Large uniform copper 1,3,5-benzenetricarboxylate metal-organic-framework particles from slurry crystallization and their outstanding CO 2 gas adsorption capacity

To prepare more and better metal organic frameworks (MOFs) from less solvent for capturing greenhouse gas, a modified slurry crystallization (MSC) method has been first demonstrated for making MOF copper 1, 3, 5-benzenetricarboxylate from a solvent-deficient system. One outstanding advantage is its drastic reduction of solvent consumption and waste liquid in the whole synthesis. In a typical process, the mass ratio of ethanol to the solid reactants is ∼0.52, which is only about 0.35%–7.5% of that used in conventional processes. A high yield of ∼98.0% is easily achieved for the product with uniform size up to 160 μm. The obtained MOFs demonstrate the characteristic microporous network with a surface area of ∼1851 m2 g−1 and a pore volume of ∼0.78 cm3 g−1, which benefit to adsorb high quantity of CO2 ∼ 6.73 mol kg−1 at ordinary pressure. X-ray diffraction studies indicate that the MOFs possess an outstanding diffraction intensity ratio of the crystal plane (2, 2, 2) to (2, 0, 0), I(222)/I(200) = 22.4. The MSC method provides a cost-effective approach for large-scale production of MOFs with more attractive properties than others. Most importantly, it can significantly cut down the waste liquid and production cost

Potential large-scale CO2 utilisation for salicylic acid production via a suspension-based Kolbe-Schmitt reaction in toluene

Conversion of CO2 into organic chemicals offers a promising route for advancing the circularity of carbon capture, utilisation, and storage in line with the international 2050 Net Zero agenda. The widely known commercialised chemical fixation of CO2 into organic chemicals is the century-old Kolbe–Schmitt reaction, which carboxylates phenol (via sodium phenoxide) into salicylic acid. The carboxylation reaction is normally carried out between the gas–solid phases in a batch reactor. The mass and heat transfer limitations of such systems require rather long reaction times and a high pressure of CO2 and are often characterised by the low formation of undesirable side products. To address these drawbacks, a novel suspension-based carboxylation method has been designed and carried out in this present study, where sodium phenoxide is dispersed in toluene to react with CO2. Importantly, the addition of phenol played a critical role in promoting the stoichiometric conversion of phenoxide to salicylic acid. Under the optimal conditions of a phenol/phenoxide molar ratio of 2:1 in toluene, a reaction temperature of 225 °C, a CO2 pressure of 30 bar, a reaction time of 2 h, and stirring at 1000 rpm, an impressive salicylic acid molar yield of 92.68% has been achieved. The reaction mechanism behind this has been discussed. This development provides us with the potential to achieve a carboxylation reaction of phenoxide with CO2 more effectively in a continuous reactor. It can also facilitate the large-scale fixing of CO2 into hydroxy aromatic carboxylic acids, which can be used as green organic chemical feedstocks for making various products, including long-lived polymeric materials

A critical review of the production of hydroxyaromatic carboxylic acids as a sustainable method for chemical utilisation and fixation of CO2

Hydroxyaromatic carboxylic acids (HACAs) such as salicylic acids, hydroxynaphthoic acids and their halogenated derivatives are essential feedstocks for the pharmaceutical, dye, fragrance, cosmetic and food industries. Large-scale production of HACAs is currently based on the Kolbe–Schmitt reaction between CO2 and petroleum-based phenolic compounds. This batch reaction is carried out at ∼125 °C, ∼85 bar and reaction times of up to 18 hours to achieve high conversions (≈99%). The long reaction times and dependence on fossil-derived phenols have negative sustainability implications. However, as a CO2-based process, HACA production has the potential for large-volume anthropogenic CO2 sequestration and contributes to net zero. A big challenge is that the current global production capacity of HACAs uses only about 41 450 tonnes per year of CO2 which is just ≈0.00012% of the annual anthropogenic emissions. Therefore, significant efforts are needed to increase both the sustainable production and demand for such CO2-based products to enhance their economic and environmental sustainability. This review covers the basic kinetic and thermodynamic stability of CO2. Thereafter, a comprehensive coverage of early and current developments to improve the carboxylation of phenols to make HACAs is given, while discussing their industrial potential. Moreover, it covers new propositions to use biomass-derived phenolic compounds for sustainable production of HACAs. There is also a need to expand the uses and applications of HACAs and recent reports on the production of HACA-based recyclable vinyl polymers point in the right direction

Atmospheric removal of methane by enhancing the natural hydroxyl radical sink

According to the latest report from the Intergovernmental Panel on Climate Change (IPCC), currently, global warming due to methane (CH4) alone is about 0.5°C while due to carbon dioxide (CO2) alone is about 0.75°C. As CH4 emissions will continue growing, in order to limit warming to 1.5˚C, some of the most effective strategies are rapidly reducing CH4 emissions and developing large scale CH4 removal methods. The aim of this review article is to summarise and propose possible methods for atmospheric CH4 removal, based on the hydroxyl radical (°OH), which is the principal natural sink of many gases in the atmosphere and on many water surfaces. Inspired by mechanisms of °OH generation in the atmosphere and observed or predicted enhancement of °OH by climate change and human activities, we proposed several methods to enhance the °OH sink by some physical means using water vapour and artificial UV radiation

A viscosity study of charcoal-based nanofluids towards enhanced oil recovery

Research into nanofluids for enhanced oil recovery (EOR) has been carried out for more than a decade. Metal oxide nanoparticles dispersed in water are usually applied and the nanofluids can recover 8–16 % more of the original oil in place after or comparing to water flooding, while the oil recovery capacity of carbon tube nanofluids can be even better. Higher viscosities of nanofluids than that of water are one of the key properties that contribute to their good performance in EOR. This work, for the first time, prepared nanofluids from two charcoal samples as well as an active carbon sample for their possible application for EOR. The relationship of nanofluid viscosities with pH values as well as nanoparticle concentrations of the nanofluids was studied for their viscous behaviour in different shear conditions. Their representative viscosity data measured at 100 rpm were examined for the values of the so-called Dispersion Factor (DF). The determined DF values for the charcoal-based nanofluids are close to those of metal oxide nanofluids that have much smaller nanoparticle sizes. The highly porous active carbon nanofluid showed strong viscosity enhancement that is comparable to the values reported for nanofluids of carbon nanotubes. Due to their significant viscosity enhancement and carbon sequestration feature, the charcoal-based nanofluids are promising to be used for EOR

Power Generation Performance of a Pilot-Scale Reverse Electrodialysis Using Monovalent Selective Ion-Exchange Membranes

Reverse electrodialysis (RED) is a promising process for harvesting energy from the salinity gradient between two solutions without environmental impacts. Seawater (SW) and river water (RW) are considered the main RED feed solutions because of their good availability. In Okinawa Island (Japan), SW desalination via the reverse osmosis (RO) can be integrated with the RED process due to the production of a large amount of RO brine (concentrated SW, containing ~1 mol/dm3 of NaCl), which is usually discharged directly into the sea. In this study, a pilot-scale RED stack, with 299 cell pairs and 179.4 m2 of effective membrane area, was installed in the SW desalination plant. For the first time, asymmetric monovalent selective membranes with monovalent selective layer just at the side of the membranes were used as the ion exchange membranes (IEMs) inside the RED stack. Natural and model RO brines, as well as SW, were used as the high-concentrate feed solutions. RW, which was in fact surface water in this study and close to the desalination plant, was utilized as the low-concentrate feed solution. The power generation performance investigated by the current-voltage (I−V) test showed the maximum gross power density of 0.96 and 1.46 W/m2 respectively, when the natural and model RO brine/RW were used. These are a 50−60% improvement of the maximum gross power of 0.62 and 0.97 W/m2 generated from the natural and model SW, respectively. The approximate 50% more power generated from the model feed solutions can be assigned to the suppression of concentration polarization of the RED stack due to the absence of multivalent ions

A mechanistic study of fire retardancy of carbon nanotube/ethylene vinyl acetate copolymers and their clay composites

A further investigation of the roles of multi-walled carbon nanotubes and clay in the fire retardancy of ethylene vinyl acetate copolymer (EVA) nanocomposites has been carried out. It was found that the nanotubes played an important role in the reduction of the peak of heat release rate by forming low permeability char containing graphitic carbon. The oxidation resistance of the char is a function of the degree of graphitisation. Adding clay into the nanotube/EVA composite tends to enhance the formation of graphitic carbon. The nanotubes also have the function of reducing surface cracks of chars to increase barrier resistance to the evolution of flammable volatiles and the oxygen ingress to the condensed phase

Critical role of chemical potential to assure effective encapsulation

HYPOTHESIS: In emulsification-polymerisation avoiding monomer escape from emulsion droplets is the key to successful encapsulation. So far, it is believed that (1) a hydrophobe needs to be included and (2) free-micelles of surfactant need to be depleted. However, these criteria do not always work. The paper explores the critical role of the chemical potential difference between the inside and outside of the emulsion droplet for successful encapsulation. EXPERIMENTS: Crossflow membrane emulsification was used to produce uniform droplets of 1-2 µm of solutions of 3-iodoprop-2-yn-1-yl butylcarbamate (a biocide), castor oil (hydrophobe) in methyl 2-methylprop-2-enoate (monomer) into aqueous solutions with a large amount of free-micelles of surfactant. The encapsulation was followed by polymerisation. The size distribution of microcapsule from different formula were examined. FINDINGS: The biocide encapsulation depends on castor oil content: >12% (full); 6-12% (either full or partial); <6% (minor). Results show a critical molar fraction ratio of the monomer in the droplet to water in the aqueous phase that provides a definitive criterion to assure size retention and full encapsulation. This critical value corresponds to an energy barrier of 116 J/mol to prevent the monomer escaping. This finding is proposed to be used as an advanced rule to guide precision formulation for desired microencapsulation

Comprehensive phenotypic analysis and quantitative trait locus identification for grain mineral concentration, content, and yield in maize (Zea mays L.)

Biofortification by enhanced mineral density in maize grain through genetic improvement is one of the efficient ways to solve global mineral malnutrition, in which one key step is to detect the corresponding Quantitative Trait Loci (QTL). In this work, a maize recombinant inbred population (RIL) was grown to maturity in four field environments with two locations × two years. Phenotypic data of mineral nutrition concentration, content and yield were determined for grain copper (Cu), iron (Fe), manganese (Mn), zinc (Zn), magnesium (Mg), potassium (K) and phosphorus (P). Analysis of variance (ANOVA) showed significant effects of genotype, location and year for all investigated traits. Location showed the highest effect for all mineral yields, and Zn and Cu content and concentration, while year had the strongest impact for Mn, K, and P content and concentration. Heritabilities (h2) of different traits varied with higher h2 (72-85%) for mineral concentration and content and lower (48-63%) for nutrient yields. Correlation coefficient analysis revealed significant positive correlations for grain concentration between several minerals. P had the closest correlations to other elements, while Cu had the lowest. When environments were analyzed individually, a total of 28, 25, and 12 QTL were identified for nutrient concentration, content and yield, respectively. Among these QTL, 8 QTL were consistent within traits across different environments. These stable QTL may be most promising for controlling mineral accumulation in maize grain. Co-localization of QTL for different traits was found for 12 chromosome regions, suggesting that common processes might contribute seed nutrient accumulatio