Na2CO3 Solution Research Articles

Phosphorylated chitosan as a hydrosoluble additive for bioactive calcium carbonate cements: Elaboration, setting mechanism, and handling properties

Chitosan is extensively used in the biomedical field owing to its biocompatibility and degradability. However, its limited solubility hinders its use as an effective additive in bone mineral cements. This study aimed to synthesize water-soluble phosphorylated chitosan and introduce it in calcium carbonate cement in view to control the composition, in vitro bioactivity, and physicochemical properties of the cement for bone repair. NMR spectroscopy results showed that chitosan was selectively functionalized (Cs–P) with phosphate groups mainly grafted at the C6 position on the chitosan backbone. For the first time, phosphorylated chitosan was associated with calcium carbonate cement; it was dissolved in a Na2CO3 solution (liquid phase of the cement) used as a setting accelerator. The quantitative XRD analysis at different time points revealed that the dissolution-recrystallization mechanism involved in the paste setting and hardening was different than for the reference cement: composite cement including 2.5 wt% Cs–P was mainly composed of vaterite (74 wt%) stabilized by Cs–P and some magnesian calcite (26 wt%). We pointed out the pivotal role of the calcium-binding ability of Cs–P phosphate groups and also of magnesium in controlling the cement setting mechanism and properties and its evolution in SBF. Interestingly, this composite cement also exhibited good physicochemical and handling properties: short initial (17 min) and final (28 min) setting times, high injectability (95%), enhanced anti-washout resistance of the paste, and a compressive strength compatible with implantation in non-load bearing bone defects. The in vitro evolution of the composite cement in SBF solution revealed some apatite formation on the cement surface and a high resorption rate (>20% at 28 days) owing to the solubility of the vaterite polymorph, making this composite cement a promising resorbable and bioactive ceramic able to be implanted through a minimally invasive technique.

Effect of waste tire rubber crumb on impermeability of cement-stabilized soil

ABSTRACT To alleviate the application limitations of cement-stabilized soil in impermeable engineering and promote the recycling of waste rubber tires, crumb rubber produced from waste rubber tires was used to improve the engineering properties of the soil. The effect of crumb rubber on the permeability of the soil under different conditions was investigated using compression, compaction, and permeability tests. Crumb rubber can effectively improve the impermeability of cement-stabilized soil. The impermeability efficiency of crumb rubber is between 11% and 45%. Cleaning crumb rubber with water and Na2CO3 solution can reduce the hydraulic conductivity of rubberized cement-stabilized soil (RCSS) by 7.9%–63.6%. This, in turn, increases the unconfined compressive strength by 4.1%–25.5%. The hydraulic conductivity of the RCSS decreases with an increase in the cement content, curing duration, and void ratio. A crumb rubber concentration of 10%–20% is suitable for enhancing the impermeability of the RCSS and satisfying its strength requirements. The NOF of the equation used to predict the hydraulic conductivity of the RCSS by the rubber content, cement content, and curing duration is less than 0.35. The linear correlation between the predicted and measured values of hydraulic conductivity was determined to be 0.995 from the k-q uc correlation model. The results show that the hydraulic conductivity of RCSS can be estimated reliably based on the mix ratio and compressive strength.

Effects of dissolution by alkali treatment on anisotropic surface properties and flotation behavior of spodumene

The effect of dissolution pretreatment of spodumene using NaOH and Na2CO3 was investigated by micro-flotation test, contact angle measurement, XPS, ICP and AFM imaging. The results showed that NaOH treatment activated the spodumene flotation whilst Na2CO3 showed little depression effect. NaOH had more significant activating effect on the spodumene (001) surface than (110) surface. The surface dissolution was confirmed by AFM, showing that weak surface dissolution was observed in ultrapure water and Na2CO3 solution, while there was strong surface dissolution in NaOH solution. Some precipitates coated the surface at the very start in NaOH and Na2CO3 solution, and the precipitates redissolved rapidly in NaOH solution while redissolved very slowly in Na2CO3 solution. The ICP results verified the release of Si, Al and Li from spodumene surface. NaOH treatment gave larger relative contents of Al on spodumene surface than Na2CO3, and the relative contents of Al on the (001) surface increased to a greater extent than on the (110) surface, as revealed by XPS analysis. From the point of crystal structure, the dissolution made more dangling Al exposed on the (001) surface, making it more favor of NaOL adsorption.

Simultaneous production of monophenol chemicals and CO2 adsorbent through salt solution-enhanced pyrolysis of electronic waste plastics

This study presented a novel method for the simultaneous generation of monophenol chemicals and carbon-based CO2 adsorbent from polycarbonate (PC) by using salt solution-enhanced pyrolysis. The regulatory functions of several factors on the production of 4-isopropenylphenol (IPP) and phenol were investigated using a laboratory-scale pyrolysis reactor, including salt solution type (neutral, acidic, and alkaline), solution concentration, and pyrolysis temperature. The results revealed that the Na2CO3 solution exhibited the best ability to enhance the preparation of IPP and phenol. At Na2CO3 concentration of 1 mol/L and pyrolysis temperature of 600 °C, the optimum yields of IPP and phenol reached 28.83 wt% and 33.77 wt%, respectively. The pyrolysis char (PCSC) obtained under this condition exhibited good CO2 adsorption behavior with a maximum adsorption capacity of 1.75 mmol/g at 30 °C because of its well-formed porous structure and copious oxygen-containing functional groups.

Micro-interface enhanced mass transfer sodium carbonate absorption carbon dioxide reaction

Micro-interface intensified reactor (MIR) can be applied in series/parallel in the absorption of CO2 in industrial gases by Na2CO3 due to the ability to produce large numbers of stable microbubbles. This work focuses on the variation pattern of mass transfer characteristics parameters of the reaction gas in Na2CO3 solution under the influence of different solution properties and operating parameters in the reaction of CO2 absorption by Na2CO3. The mass transfer characteristics parameters include bubble Sauter mean diameter, gas holdup, interfacial area, liquid side mass transfer coefficient, and liquid side volume mass transfer coefficient kLa. The solution properties and operating parameters include Na2CO3 concentration (0.05–2.0 mol·L−1), superficial gas velocity (0.00221–0.01989 m·s−1), superficial liquid velocity (0.00332–0.02984 m·s−1), and ionic strength (1.42456–1.59588 mol·kg−1). And volumetric mass transfer coefficients kLa and superficial reaction rates r of the MIR and the bubble column reactor are compared in the reaction of sodium carbonate absorption of carbon dioxide, and the former shows a greater improvement under different solution properties and operating parameters. The enhanced role of MIR in mass transfer in non-homogeneous reactions is verified and the feasibility of industrial practical applications of MIR is demonstrated.

Peroxocarbonate production by using a divided cylindrical electrochemical reactor

The production of peroxocarbonate was studied in a cylindrical electrochemical reactor divided by a cationic exchange membrane. The anode was a platinum helical wire and the cathodic reaction was either oxygen reduction by using a rotating reticulated vitreous carbon or hydrogen evolution at nickel or platinised titanium static electrodes. Fundamental studies performed with a rotating disc electrode or a rotating ring-disc electrode are reported which orientate the adoption of the operating conditions for the cylindrical reactor. The best results were obtained using a 1 mol/dm3 Na2CO3 solution in the anodic compartment at a current density of 140 mA/cm2 and 10 °C of temperature. The maximum sodium peroxocarbonate concentration was 64.7 mmol/dm3 with a current efficiency of 19.2%. The space time yield was 5.4 kg/m3/h and 11.1 kW h/kg the specific energy consumption. The process performance is similar with both cathodic reactions. The reactor showed a promising behaviour for the electrosynthesis of this oxidising agent.

Lignin-facilitated growth of Ag/CuNPs on surface-activated polyacryloamidoxime nanofibers for superior antibacterial activity with improved biocompatibility

IntroductionNanofibers are one of the role-playing innovations of nanotechnology. Their high surface-to-volume ratio allows them to be actively functionalized with a wide range of materials for a variety of applications. The functionalization of nanofibers with different metal nanoparticles (NPs) has been studied widely to fabricate antibacterial substrates to battle antibiotic-resistant bacteria. However, metal NPs show cytotoxicity to living cells, thereby restricting their application in biomedicine. ObjectivesTo minimize the cytotoxicity of NPs, biomacromolecule lignin was employed as both a reducing and capping agent to green synthesize silver (Ag) and copper (Cu) NPs on the surface of highly activated polyacryloamidoxime nanofibers. The activation of polyacrylonitrile (PAN) nanofibers via amidoximation was employed for enhanced loading of NPs to achieve superior antibacterial activity. MethodologyAt first, electrospun PAN nanofibers (PANNM) were activated to produce polyacryloamidoxime nanofibers (AO-PANNM) by immersing PANNM in a solution of Hydroxylamine hydrochloride (HH) and Na2CO3 under controlled conditions. Later, Ag and Cu ions were loaded by immersing AO-PANNM in different molar concentrations of AgNO3 and CuSO4 solutions in a stepwise manner. The reduction of Ag and Cu ions into NPs to fabricate bimetal-coated PANNM (BM-PANNM) was carried out via alkali lignin at 37 °C for 3 h in a shaking incubator with ultrasonication every 1 h. ResultsAO-APNNM and BM-PANNM hold their nano-morphology except for some changes in fiber orientation. XRD analysis demonstrated the formation of Ag and CuNPs as evident from their respective spectral band. Maximum 8.46 ± 0.14 wt% and 0.98 ± 0.04 wt% Ag and Cu species were loaded on AO-PANNM, respectively as revealed by ICP spectrometric analysis. The hydrophobic PANNM turned into super hydrophilic, having WCA of 14 ± 3.32° after amidoximation which further reduced to 0° for BM-PANNM. However, the swelling ratio of PANNM reduced from 13.19 ± 0.18 g/g to 3.72 ± 0.20 g/g for AO-PANNM. Even at the third cycle test against S. aureus strains, 0.1Ag/Cu-PANNM, 0.3Ag/Cu-PANNM, and 0.5Ag/Cu-PANNM displayed bacterial reduction of 71.3 ± 1.64 %, 75.2 ± 1.91 %, and 77.24 ± 1.25 %, respectively. On 3rd cycle test against E. coli, above 82 % bacterial reduction was noticed for all BM-PANNM. Amidoximation increased COS-7 cell viability up to 82 %. The cell viability of 0.1Ag/Cu-PANNM, 0.3Ag/Cu-PANNM, and 0.5Ag/Cu-PANNM was found to be ∼68 %, ∼62, and 54 %, respectively. In LDH assay, almost no release of LDH was detected, suggesting the compatibility of the cell membrane in contact with BM-PANNM. The improved biocompatibility of BM-PANNM even at higher loading (%) of NPs must be ascribed to the controlled release of metal species in the early stage, antioxidant, and biocompatible lignin capping of NPs. ConclusionsBM-PANNM displayed superior antibacterial activity against E. coli and S. aureus bacterial strains and acceptable biocompatibility of COS-7 cells even at higher loading (%) of Ag/CuNPs. Our findings suggest that BM-PANNM can be used as a potential antibacterial wound dressing and other antibacterial applications where sustained antibacterial activity is needed.

SPECTRAL AND PHOTOPHYSICAL CHARACTERISTICS OF ASYMMETRIC POLYMETHINE DYES IN POLYURETHANE MATRICES

Here the composite polymer sorbent hydrogels were synthesized by in situ technique via free radical polymerization of acrylamide (AAm), 2-hydroxyethyl methacrylate (2HEMA) and N,N’-methylene-bis(acrylamide) crosslinker mixture in the presence of as-prepared dispersion of nickel-aluminum layered double hydroxide (NiAl-LDH). A content of active NiAl-LDH filler in the polymer matrix was varied in a range of 30 – 70 wt.%. It was found a high filler content suppresses a molecular mobility of copolymer matrix chains and reduces a beginning of glass transition temperature of the polymer constituent. The results of thermal analysis of polymer composites demonstrate a high hydrophilicity level of polymer matrix and high solvation energy of polar functionalities by Н2О molecules that was concluded from slow moisture elimination process while the temperature grows up to 200–210 оС. Additionally, a dehydration process and changes in a structure of thermally labile filler were also observed at the same temperature interval. At higher temperatures a thermal degradation of polymer poly(AAm-co-2HEMA) matrix is carried out. When a temperature overcomes 400 оС the partially changed filler demonstrates a chemical interaction with degraded organic constituents of the composites and defined catalytic activity as well. Studying sorption activity of the composites shown that introducing NiAl-LDH into hydrophilic polymer matrix provides anion-exchange activity to the composite sorbents and, correspondingly, the ability to eliminate the anionic contaminants from aqueous media while the polymer matrix doesn’t absorb these substances at such conditions. The highest sorption capacity of 11,40 μmol/g against model contaminant – methyl orange dye was determined for composite sorbent with filler content of 70 wt. %. At the same time sorption capacity of NiAl-LDH filler in composite sorbents reduces from 25,7 to 16,6 μmol/g while a filler content grows from 30 to 70 wt.% as a result of filler particles aggregation processes during composites formation stage. To evaluate the ability of the composite sorbents to reuse the experiment of materials recycling was performed. It was stated out the using of anion-exchange technique and aqueous Na2CO3 solution as an efficient and non-hazardous eluent provides 80 % recovering efficiency of the active filler in the composites. It can be concluded the composite sorbents demonstrate a high overall efficiency and are valuable materials for practical application for decontamination of waste water.

Depression mechanism of ZnSO4 and Na2CO3 on talc flotation

The depression mechanism of a combination of ZnSO4 and Na2CO3 on talc during chalcopyrite and molybdenite flotation was investigated in-depth using flotation tests, solution speciation calculations, and various characterization techniques. Flotation tests indicate that the effective depression of talc flotation occurred in the pH range of 7−9. In this pH range, speciation calculations for the mixed solution of ZnSO4 and Na2CO3 showed that the Zn5(OH)6(CO3)2 precipitate was the predominant zinc-bearing species, which was further proven by X-ray diffraction and infrared spectroscopy measurements. Zeta potential measurement highlighted that the Zn5(OH)6(CO3)2 precipitate was positively charged while the talc surface was negatively charged in the pH range where talc depression occurred. X-ray photoelectron spectroscopy and field emission scanning electron microscopy confirmed the presence of the zinc-bearing precipitate on the surface of the talc particles treated by the combination of ZnSO4 and Na2CO3. These findings suggested that heterocoagulation between the formed Zn5(OH)6(CO3)2 and talc occurred mainly due to the electrostatic attraction, thereby leading to the depression of talc flotation.

Penetapan Kadar Fenolik Total Ekstrak Daun Jotang (Sphagneticola Trilobata) Dengan Spektrofotometri UV-Vis

Phenolic compounds are the largest group of compounds that act as natural antioxidants in plants. One of the plants that has the potential as a natural antioxidant is Jotang (Sphagneticola trilobata). This study aims to determine whether jotang leaf extract (Sphagneticola trilobata) has phenolic content and to determine the total phenolic content in jotang leaf extract (Sphagneticola trilobata). Jotang leaves were extracted by maceration method using methanol solvent. The method of determining total phenolic content was carried out using Folin-ciocaltaeu reagent because phenolic compounds can react with Folin-Ciocalteu to form a solution that can be measured absorbance. As a standard solution, gallic acid is used which is reacted with Folin-Ciocalteau reagent to produce a yellow color indicating that it contains phenolics, after which it is added with Na₂CO₃ solution as a base atmosphere giver. The phytochemical screening of jotang leaf extract showed positive results containing flavonoids, alkaloids, saponins, phenolic compounds, and triterpenoids. Determination of the wavelength of gallic acid obtained maximum 653 nm. The results showed that jotang leaf extract (Sphagneticola trilobata) has phenolic content and obtained total phenolic content of jotang leaf extract of 0.909 mg /g.

Comparison of NaOH and Na2CO3 as absorbents for CO2 absorption in carbon capture and storage technology

CO2 gas is a greenhouse gas that causes global warming. Greenhouse gases are gases in the atmosphere that can absorb and reflect infrared radiation from the Earth's surface. Currently, the energy demand still depends on fossil fuels. On the other hand, CO2 emissions from burning fossil fuels continue to increase and contribute as greenhouse gases to the atmosphere. CO2 capture is an effort to reduce the burden of CO2 emissions into the atmosphere and is part of the Carbon, Capture, and Storage (CCS) protocol. The CO2 absorption process applied in the chemical industry is one of the CO2 absorptions using NaOH and Na2CO3 solutions as absorbents. This research aims to determine the effect of absorbent flow rate on the percentage of absorbed CO2. The method used in this research is the SLR (Systematic Literature Review) method to identify all available research. The absorbent flow rate variations used are 1 liter/minute, 1.5 liters/minute, 2 liters/minute, 2.5 liters/minute, and 3 liters/minute. The absorption process using NaOH absorbent is capable of absorbing CO2 gas with a maximum absorption of 95.52% and a minimum of 79.14%. Meanwhile, in the Na2CO3 absorbent, it is capable of absorbing CO2 gas with a maximum amount absorbed of 72.45% and a minimum of 35.47%.

Research on migration and transformation behavior of selenium during the dual-alkali wet flue gas deacidification process in the simulated flue gas

Selenium easily escapes from the existing air pollution control devices (APCDs) used in municipal waste solid incineration (MSWI), which poses a threat to both the ecosystem and human health. Dual-alkali wet flue gas deacidification (DAWFGD) has been recently applied in MSWI power plants to improve the purification of flue gas. This technology provides a new route for the coordinated control of selenium in the DAWFGD device, which removes acidic gas simultaneously. In this study, a laboratory-scale DAWFGD system was constructed to investigate the migration and transformation behavior of selenium during the absorption and regeneration process in the DAWFGD system. The results showed that the Na2CO3 solution could effectively absorb SeO2, and the absorption efficiency could reach up to 97.09% by increasing the Na2CO3 concentration. High-concentration CO2 has less of an absorption inhibition effect on gaseous selenium compared to low-concentration HCl and SO2. The absorption of SeO2 was adversely affected by the decrease in pH value of the absorption solution caused by an increase in SO2 concentration. However, the addition of a small amount of alkali solution (OH–) into the absorption solution could well recover its absorption performance for SeO2. During the regeneration process, the precipitation ratio of selenium from the aqueous phase to the solid phase increased with the molar ratio of Ca/S increasing. Besides, selenium was found to be in the form of selenite during both the absorption and regeneration processes. This study helps to evaluate the potential of DAWFGD in MSWI power plants for removing SeO2 from flue gas and provides a theoretical reference for the treatment of gas-phase selenium in the waste incineration process.

Prediction of Salt-Tolerant Earthworms’ Cultivation Conditions Based on the Robust Artificial Intelligence Model

Soil pollution is a very important field among current global ecological environmental problems. Many countries have focused their scientific research power on the process of soil remediation and biological detoxification, hoping to achieve the remediation effect of contaminated soil by means of biological free activity and survival mechanisms. These studies are meant to achieve a virtuous ecological cycle and provide a biological basis for the sustainable utilization and development of resources. The purpose of this study was: (1) to screen the best conditions for the cultivation and domestication of salt-tolerant earthworms; (2) to explore the influence (correlation) relationship between salt-tolerant earthworms’ growth variables and living environmental factors; (3) an improved BP neural network model was constructed to predict the expected values of variables such as C:N, NaHCO3:Na2CO3 and base:soil, so as to provide an initial cultivation model for earthworm-resistant cultivators. The materials used in this study are cow dung that was collected from Changchun LvYuan District PengYu farm; straw that was collected from the Key Laboratory of Comprehensive Straw Utilization and Black Land Protection; soil that was collected from ordinary soil in the experimental shed of Jilin Agricultural University. We also purchased “Daping No. 2” earthworms from Hunan Zengren Earthworm Breeding Base. In order to simulate the extreme living environment with high salinity and alkalinity, this paper prepared 0.1 mol/L and 0.15 mol/L NaHCO3 solution, 0.1 mol/L, and 0.2 mol/L Na2CO3 solutions. We mixed the above solutions according to the proportion of 0.1 mol/L NaHCO3 solution: 0.1 mol/L Na2CO3 solutions, 0.15 mol/L NaHCO3 solution: 0.1 mol/L Na2CO3 solution, 0.1 mol/L NaHCO3 solution: 0.2 mol/L Na2CO3 solutions. At the same time, we prepared the mixed environment of base material and soil (base material:soil = 1:1; base material:soil = 1:2); the base material was composed of cow dung and straw. The conclusions are as follows: (1) earthworms living under simulated conditions have stronger tolerance to the saline-alkali environment; (2) the situation of C:N = 30:1, NaHCO3:Na2CO3 = 1:1, base:soil = 1:2 is the ideal state for earthworms to survive; (3) earthworms with a high tolerance can provide more enzyme activities for the simulated environment, especially cellulase activity, urease activity, sucrase activity, and alkaline phosphatase activity; (4) compared with the ordinary practical operation, the average prediction accuracy of a three output neuron BP prediction model is 99.40% (>95%). The results of this study indicate that the BP neural training set established can be used to reduce breeding costs, and also to improve the productivity of earthworms, provide a mathematical model basis for ecological sustainable utilization and circular production between earthworms and soil, and rapidly encourage the ability of earthworms to repair contaminated soil or transform agricultural waste, providing basic data support conditions for soil ecological remediation systems and the sustainable utilization of agricultural waste.

STUDY OF SILK STRAIN AND ITS PREPARATION FOR MENISCUS TISSUE ENGINEERING SCAFFOLD

Silk fibroin (SF) has been used as a scaffold for cartilage tissue engineering. Different silkworms strain produced different protein. Also, molecular weight of SF depends on extraction method. We hypothesised that strain of silkworm and method of SF extraction would effect biological properties of SF scaffold. Therefore, cell viability and chondrogenic gene expression of human chondrogenic progenitor cells (HCPCs) treated with SF from 10 silkworm strains and two common SF extraction methods were investigate in this study.Twenty g of 10 strains silk cocoons were separately degummed in 0.02M Na2CO3 solution and dissolved in 100๐C for 30 minutes. Half of them were then dissolved in CaCl2/Ethanol/H2O [1:2:8 molar ratio] at 70±5๐C (method 1) and other half was dissolved in 46% w/v CaCl2 at 105±5๐C (method 2) for 4 hours. HCPCs were cultured in SF added cultured medial according to strain and extraction method. Cell viability at day 1, 3, and 7, were determined. Expression of collagen I, collagen II, and aggrecan at day 7 and 14, was studied. All experiment were done in triplicated samples.Generally, method 1 SF extraction showed higher cell viability in all strains. Cell viability from Nanglai Saraburi, Laung Saraburi and Nangtui strains were higher than those without SF in every time point while Wanasawan and J108 had higher viability at day 1 and decreased by time. Expression in collagen 1, collagen 2 and aggrecan in method 1 are higher at day 7 and day 14. Collagen 1 expression was highest in Nangnoi Srisaket, followed by Laung Saraburi and Nanglai Saraburi in day 7. Nangnoi Srisaket also had highest expression at day 14, followed by Nanglai Saraburi and Laung Saraburi respectively. Nangseaw had highest collagen 2 expression, follow by Laung Saraburi and Nangnoi Srisaket respectively. Higher aggrecan gene expression of Tubtimsiam, Wanasawan, UB 1 and Nangnoi Srisaket was observed at day 7 and increased expression of all strains at day 14.SF extraction using CaCl2/Ethanol/H2O offered better cell viability and chondrogenic expression. Nangseaw, Laung Saraburi and Nangnoi Srisaket strains expressed more chondrogenic phenotype.

Extraction of calcareous dacryoconarid microfossils from limestones and mudrocks by surfactants paired with freeze-thaw processing

Microfossils offer a wealth of paleoenvironmental information, but their extraction from consolidated material, especially ancient rocks, is time-consuming and often lacks systematic methodological development. This study examined the efficacy of repeated freeze-thaw processing paired with different surfactants (anionic, cationic, and detergent) on the extraction of fossils from the order Dacryoconarida, conically shaped calcareous microfossils that occur in diverse marine facies of the Devonian Period. A stepwise technique was developed involving saturation of rocks in either 18 Ω water or 25% NaCl, followed by freezing and then boiling in surfactant (Pinequat, Decon 90, or Calgon in Na2CO3 solution). In comparison with saturation in NaCl solution, saturation in water generally had higher yields of disaggregated material and more intact fossils. All surfactants performed better at extraction compared to boiling in pure water. Across all lithologies examined, Na2CO3-buffered Calgon (sodium hexametaphosphate) disaggregated rock most efficiently, but Na2CO3 solution alone generally had the highest yield of total and intact fossil specimens. Pinequat, a cationic surfactant, yielded more disaggregate for siliclastic samples compared to calcareous samples, but had lower fossil yield. Decon 90, an anionic surfactant, performed better at disaggregating limestones and had higher fossil extraction efficiency than Pinequat across all lithologies. Freeze-thaw processing pairing water saturation and 5% Na2CO3 simmering is an effective treatment for the disaggregation of rocks to extract analytically viable amounts of dacryoconarids from fossiliferous samples. This pairing had greater fossil extraction potential than surfactants at the concentrations tested in this study and is recommended if the elemental composition of the target rocks is unconstrained.

Unveiling the role of post-treatment in thin-film composite nanofiltration membranes: Performance and mechanism

The deep role and mechanism of post-treatment in the morphology and performance of thin-film composite (TFC) nanofiltration (NF) membranes have rarely been revealed. In this work, four solutions of pure water, hexane, Na2CO3, and glycerol were selected for the post-treatment of TFC-NF membranes, and the performances of the resultant NF membranes were systematically investigated. The results showed that the hexane could effectively remove the residual acyl chloride groups and prevent the subsequent second growth of polyamide (PA) layers, thus leading to the formation of smoother and thinner PA membranes with higher water permeance and excellent salt rejections. Hydrolysis and swelling of unstable PA fragments in solutions (water, Na2CO3, and glycerin) contributed to greater negative charge, higher hydrophilicity, and enlarged pore size. The resultant NF membranes exhibited significantly enhanced water permeance and comparable separation behaviors to the control NF membrane. In addition, the well-constructed NF membranes possessed superior monovalent/multivalent ion selectivity, excellent antifouling, and stability. The mechanisms of the post-treatment on the performance enhancement of NF membranes were proposed from the perspective of interfacial interactions. The facile post-treatment strategy provides new insights into tailoring high-performance NF membranes for water treatment applications.

The effect of waste-expanded perlite on alkali activation of ground granulated blast furnace slag

The purpose of this study was to evaluate the possibility of using ground waste-expanded perlite (WP) as a sustainable replacement for ground granulated blast-furnace slag (GGBFS) precursor in alkali-activated systems. The nature and amount of hydration products, microstructure, and compressive strength development were investigated in mixtures where GGBFS was substituted with 10, 20 and 40% by weight of WP and activated by two alkali activators: sodium carbonate and sodium hydroxide. The results show that WP can be successfully used as a partial replacement for GGBFS in alkali-activated materials. Activation by the Na2CO3 solution was more profitable in terms of compressive strength than NaOH, as well as the amount of water bound in the hydration products was higher. Substitution of GGBFS with 20 wt.% of WP activated with sodium carbonate resulted in a compressive strength of 93 MPa at 90 days of hydration while for the equivalent sample activated by sodium hydroxide, 29 MPa. Further incorporation of WP into Na2CO3 activated systems resulted in a reduction in performance development, especially at the early age. In addition to C–S–H, hydrotalcite, and three different types of carbonates in the samples activated by NaOH solution, a rich in sodium C(–N)–S–H was found.

Sequential extraction, structural characterization, and antioxidant activity of polysaccharides from Dendrocalamus brandisii bamboo shoot shell

Polysaccharides including water-soluble fraction (W), 1,2-Cyclohexanediaminetetraacetic acid (CDTA)-soluble fraction (CA), sodium carbonate (Na2CO3)-soluble fraction (SC), 1 M potassium hydroxide (KOH)-soluble fractions (PH1), and 4 M KOH-soluble fraction (PH4) were successively extracted from Dendrocalamus brandisii bamboo shoot shells using water, CDTA, Na2CO3, and KOH solution. The analytical methods were employed to initially identify the structural characteristics of the five polysaccharide fractions, and their antioxidant capacities in vitro were determined. According to the data, the average molecular weight of the five polysaccharide fractions was between 4 816 and 993 935 Da. In all four types (CA, SC, PH1, and PH4), xylose was the most abundant monosaccharide, especially in PH1 and PH4. Both PH1 and PH4 were found to contain 1,4-β-d-Xylp as their main chain, as determined by nuclear magnetic resonance (NMR) spectroscopy. Additional research into CA and SC's antioxidant potential is required since they both showed potent in vitro antioxidant activities.

Cyclodextrin-Calcium Carbonate Micro- to Nano-Particles: Targeting Vaterite Form and Hydrophobic Drug Loading/Release

Tailor-made and designed micro- and nanocarriers can bring significant benefits over their traditional macroscopic counterparts in drug delivery applications. For the successful loading and subsequent release of bioactive compounds, carriers should present a high loading capacity, trigger release mechanisms, biodegradability and biocompatibility. Hydrophobic drug molecules can accumulate in fat tissues, resulting in drawbacks for the patient's recovery. To address these issues, we propose to combine the advantageous features of both host molecules (cyclodextrin) and calcium carbonate (CaCO3) particles in order to load hydrophobic chemicals. Herein, hybrid cyclodextrin-CaCO3 micro- to nano-particles have been fabricated by combining Na2CO3 solution and CaCl2 solution in the presence of an additive, namely poly (vinylsulfonic acid) (PVSA) or glycerol (gly). By investigating experimental parameters and keeping the Na2CO3 and CaCl2 concentrations constant (0.33 M), we have evidenced that the PVSA or gly concentration and mixing time have a direct impact on the final cyclodextrine-CaCO3 particle size. Indeed, by increasing the concentration of PVSA (5 mM to 30 mM) or gly (0.7 mM to 4 mM) or the reaction time (from 10 min to 4 h), particles with a size of 200 nm could be reached. Interestingly, the vaterite or calcite form could also be selected, according to the experimental conditions. We hypothesised that the incorporation of PVSA or gly into the precipitation reaction might reduce the nucleation rate by sequestering Ca2+. The obtained particles have been found to keep their crystal structure and surface charge after storage in aqueous media for at least 6 months. In the context of improving the therapeutic benefit of hydrophobic drugs, the developed particles were used to load the hydrophobic drug tocopherol acetate. The resulting particles are biocompatible and highly stable in a physiological environment (pH 7.4, 0.15 M NaCl). A selective release of the cargo is observed in acidic media (pH lower than 5).

Synthesis and property of superabsorbent polymer based on cellulose grafted 2-acrylamido-2-methyl-1-propanesulfonic acid

An eco-friendly superabsorbent polymer (SAP) was prepared by grafting 2-acrylamido-2-methyl-1-propanesulfonic acid onto microcrystalline cellulose in lithium chloride/N, N-dimethylacetamide system. The synthesized SAP (cellulose-g-PAMPS) was characterized by FTIR, TGA, SEM, 1H NMR, 13C NMR and XRD. The water absorption equilibrium of cellulose-g-PAMPS could be achieved within 10 min in distilled water. Moreover, the maximum water absorption capacities of cellulose-g-PAMPS in distilled water, 0.9 wt% NaCl solution and 3.2 wt% Na2CO3 solution were 648.9, 298.4 and 207.3 g·g−1, respectively. The water absorption behavior of cellulose-g-PAMPS was interpreted by the pseudo-second-order model. Furthermore, cellulose-g-PAMPS could be used in some extreme conditions due to its high acid and alkali resistance. The water retention rate of cellulose-g-PAMPS could be maintained above 90 % at 25 °C for 6 h. As a consequence, the synthesized SAP can be applied to increase the plant growth and survival time under drought conditions, even under saline alkali conditions.