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The remarkable characteristics of porous biochar have generated significant interest in various fields, such as CO 2 capture and supercapacitors. The modification of aerogel-derived porous biochar through activation and heteroatomic doping can effectively enhance CO 2 adsorption and improve supercapacitor performance. In this study, a novel N, B-co-doped porous biochar (NBCPB) was synthesized by carbonating and activating the N, B dual-doped cellulose aerogel. N and B atoms were doped in-situ using a modified alkali-urea method. The potassium citrate was served as both an activator and a salt template to facilitate the formation of a well-developed nanostructure. The optimized NBCPB-650-1 (where 650 corresponded to activation temperature and 1 represented mass ratio of potassium citrate activator to carbonized NBCPB-400 precursor) displayed the largest micropore volume of 0.40 cm 3 ·g -1 and a high specific surface area of 891 m 2 ·g -1 , which contributed to an excellent CO 2 adsorption capacity of 4.19 mmol·g -1 at 100 kPa and 25 °C, a high CO 2 /N 2 selectivity, and exceptional reusability (retained >97.5 % after 10 adsorption-desorption cycles). Additionally, the NBCPB-650-1 electrode also delivered a high capacitance of 220.9 F·g -1 at 1 A·g -1 . Notably, the symmetrical NBCPB-650-1 supercapacitor exhibited a high energy density of 9 Wh·kg -1 at the power density of 100 W·kg -1 . This study not only presents the potential application of NBCPB-650-1 material in CO 2 capture and electrochemical energy storage, but also offers a new insight into easy-to-scale production of heteroatomic-modified porous biochar., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Some methanogens are electrotrophic bio-corroding microbes that can acquire electrons from solid surfaces including metals. In the laboratory, pure cultures of methanogenic cells oxidize iron-based materials including carbon steel, stainless steel, and Fe 0 . For buried or immersed pipelines or other metallic structures, methanogens are often major components of corroding biofilms with complex interspecies relationships. Models explaining how these microbes acquire electrons from solid donors are multifaceted and include electron transfer via redox mediators such as H 2 or by direct contact through membrane proteins. Understanding the electron uptake (EU) routes employed by corroding methanogens is essential to develop efficient strategies for corrosion prevention. It is also beneficial for the development of bioenergy applications relying on methanogenic EU from solid donors such as bioelectromethanogenesis, hybrid photosynthesis, and the acceleration of anaerobic digestion with electroconductive particles. Many methanogenic species carrying out biocorrosion are the same ones forming the extensive abiotic-biological interfaces at the core of these bio-applications. This review will discuss the interactions between corrosive methanogens and metals and how the EU capability of these microbes can be harnessed for different sustainable biotechnologies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Sporomusa ovata is a Gram-negative acetogen of the Sporomusaceae family with a unique physiology. This anerobic bacterium is a core microbial catalyst for advanced CO 2 -based biotechnologies including gas fermentation, microbial electrosynthesis, and hybrid photosystem. Until now, no genetic tools exist for S. ovata , which is a critical obstacle to its optimization as an autotrophic chassis and the acquisition of knowledge about its metabolic capacities. Here, we developed an electroporation protocol for S. ovata . With this procedure, it became possible to introduce replicative plasmids such as pJIR751 and its derivatives into the acetogen. This system was then employed to demonstrate the feasibility of heterologous expression by introducing a functional β-glucuronidase enzyme under the promoters of different strengths in S. ovata . Next, a recombinant S. ovata strain producing the non-native product acetone both from an organic carbon substrate and from CO 2 was constructed. Finally, a replicative plasmid capable of integrating itself on the chromosome of the acetogen was developed as a tool for genome editing, and gene deletion was demonstrated. These results indicate that S. ovata can be engineered and provides a first-generation genetic toolbox for the optimization of this biotechnological workhorse.IMPORTANCE S. ovata harbors unique features that make it outperform most microbes for autotrophic biotechnologies such as a capacity to acquire electrons from different solid donors, a low H 2 threshold, and efficient energy conservation mechanisms. The development of the first-generation genetic instruments described in this study is a key step toward understanding the molecular mechanisms involved in these outstanding metabolic and physiological characteristics. In addition, these tools enable the construction of recombinant S. ovata strains that can synthesize a wider range of products in an efficient manner., Competing Interests: The authors declare no conflict of interest.

Understanding the gap between potential productivity and the actual productivity of vegetation (vegetation productivity gap, VPG) is the basis to explore the potential productivity improvement and identify its constraints. In this study, we used the classification and regression tree model to simulate the potential net primary productivity (PNPP) based on the flux-observational maximum net primary productivity (NPP) across different vegetation types, that is, potential productivity. The actual NPP (ANPP) is obtained from the grid NPP averaged over five terrestrial biosphere models, and the VPG is subsequently calculated. On this basis, we used the variance decomposition method to separate the effects of climate change, land-use change, CO 2 , and nitrogen deposition on the trend and the interannual variability (IAV) of VPG from 1981 to 2010. Meanwhile, the spatiotemporal variation characteristics and influencing factors of VPG under future climate scenarios are analyzed. The results showed an increasing trend in PNPP and ANPP, while there was a decreasing trend of VPG in most parts of the world and this trend is more significant under representative concentration pathways (RCPs). The turning points (TP) of VPG variation are found under RCPs and the reduction trend of VPG before TP is more than that after TP. The VPG reduction in most regions was caused by the combined effects of PNPP and ANPP (41.68 %) from 1981 to 2010. However, the dominant factors of global VPG reduction are changing under RCPs, and the increment of NPP (39.71 % - 49.3 %) has become the dominating factor of VPG variation. CO 2 plays a decisive role in the multi-year trend of VPG, while climate change is the main factor determining the IAV of VPG. Under changing climate, temperature and precipitation are negatively correlated with VPG in most parts of the world, and the relationship between radiation and VPG from weak negative to positive correlation., Competing Interests: Declaration of competing interest We solemnly declare: this paper is our original work and it has not been submitted to any other journal for publication and reviews, and there exists no conflict of interest in this manuscript submission., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The development of efficient, recyclable and low‐cost heterogeneous catalysts for conversion of carbon dioxide (CO2) into epoxides is highly desired, yet remain a challenge. Herein, we have prepared three two‐dimensional (2D) copper(I) cyclic trinuclear units (Cu(I)‐CTUs) based covalent metal–organic frameworks (CMOFs), namely JNM‐13, JNM‐14, and JNM‐15, via a one‐pot reaction by combination of coordination and dynamic covalent chemistry. Among them, JNM‐15 contained the highest density of copper catalytic sites, and exhibited the highest capacity for adsorption of CO2. More interestingly, JNM‐15 delivered the highest catalytic activity for cycloaddition of CO2 to epoxides with good yields (up to 99 %), good substrate compatibility (11 examples) and reusability (four catalytic cycles) under mild condition. [ABSTRACT FROM AUTHOR]

Among CCUS methods, carbon dioxide-enhanced coalbed methane (CO2-ECBM) is one of the most important applications. The CO 2 migration range in the reservoir and impact on the fractures are the keys to safe storage. Multiple geophysical methods of time-lapse DAS-VSP, passive microseismic, and InSAR have been taken to monitor the CO 2 -ECBM project in Shizhuang Town, Shanxi Province, China. The time-lapse DAS-VSP technology captures the changes of seismic amplitude due to CO 2 injection. Three phases of passive microseismic monitoring detected 217 microseismic events and 48 earthquakes. Based on the distribution of the microseismic events, the CO 2 migration direction was inferred to be northeast of the injection well. A quantitative calculation method for the impact of natural earthquakes on the storage site was proposed. Studies on the relationship between microseismicity and earthquakes suggest that natural earthquakes do not significantly affect CO 2 storage in the study area. InSAR combined unmanned aerial vehicle (UAV) photography measurement technology obtained the surface deformation results with a maximum displacement of 21 mm. The surface deformation also shows CO 2 migration in a northeast direction, consistent with microseismic results. Finally, in order to verify the monitoring results of the above methods, the gas detection in the production well around the injection site was analyzed. The analysis results show that the primary direction of CO 2 migration in the study area is the northeast direction, followed by the east direction. These geophysical techniques validate the accuracy of the monitoring results and provide new technical support for future CCUS projects. [ABSTRACT FROM AUTHOR]

Carbon neutrality is a goal the world is striving to achieve in the context of global warming. Carbon capture and storage (CCS) has received extensive attention as an effective method to reduce carbon dioxide (CO2) in the atmosphere. What follows is the migration pathway and leakage monitoring after CO2 injection. Interferometric synthetic aperture radar (InSAR) technology, with its advantages of extensive coverage in surface deformation monitoring and all-weather traceability of the injection processes, has become one of the promising technologies frequently adopted in worldwide CCS projects. However, there is no mature evaluation system to determine whether InSAR technology is suitable for each CO2 sequestration area. In this study, a new evaluation model is proposed based on the eight factors that are selected from the principle of the InSAR technique and the unique characteristics of the CO2 sequestration area. According to the proposed model, the feasibility of InSAR monitoring is evaluated for the existing typical sequestration areas in the world. Finally, the challenges and prospects of InSAR in the CCS project are discussed. [ABSTRACT FROM AUTHOR]

Carbon Capture, Utilization and Storage, also referred to as Carbon Capture, Utilization and Sequestration (CCUS), is one of the novel climate mitigation technologies by which CO2 emissions are captured from sources, such as fossil power generation and industrial processes, and further either reused or stored with more attention being paid on the utilization of captured CO2. In the whole CCUS process, the dominant migration pathway of CO2 after being injected underground becomes very important information to judge the possible storage status as well as one of the essential references for evaluating possible environmental affects. Interferometric Synthetic Aperture Radar (InSAR) technology, with its advantages of extensive coverage in surface deformation monitoring and all-weather traceability of the injection processes, has become one of the promising technologies frequently adopted in worldwide CCUS projects. In this study, taking the CCUS sequestration area in Shizhuang Town, Shanxi Province, China, as an example, unmanned aerial vehicle (UAV) photography measurement technology with a 3D surface model at a resolution of 5.3 cm was applied to extract the high-resolution digital elevation model (DEM) of the study site in coordination with InSAR technology to more clearly display the results of surface deformation monitoring of the CO2 injection area. A 2 km surface heaving dynamic processes before and after injection from June 2020 to July 2021 was obtained, and a CO2 migration pathway northeastward was observed, which was rather consistent with the monitoring results by logging and micro-seismic studies. Additionally, an integrated monitoring scheme, which will be the trend of monitoring in the future, is proposed in the discussion. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO 2 reduction (CO 2 ER) to produce formic acid (HCOOH) would be an attractive means for carbon neutralization. In order to realize efficient CO 2 ER and economical conversion of CO 2 , the applying of metal active sites on surface of semiconductor has emerged as a promising strategy. Herein, we report the preparation of alkaline modified TiO 2 nanowires (NWs) as the substrate for Au photodeposition. The as-fabricated Au/TiO 2 NWs exhibits high activity and selectivity towards HCOOH production compared with traditional catalysts. The key factors including deposition time, solution, and etc. And their effects on CO 2 ER performance have been systematically investigated. At −0.8 V vs RHE, the Faraday efficiency of the HCOOH can reach to 86.49 %, while the current density is 15.94 mA cm−2. In addition, Au/TiO 2 NWs also exhibited good stability after 18 h electrocatalytic CO 2 RR under the voltage of −0.8 V vs RHE. Electrochemical tests indicated that Au/TiO 2 NWs process favorable intrinsic electrochemical properties, high ESCA and accelerating charge transfer process make Au/TiO 2 NWs obtain abundant active sites and kinetically favorable. This work provides a convenient fabrication strategy of Au/TiO 2 based catalyst, which can guide the design and modification of gold for CO 2 ER into formic acid. [Display omitted] • A low-cost fabrication strategy of self-supported Au/TiO 2 from alkaline modified TiO 2 nanowires and photodeposited Au. • The photodeposition conditions were optimized to tune the CO 2 reduction active sites on Au/TiO 2. • Metal-support interaction between Au and TiO 2 modulate the electronic structure and promote CO 2 reduction. • Prepared Au/TiO 2 NWs efficient catalytic CO 2 conversion to formic acid (FE HCOOH = 86.49 %, @−0.8 V vs. RHE). [ABSTRACT FROM AUTHOR]

• Direct synthesis of N-doped porous carbons (PCs) using PAN and NaNH 2 simplifies production. • Optimized sample PN-3 shows a high specific surface area (SSA) of 2490 m2/g. • PN-3 exhibits significant CO 2 adsorption: 7.15 mmol/g at 273 K, 4.56 mmol/g at 298 K. • Outstanding CO 2 /N 2 selectivity (∼102) surpasses many other N-doped carbons. • Modest heat of adsorption (39.10 kJ/mol) allows energy-efficient regeneration. N-doped porous carbons (PCs) are extensively researched for CO 2 capture and separation under flue gas conditions, but their complex and expensive preparation methods hinder widespread industrial use. Herein, we present a direct approach for synthesizing N-doped PCs by utilizing polyacrylonitrile (PAN) and NaNH 2 as precursors, without the need for any solvents. The utilization of NaNH 2 as both a porogen and nitrogen supply during carbonization is primarily responsible for the formation of the well-developed pore structure and high specific surface area of N-doped PCs. The optimized sample "PN-3" demonstrated excellent textural features with an excellent specific surface area (SSA) of 2490 m2/g, a pore volume of 2.0559 cm3/g, a well-defined pore size distribution (PSD), and abundant micropores (<1 nm). In addition, PN-3 has the highest pyrrolic nitrogen content (∼40.1 at.%), resulting in a significant capacity for CO 2 adsorption (7.15 mmol/g at 273 K/1bar, 4.56 mmol/g at 298 K/1 bar, 26.2 mmol/g at 298 K/ 40 bar). Furthermore, it exhibits an outstanding CO 2 /N 2 selectivity (∼102) based on the ideal adsorbed solution theory (IAST) at 273 K, surpassing the performance of most of previously reported biomass and polymer-derived N-doped carbons in terms of CO 2 adsorption and separation. In addition, the adsorption process is characterized by a modest heat of adsorption (39.10 kJ/mol) and a steady cyclic pattern of CO 2 adsorption–desorption under flue gas settings (15 % CO 2 and 85 % N 2). This indicates that the adsorption is mostly governed by physisorption, which allows for an energy-efficient regeneration process. In summary, this study showcases the successful production of highly PCs that can effectively adsorb CO 2 , enlightening the way toward establishment of a cost-effective and facile synthetic protocol for achieving CO 2 capture/separation at the commercial scale. [ABSTRACT FROM AUTHOR]

[Display omitted] • N-doped porous carbon (NPC) was fabricated via a novel one-step solvent-free melt polycondensation. • Potassium citrate served as both a template and an activator to create abundant microporous structure. • NPC delivered an excellent CO 2 adsorption capability at 4.16 mmol·g−1 at 100 kPa. • NPC exhibited a fast adsorption kinetics and an outstanding uninterrupted recyclability. • The CO 2 adsorption mechanism on NPC was ascribed to multi-layer adsorption by the micropore filling. Heteroatomic doped porous carbon (HPCs) is a promising advanced material, showing great application potential in greenhouse gas capture. Here, in-situ N-doped porous carbon (NPC) was developed via a novel and readily scalable strategy − one-step solvent-free melt polycondensation assisted by organic potassium salts, followed by pyrolysis and activation. As both a template and an activator, the added C 6 H 5 K 3 O 7 played an important role to create abundant microporous structure. The as-fabricated NPC-650–0.5 showed a rich N content (6.11 at.%), abundant narrow micro-porosity (0.3437 cm3·g−1), and a high surface area (1209.37 m2·g−1) and delivered an excellent CO 2 static adsorption capacity (4.16 mmol·g−1 and 8.40 mmol·g−1 at 100 and 500 kPa), a fast adsorption kinetics (circa 98% of balance capacity in 12 min), moderate heat of adsorption (25 to 30 kJ/mol), high selectivity of CO 2 /N 2 , and outstanding uninterrupted recyclability. Both the narrow micropore volume and N-doping sites had strong effects on the CO 2 adsorption capacity, indicating a physical and chemical adsorption process with the mechanism being multi-layer adsorption by the micropore filling. This work highlights the great potential of the NPC-650–0.5 for capturing CO 2 and offers new insights into a green activator and a simple and easy-to-scale method for preparing HPCs. [ABSTRACT FROM AUTHOR]

Heteroatom-doped porous carbon materials (HPCMs) have attracted great attention due to their excellent physical and chemical properties and the enhanced performance of multiple heteroatom co-doping. Herein, N, P-co-doped porous carbon materials (NPPCs) are developed via a novel synthesis of the phytic acid-induced self-assembled chitosan aerogel followed by pyrolysis and activation. Phytic acid serves as a P source, acid regulator and structure-directing agent for improved activation efficiency to create more pores. A little of NaNO 3 is used both as a template and activator simultaneously. The porosity and N content of such NPPCs are controlled by rationally tuning the pyrolysis temperature and the mount of NaNO 3. The NPPC-0.75-600 delivers a good CO 2 adsorption capability of 3.02 and 5.31 mmol g−1 at 100 and 500 kPa, respectively, and has an excellent stability with almost no adsorption capacity decay even after successive 20 cycles. For supercapacitors (SCs), the NPPC-0.75-700 also displays a high capacitance of 231.2 F g−1 at 1 A g−1 and an outstanding stability at circa 96.7% initial capacity after 10000 cycles. These results highlight the great potential of such NPPCs in CO 2 capture and SCs, and the novel synthetical route offers new insights for the readily scalable production of HPCMs. [Display omitted] • Phytic acid induced chitosan gel and served as a P source and activation agent. • N,P-co-doped porous carbon delivered a CO 2 capture ability of 5.31 mmol g−1 at 298 K. • N,P-co-doped porous carbon exhibited specific capacitance at 231.2 F g−1 at 1 A g−1. • CO 2 capture and supercapacitor performances were substantially improved by P doping. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quantitatively CO 2 -responsive, ratiometric fluorescence sensor synergizing TPE and Au NCs was firstly reported. • Water-soluble TPE-ssHPA-Ac@Au NCs composites without participation of any free organic compounds were constructed. • The ratiometric sensor showed reversible photoluminescence response to CO 2 /N 2 cycling. • The ratiometric sensor showed reversible emission color change to CO 2 /N 2 cycling. Nowadays, developing effective CO 2 detecting methodologies is of great significance. Herein, a hybrid ratiometric fluorescence sensor by decorating tetraphenylethene (TPE) and gold nanoclusters (Au NCs) into disulfide functionalized hyperbranched poly(amido amine) skeleton was designed for efficient and accurate ratiometric detection of dissolved CO 2 in the range of 3.8 × 10−4 – 1.9 × 10-2 mol·L-1 with a detection limit of 7.8 μ M. The emission ratio and color were reversible through switching the CO 2 /N 2 stimuli. Finally, this fluorescent probe was proven to be effective for determining the CO 2 concentration in real samples. This is the first report of water-soluble, quantitatively CO 2 -responsive, ratiometric fluorescence sensor synergizing TPE and Au NCs in the amino-rich hyperbranched skeleton without participation of any free organic compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] • N,S-containing polycondensates were synthesized by one-pot polycondensation reaction. • The N,S codoped porous carbon was fabricated by pyrolysis and activation of N,S-containing polycondensates. • The N,S-codoped porous carbon exhibited a high CO 2 capture ability of 5.56 mmol/g at 298.15 K. • The N,S-codoped porous carbon showed an ultrahigh specific capacitance at 224.3F·g−1 at 1 A·g−1. • The all solid-state symmetrical NSPC-1-650-based supercapacitors delivered a high energy density and power density. Nitrogen-sulfur codoped porous carbon (NSPC) is a promising advanced material, showing great application potential in greenhouse gas capture and energy storage. Here, a novel NSPC with controllable porous structure was fabricated via pyrolysis and activation of N, -containing polycondensates, which were synthesized by one-pot polycondensation reaction of triglycidyl isocyanurate, glucose and thiourea. The obtained sample NSPC-1-650 showed cross-linked spherical morphology with uniform pore size (2.61 nm), large specific surface areas (1927.46 m2·g−1), and the doping of nitrogen (4 wt%) and sulfur (2 wt%), which leaded to a good CO 2 adsorption capability (5.56 mmol·g−1 at 298.15 K, 5 bar) and excellent stability. Additionally, when used as a supercapacitor, the NSPC-1-650 sample showed an ultrahigh specific capacitance (224.3F·g−1 at 1 A·g−1 in 6 M KOH electrolyte), an excellent rate capability, and good stability (retained > 85% capacity after 5000 cycles). Notably, the all solid-state symmetrical NSPC-1-650-based supercapacitors delivered a high energy density (the maximal value = 7.8 Wh·Kg−1) and power density (the maximal value = 4500 W·Kg−1). These results suggest that NSPC-1-650 be a competitive candidate as a CO 2 adsorbent and supercapacitor. [ABSTRACT FROM AUTHOR]

The functionalization of silver surface with cobalt (II)-complexes allows to build functional electrodes for efficient electrolysis CO 2 reduction to CO. The interplays between surface ligands and the multiple constituents of the electrocatalytic interface are critical to improve catalytic performance during CO 2 electrolysis, which would provide new opportunities for construction and design of high-efficient catalysts toward CO 2 reduction. [Display omitted] • Metal-molecule interaction constructed by cobalt complexes improved the electrocatalytic CO 2 reduction performance of bulk silver. • Interaction between metal–molecule catalysts adjusts electrocatalytic performance by tuning electronic structure, inhabiting strong hydrogen evolution, and enhancing silver-based catalyst activity for CO 2 RR. • Co(bpy) 3 2+ molecules increasing the number of electrochemically working sites, it is possible to increase the electrocatalytic activity. • Co(bpy) 3 2+ molecules adsorbed on the surface of Ag forming a metal–molecule catalyst, increasing local concentration of CO 2 and stabilizing the intermediate, performance is improved in metallic electrocatalysts. Electrochemical conversion of CO 2 into CO, powered by renewable electricity, offers one means to address the need for the storage of intermittent renewable energy. However, it is challenging because the competing HER is hard to avoid, which significantly compromises the selectivity to CO and reduces the efficiency of CO 2 RR devices. This study reports a cooperative catalyst design of metal–molecule catalyst interfaces with the goal of high local concentration of CO 2 and stabilizing the intermediate, which improves the electrosynthesis of CO. The strategy is implemented by functionalizing the silver surface with cobalt (II)-complexes to promote the selective electrolysis of CO 2 to CO. We report a CO 2 -to-CO Faradaic efficiency of 98.5 % and a partial current density of 16.52 mA cm−2 at − 1.1 V vs. RHE. Mechanism studies reveal that the catalytic performance of the Ag/Co(bpy) 3 2+ correlates with the metal–molecule interaction, which provide new opportunities for construction and design of high-efficient catalysts toward CO 2 reduction. [ABSTRACT FROM AUTHOR]

Traditional wet and dry Chromite Ore Processing Residue (COPR) detoxification methods consume acid for pH adjustment and produce greenhouse gasses (CO 2), yielding potential secondary pollution. It is imperative to develop an environmentally-friendly, efficient, and effective method for COPR treatment. This study reported the one-step natural pyrite-assisted mechanochemical detoxification of Cr(VI) in COPR. Under optimal conditions (i.e., the pyrite/COPR mass ratio of 5% and mechanochemical treatment at 600 rev./min for 2.5 h), Cr(VI) in COPR was efficiently reduced and immobilized, and the leaching concentration of total Cr met the regulatory limit of 5 mg/L. The X-ray absorption near-edge structure (XANES) analysis further verified that the Cr(VI) in treated COPR was 100% reduced to Cr(III). Potential mechanism could be that the enclosed non-exchangeable Cr(VI) in the chromite matrix was exposed to the COPR particle surface under the mechanical action; then, the redox reaction between pyrite and Cr(VI) were induced and enhanced through accumulated crystal defects and generated new surfaces with dangling bonds under mechanical forces. Life cycle assessment (LCA) results highlight that the high energy input is the major contributor eliciting environmental impacts for this current technology. More efficient and cleaner energy supplies should be sought alternatively to overcome the overall sustainability. [Display omitted] • Chromite liberation and destruction exposed Cr(VI) for reduction by pyrite. • XANES analysis verified that the Cr(VI) was 100% reduced to Cr(III). • The mechanochemical treatment produces low wastewater and greenhouse gas emissions. [ABSTRACT FROM AUTHOR]