Apparent Density Values Research Articles

Studying the effect of irrigation water quality (fresh water, treated water and wastewater) on some soil physical and chemical proper-ties and the protein content in the paulownia leaves.

Samples of soil irrigated with three types of water: Fresh water (F), wastewater (W), fresh water and wastewater (F1W1, alternative irrigation) were collected at two depths (0-15 cm and 15-30 cm) for two consecutive years. The bulk density, true density, soil total porosity, electrical conductivity, pH, percentage of organic matter, and concentration of phosphorus and potassium were measured. In addition, the length and circumference of paulownia tree trunk were measured, and the protein content of dry and green leaves was estimated. The results showed the differences in the apparent density values, as wastewater irrigation decreases the apparent density and increased the soil total porosity. The results also indicated that there were significant differences in the soil PH between the three treatments, as treated water irrigation decreased the pH and insignificantly increased the soil electrical conductivity. However, there were significant differences when irrigating with wastewater, as the electrical conductivity and organic matter content increased in the soil irrigated with wastewater compared to soil irrigated with fresh water at two depths (0-15cm and 15-30cm). Moreover, the concentrations of phosphorus and potassium increased in the soil irrigated with wastewater and treated water compared to fresh water. Furthermore, there were significant differences in the height of paulownia tree and its trunk circumference when irrigating with treated water compared to wastewater and fresh water. As for the protein content in paulownia leaves, it was observed that there were significant differences when irrigating with wastewater compared to treated water and fresh water. There was high protein content in the dry and green leaves when irrigating with the three types of water, but the highest protein content was for wastewater irrigation.

Liquefaction optimization of grape pulp using response surface methodology for biopolyol production and bio-based polyurethane foam synthesis.

Both environmental and economic disadvantages of using petroleum-based products have been forcing researchers to work on environmentally friendly, sustainable, and economical alternatives. The purpose of this study is to optimize the solvothermal liquefaction process of grape pomace using response surface methodology coupled with a central composite design. After investigating the physicochemical properties of the liquified products (biopolyol) in detail, a bio-based rigid polyurethane foam (RPUF) was synthesized and characterized. The hydroxyl and acid numbers and viscosity values of all the biopolyols were analyzed. According to variance analysis results (%95 confidence range), both the reaction temperature and catalyst loading were determined as significant parameters on the liquefaction yield (LY). The model was validated experimentally in the following reaction conditions: 4.25% catalyst loading, 50 min reaction time, and 165 °C reaction temperature, which yields an LY of 81.3%. The biopolyols produced by the validation experiment display similar characteristics (hydroxyl number: 470.5 mg KOH/g; acid number: 2.31 mg KOH/g; viscosity: 1785 cP at 25 °C) to those of commercial polyols widely preferred in the production of polyurethane foam. The physicochemical properties of bio-based foam obtained from the biopolyol were determined and the thermal conductivity, closed-cell content, apparent density, and compressive strength values of bio-based RPUF were 31.3 mW/m·K, 71.1%, 33.4 kg/m3, and 105.3 kPa, respectively.

Impact of the partial substitution of cement and sand by ash from several types of wood species in cementitious materials manufacture: valorization in the industrial field

The main objective of this article is to evaluate the potential use of wood ash as a substitute for cement and sand in mortars. Three types of wood were selected: Ayous, Sapelli and Fraké, all of which were sourced from carpentry in Cameroon. The sawdust was dried and combusted to obtain ash, then ground and sieved. Six types of mortar were produced, with cement substitution at 0%, 5%, 10%, 15%, 20% and 25%. The physico-mechanical properties of these substitutions were determined after 7, 28 and 56 days. The results of the cement paste consistency show that it increases with the addition of ash, due to the fact that sawdust ash requires a large quantity of water. The addition of ash caused an increase in setting time due to the fact that sawdust ash is less reactive than Ordinary Portland cement, resulting in a delay in the rate of cement hydration. Apparent density values decreased with the addition of sawdust ash, probably due to the hygroscopic behavior of type of ash in mortar specimens. The highest pozzolanic index is that of 5% replacement by ash and almost identical absorption for all mortars at this substitution percentage. Acid attack results revealed a higher durability of mortar specimens with the higher percentage of ash substitution. Optimum compressive strengths for the different substitution percentages were observed at 5%, 15% and 10% respectively for Ayous, Sapelli and Fraké. The best wood ash is Sapelli because of its chemical composition and resistance to compression in mortars. At 56 days, compressive strength values exceed those of the reference composition. This may be due to pozzolanic reactions in the mortars of ash.

Influence of zinc-containing compounds on the properties of ceramic materials based on the Li<sub>2</sub>O–MgO–Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> system

The results of a study the influence of magnesium oxide substitution with zinc oxide in the Li2O–MgO– Al2O3–SiO2 system, as well as the introduction of pre-synthesized ganite ZnAl2O4, on sintering, phase formation and thermal expansion of synthesized materials are presented. It was found that after substitution of 4 % magnesium oxide MgO with zinc oxide ZnO, the ceramic material synthesized at a temperature of 1 150 °C was characterized by higher values of apparent density (not less than 1 835 kg/m3), mechanical compressive strength (300 MPa), and heat resistance (more than 80 thermal cycles), as well as low values of LTEC (–0,25 ∙ 10–6 K–1), which is due to the formation of crystalline phases of spodumene, spinel, forsterite, corundum, ganite and quartz.

Rowanberry/vermiculite modified rigid polyurethane foams

Rigid polyurethane (PU) foams were modified with rowanberry/vermiculite fillers. The impact of fillers on selected properties of composites, such as rheological properties (dynamic viscosity, foaming behavior), mechanical properties (compressive and flexural strength, toughness), thermal properties (temperature of thermal decomposition stages, char residues at 600°C), flame retardancy (ignition time IT, total heat, and smoke release THR and TSR, maximum average rate of heat emission MARHE) was investigated. The results show that the incorporation of rowanberry/vermiculite fillers improves the properties of polyurethane foams. For instance, compared with the reference foam, modified foams showed increased synthesis times and higher values of apparent density, which then influenced the mechanical properties. Compared to the unmodified foam, modified foams showed an improvement in compressive strength (up to 7.8%, measured parallel to the foam growth direction), flexural strength (up to 5.8%), and toughness (up to 6.8%). Most importantly, the modified foams showed improved thermal stability and flammability parameters such as elongated ignition time, lowered values of THR, TSR, and MARHE parameters.

Optimization of Spark Plasma Sintering Technology by Taguchi Method in the Production of a Wide Range of Materials: Review.

This paper reviews the production of sinters using the spark plasma sintering method. SPS (spark plasma sintering) technology has been used for several decades, mainly in laboratories, to consolidate a huge number of both new and traditional materials. However, it is now more often introduced into practical industrial use, with equipment as early as the fifth generation capable of producing larger-size components at competitive costs. Although the mechanism of sintering with the use of this method is not yet understood, the effectiveness of the SPS process for the rapid and efficient consolidation of a wide range of materials with novel micro-structures remains indisputable. With a relatively wide variation in chemical composition, the structure allows the selection of appropriate consolidation parameters for these materials. The influence on the values of apparent density and mechanical properties depends on the parameters of the spark plasma sintering process. In order to achieve a density close to the theoretical density of sinters, optimization of the sintering parameters, i.e., sintering temperature, heating rate, sintering time, pressing pressure and protective atmosphere, should be carried out. In this paper, the optimization of spark plasma sintering of Si3N4-Al2O3-ZrO2 composite was carried out using the Taguchi method. The effects of four sintering factors, namely heating rate, sintering time, sintering temperature and sintering pressure, on the final density were investigated. Optimal sintering conditions were proposed and a confirmation experiment was conducted. The optimal combination of sintering conditions for spark plasma sintering (SPS) of Si3N4-Al2O3-ZrO2 composite for high apparent density was determined as A3-B3-C3-D2. Based on ANOVA analysis, it was found that the apparent density of sintering was significantly influenced by sintering temperature, followed by pressing pressure, sintering time and heating rate. Validation of the developed mathematical model predicting the apparent density of sinters showed close agreement between the predicted response results and experimental results.

Relationship between soil porosity and the apparent density of Astronium fraxinifolium (Anacardiaceae) wood

Summary Plants can modify their anatomy and physiology to improve their survival. Water stress is one of several factors that have been identified as potential wood modifiers. This study aimed to analyse whether soil physical properties and dioecy influence the wood density of Astronium fraxinifolium (Anacardiaceae). Samples of A. fraxinifolium trees were obtained from 20 male and 20 female individuals in two fields (an impacted area (IA) and a non-impacted area (NIA)) and the physical properties of soils from both areas were analysed. The apparent densities of the bark-to-bark wood samples were determined by X-ray densitometry. The apparent density values were calculated using QMS software. The IA soil showed lower porosity (macroporosity and microporosity) than the NIA soil. The wood densities of IA trees differed significantly, with IA trees having higher values than the NIA trees. The results indicated that trees growing in soils with low porosity and high soil bulk density had higher wood density. Based on the results of this study, which showed that species in areas with compacted soils had relatively high wood densities, it was concluded that A. fraxinifolium trees in environments with low water availability have dense wood with conducting vessels of large diameters. None of the wood features were influenced by the dioecy of A. fraxinifolium.

Production of perlite-based-aerated geopolymer using hydrogen peroxide as eco-friendly material for energy-efficient buildings

Using ground raw perlite through alkali activation to produce various construction materials such as plaster, grouting, and concrete can provide economic and environmental advantages by reducing Portland cement consumption. It is aimed to produce cementless pastes and cementless mortars based on the alkali activation of raw perlite and standard sand for this study. Perlite and alkali activators (NaOH and Na2SiO3) were used as binding materials to produce cementless paste and mortar. In addition, aerated lightweight pastes and mortars were produced using hydrogen peroxide (H2O2) as a blowing agent. Thus, the aeration mechanism of the sample was examined, and the changes in apparent density, compressive strength, and flexural strength values were determined. At the same time, the thermal conductivity properties of aerated paste and mortars were investigated. Geopolymers in various Water/Perlite and H2O2/Perlite ratios were produced, and their thermal conductivity, apparent density, compressive and flexural strength were contrasted. The experimental finding revealed that adding 0.25% H2O2 (by mass of perlite) to the mixtures enabled the production of lightweight pastes and mortars with lower density and lower thermal conductivity coefficient without a significant loss of ultimate strength. The developed perlite based aerated geopolymer is a eco-friendly and energy efficient solution to the buildings. Based on the results, H2O2/Perlite% above 0.5% and water/Perlite% above 45% should be avoided for both paste and mortars. In order to obtain optimum results in terms of workability, strength, density, and thermal conductivity, it is recommended that the H2O2/Perlite ratio for all samples should be 0.25% and the Water/Perlite percentage should be 40%.

Physicochemical and techno-functional properties of mixtures of Michigan bean protein concentrate (Phaseolus vulgaris L): maltodextrin

The objective of this research was to evaluate some physicochemical and techno-functional properties of mixtures of Michigan bean protein concentrate: maltodextrin. The beans were cleaned and hulled, then dried (55 °C/1 h), ground to obtain the flour, then the concentrate was obtained by the isoelectric precipitation technique. The mixtures were established based on preliminary tests with a maximum concentration of 60% bean protein concentrate, 0:100, 9:91, 30:70, 51:49, 60:40 w/w, bean protein concentrate:maltodextrin, respectively. The chemical composition proximal to the flour and concentrate was determined, while the pH color, apparent density and the techno-functional properties were made to the mixtures, in addition to the flour, concentrate and maltodextrin. The protein concentrate presented the highest water absorption capacity (4.46 g/g) and the highest apparent density (0.66 g/cm3). Maltodextrin and the 60:40 mixture were the ones that presented the lowest apparent density values (0.52 g/cm3). The flour presented the highest emulsifying capacity (39.60%), while the 0:100 mixture did not present water absorption capacity and lower oil absorption capacity (2.08 g/g). The 9:91 mixture presented the highest oil absorption capacity (2.68 g/g) and the lowest emulsifying capacity (7.44%). The flour presented a pH of 6.68 while the concentrate and the mixtures presented similar values (4.43). These studies indicate that flour and concentrate or protein concentrate:maltodextrin mixtures can be used as ingredients for the production or development of new food products, or their possible use as wall material in microencapsulated.

On the feasibility of using Sm2Fe17Nx powders obtained via HDDR process for laser powder bed fusion of bonded permanent magnets

Powders to be used as the main feedstock component for additive manufacturing processes, such as Laser Powder Bed Fusion (LPBF) technique, must present suitable technological properties, mainly high values of apparent density (AD) and flow rate (FR). These features are directly related to particle size, morphology, and size distribution. Although these issues have already been addressed to feedstocks based on Nd-Fe-B powders, the potential use of Sm-Fe-N powder as a raw material for feedstock processes has been scarcely explored thus far. If on one hand it is well established in the literature that Sm-Fe-N particles should be small (≈ 2 μm) to present sufficiently high values of intrinsic coercivity (Hcj, > 700 kA/m), on the other hand, however, smaller particles exhibit AD and FR values that are not appropriate for use in LPBF. An alternative to circumvent this apparently conflicting situation is to refine the microstructure of the particles in order to increase coercivity, instead of reducing particle size itself, which could be achieved via Hydrogenation-Disproportionation-Desorption-Recombination (HDDR). Considering this context, the main objective of this work is to study the feasibility of using Sm2Fe17Nx-based powders produced via the HDDR process followed by nitrogenation to obtain as-printed bonded magnets by the LPBF process. AD and FR of sieved powders with two distinct granulometry (< 45 μm and 45 < x < 63 μm) were evaluated. The obtained HDDR Sm-Fe-N powders presented values of Hcj = 683–777 kA/m, comparable to commercial nanocrystalline powders obtained by melt spinning. Powders were mixed with polyamide-12 (PA12) powder and used as feedstock to obtain bonded magnets by the LBPF technique. Microstructural properties of the as-printed bonded magnets were analyzed by Scanning Electron Microscopy (SEM). The effect of the LPBF process on the structural and magnetic properties of HDDR Sm-Fe-N powders was evaluated by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). Both coarser and finer powders presented no structural modifications or reduction in magnetic property values after the laser processing. However, denser as-printed bonded magnets were obtained using the coarser one, emerging as a potential candidate to be used as feedstock in LPBF process.

Effects of termal treatment on the physical properties of Buchenavia sp. (branquilho) wood

Abstract This work aimed to evaluate the effect of heat treatment on the physical properties of wood from Buchenavia sp. The heat treatments were carried out at temperatures of 180 °C and 200 °C for 2 h. Apparent density (AD), basic density (BD), porosity (Ф), mass loss, longitudinal (LS), radial (RS), tangential (TS) and volumetric (VS) shrinkages and anisotropic factor (AF) were determined. The lowest values of basic density (0.67 g cm-3), apparent density (0.77 gcm-3), and porosity (43.3%) were observed for the wood treated at a temperature of 200 °C. Mass losses increased with increasing temperature and the highest values were observed under the condition of 200 °C (9.3%). The LS and AF was not affected by heat treatments. The mean values for RS (3.1%), TS (5.1%), and VS (9.1%) were reduced after the performance of heat treatments at temperatures of 180°C and 200°C, which did not differ from each other. The thermal treatments were able to reduce the dimensional instability of Buchenavia sp. Thermal treatments enhance the use of less prestigious Amazonian woods in the civil construction market.

Deciphering microstructure-defect-property relationships of vacuum-sintered binder jetted fine 316 L austenitic stainless steel powder

Austenitic 316 L stainless steel (SS) powder with a mean particle size of 10.7 µm was binder jetted followed by vacuum sintering to study microstructure-defect-property relationships. It was demonstrated that supersolidus liquid phase sintering (SLPS) facilitated densification to attain a final relative density of 99.4% at 1400 °C for 2 h. Surface topology analysis revealed an average surface roughness of 1.0 µm and a trace number of open-to-surface pores in agreement with the apparent Archimedes density values. Microstructure analysis of the samples sintered at temperatures ≥ 1370 ℃ displayed the formation of equiaxed austenitic grains with a mean size of ∼33 µm in which δ-ferrite (eutectic phase enriched in Cr and Mo) and σ (intermetallic compound of Fe-Cr-Mo) phases formed at the grain boundaries. Anisotropy shrinkage was seen with a maximum linear shrinkage of 18.4%, 17.7%, and 21.5% in X- , Y- , and Z- directions, respectively. Mechanical testing results showed a yield strength of 202 MPa, tensile strength of 574 MPa, elongation of 90%, and microhardness of 132 HV 0.5 at the optimum sintering temperature of 1400 °C. Finally, fractography revealed a brittle-ductile fracture when porosity was more than 10% (sintered at <1370 °C) while a failure containing a combination of deep dimples (sintered at 1400 °C) as well as secondary central cracks and parabolic dimples (sintered at 1430 °C, due to a high shear fracture) was detected in the sintered parts that possess densities above 99%.

An open-access plug-in program for 3D modelling distinct material properties of cortical and trabecular bone

BackgroundFinite element modelling the material behavior of bone in-silico is a powerful tool to predict the best suited surgical treatment for individual patients.ResultsWe demonstrate the development and use of a pre-processing plug-in program with a 3D modelling image processing software suite (Synopsys Simpleware, ScanIP) to assist with identifying, isolating, and defining cortical and trabecular bone material properties from patient specific computed tomography scans. The workflow starts by calibrating grayscale values of each constituent element with a phantom – a standardized object with defined densities. Using an established power law equation, we convert the apparent density value per voxel to a Young’s Modulus. The resulting “calibrated” scan can be used for modeling and in-silico experimentation with Finite Element Analysis.ConclusionsThis process allows for the creation of realistic and personalized simulations to inform a surgeon’s decision-making. We have made this plug-in program open and accessible as a supplemental file.

Chitosan-Gelatin Films Cross-Linked with Dialdehyde Cellulose Nanocrystals as Potential Materials for Wound Dressings.

In this study, thin chitosan-gelatin biofilms cross-linked with dialdehyde cellulose nanocrystals for dressing materials were received. Two types of dialdehyde cellulose nanocrystals from fiber (DNCL) and microcrystalline cellulose (DAMC) were obtained by periodate oxidation. An ATR-FTIR analysis confirmed the selective oxidation of cellulose nanocrystals with the creation of a carbonyl group at 1724 cm−1. A higher degree of cross-linking was obtained in chitosan-gelatin biofilms with DNCL than with DAMC. An increasing amount of added cross-linkers resulted in a decrease in the apparent density value. The chitosan-gelatin biofilms cross-linked with DNCL exhibited a higher value of roughness parameters and antioxidant activity compared with materials cross-linked with DAMC. The cross-linking process improved the oxygen permeability and anti-inflammatory properties of both measurement series. Two samples cross-linked with DNCL achieved an ideal water vapor transition rate for wound dressings, CS-Gel with 10% and 15% addition of DNCL—8.60 and 9.60 mg/cm2/h, respectively. The swelling ability and interaction with human serum albumin (HSA) were improved for biofilms cross-linked with DAMC and DNCL. Significantly, the films cross-linked with DAMC were characterized by lower toxicity. These results confirmed that chitosan-gelatin biofilms cross-linked with DNCL and DAMC had improved properties for possible use in wound dressings.

Environmentally-benign rigid polyurethane foam produced from a reactive and phosphorus-functionalized biopolyol: Assessment of physicomechanical and flame-retardant properties

In the present study, after the epoxidation reaction of sunflower oil (SF) was optimized using a response surface methodology (RSM) of central composite design (CCD), the oxirane ring-opening reaction of epoxidized SF was carried out with 1,4-butanediol, and consequently, the SF-based biopolyol (14BD-pol) was obtained. A novel and reactive phosphorylated biopolyol (DPP-14BD-pol) was synthesized using the Atherton-Todd reaction of diphenyl phosphite (DPP) with the 14BD-pol. The DPP-14BD-pol was characterized in detail and a series of environmentally-benign RPUFs were fabricated using one-shot and free-rising methods with the partial substitution of DPP-14BD-pol (10, 25, 50 php). The obtained bio-RPUFs were assessed through the effect of the increasing amount of DPP-14BD-pol on the morphology, physicomechanical, thermal, and flame retardant properties. With the increase in DPP-14BD-pol addition, the apparent density and compressive strength values of bio-based RPUFs increased from 43.1 to 46.7 kg/m3 and from 239 to 260 kPa, respectively. The thermal conductivity values of bio-based RPUFs varied between 27.49 and 28.14 mW/m.K. The cellular structures were in polyhedral form, and the cell size distributions were quite homogeneous. The LOI values slightly improved from 19.3% to 20.5% up to the amount of 50 php DPP-14BD-pol. These results show that DPP-14BD-pol can partly replace the petroleum-based polyol to synthesize water-blown bio-based RPUFs with the properties that meet the demands of the polyurethane industry.

Synthesis and mechanical behavior of poly (vinyl alcohol) / poly (vinyl acetate) microspheres

ABSTRACT In this work, the effect of an organic solvent (tert-butanol) during the polymerization of vinyl acetate (VAc) on the structural and elastic properties of poly(vinyl alcohol)/poly(vinyl acetate) microspheres fabricated by the suspension polymerization method was investigated. As a result, two types of microspheres were obtained: without tert-butanol (Ms-P) and with tert-butanol (Ms-T), the later was added during the polymerization. For the experimental conditions used in this work, both types of Ms had spherical shape. Also, Ms-P exhibits a size distribution ranging from 10 µm to 1200 µm with an apparent density value ~1.18 ± 0.03 g/cm3, a solid structure and a saponification grade α ~ 0.8. In turn, Ms-T shows a size distribution between 400 and 1900 µm, porous structure, a lower density value ρ ~ 0.87 ± 0.03 g/cm3 and α ~ 0.5. The mechanical tests performed on Ms-P and Ms-T in three different conditions (dry, suspended in distilled water and saline solution) showed Young’s modulus (E) values of 569 ± 162 MPa (dried), 8 ± 9 MPa (distilled water), 11 ± 9 MPa (saline solution) for Ms-P measured up to 30% of deformation. For Ms-T, 242 ± 63 MPa (dried), 0.52 ± 0.08 MPa (distilled water), 0.9 ± 0.5 MPa (saline solution) values were obtained. Thus, we have found that the E values for Ms-T are more than one order of magnitude lower than for Ms-P. Also, it was observed that keeping Ms in an aqueous medium helps decrease the E value. This work shows that the ability to control the structural and elastic properties in Ms employing addition to an organic solvent gives the possibility of tuning its behavior for possible use in the treatment of embolization and chemoembolization.

Innovative use of thermally treated cement-asbestos in the production of foaming materials: Effect of composition, foaming agent, temperature and reaction time

The management of asbestos-containing wastes in European Union (EU) is still based on landfilling, which, in the long term, may pose a problem of dispersion of their carcinogenic fibres into the air and water. Therefore, solutions based on inertization of asbestos fibres and subsequent recycling are preferred. In this study, following the principles of circular economy, thermally treated cement-asbestos (KRY·AS) and glass wastes (RG) were used as main raw materials to manufacture foam glass, given its potential to incorporate waste materials. However, the low carbon compound content of both raw materials and the high amount of thermostable crystalline phases contained in KRY-AS made the introduction of foaming agents and powerful fluxing agents necessary. Contrary to what was expected, the addition of Na2CO3 as fluxing agent was observed to be ineffective in the tested compositions, because of the devitrification of crystalline phases, namely åkermanite (Ca2MgSi2O7) and combeite (Na2Ca2Si3O9), which reduced the formation of vitreous phase, limiting the foaming process. Li2CO3 as alternative fluxing agent was chosen, despite being aware of its current higher cost. The methodology developed has allowed to investigate the influence of the RG:KRY·AS ratio, the type and content of the fluxing agents and the content and size of the foaming agent (SiC), to establish the optimum firing conditions (maximum temperature and soaking time), as well as to unveil the main foaming mechanisms involved. Finally, specimens with good properties were obtained with a composition with high waste material content, namely (values in weight) 55% RG, 40% KRY-AS, 5% Li2CO3 as fluxing agent and 2.5% SiC-1500 as foaming agent, when fired at temperatures and soaking times of 1100 °C and 1 min respectively. The obtained product presented values of apparent density (0.55–0.68 g/cm3) and compressive strength (0.56 MPa) comparable with those reported in the literature for foam glasses obtained from wastes and close to commercial foam glasses. Despite the technical and economic limitations of the process, this work opens up new possibilities in a circular economy context for waste materials which encountered serious problem to be recycled and mostly ended up in landfills.

Synthesis and Sulfation with Sulfamic Acid of Aerogels Based on Birch-Wood and Cotton Celluloses

Firstly, the structure and properties of cellulose aerogels produced from birch-wood and cottoncellulose and of, and products of their sulfation with a non-toxic sulfamic acid-urea complex in an environmentally safe solvent – a mixture of polyethylene glycol and sodium hydroxide are compared. Aerogels based on birch and cotton celluloses have similar values of apparent density (0,071–0,078 г/см3) and porosity (near 95 %). The products of sulfating of cellulose aerogels, in contrast to the originalbirch and cotton celluloses, are completely soluble in water. Their yield and degree of substitution are higher when using birch cellulose aerogel. By drying the dissolved products of sulfating of cellulose aerogels, smooth and transparent films were produced. The structure and morphology of the obtained aerogels and films were established by metods of scanning electron microscopy and atomic force microscopy. Birch cellulose aerogel (BCA) has a reticular microfibrillated porous structure, and cotton cellulose aerogel (CCA) has a spongy structure in which more cavities and cracks are observed than in the case of CCA. The surface of the film of sulfated BCA is formed by particles with a length 100–200 nm and width of 50–70 nm, and the films of sulfated CCA is formed by spherical particles with a diameter of 70–100 nm. The developed methods for obtaining sulfated cellulose films can be used in medicine to oreate anticoagulant coatings

Evaluation of Techniques for Intensifying the Process of the Alcoholic Extraction of Coffee Ground Oil Using Ultrasound and a Pressurized Solvent.

Ultrasound-assisted extraction (UAE) and pressurized liquid extraction (PLE) techniques were evaluated and compared with conventional extraction for obtaining spent coffee ground oil (SCGO). The use of absolute ethanol (ET0) and hydrated ethanol (ET6) as solvents, two levels of SCG mass ratio:solvent, 1:4 (U4) and 1:15 (U15), and ultrasound powers of 0, 200, 400, and 600 W were tested. ET0 and U15 resulted in higher extraction yields of SCGO (YSCGO, 82%). A positive effect of sonication on YSCGO was observed only for condition U4. UAE resulted in defatted solids (DS) with higher apparent density values, corroborating the increase in the amount of smaller diameter particles due to sonication. The micrographs showed changes in the surfaces of the solids from the UAE and PLE, although the crystalline structures of the DS were not altered. UAE and PLE, compared to conventional extraction, did not allow significant gains in terms of YSCGO and, consequently, in the number of contact stages in an extractor configured in cross-currents.

Synergistic enhancement effect of recycled fine powder (RFP) cement paste and carbonation on recycled aggregates performances and its mechanism

The recyled aggregate (RA) prepared from construction and demolition (C&D) waste is used for concrete materials, which helps to save natural resources and solve the problem of construction waste disposal. However, the defects of RA with the loose surface, cracks, and pores limit its resource utilization in building materials. In this study, RA was reinforced by wrapping with recycled fine powders (RFP) cement paste. On the basis, the synergistic effect of RFP cement paste and carbonation on the performance of RA was studied, and its strengthening mechanism was also analyzed. The results showed that the apparent density and crush value of RA were improved to some extent after RFP cement paste treatment, but the water absorption was increased significantly. RA showed a more significant effects after the synergistic treatment of 20% RFP cement paste and carbonation: the apparent density of RA increased by 5.6% and the crushing value decreased by 44.87%, while the water absorption increased by only 11.2%. Microscopic analysis showed that the treated RA with RFP cement paste and carbonation to generate a large amount of calcium silicate hydrate (C–S–H) gels and CaCO3 products, which filled the pores, microcracks, and interfacial transition zone (ITZ) of RA and also reinforced the loose particles on the RA surface. The parameters showed that the porosity of RA decreased by 25.1%, and the CaCO3 content increased from 11.1% (only wrapped paste treatment) to 20.75% (synergistic treatment). Adding an appropriate amount of RFP can not only save cement and reduce cost, but also improve the strengthening effect.