for electron transport optimization. These metabolic adaptations increased membrane permeability and accelerated reactive oxygen species diffusion. The findings highlight Cr(VI) as a metabolic modulator that reprograms microbial catabolism via redox signaling, providing a mechanistic basis for developing biocatalysis strategies in multi-pollutant environments.
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CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Shuyu He,Shaohua Chen,Liwen Zhang,Shanyi Tan,Huizi Wen,Luyao Xi,Xiangru Zuo,Dongyun Du
Dissimilatory iron-reducing bacteria (DIRB) offer an eco-friendly approach to address nanoscale zero-valent iron (nZVI) surface passivation problem, yet their efficacy is limited by the slow direct extracellular electron transfer (EET) between DIRB and Fe(III) oxide passivation layers (Fe( III )OPL). This study demonstrates that natural dissolved humic substances (DHS)-mediated electron shuttling unlocking nZVI reactivity in Shewanella oneidensis MR-1 (MR-1) system for enhance Cr(VI) removal. Seven DHSs from diverse sources were evaluated, revealing that Cr(VI) removal rate constants ( k obs ) correlate strongly with DHS's quinone content (C=O) and electron transfer capacity (ETC), quantified as k obs = 1.66 C C = O − 9.39 ( P < 0.0007) and k obs = 19.37 ETC + 0.74 ( P < 0.0005). DHS-mediated systems achieve 2.0–12.1-fold higher k obs than nZVI/MR-1 alone. The enhancement mechanism of DHS-mediated Cr(VI) removal by nZVI/MR-1 is that DHS effectively facilitates Fe( III )OPL dissolution on the nZVI surface via electron shuttling, maintaining nZVI reactivity and amplifying Fe(II) generation by 1.65-fold. Moreover, DHS stimulates MR-1 to secrete more extracellular polymeric substances (EPS), enhancing Cr(VI) adsorption and reduction. This work elucidates DHS's dual role in maintaining nZVI activity and amplifying Cr(VI) removal by nZVI/MR-1, while establishing a predictive framework linking DHS molecular traits parameters to Cr(VI) removal kinetic, offering sustainable strategies for heavy metal-contaminated water bodies remediation by integrating biogeochemical and material engineering principles.
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IET Nanobiotechnology
·
2018
·Vol. 12
·期 4
·441-445
·
IF 2.059
Xiaojie Song,Xianyang Shi,Mi Yang
Biosynthesised nanocomposites have attracted growing interests attributed to their ‘green’ synthesis nature in recent years. Shewanella oneidensis MR-1, a dissimilatory metal-reducing bacterium, was used to reduce palladium (II) nitrate to palladium (0) nanoparticles (Pd NPs) under anaerobic conditions, resulting in the in situ formation of Pd NPs immobilised on TiO 2 nanotubes (TNTs) (Pd/TNTs nanocomposites). The Pd/TNTs nanocomposites were characterised by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray, and electron spin resonance, respectively. The results indicated that Pd NPs are successfully grown on the TNTs without aggregation. Photocatalytic degradation of methylene blue (MB) by Pd/TNTs nanocomposites under simulated sunlight was also investigated. Pd/TNTs nanocomposites had photocatalytic efficiency superior to that of single TiO 2 nanomaterials. The photocatalytic activity of Pd/TNTs nanocomposites can be enhanced by S. oneidensis MR-1. The results showed that after only 10 min, the degradation ratio of MB reached 98.7% by Pd/TNTs nanocomposites when simultaneously assisted with S. oneidensis MR-1.
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