This week’s publication highlights relate to direct air capture, biochar, enhanced weathering and geochemical CDR.
Ph-Dependent Redox Hydrogen Pump for Electrochemical Direct Air Capture of CO2
Abstract
Redox-mediated electrochemical DAC offers a promising, energy-efficient alternative to conventional thermal methods but faces challenges with the oxidative degradation of organic redox mediators in air. While multi-electrolyzer systems mitigate oxygen exposure and solvent loss, the use of common pH-independent redox limits further voltage reductions. To overcome the voltage limitation of pH-independent mediators in electrochemical DAC, this study introduces a new electrochemical DAC strategy utilizing a pH-dependent redox mediator, anthraquinone-2,7-disulfonic acid salt (AQDS), within a dual-electrolyzer system coupled with a hydrogen pump. The pH-dependent redox potential of AQDS lowers the electrolyzer voltage, enabling an actual energy consumption of 257 kJ mol−1 CO2.
Zhang, X. et al. (2026) Ph-Dependent Redox Hydrogen Pump for Electrochemical Direct Air Capture of CO2 16 RSC Advances 3623-3629.
Read the full paper here: Ph-Dependent Redox Hydrogen Pump for Electrochemical Direct Air Capture of CO2 I RSC Advances.
Recent Advances of Biochar-based Engineered Materials for Efficient Removal of CO2: From Lab to Industrial Scale Applications
Abstract
Growing concerns about greenhouse gas emissions have driven significant efforts toward developing advanced materials for the capture and removal of carbon dioxide (CO2) from different environments. Among these, biochar-based engineered materials have emerged as promising sorbents for physical adsorption and separation processes, owing to their tunable structure, surface functionality, and potential for scalable production. This review summarizes recent advances in the preparation and application of biochar-based engineered materials for CO2 capture, highlighting the influence of synthesis methods on their structural properties and adsorption performance. A comparative analysis of different biochar-derived materials is presented, focusing on adsorption capacity, selectivity, and reusability. Notably, woody biomass-derived biochar modified with vanadium oxide demonstrated exceptional performance, achieving a CO2 adsorption capacity of 9.8 mmol/g and maintaining stability over 11 adsorption–desorption cycles with minimal loss of efficiency. The review also discusses the key challenges that currently limit large-scale deployment of biochar-based adsorbents and proposes potential strategies to overcome these barriers, thereby outlining future research directions toward sustainable and efficient CO2 capture technologies.
Wahby, A. et al. (2026) Recent Advances of Biochar-based Engineered Materials for Efficient Removal of CO2: From Lab to Industrial Scale Applications. Environmental Science Advances.
Read the full paper here: Recent Advances of Biochar-based Engineered Materials for Efficient Removal of CO2: From Lab to Industrial Scale Applications I Environmental Science Advances.
Requirement of Trichome Formation for the Growth-promoting Effects of Olivine for Enhanced Weathering in Arabidopsis Thaliana
Abstract
Enhanced rock weathering helps remove CO2 from air and cools the Earth over geological time periods, while also promoting plant growth, but the molecular mechanism underlying enhanced plant growth is unclear. In this study, ionome and transcriptome analyses revealed the importance of trichome formation for the growth-promoting effects of olivine ground to enhance weathering. In Arabidopsis, the application of 10% (w/w) olivine improved plant growth (a 64.2% increase in leaf area) and caused a 24.7% increase in Mg accumulation determined by ICP-AES at 23 days after germination (DAG) under long-day (16 h light/8 h dark cycle) conditions. Elemental maps of olivine-treated plants at 10 DAG produced by micro-particle-induced x-ray emission showed that olivine significantly altered Mg, K, and S accumulation in trichomes on true leaves, suggesting that trichomes may be critical for olivine-induced growth. The growth of glabrous1 (gl1-1 and gl1-4) mutants defective in trichome initiation was not promoted by olivine. A transcriptome analysis of shoots by RNA-seq from wild-type plants at 16 DAG indicated olivine suppressed biotic stress-responsive gene expression. Additionally, Zn homeostasis was disrupted by olivine in gl1 mutants, implying that decreased Zn availability may inhibit the positive effect of olivine on growth. Collectively, our data uncovered the importance of trichomes to the adaptation of plants to soils containing rock-powders for crop improvement and agricultural sustainability and suggest the possibility that applying olivine might modulate the growth–defense trade-off governed by ion homeostasis mediated through trichome development, leading to improved plant growth
Ueda, M. et al. (2026) Requirement of Trichome Formation for the Growth-promoting Effects of Olivine for Enhanced Weathering in Arabidopsis Thaliana. Journal of Plant Growth Regulation.
Read the full paper here: Requirement of Trichome Formation for the Growth-promoting Effects of Olivine for Enhanced Weathering in Arabidopsis Thaliana I Journal of Plant Growth Regulation.
A Review on Geochemical Carbon Dioxide Removal Potential of Mafic and Ultramafic Rocks in India
Abstract
Scalable geochemical Carbon Dioxide Removal (CDR) technologies are essential for limiting global warming to 1.5 °C. These technologies capture and permanently store atmospheric CO₂ as carbonates using alkaline substrates such as mafic and ultramafic rocks rich in calcium (Ca) and magnesium (Mg) minerals. This study is the first to comprehensively map and assess the significant geological resources of India for geochemical CDR. Ophiolitic sequences, mafic dyke swarms in cratons, and basaltic formations contain diverse Ca- and Mg-rich silicate minerals, providing substantial alkalinity sources for effective CO₂ sequestration through aqueous engineered carbon mineralisation and enhanced chemical weathering. Analysis of 500 data points across India revealed an average CDR potential of ∼424 gCO₂/kg through alkalinity production and ∼270 gCO₂/kg via carbonation. Ultramafic rocks, including dunite, harzburgite, and peridotite, demonstrated the highest average CDR potential (∼647 gCO₂/kg), while mafic rocks, such as gabbro and basalt, showed moderate potential (∼308 gCO₂/kg). A shrinking core model assessed how rock composition affects cumulative CDR potential over 0–70 years under ambient conditions. Dunite showed the highest sCDR potential (∼441 gCO₂/kg), followed by peridotite (∼298 gCO₂/kg), while plagioclase-rich rocks like gabbro exhibited much lower rates (<30 gCO₂/kg). These results underline the high CDR efficiency of ultramafic rocks and highlight olivine-rich rocks as promising candidates for rapid CO₂ mineralisation, achieving substantial sequestration on human timescales. In summary, this study highlights the vast potential of India’s geological resources for CDR through geochemical pathways.
Katre, S. et al. (2026) A Review on Geochemical Carbon Dioxide Removal Potential of Mafic and Ultramafic Rocks in India 275 (105419) Earth-Science Reviews.
Read the full paper here: A Review on Geochemical Carbon Dioxide Removal Potential of Mafic and Ultramafic Rocks in India I Earth-Science Reviews.
Contribution of Dissolved Organic Carbon to Total Alkalinity in Enhanced Weathering Experiments
Abstract
Total Alkalinity (TA) is widely used as a proxy for captured CO2 in enhanced weathering (EW) applications. However, organic anions can also contribute to TA. To improve carbon accounting in EW, which is often simplified to that TA equals carbonate alkalinity, their contribution should be taken into account.
In this study, we tested how dissolved organic carbon (DOC) contributes to non-carbonate alkalinity (ANC) using microcosm experiments with artificial organo-mineral mixtures. We used different combinations of rock powder with straw, microbes and earthworm additions, under ambient air conditions. The microcosms were flow-through columns placed in a climate chamber at 25 °C, which were irrigated with groundwater at rates between 1200 and 3600 mm/yr. The concentrations of several low-molecular-weight organic acids (oxalate, citrate, acetate, gluconate) were quantified to assess which conjugate base anions impact the measured TA.
Results revealed a ratio of 3.5 mol DOC per ANC equivalent. In the overall experiment the median contribution of ANC to TA was around 5.5 %. A positive correlation between DOC and charge-balance error suggests that some organic acid anions remained deprotonated during TA titration. Acetate anions found in DOC-rich water samples further support a substantial contribution of organic anions to TA. To investigate the relevance of ANC for natural EW systems, we also quantified ANC contributions in natural waters and leachates from soil EW experiment mesocosms. Because DOC levels were lower, ANC contributions were smaller, ranging from a median of 4.1 % in soil mesocosm leachates down to 0.9 % in Elbe estuary water samples. This ANC contribution, despite seeming small, is relevant for carbon accounting in terrestrial EW practices, where TA is often assumed to be solely carbonate alkalinity.
Rieder, L. et al. (2026) Contribution of Dissolved Organic Carbon to Total Alkalinity in Enhanced Weathering Experiments 198 (106685) Applied Geochemistry.
Read the full paper here: Contribution of Dissolved Organic Carbon to Total Alkalinity in Enhanced Weathering Experiments I Applied Geochemistry.