CO2 Treatment Research Articles

Experimental Study on the Impact of CO2 Treatment on Different Lithofacies in Shale Oil Reservoirs

CO2 technology has been progressively used in the development of shale oil. After injection, CO2 can react with formation water to form carbonic acid, which then reacts with carbonate and silicate minerals, resulting in changes in porosity and permeability. However, there are some debates as to whether the effect of CO2 improves or damages porosity and permeability. So, in this paper, systematic experiments were carried out to clarify the interaction between CO2 and shale in different lithofacies and to draw a pertinent conclusion. The results showed that the shale in Qingshankou Formation could be divided into three main lithofacial types: foliaceous shale, laminated feisic shale and laminated diamictic shale. There were relatively more pores, some natural microfractures and small mineral particles in foliaceous shale, a few micropores and large mineral particles in laminated feisic shale, some biogenic calcium carbonate minerals and hardly any micropores in laminated diamictic shale. Due to the diversity of micromorphology and mineral composition, the effects of CO2 treatment had significant differences. For foliaceous shale, CO2 treatment had both improving and damaging effects on porosity and permeability; for laminated shale, both porosity and permeability improved significantly. So, it is necessary to identify the main lithofacies of target formation before the application of CO2 technology in shale oil reservoirs.

Spin trapping analysis of the thermal degradation of polypropylene

The thermal degradation mechanism of poly(propylene) (PP) fabric from room temperature to 220 °C was analyzed using the electron spin resonance (ESR) spin-trapping technique. This method was adopted to prolong the lifetime of the short-lived radical intermediates generated by thermal degradation with the object of inspecting their molecular structure. A spin-trapping reagent, 2,4,6-tri‑tert-butylnitrosobenzene (TTBNB), was impregnated into the PP fabric using supercritical CO2 (scCO2) treatment in the presence of a co-solvent. The impregnation efficiency and effect were evaluated using proton nuclear magnetic resonance (1H NMR) spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM). ESR analysis showed that the degradation of PP is initiated from the tertiary carbon positions via two pathways: homolysis to generate ·CH3 and −CH2−·CH−CH2− radicals, and hydrogen abstraction to generate −CH2−·C(CH3)−CH2− radicals. These radicals are also attacked by oxygen to form hydroperoxides, which then decompose to form the alkoxy radicals −CH2−CH(O·)−CH2− and −CH2−C(CH3)(O·)−CH2−. These radicals are involved in the subsequent β-scission reactions that produce primary and secondary carbon radicals. Alkoxy radicals also take part in the β-scission reactions involving the main chain carbon radicals, which have a hydroxyl group in the β-position, and in hydrogen abstraction from a five-membered ring at temperatures higher than the melting-point to produce an α‑hydroxyl carbon radical, ·CH(OH)−. These inferred processes involved in the thermal degradation of PP fabric were supported by other methods of analysis, including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA).

CO2 -Induced Exposure of the Intrinsic Magnetic Surface of BaTiO3 to Give Room-Temperature Ferromagnetism.

Preparation of low-dimensional ferromagnetic nanomaterials and investigation of their magnetic origin is critical to the exploration of novel materials with various applications such as data storage. Herein, non-van der Waals (non-vdW) BaTiO3 was successfully stripped to a low-dimensional structure by treating the materials with supercritical CO2 (SC CO2 ). Under different CO2 pressures, SC CO2 selectively cleaves the covalent bonds of the bulk BaTiO3 , leading to the exposure of various surfaces. After SC CO2 treatments, the BaTiO3 exhibits room-temperature ferromagnetism, which is significantly stronger than conventional treatments. According to the experimental and theoretical investigations, the enhanced ferromagnetic property is attributed to the exposure of the intrinsic surfaces of BaTiO3 .

CO2‐Induced Exposure of the Intrinsic Magnetic Surface of BaTiO3 to Give Room‐Temperature Ferromagnetism

AbstractPreparation of low‐dimensional ferromagnetic nanomaterials and investigation of their magnetic origin is critical to the exploration of novel materials with various applications such as data storage. Herein, non‐van der Waals (non‐vdW) BaTiO3 was successfully stripped to a low‐dimensional structure by treating the materials with supercritical CO2 (SC CO2). Under different CO2 pressures, SC CO2 selectively cleaves the covalent bonds of the bulk BaTiO3, leading to the exposure of various surfaces. After SC CO2 treatments, the BaTiO3 exhibits room‐temperature ferromagnetism, which is significantly stronger than conventional treatments. According to the experimental and theoretical investigations, the enhanced ferromagnetic property is attributed to the exposure of the intrinsic surfaces of BaTiO3.

Identification and expression analysis of genome-wide long noncoding RNA responsive CO2 fluctuated environment in marine microalga Nannochloropsis oceanica

Long non-coding RNAs (lncRNAs) have been demonstrated to participate in plant growth and development as well as response to different biotic and abiotic stresses. However, the knowledge of lncRNA was limited in microalgae. In this study, by RNA deep sequencing, 134 lncRNAs were identified in marine Nannochloropsis oceanica in response to carbon dioxide fluctuation. Among them, there were 51 lncRNAs displayed differentially expressed between low and high CO2 treatments, including 33 upregulation and 18 downregulation lncRNAs. Cellulose metabolic process, glucan metabolic process, polysaccharide metabolic process, and transmembrane transporter activity were functionally enriched. Multiple potential target genes of lncRNA and lncRNA-mRNA co-located gene network were analyzed. Subsequent analysis had demonstrated that lncRNAs would participate in many biological molecular processes, including gene expression, transcriptional regulation, protein expression and epigenetic regulation. In addition, alternative splicing events were firstly analyzed in response to CO2 fluctuation. There were 2051 alternative splicing (AS events) identified, which might be associated with lncRNA. These observations will provide a novel insight into lncRNA function in Nannochloropsis and provide a series of targets for lncRNA-based gene editing in future.

CO2 treatment of ground granulated blast furnace slag for enhancing geopolymer properties

A novel and cost-effective method was developed for CO2 incorporation into ground granulated blast furnace slag as distorted carbonates, and subsequent value-added use of the captured carbon dioxide towards enhancement of the alkali-activated slag binding qualities. The distorted carbonate structures formed in slag induce carbonation reactions in the course of alkali-activation, yielding a hybrid system of carbonates and alkali aluminosilicates that act synergistically to produce improved binding effects. Integration of carbon dioxide into slag was accomplished by simple ball milling in the presence of CO2. Geopolymer binder was prepared via alkali activation of slag. Fundamental studies were conducted on the microstructure, chemical composition and bond environment, and crystalline structure of the slag particles, and also on the hybrid binders produced via concurrent alkali-activation and carbonation reactions. Concrete materials prepared with the hybrid binder were also characterized to confirm the value offered by the captured carbon dioxide towards enhancing the properties of concrete.

Developing a high‐throughput method to screen soybean germplasm for hypoxia tolerance in a hydroponic system

AbstractCurrent field screening methods for soybean [Glycine max L. (Merr.)] flood tolerance are time‐ and labor‐intensive. The purpose of this research was to develop a method of screening soybean in a low‐O2 and CO2–rich treatment using hydroponic culture in a greenhouse setting. Growth media, solution, and plant response were evaluated at various days after termination of gas treatment (DAT). Initially, a flood‐susceptible genotype at early vegetative stage was subjected to a hypoxic treatment, displacing O2 by bubbling CO2 into the system for 5 d. The methodology was tested with 33 soybean genotypes, and normalized difference vegetation index (NDVI), soil–plant analysis development (SPAD), and foliar damage score (FDS) were measured. Then, the reaction of 17 genotypes was compared between hydroponic and field conditions. Expanded clay pebbles were identified as the best substrate for the screening method, as germination rate was not different from control. Gas treatment was shown to affect the level of dissolved O2 in solution and to elicit phenotypic responses, of which NDVI was the most effective for differentiating germplasm, with an average of 0.29 and 0.69 for the CO2 treatment and ambient air control, respectively (p < .0001). Also, repeatability of NDVI response across genotypes was 94.5%. Finally, preliminary field validation supported the ability of this new hydroponic methodology to separate susceptible and tolerant genotypes under hypoxia and water‐logged conditions.

Effects of postharvest deastringency and 1-methylcyclopropene treatments on membrane permeability, membrane-degrading enzymes and their encoding genes in persimmon (Diospyros kaki, cv Mopanshi) fruit

Astringent persimmon fruit softens rapidly after harvest deastringency treatment. The purpose of this study was to understand the characteristics of membrane deterioration and its mechanism during rapid softening. The experiment included three treatments: (1) control, (2) CO2 treatment (≈100% CO2, 24 h), and (3) CO2 plus 1-methylcyclopropene (1-MCP, 1.5 μL∙L-1) treatment. CO2 treatment can effectively remove the astringency of persimmon fruit and cause a sharp drop in fruit firmness. The addition of 1-MCP was beneficial for firmness maintenance, but the process of astringency removal was delayed by one day. The fruit respiration rate and ethylene evolution rate were significantly increased by CO2 treatment, regardless of the presence or absence of 1-MCP, but the addition of 1-MCP could reduce the peak value and delay the occurrence of ethylene peaks by one day. The deastringency treatment resulted in a significant increase in membrane permeability and malondialdehyde content, and 1-MCP could significantly reduce membrane damage. CO2 treatment induced an enormous increase in LOX activity and the transcription of DkLOX3; however, 1-MCP significantly inhibited these increases. The PLD activity and DkPLDα1 expression level of the CO2-treated fruit were significantly promoted, and the addition of 1-MCP had less inhibition effect on the PLD activity and no significant inhibition on the DkPLDα1 expression. These results demonstrate that CO2 deastringency treatment could cause severe damage to the membrane integrity by promoting LOX and PLD activities and related gene expression. 1-MCP may ameliorate membrane damage mainly by inhibiting LOX activity and DkLOX3 gene expression and partly by suppressing PLDα1 expression.

Ultrahigh permeation of CO2 capture using composite organosilica membranes

The excessive release of CO2 from the burning of fossil fuels is of great concern, and effective treatment methods are urgently needed to solve the resulting crisis. Membrane-based separation processes have attracted significant attention due to their advantages, such as low investment cost, low energy consumption, and ease of operation. Herein, composite organosilica membranes were fabricated via co-polymerization reactions between bis(triethoxysilyl)acetylene (BTESA), bis(triethoxysilyl)benzene (BTESB), and 4,4′-bis(triethoxysilyl)-1,1′-biphenyl (BTESBPh). Then, dynamic light scattering (DLS), Fourier-transform infrared (FT-IR) spectrometry, and sorption measurements were used to assess the evolution of the network structures. We found that the addition of BTESB into BTESA densified membrane structures, while the co-polymerization reactions between BTESA and BTESBPh increased membrane pore sizes. Thus, all membranes exhibited great potential for CO2 capture and would be competitive candidates as suitable membrane materials for CO2 treatment applications.

Ultra-ductile and strong in-situ fibrillated PLA/PTFE nanocomposites with outstanding heat resistance derived by CO2 treatment

Polylactic acid (PLA) is a green substitution of traditional petroleum-based polymers due to its bio-friendly natures. However, high brittleness and poor heat-resistance significantly limit the wide applications of PLA. Herein, a novel strategy by coupling in-situ fibrillation and CO2 treatment was developed to fabricate strong and ductile PLA/PTFE nanocomposites with outstanding heat resistance. Reticulated PTFE nanofibrils with diameters of 100–200 nm were created in an in-situ way, which dispersed uniformly in PLA matrix. By further CO2 treatment under room temperature, those PTFE nanofibrils can derive many nanoscale transcrystals due to heterogenous nucleation effect. These nanocrystals together with PTFE nanofibrils led to dramatically enhanced ductility, strength, and heat resistance of PLA. Compared with pure PLA, the PLA/PTFE nanocomposite’s ductility, strength, and Vicat softening temperature after CO2 treatment were increased by 270%, 17%, and 130%, respectively. Thus, this advanced methodology provides a promising way for developing high-performance environmentally friendly biocomposites.

Effect of Elevated CO2 during Low Temperature Storage on the Quality Attributes of Cut Spearmint

The effect of elevated CO2 in a controlled atmospheric condition (CA) on the quality attributes of fresh-cut spearmint (Mentha spicata) during refrigerated storage is investigated in the present study. Cut stems of spearmint were exposed to the continuous flow of humidified air enriched with 0 (as a control), 5, 10 and 20% CO2 during storage at 5 °C. Weight loss, leaf colour, total phenols, antioxidant activity, aromatic profile, ascorbic acid, ethanol, ammonia and ethanol-acetaldehyde concentrations were measured before and after storage for 5, 10 and 14 days. Over time, CO2 treatments increased the weight loss, surface colour, L* (from white to black) and b* (from blue to yellow) values, but lowered a* (from green to red). When compared to fresh spearmint, the lowest CO2 concentration was able to maintain the overall colour variations. The 20% CO2 treatment showed significant declines in the total phenolic content, antioxidant potential and low appearance score after 10 days, thus its quality assessment was terminated. Vitamin C levels decreased with time in all the treatments, although the 10% and 20% CO2 treatments had the lowest levels. The toxicity of the cell structures detected by the ammonia content increased and was significantly higher in all CO2 treatments. Storage in the CA with the gas composition at 5% preserved the aromatic profiles similar to those stored in air. In conclusion, increased CO2 did not improve the storability of fresh cut spearmint held at low temperatures, and the 20% gas composition had a significant negative impact on the visual quality.

Distinctive correlations between cell concentration and cell size to microalgae biomass under increasing carbon dioxide

Carbon capture and storage (CCS) via microalgae cultivations is getting renewed interest as climate change mitigation effort, owing to its excellent photosynthetic and CO2 fixation capability. Microalgae growth is monitored based on their biomass, cell concentrations and cell sizes. The key parametric relationships on microalgae growth under CO2 are absent in previous studies and this inadequacy hampers the design and scale-up of microalgae-based CCS. In this study, three representative microalgae species, Chlorella, Nostoc and Chlamydomonas, were investigated for establishing key correlations of cell concentrations and sizes towards their biomass fluctuations under CO2 influences of 0% to 20% volume ratios (v/v). This revealed that Chlorella and Chlamydomonas cell concentrations significantly contributed towards increasing biomass concentration under CO2 elevations. Chlorella and Nostoc cell sizes were enhanced at 20% (v/v). These findings provided new perspectives on growth responses under increasing CO2 treatment, opening new avenues on CCS schemes engineering designs and biochemical production.

CO2-triggered switchable solvent for lipid extraction from microalgal biomass

This study proposed a novel and energy-efficient method using switchable polarity solvents for lipid recovery from microalgae. Different from the existing methods, use of switchable polarity solvents does not require the fractional distillation for separation of lipid and solvent by only converting the polarity of the solvent after lipid extraction. When a non-polar amine solvent reacts with CO2, amino group (NH) can be transformed to a polar form, i.e. carbamate (NHCOO−). Nuclear magnetic resonance (NMR) spectrum indicated that only secondary amines are convertible to a polar compound of carbamate after CO2 treatment. The polarity switching potential of each amine candidate was quantitatively evaluated by normalized polarity energy (ETN). Dipropylamine (DPA) showed the greatest change in ETN from 0.452 to 0.789 kcal/mol (ETN of water = 1.0 kcal/mol) before and after CO2 treatment. DPA is a potential polarity switchable solvent capable of achieving an excellent lipid extraction yield of 7.51% from tested microalgal biomass (Chlorella vulgaris) with 9.16% of total lipid content and 95.5% fatty acid methyl esters (FAMEs) content. Furthermore, the used solvent could be recovered at the high efficiency of 84.0%. With a significant polarity switchability from nonpolar amine to carbamate in the presence of CO2, DPA, a secondary amine, could be suggested as a suitable solvent used for both extraction of lipids with a higher FAMEs content from microalgae and separation of lipid by only adding CO2.

Enhancement of diatom growth and phytoplankton productivity with reduced O2 availability is moderated by rising CO2

Many marine organisms are exposed to decreasing O2 levels due to warming-induced expansion of hypoxic zones and ocean deoxygenation (DeO2). Nevertheless, effects of DeO2 on phytoplankton have been neglected due to technical bottlenecks on examining O2 effects on O2-producing organisms. Here we show that lowered O2 levels increased primary productivity of a coastal phytoplankton assemblage, and enhanced photosynthesis and growth in the coastal diatom Thalassiosira weissflogii. Mechanistically, reduced O2 suppressed mitochondrial respiration and photorespiration of T. weissflogii, but increased the efficiency of their CO2 concentrating mechanisms (CCMs), effective quantum yield and improved light use efficiency, which was apparent under both ambient and elevated CO2 concentrations leading to ocean acidification (OA). While the elevated CO2 treatment partially counteracted the effect of low O2 in terms of CCMs activity, reduced levels of O2 still strongly enhanced phytoplankton primary productivity. This implies that decreased availability of O2 with progressive DeO2 could boost re-oxygenation by diatom-dominated phytoplankton communities, especially in hypoxic areas, with potentially profound consequences for marine ecosystem services in coastal and pelagic oceans.

Knockout of Cia5 gene using CRISPR/Cas9 technique in Chlamydomonas reinhardtii and evaluating CO2 sequestration in control and mutant isolates

CRISPR/Cas9 technology is one of the common methods of genome editing and targeted gene mutation, which has recently been used for manipulating microalgae such as Chlamydomonas reinhardtii. Besides, this technology can play a role in the fight against greenhouse gases (e.g., carbon dioxide) production by studying genetic pathways to improve algal strains. Among several genes in algae that respond to CO2 and regulators control the expression of each; Cia5 is one of the most critical transcriptional regulators. In this research, we knocked out the Cia5 gene using the CRISPR/Cas9 technique and analysed the ability of C. reinhardtii to perform CO2 sequestration. Our results showed that C. reinhardtii has better performance (i.e., response to CO2 treatment) in both control and mutant species at 0.5% CO2 concentration than other concentrations. However, the difference between the control microalgae species and the mutant species was in the CO2 removal efficiency. Additionally, our findings revealed that the control type isolate in CO2 concentrations of 0.04%, 0.5% and 1% had removal efficiencies of 27%, 37% and 21%, respectively. Nevertheless, for mutant species in the same concentrations, the observed removal efficiencies were 16%, 23% and 9%.

Elevated atmospheric CO2 enhances the phytoremediation efficiency of tall fescue (Festuca arundinacea) in Cd-polluted soil

With the economic development of society, concentrations of atmospheric CO2 and heavy metals in soils have been increasing. The physiological responses of plants to the interaction between soil pollution and climatic change need to be understood. Pot experiments were designed to assess variations in Festuca arundinacea dry weight, leaf type, chlorophyll content, antioxidase activities, and Cd accumulation ability, under different atmospheric CO2 treatments. The results showed that the total dry weights increased with increasing CO2, and Cd concentrations in falling leaf tissues increased with raised atmospheric CO2, before reaching a peak at 600 ppm, above which they remained constant. Compared with the control (400 ppm), 600, 650, and 700 ppm CO2 treatments increased the proportions of the falling tissues by 1.7%, 3.3%, and 4.5%, respectively. Antioxidant enzyme activities in plant leaves increased with increasing atmospheric CO2 levels. The concentration of H2O2 in leaf tissues increased with increasing CO2, reaching a peak at 600 ppm, and then decreased significantly as the CO2 content increased further, to 700 ppm. The results in this study suggest that F. arundinacea could be regarded as a potential candidate for phytoremediation of Cd-polluted soil; especially if senescent and dead leaf tissues could be harvested, and that raised atmospheric CO2 levels could improve its soil remediation efficiency. Novelty statement Extrapolation of results from experiments of environmental impacts in greenhouse to real scale field requires to be considered cautiously. External factors such as water, temperature, humidity, and pollution are variable in real field. Plants will face a lot of beneficial or detrimental conditions which will influence the magnitude of the results. However, the elevation of CO2 is an inevitable phenomenon in future. Therefore, findings from experiments under artificial conditions are sometime a good choice to obtain knowledge about elevated CO2 related impacts on phytoremediation efficiency of a specific plant. The final goal of this work is to find a suitable CO2 fumigation strategy optimized for soil remediation. We report on that elevated atmospheric CO2 can increase the phytoremediation efficiency of Festuca arundinacea for Cd. This is significant because the combined influences of elevated atmospheric CO2 and metal pollution in terms of biomass yield, pollutant uptake, and phytoremediation efficiency would be more complex than the effects of each individual factor.

A meta-analysis of the effects of climate change on the mutualism between plants and arbuscular mycorrhizal fungi.

Climate change and other anthropogenic activities have the potential to alter the dynamics of resource exchange in the mutualistic symbiosis between plants and mycorrhizal fungi, potentially altering its stability. Arbuscular mycorrhizal (AM) fungi, which interact with most plant species, are less cold‐tolerant than other groups of fungi; warming might therefore lead to increased fungal‐mediated nutrient transfers to plants, which could strengthen the mutualism. By stimulating photosynthesis, rising CO2 could reduce the carbon cost of supporting AM fungi, which may also strengthen the mutualism. Furthermore, rising temperature and CO2 could have stronger effects on the mutualism in wild plants than in domesticated plants because the process of domestication can reduce the dependence of plants on mycorrhizal fungi. We conducted a multi‐level random effects meta‐analysis of experiments that quantified the strength of the mutualism as plant growth response to AM fungal inoculation (i.e., mycorrhizal growth response) under contrasting temperature and CO2 treatments that spanned the Last Glacial Maximum (LGM) to those expected with future climate change. We tested predictions using a three‐level mixed effects meta‐regression model with temperature or CO2, domestication status and their interaction as moderators. Increases from subambient to ambient temperature stimulated mycorrhizal growth response only for wild, but not for domesticated plant species. An increase from ambient to superambient temperature stimulated mycorrhizal growth response in both wild and domesticated plants, but the overall temperature effect was not statistically significant. By contrast, increased CO2 concentration, either from subambient to ambient or ambient to super ambient levels, did not affect mycorrhizal growth response in wild or domesticated plants. These results suggest the mutualism between wild plants and AM fungi was likely strengthened as temperature rose from the past to the present and that forecasted warming due to climate change may have modest positive effects on the mutualistic responses of plants to AM fungi. Mutualistic benefits obtained by plants from AM fungi may not have been altered by atmospheric CO2 increases from the past to the present, nor are they likely to be affected by a forecasted CO2 increase. This meta‐analysis also identified gaps in the literature. In particular, (i) a large majority of studies that examined temperature effects on the mutualism focus on domesticated species (>80% of all trials) and (ii) very few studies examine how rising temperature and CO2, or other anthropogenic effects, interact to influence the mutualism. Therefore, to predict the stability of the mycorrhizal mutualism in the Anthropocene, future work should prioritize wild plant species as study subjects and focus on identifying how climate change factors and other human activities interact to affect plant responses to AM fungi.

Simulating climate change in situ in a tropical rainforest understorey using active air warming and CO2 addition.

Future climate‐change effects on plant growth are most effectively studied using microclimate‐manipulation experiments, the design of which has seen much advance in recent years. For tropical forests, however, such experiments are particularly hard to install and have hence not been widely used. We present a system of active heating and CO2 fertilization for use in tropical forest understoreys, where passive heating is not possible. The system was run for 2 years to study climate‐change effects on epiphytic bryophytes, but is also deemed suitable to study other understorey plants. Warm air and CO2 addition were applied in 1.6‐m‐tall, 1.2‐m‐diameter hexagonal open‐top chambers and the microclimate in the chambers compared to outside air. Warming was regulated with a feedback system while CO2 addition was fixed. The setup successfully heated the air by 2.8 K and increased CO2 by 250 ppm on average, with +3 K and +300 ppm as the targets. Variation was high, especially due to technical breakdowns, but not biased to times of the day or year. In the warming treatment, absolute humidity slightly increased but relative humidity dropped by between 6% and 15% (and the vapor pressure deficit increased) compared to ambient, depending on the level of warming achieved in each chamber. Compared to other heating systems, the chambers provide a realistic warming and CO2 treatment, but moistening the incoming air would be needed to avoid drying as a confounding factor. The method is preferable over infrared heating in the radiation‐poor forest understorey, particularly when combined with CO2 fertilization. It is suitable for plant‐level studies, but ecosystem‐level studies in forests may require chamber‐less approaches like infrared heating and free‐air CO2 enrichment. By presenting the advantages and limitations of our approach, we aim to facilitate further climate‐change experiments in tropical forests, which are urgently needed to understand the processes determining future element fluxes and biodiversity changes in these ecosystems.

Modification of the petrophysical properties of artificially consolidated core samples with supercritical CO2 treatment

During the evaluation of certain hydrocarbon fields, for the petroleum engineering tests, natural rock core samples are needed. If there is a shortage of such samples, preparation and development of artificially consolidated rock samples become necessary. These samples can be made of different compositions and by using different technologies. The used model materials can play a role in the exploitation of petroleum and natural gas, and they can also promote the development, selection or application of secondary or tertiary technologies in conventional and non-conventional reservoirs. The process developed and used by us makes it available to construct these rock samples from different raw materials, under different pressure and temperature conditions and by using different post-treatment methods. In this paper, the changes of petrophysical parameters (porosity, permeability) originating from a CO2-rich environment ensured by a post-treatment (cure) were analyzed. The authors proposed further investigations of additional important parameters – zeta-potential, wettability – which could alter during different preparation methods of artificially consolidated rock samples, and by this, they could also enhance the research of geological storage of CO2 and EOR technologies.

An Eco-Friendly Surface Modification Method of Para-Aramid by Supercritical CO<sub>2</sub>

The structures and properties of para-aramid yarn were investigated under different treatment temperatures from 80 °C to 200 °C with supercritical CO2 and air, respectively, which were observed by Scanning electron microscopy (SEM), Dynamic wetting measurements, Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), and Thermogravimetric instrument (TG). It is confirmed that the surface morphology of para-aramid yarn was changed remarkably with the supercritical CO2 treatment temperature increasing compared to untreated yarn and treated with air, and the oligomers and disaggregates of yarn were migrated to the yarn surface. Furthermore, the water contact angle of para-aramid was reduced significantly from 136.22° to 91.37° with supercritical CO2 treatment at 200 °C, and the wettability was improved. Overall, supercritical CO2 modification for para-aramid has been proved to be feasible.