RESUMO
In the context of peaking carbon dioxide emissions and carbon neutrality, development of feasible methods for converting CO2 into high value-added chemicals stands out as a hot subject. In this study, P[D+COO-][Br-][DBUH+], a series of novel heterogeneous dual-ionic poly(ionic liquid)s (PILs) were synthesized readily from 2-(dimethylamino) ethyl methacrylate (DMAEMA), bromo-substituted aliphatic acids, organic bases and divinylbenzene (DVB). The structures, compositions and morphologies were characterized or determined by nuclear magnetic resonance (NMR), thermal gravimetric analysis (TGA), infrared spectroscopy (IR), scanning electron microscopes (SEM), and Brunauer-Emmett-Teller analysis (BET), etc. Application of the P[D+COO-][Br-][DBUH+] series as catalysts in converting CO2 into cyclic carbonates showed that P[D+COO-][Br-][DBUH+]-2/1/0.6 was able to catalyze epiclorohydrin-CO2 cycloaddition the most efficiently. This afforded chloropropylene carbonate (CPC) in 98.4% yield with ≥ 99% selectivity in 24 hr under solvent- and additive-free conditions at atmospheric pressure. Reusability experiments showed that recycling of the catalyst 6 times only resulted in a slight decline in the catalytic performance. In addition, it could be used for the synthesis of a variety of differently substituted cyclic carbonates in good to excellent yields. Finally, key catalytic active sites were probed, and a reasonable mechanism was proposed accordingly. In summary, this work poses an efficient strategy for heterogenization of dual-ionic PILs and provides a mild and environmentally benign approach to the fixation and utilization of carbon dioxide.
Assuntos
Dióxido de Carbono , Carbonatos , Líquidos Iônicos , Líquidos Iônicos/química , Dióxido de Carbono/química , Carbonatos/química , Catálise , Modelos QuímicosRESUMO
Biofuel can be generated by different organisms using various substrates. The green alga Chlorococcum humicola OQ934050 exhibited the capability to photosynthesize carbonate carbon, maybe via the activity of carbonic anhydrase enzymes. The optimum treatment is C:N ratio of 1:1 (0.2 mmoles sodium carbonate and 0.2 mmoles sodium nitrate) as it induced the highest dry mass (more than 0.5 mg.mL-1). At this combination, biomass were about 0.2 mg/mL-1 carbohydrates, 0.085 mg/mL-1 proteins, and 0.16 mg/mL-1 oil of this dry weight. The C/N ratios of 1:1 or 10:1 induced up to 30% of the Chlorococcum humicola dry mass as oils. Growth and dry matter content were hindered at 50:1 C/N and oil content was reduced as a result. The fatty acid profile was strongly altered by the applied C.N ratios. The defatted leftovers of the grown alga, after oil extraction, were fermented by a newly isolated heterotrophic bacterium, identified as Bacillus coagulans OQ053202, to evolve hydrogen content as gas. The highest cumulative hydrogen production and reducing sugar (70 ml H2/g biomass and 0.128 mg/ml; respectively) were found at the C/N ratio of 10:1 with the highest hydrogen evolution efficiency (HEE) of 22.8 ml H2/ mg reducing sugar. The optimum treatment applied to the Chlorococcum humicola is C:N ratio of 1:1 for the highest dry mass, up to 30% dry mass as oils. Some fatty acids were induced while others disappeared, depending on the C/N ratios. The highest cumulative hydrogen production and reducing sugar were found at the C/N ratio of 10:1.
Assuntos
Bacillus , Biocombustíveis , Biomassa , Carbonatos , Hidrogênio , Nitratos , Hidrogênio/metabolismo , Bacillus/metabolismo , Nitratos/metabolismo , Carbonatos/metabolismo , Fermentação , Clorófitas/metabolismo , Clorófitas/crescimento & desenvolvimento , Fotossíntese , Ácidos Graxos/metabolismoRESUMO
Tyrosol and hydroxytyrosol are powerful phenolic antioxidants occurring in olive oil and in by-products from olive processing. Due to their high polarity, esterification or other lipophilization is necessary to make them compatible with lipid matrices. Hydroxytyrosol methyl carbonate is a more effective antioxidant than dibutylhydroxytoluene or α-tocopherol and together with tyrosol methyl carbonate exerts interesting pharmacological properties. The purpose of this work was the enzymatic preparation of alkyl carbonates of tyrosol and hydroxytyrosol. A set of 17 hydrolases was tested in the catalysis of tyrosol methoxycarbonylation in neat dimethyl carbonate to find an economically feasible alternative to the recently reported synthesis of methyl carbonates catalyzed by Novozym 435. Novozym 435 was, however, found to be the best performing catalyst, while Novozym 735, pig pancreatic lipase, lipase F-AK and Lipex 100T exhibited limited reactivity. No enzyme accepted 1,2-propylene carbonate as the acylation donor. Under optimized reaction conditions, Novozym 435 was used in the batch preparation of tyrosol methyl carbonate and hydroxytyrosol methyl carbonate in quantitative yields. The enzymatic methoxycarbonylation of tyrosol and hydroxytyrosol can also be used as a method for their selective protection in enzymatic syntheses of phenylethanoid glycosides catalyzed with enzymes comprising high levels of acetyl esterase side activity.
Assuntos
Enzimas Imobilizadas , Proteínas Fúngicas , Lipase , Álcool Feniletílico , Álcool Feniletílico/análogos & derivados , Álcool Feniletílico/metabolismo , Álcool Feniletílico/química , Enzimas Imobilizadas/metabolismo , Enzimas Imobilizadas/química , Proteínas Fúngicas/metabolismo , Lipase/metabolismo , Lipase/química , Animais , Antioxidantes/química , Suínos , Carbonatos/química , Hidrolases/metabolismoRESUMO
Current evidence suggests that macroalgal-dominated habitats are important contributors to the oceanic carbon cycle, though the role of those formed by calcifiers remains controversial. Globally distributed coralline algal beds, built by pink coloured rhodoliths and maerl, cover extensive coastal shelf areas of the planet, but scarce information on their productivity, net carbon flux dynamics and carbonate deposits hampers assessing their contribution to the overall oceanic carbon cycle. Here, our data, covering large bathymetrical (2-51 m) and geographical ranges (53°N-27°S), show that coralline algal beds are highly productive habitats that can express substantial carbon uptake rates (28-1347 g C m-2 day-1), which vary in function of light availability and species composition and exceed reported estimates for other major macroalgal habitats. This high productivity, together with their substantial carbonate deposits (0.4-38 kilotons), renders coralline algal beds as highly relevant contributors to the present and future oceanic carbon cycle.
Assuntos
Ciclo do Carbono , Ecossistema , Oceanos e Mares , Rodófitas , Rodófitas/metabolismo , Carbonatos/metabolismo , Carbono/metabolismo , Alga Marinha/metabolismo , Água do Mar/químicaRESUMO
Buffering of stomach acid by antacids is a well-established symptomatic therapy for heartburn. In addition, preparations from prickly pear (Opuntia ficus-indica) have been shown to reduce tissue damage in experimental gastritis models and to attenuate gastrointestinal discomfort in patients. Both active principles have been included in a fixed-combination product for symptomatic treatment of heartburn containing carbonate antacids (CaCO3 and MgCO3) and an extract from Opuntia ficus-indica cladodes. The aim of the study was to characterize the acid neutralization and esophageal cell protective activities of the product and its individual active ingredients in a set of in vitro assays. Acid neutralization was assessed in a simulated stomach model. Protective activity of individual constituents and in combination was analyzed in an esophageal cell line (COLO-680 N) exposed to low pH and deoxycholic acid to simulate acidic and non-acidic reflux challenge. The combination product protected cells against low pH mediated cytotoxicity via acid neutralization by carbonates. Opuntia extract itself and the combination product attenuated bile acid-induced cell irritation as measured by reduced release of proinflammatory interleukin-6 and -8. In conclusion, addition of Opuntia extract to a mineral antacid provides dual protection against acidic and non-acidic simulated reflux challenge.
Assuntos
Antiácidos , Opuntia , Extratos Vegetais , Opuntia/química , Extratos Vegetais/farmacologia , Extratos Vegetais/química , Humanos , Antiácidos/farmacologia , Concentração de Íons de Hidrogênio , Carbonatos/química , Carbonatos/farmacologia , Refluxo Gastroesofágico/tratamento farmacológico , Esôfago/efeitos dos fármacos , Esôfago/metabolismo , Linhagem CelularRESUMO
In recent years, alkaline soda soil has stimulated numerous biological research on plants under carbonate stress. Here, we explored the difference in physiological regulation of rice seedlings between saline (NaCl) and alkaline carbonate (NaHCO3 and Na2 CO3 ) stress. The rice seedlings were treated with 40mM NaCl, 40mM NaHCO3 and 20mM Na2 CO3 for 2h, 12h, 24h and 36h, their physiological characteristics were determined, and organic acid biosynthesis and metabolism and hormone signalling were identified by transcriptome analysis. The results showed that alkaline stress caused greater damage to their photosynthetic and antioxidant systems and led to greater accumulation of organic acid, membrane damage, proline and soluble sugar but a decreased jasmonic acid content compared with NaCl stress. Jasmonate ZIM-Domain (JAZ), the probable indole-3-acetic acid-amido synthetase GH3s, and the protein phosphatase type 2Cs that related to the hormone signalling pathway especially changed under Na2 CO3 stress. Further, the organic acid biosynthesis and metabolism process in rice seedlings were modified by both Na2 CO3 and NaHCO3 stresses through the glycolate/glyoxylate and pyruvate metabolism pathways. Collectively, this study provides valuable evidence on carbonate-responsive genes and insights into the different molecular mechanisms of saline and alkaline stresses.
Assuntos
Carbonatos , Oryza , Reguladores de Crescimento de Plantas , Plântula , Transdução de Sinais , Estresse Fisiológico , Oryza/metabolismo , Oryza/efeitos dos fármacos , Oryza/genética , Plântula/efeitos dos fármacos , Plântula/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Transdução de Sinais/efeitos dos fármacos , Carbonatos/metabolismo , Estresse Fisiológico/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Oxilipinas/metabolismo , Ciclopentanos/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Bicarbonato de Sódio/farmacologia , Bicarbonato de Sódio/metabolismo , Cloreto de Sódio/farmacologia , Cloreto de Sódio/metabolismo , Fotossíntese/efeitos dos fármacosRESUMO
Large amounts of waste activated sludge are generated daily worldwide, posing significant environmental challenges. Anaerobic fermentation is a promising method for sludge disposal, but it has two technical bottlenecks: the availability of short-chain fatty acids (SCFAs)-producing substrates and SCFAs consumption by methanogenesis. This study proposes a pretreatment strategy combining sodium percarbonate (SPC) and magnetite (Fe3O4) to address these issues. Under optimized conditions (20 mg Fe3O4/g TSS and 15 mg SPC/g TSS), SCFAs production increased to 3244.10 ± 216.31 mg COD/L, about 3.06 times the control (1057.29 ± 35.06 mg COD/L) and surpassing reported treatments. The combined pretreatment enhanced the disruption of extracellular polymeric substances, increased the release of biodegradable matters, improved acidogenesis enzyme activities, and inhibited methanogenesis. Additionally, it increased NH4+-N release in favor of the recovery of phosphorus from sludge residual. This study demonstrates an efficient pretreatment for high SCFAs production and resource recovery from WAS.
Assuntos
Carbonatos , Ácidos Graxos Voláteis , Fermentação , Óxido Ferroso-Férrico , Esgotos , Eliminação de Resíduos Líquidos , Ácidos Graxos Voláteis/metabolismo , Anaerobiose , Eliminação de Resíduos Líquidos/métodos , Acetatos/metabolismo , Reatores BiológicosRESUMO
In this research paper, we introduce a novel and sustainable approach for forecasting the hydraulic conductivity of sand layers subjected to microbial-induced carbonate precipitation (MICP) to mitigate the diffusion of toxic pollutants. The proposed model uniquely integrates the impact of varying CaCO3 contents on the void ratio and estimates the average particle size of CaCO3 crystals through scanning electron microscopy (SEM) analysis. By incorporating these parameters into the K-C equation, a simplified predictive model is formulated for assessing the hydraulic conductivity of MICP-treated sand layers. The model's effectiveness is validated through comparison with experimental data and alternative models. The outcomes demonstrate a substantial reduction in hydraulic conductivity, with a decrease ranging between 93 and 97% in the initial assessment and a decrease between 67 and 92% in the follow-up assessment, both at 10% CaCO3 content. Notably, the hydraulic conductivity shows an initial sharp decrease followed by stabilization. These findings provide valuable insights into improving the prediction of hydraulic conductivity in MICP-treated sand layers, promoting a sustainable method for preventing pollution dispersion.
Assuntos
Areia , Areia/química , Carbonato de Cálcio/química , Modelos Teóricos , Carbonatos/químicaRESUMO
Amidst the increasing significance of innovative solutions for bioremediation of heavy metal removal, this paper offers a thorough bibliometric analysis of microbial-induced carbonate precipitation (MICP) for heavy metal removal, as a promising technology to tackle this urgent environmental issue. This study focused on articles published from 1999 to 2022 in the Scopus database. It assesses trends, participation, and key players within the MICP for heavy metal sequestration. Among the 930 identified articles, 74 countries participated in the field, with China being the most productive. Varenyam Achal, the Chinese Academy of Sciences, and Chemosphere are leaders in the research landscape. Using VOSviewer and R-Studio, keyword hotspots like "MICP", "urease", and "heavy metals" underscore the interdisciplinary nature of MICP research and its focus on addressing a wide array of environmental and soil-related challenges. VOSviewer emphasises essential terms like "calcium carbonate crystal", while R-Studio highlights ongoing themes such as "soil" and "organic" aspects. These analyses further showcase the interdisciplinary nature of MICP research, addressing a wide range of environmental challenges and indicating evolving trends in the field. This review also discusses the literature concerning the potential of MICP to immobilise contaminants, the evolution of the research outcome in the last two decades, MICP treatment techniques for heavy metal removal, and critical challenges when scaling from laboratory to field. Readers will find this analysis beneficial in gaining valuable insights into the evolving field and providing a solid foundation for future research and practical implementation.
Assuntos
Biodegradação Ambiental , Carbonatos , Metais Pesados , Carbonatos/química , BibliometriaRESUMO
Chemically activated biochar is effective in supercapacitors and water splitting, but low conductivity hinders its application as a carbon support in carbon dioxide reduction reaction (CO2RR). Based on the observed CO2RR performance from potassium hydroxide (KOH)-activated biochar, increased microporosity was hypothesized to enhance the performance, leading to selection of potassium carbonate (K2CO3) for activation. K2CO3 activation at 600â increased microporosity significantly, yielding a total Faradaic efficiency of 72%, compared to 60% with KOH at 800â. Further refinement of thermal ramping rate enriched micropore content, directly boosting FEC to 82%. Additionally, K2CO3's lower activation temperature could preserve hydroxyl groups to improve ethylene selectivity. These findings demonstrate that optimizing microporosity and surface chemistry is critical for designing activated biochar-based CO2RR electrocatalysts. Despite lower electrical conductivity of activated biochar, selecting the appropriate activating agents and conditions can make it a viable alternative to carbon black-based electrocatalysts.
Assuntos
Dióxido de Carbono , Carvão Vegetal , Oxirredução , Dióxido de Carbono/química , Carvão Vegetal/química , Compostos de Potássio/química , Porosidade , Hidróxidos/química , Carbonatos/química , Catálise , Temperatura , PotássioRESUMO
The application of manganese-oxidizing bacteria (MnOB) to produce manganese oxides (MnOx) has been widely studied, but often overlooking the concurrent formation of MnCO3. In this study, we found Ca2+ plays a crucial role in controlling Mn(II) removal in the bacterium Aurantimonas sp. HBX-1. Under conditions with 6.8 mM Ca2+ and without adding Ca2+, 100 µM Mn(II) was removed by 96.96 % and 38.28 % within 8 days, respectively. X-ray photoelectron spectroscopy (XPS) showed that adding Ca2+ increased the average oxidation state (AOS) of the solid products from 2.05 to 2.37. X-ray absorption fine structure (XAFS) analysis revealed the product proportions as follows: under Ca2+-supplemented condition, the ratio of MnOx (1 < x ≤ 2) to MnCO3 was 52 % to 28.1 %, while under Ca2+-free condition, the ratio shifted to 4.6 % for MnOx (1 < x ≤ 2) and 55.2 % for MnCO3. Urease activity assay and proteomic analysis confirmed the expression of urease and carbonic anhydrase, leading to the formation of MnCO3. Additionally, animal heme peroxidase (AHP) in strain HBX-1 was found to be responsible for Mn(II) oxidation through superoxide production, with Ca2+ addition promoting its expression level. Given the widespread presence of Ca2+ in wastewater, its potential impact on the biogeochemical Mn(II) cycle driven by bacteria should be reconsidered.
Assuntos
Cálcio , Manganês , Oxirredução , Manganês/metabolismo , Cálcio/metabolismo , Óxidos , Carbonatos/metabolismo , Poluentes Químicos da Água/metabolismo , Compostos de Manganês/metabolismoRESUMO
The objective of this study was to investigate the changes in physicochemical and structural properties of starch isolated from hot-dry noodles (HDNS) treated with different contents of potassium carbonate (K2CO3). The results demonstrated that the existence of K2CO3 increased the WHC and hardness of HDNS gel with an elevated storage modulus. Meanwhile, K2CO3 promoted the gelatinization of HDNS, which displayed higher viscosity and swelling power. Moreover, the relative crystallinity of HDNS were improved. K2CO3 facilitated the transformation of HDNS from an amorphous to a more ordered and crystalline structure. Simultaneously, the microscopic characteristics exhibited that K2CO3 promoted the partial fusion of starch particles to form aggregates, and the particle size became larger. In conclusion, the physicochemical and structural properties of HDNS were improved effectively with the incorporation of K2CO3, and the research results provided new insights for the processing of high-quality hot-dry noodles.
Assuntos
Carbonatos , Potássio , Amido , Amido/química , Potássio/química , Carbonatos/química , Viscosidade , Temperatura Alta , Fenômenos Químicos , Tamanho da PartículaRESUMO
BACKGROUND: The fossil record provides the unique opportunity to observe evolution over millions of years, but is known to be incomplete. While incompleteness varies spatially and is hard to estimate for empirical sections, computer simulations of geological processes can be used to examine the effects of the incompleteness in silico. We combine simulations of different modes of evolution (stasis, (un)biased random walks) with deposition of carbonate platforms strata to examine how well the mode of evolution can be recovered from fossil time series, and how test results vary between different positions in the carbonate platform and multiple stratigraphic architectures generated by different sea level curves. RESULTS: Stratigraphic architecture and position along an onshore-offshore gradient has only a small influence on the mode of evolution recovered by statistical tests. For simulations of random walks, support for the correct mode decreases with time series length. Visual examination of trait evolution in lineages shows that rather than stratigraphic incompleteness, maximum hiatus duration determines how much fossil time series differ from the original evolutionary process. Gradual directional evolution is more susceptible to stratigraphic effects, turning it into punctuated evolution. In contrast, stasis remains unaffected. CONCLUSIONS: ⢠Fossil time series favor the recognition of both stasis and complex, punctuated modes of evolution. ⢠Not stratigraphic incompleteness, but the presence of rare, prolonged gaps has the largest effect on trait evolution. This suggests that incomplete sections with regular hiatus frequency and durations can potentially preserve evolutionary history without major biases. Understanding external controls on stratigraphic architectures such as sea level fluctuations is crucial for distinguishing between stratigraphic effects and genuine evolutionary process.
Assuntos
Evolução Biológica , Carbonatos , Simulação por Computador , Fósseis , Sedimentos Geológicos/químicaRESUMO
The presence of antinutrients and undesirable flavours in kidney bean flour poses challenges to consumer acceptance. Although extrusion can mitigate antinutrients to some extent, its impact on reducing beany flavour in bean flour remains underexplored. This study investigated the effects of injecting acetic acid or sodium carbonate solutions at three concentration levels (0.05, 0.1, 0.15 mol/L), in conjunction with three temperature profiles (40/60/80/80/90, 40/60/80/90/110, 50/70/90/110/130 °C) and two feed moisture levels (25, 30 %), on the removal of antinutrients (condensed tannins, trypsin inhibitor activity, phytic acid, raffinose family oligosaccharides) and reduction of volatile compounds that contribute to beany flavour in whole kidney bean flour. The results showed that all concentrations of acetic acid and sodium carbonate solutions effectively reduced condensed tannins compared to water, especially at 130 °C extrusion temperature. Introducing acetic acid and sodium carbonate solutions at a concentration of 0.15 mol/L led to 72 and 90 % reduction of total raffinose family oligosaccharide content, respectively, in contrast to the 17 % reduction observed with water alone. The incorporation of sodium carbonate solution reduced the total volatile compounds by 45-58 % as compared with water (23-33 %) and acetic acid (11-27 %). This reduction was primarily due to the reduction of aldehydes, alcohols, and aromatic hydrocarbons. These results indicate that injecting sodium carbonate solution during extrusion can effectively reduce antinutrients and beany flavour compounds in kidney bean flour.
Assuntos
Ácido Acético , Carbonatos , Farinha , Manipulação de Alimentos , Phaseolus , Ácido Fítico , Paladar , Farinha/análise , Carbonatos/química , Manipulação de Alimentos/métodos , Ácido Fítico/análise , Phaseolus/química , Proantocianidinas/análise , Rafinose/química , Temperatura , Concentração de Íons de Hidrogênio , Compostos Orgânicos Voláteis/análiseRESUMO
Ocean alkalinity enhancement is considered as an effective atmospheric CO2 removal approach, but currently, little is known about the carbon sequestration potential of implementing olivine addition in offshore waters. We investigated the effect of olivine addition on the seawater carbonate system by carrying out a deck incubation experiment in the Northern Yellow Sea; the dissolution rate of olivine was calculated based on the increase in seawater alkalinity (TA), and the CO2 sequestration potential was evaluated. The results showed that the dissolution of olivine increased seawater TA and decreased partial pressure of CO2, resulting in oceanic CO2 uptake from the atmosphere through sea-air exchange; it also increased seawater pH and mitigated ocean acidification to a certain extent. The addition of 1 olivine had a more significant effect on the seawater carbonate system than 0.5 olivine addition. The average dissolution rate constant of olivine was 1.44 ± 0.15 µmol m-2 d-1. Assuming that olivine settles completely on the seabed due to gravity, the theoretically maximum amount of CO2 removed by applying 1 tonne of olivine per square meter area in the Northern Yellow Sea is only 2.0 × 10-4 t/m2. Therefore, when olivine addition is implemented in the offshore waters, it is necessary to consider reducing the olivine size, prolonging the settling time of olivine in the water column; and spreading olivine in well-mixed waters to prolong the residence time through repeated resuspension, thus increasing its potential in carbon sequestration.
Assuntos
Dióxido de Carbono , Sequestro de Carbono , Compostos de Ferro , Compostos de Magnésio , Água do Mar , Silicatos , Dióxido de Carbono/análise , Água do Mar/química , Silicatos/química , Compostos de Magnésio/química , Compostos de Ferro/química , Navios , Concentração de Íons de Hidrogênio , Carbonatos/químicaRESUMO
The geological record of stable carbon isotopes preserved in marine carbonate rocks spans nearly 4 billion years. Numerous perturbations mark this record, but one stands out for its magnitude, the Lomagundi-Jatuli Event, which spanned the transition of the Earth's surface from an anoxic to an oxic state. An Applied and Environmental Microbiology article by D. Y. Sumner (90:e00093-24, 2024, https://doi.org/10.1128/aem.00093-24) provides, for the first time, a biological explanation for its initiation, cessation, environmental specific restriction, and geological singularity.
Assuntos
Isótopos de Carbono , Microbiologia Ambiental , Sedimentos Geológicos , Isótopos de Carbono/análise , Sedimentos Geológicos/microbiologia , Sedimentos Geológicos/química , Planeta Terra , Carbonatos/metabolismoRESUMO
Human activities emitting carbon dioxide (CO2) have caused severe greenhouse effects and accelerated climate change, making carbon neutrality urgent. Seawater mineral carbonation technology offers a promising negative emission strategy. This work investigates current advancements in proposed seawater mineral carbonation technologies, including CO2 storage and ocean chemical carbon sequestration. CO2 storage technology relies on indirect mineral carbonation to fix CO2, involving CO2 dissolution, Ca/Mg extraction, and carbonate precipitation, optimized by adding alkaline substances or using electrochemical methods. Ocean chemical carbon sequestration uses natural seawater for direct mineral carbonation, enhanced by adding specific materials to promote carbonate precipitation and increase CO2 absorption, thus enhancing marine carbon sinks. This study evaluates these technologies' advantages and challenges, including reaction rates, costs, and ecological impacts, and analyzes representative materials' carbon fixation potential. Literature indicates that seawater mineral carbonation can play a significant role in CO2 storage and enhancing marine carbon sinks in the coming decades.
Assuntos
Dióxido de Carbono , Sequestro de Carbono , Água do Mar , Água do Mar/química , Dióxido de Carbono/análise , Mudança Climática , Carbonatos/química , Minerais/químicaRESUMO
Sulfide-carbonate-mineralized functional bacterial consortium was constructed for flue gas cadmium biomineralization. A membrane biofilm reactor (MBfR) using the bacterial consortium containing sulfate reducing bacteria (SRB) and denitrifying bacteria (DNB) was investigated for flue gas cadmium (Cd) removal. Cadmium removal efficiency achieved 90%. The bacterial consortium containing Citrobacter, Desulfocurvus and Stappia were dominated for cadmium resistance-nitrate-sulfate reduction. Under flue gas cadmium stress, ten cadmium resistance genes (czcA, czcB, czcC, czcD, cadA, cadB, cadC, cueR, copZ, zntA), and seven genes related to sulfate reduction, increased in abundance; whereas others, nine genes related to denitrification, decreased, indicating that cadmium stress was advantageous to sulfate reduction in the competition with denitrification. A bacterial consortium could capable of simultaneously cadmium resistance, sulfate reduction and denitrification. Microbial induced carbonate precipitation (MICP) and biological adsorption process would gradually yield to sulfide-mineralized process. Flue gas cadmium could transform to Cd-EPS, cadmium carbonate (CdCO3) and cadmium sulfide (CdS) bioprecipitate. The functional bacterial consortium was an efficient and eco-friendly bifunctional bacterial consortium for sulfide-carbonate-mineralized of cadmium. This provides a green and low-carbon advanced treatment technology using sulfide-carbonate-mineralized functional bacterial consortium for the removal of cadmium or other hazardous heavy metal contaminants in flue gas.
Assuntos
Cádmio , Carbonatos , Desnitrificação , Sulfetos , Cádmio/metabolismo , Sulfetos/metabolismo , Carbonatos/química , Carbonatos/metabolismo , Bactérias/metabolismo , Bactérias/genética , Biodegradação Ambiental , Biofilmes , Poluentes Atmosféricos/metabolismo , Consórcios Microbianos , Sulfatos/metabolismo , Compostos de CádmioRESUMO
Soil improvement techniques utilizing the metabolic functions of microorganisms, including microbially induced carbonate precipitation (MICP), have been extensively researched over the past few decades as part of bio-inspired geotechnical engineering research. Given that metabolic reactions in microorganisms produce carbonate minerals, an enhanced understanding of microbial interaction with soils could improve the effectiveness of MICP as a soil improvement technique. Therefore, this study investigated the effects of sands on MICP by denitrification to employ MICP for geotechnical soil improvement. Under the coexistence of natural sand and artificial silica sand, nitrate-reducing bacteria were cultured in a mixed liquid medium with nitrate, acetate, and calcium ions at 37 °C. Nitrate reduction occurred only in the presence of natural sand. However, the lack of chemical weathering of the composed minerals likely prevented the progress of bacterial growth and nitrate reduction in artificial silica sands. For natural sand, artificial chemical weathering by acid wash and ferrihydrite coating of the sand improved bacterial growth and accelerated nitrate reduction. The calcium carbonate formation induced by denitrification was also influenced by the state of the minerals in the soil and the nitrate reduction rate. The observed MICP enhancement is due to the involvement of coexisting secondary minerals like ferrihydrite with large specific surface areas and surface charges, which may improve the reaction efficiency by serving as adsorbents for bacteria and electron donors and acceptors in the solid phases, thereby promoting the precipitation and crystallization of calcium carbonate on the surfaces. This crystal formation in the minerals provides valuable insights for improving sand solidification via MICP. Considering the interactions between the target soil and microorganisms is essential to improving MICP processes for ground improvement.
Assuntos
Carbonatos , Precipitação Química , Desnitrificação , Minerais , Nitratos , Areia , Microbiologia do Solo , Solo , Nitratos/metabolismo , Areia/química , Carbonatos/química , Minerais/química , Solo/química , Dióxido de Silício/química , Carbonato de Cálcio/química , Bactérias/metabolismoRESUMO
Adsorption methods offer efficient recovery of phosphorus from water bodies. Modification adsorption materials combining lanthanum (La) and zirconium (Zr) dual-metal immobilized via co-precipitation method have been widely applied in the adsorption and recovery of phosphate. Meanwhile, sodium carbonate (Na2CO3) is gradually replacing sodium hydroxide (NaOH) as the mainstream co-precipitant for immobilizing metals into supporting matrices due to its excellent performance and environmental friendliness. However, the adsorption mechanisms of materials synthesized with different co-precipitants and the synergistic effects between dual-metal components are not well understood, which is not conducive to the further optimization of dual-metal adsorption materials. In this study, anion exchange resin was utilized as the supporting matrices, and La&Zr dual-metal-modified materials, La&Zr-CO32- and La&Zr-OH-, were prepared using Na2CO3 and NaOH as co-precipitants, respectively. The results indicate that La&Zr-CO32- exhibits superior performance in phosphate adsorption and recovery, with adsorption capacity and recovery efficiency reaching 36.28 mg/g and 82.59%, respectively. Additionally, this material demonstrates strong stability in reuse, phosphate selectivity, and a wide pH applicability range. La&Zr-CO32- achieves phosphate adsorption through surface electrostatic affinity, ligand exchange, and intraspherical complexation, whereas La&Zr-OH- primarily relies on electrostatic adsorption on the surface and interior of the material. Synergistic effects between La and Zr result in enhanced adsorption performance of the dual-metal material compared to individual metals. Specifically, phosphate adsorption is predominantly governed by La, while the presence of Zr further enhances ligand exchange between lattice oxygen and metals. Simultaneously, Zr doping enhances the phosphate recovery capacity and reusability of the materials. Continuous flow adsorption results from actual water bodies demonstrate that La&Zr-CO32- is more suitable for the removal and recovery of phosphate in water treatment engineering. This study provides a theoretical basis and technical support for the adsorption and recovery of phosphate using dual-metal-modified materials.