Amorphous Part Research Articles

Binary dyes adsorption onto novel designed magnetic clay-biopolymer hydrogel involves characterization and adsorption performance: Kinetic, equilibrium, thermodynamic, and adsorption mechanism

Nowadays, the treatment of dyes and pigments was considered a serious challenge in the world. In this work, a novel high-performance magnetic bio-based κ-carrageenan-kaolinite hydrogel (CKAlFe) was designed, characterized, and used for the simultaneous adsorption of Alizarin red and Congo red dyes from an aqueous solution. The morphological characterization revealed the successful preparation of non-rigid and plate-like CKAlFe adsorbent with the microporosity structure, in which the κ-carrageenan forms the amorphous part and kaolinite clay, Al2O3, and Fe3O4 are involved in the crystalline part of the structure. It was found as an efficient adsorbent with maximum adsorption capacities of 26.9 and 33.5 mg/g toward Congo red and Alizarin red molecules respectively. The adsorption capacity of CKAlFe was decreased in acidic media. The adsorption kinetics followed the pseudo-second-order kinetic model. The intra-particle diffusion controlled the adsorption rate at low initial concentrations, while the transfer rate of molecules from solution to the surface of CKAlFe played this role at higher concentrations. Also, the adsorption isotherm followed the extended Langmuir isotherm model. The thermodynamic study demonstrated that Congo red and Alizarin red binary adsorption onto CKAlFe was endothermic and spontaneously occurred, while Alizarin red molecules required more energy than Congo red to be adsorbed and a higher fraction of the active sites were occupied by Congo red molecules. The mechanism study showed that multiple interactions including π-π stacking, electrostatic interaction, dipol-dipol H bonding, and Yoshida H bonding can be involved in the adsorption process of studied dyes onto CKAlFe. Besides, the isosteric enthalpy of adsorption revealed that the adsorption type varied from physical to chemical process, increasing the amount of adsorbed dyes. The prepared magnetic hydrogel is highly capable of being used in drug delivery for selectively detection, hyperthermia/thermal ablation, and different products already on the market.

Recent Trends in the Preparation of Nano-Starch Particles.

Starch is affected by several limitations, e.g., retro-gradation, high viscosity even at low concentrations, handling issues, poor freeze–thaw stability, low process tolerance, and gel opacity. In this context, physical, chemical, and enzymatic methods have been investigated for addressing such limitations or adding new attributes. Thus, the creation of biomaterial-based nanoparticles has sparked curiosity. Because of that, single nucleotide polymorphisms are gaining a lot of interest in food packaging technology. This is due to their ability to increase the mechanical and water vapor resistance of the matrix, as well as hide its re-crystallization during storage in high-humidity atmospheres and enhance the mechanical properties of films when binding in paper machines and paper coating. In medicine, single nucleotide polymorphisms (SNPs) are suitable as carriers in the field of drug delivery for immobilized bioactive or therapeutic agents, as well as wastewater treatments as an alternative to expensive activated carbons. Starch nanoparticle preparations can be performed by hydrolysis via acid hydrolysis of the amorphous part of a starch molecule, the use of enzymes such as pullulanase or isoamylase, or a combination of two regeneration and mechanical treatments with the employment of extrusion, irradiation, ultrasound, or precipitation. The possibility of obtaining cheap and easy-to-use methods for starch and starch derivative nanoparticles is of fundamental importance. Nano-precipitation and ultra-sonication are rather simple and reliable methods for nanoparticle production. The process involves the addition of a diluted starch solution into a non-solvent, and ultra-sonication aims to reduce the size by breaking the covalent bonds in polymeric material due to intense shear forces or mechanical effects associated with the collapsing of micro-bubbles by sound waves. The current study focuses on starch nanoparticle manufacturing, characterization, and emerging applications.

Thermal study on cotton candy by differential scanning calorimetry

Cotton candy is a confection made by solidifying melted sugar into fibers. Differential scanning calorimetry (DSC) was performed for two kinds of cotton candy made in an air (CCA) and in a nitrogen gas (CCN) and for crystalline sucrose (CS) and its quenched melt as amorphous sucrose (AS). The CCA was mainly crystalline with a small amorphous part and easily degraded by aging. The CCN exhibited a more glassy structure, and its aging behavior was different from that of the CCA. Gas conditions in cooking were found to be crucial to the physical state and thermal stability of cotton candy.

Effect of alfa fiber loading on the mechanical, physical and dielectric properties of epoxy-amine composite

In this work, a varied content of alfa fiber was used as reinforcement and epoxy resin as matrix material. In order to eliminate the amorphous part of the alfa fiber, the fibers are treated with 5% of sodium hydroxide solution and their weight fraction is varied between 10% and 30%. Dielectric and water characteristics of different content of untreated and alkali treated alfa reinforced epoxy matrix is carried out in order to determine the role of cellulosic fibers in electrical field. Then, the Fourier transform infrared (FTIR) is employed to analyze the chemical structure of epoxy resin before and after curing with amine hardener. FTIR and Differential Scanning Calorimetry analysis confirm that epoxy resin is completely cured with amine hardener at room temperature. For composites loaded with 30% treated and untreated alfa fiber, a decrease in tensile and dielectric properties has been obtained, this may be related to the random distribution of alfa fiber in the epoxy matrix. Scanning electron microscopy analysis highlight the microstructure of epoxy matrix and its composites. The bio composites elaborated on the basis of alfa fiber and epoxy matrix have good physical and dielectric properties can be applied in different fields.

Study of visible, NIR, and MIR spectroscopic properties of Er3+‐doped tellurite glasses and glass–ceramics

AbstractIn this paper, the structural, thermal, optical, and spectroscopic properties of Er3+‐doped tellurite glasses with the composition 68.25TeO2–19.5ZnO–9.75X–2.5Er2O3 (in mol%) with X = BaO, Na2O, and Bi2O3 are reported. The glasses were prepared using the standard melt quenching method. The investigated glasses exhibit low phonon energy (∼745 cm−1) and low glass transition temperature varying between 300 and 350°C depending on the glass composition. The Raman spectra show a regular tellurite structure with variations in the number of bridging and non‐bridging oxygens depending on the glass composition, the Na2O and Bi2O3‐containing glasses having the most and the least polymerized network, respectively. A thermal treatment of the glasses leads to the formation of crystals, the composition of which depends on the glass composition, as revealed by X‐ray diffraction analysis and confirmed using scanning electron microscope‐energy‐dispersive spectroscopy. The precipitation of Er‐containing crystals in the Na2O and BaO‐containing glasses leads to an increase in the intensity of the upconversion emissions. Although the Er3+ ions remain in the amorphous part of the Bi2O3‐containing glass after heat treatment, it is the precipitation of Bi3.2Te0.8O6.4 crystals in this glass, which is thought to decrease the distance between the Er3+ ions leading to an increase in the intensity of the upconversion and mid‐infrared emissions.

(INVITED)Transparent Er3+ doped Ag2O containing tellurite glass-ceramics

Transparent Er3+ doped Ag2O containing tellurite glass-ceramics were fabricated by melting process followed by a heat treatment at 20 °C above the glass transition temperature of the glass for 2 to 17 h. The effects of the crystallization on the optical and luminescence properties of the glasses are presented and discussed. The precipitation of Bi4TeO8 crystal was confirmed in all the glasses, independently of their composition. From the spectroscopic properties, the heat treatment was found to have no impact on the site of the Er3+ ions indicating that the Er3+ ions remain in the amorphous part of the glass-ceramic. Although Ag nanoparticles could be evidenced using transmission electron microscopy and nonlinear optical imaging, no surface plasmon resonance band of Ag nanoparticles appeared in the absorption spectrum of the heat treated glasses. No enhancement of the NIR emission centered at 1.5 μm was observed probably due to the low concentration of Ag nanoparticles precipitating in the glasses. However, an increase in the intensity of the upconversion and mid-infrared emissions was observed from the glass-ceramics prepared with the low amount of Ag2O (<1 mol%). As evidenced using Raman spectroscopy, the addition of Ag2O was found to depolymerize the tellurite network. The precipitation of the Bi4TeO8 crystal in the most polymerized glasses is suspected to reduce the Er–Er distances whereas it has no significant impact on the Er–Er distances in glasses with a depolymerized network.

MACROSTRUCTURE OF CROSS SECTION OF BLAST-FURNCACE SLAG SAMPLES IN IRON MELTING WITH DUST-COAL FUEL INJECTION

The macrostructure of blast furnace slag cross section samples during melting of pig iron with pulverized coal fuel injection on three blast furnaces with a volume of 1500 and 1386 m3 (2 units) was studied. The range of changes in the basicity of the studied slag samples (СаО/SiO2) was 0.98—1.30; corresponding to the temperature samples of cast iron and its silicon content ranged from 1324—1510 °С and 0.13— 1.17 %. To identify blast furnace slag samples in specific operating conditions, the samples were basically divided into five groups from acidic (В1&lt;1,0) to highly basic (В1&gt;1,25). By its physical heating characterictics the cast iron was divided into 3 groups: cold (&lt;1400 °С ); heated (1400—1480 °С ); hot (&gt;1480 °С ). According to chemical heating, the division was also carried out into three groups: cold (&lt;0.5% Si); heated (0.5—0.8) hot (&gt; 0.8). The look of cross section surface of acidic and low-basic slag is the same for former slag regime and the new, due to the use of coke and pulverized fuel with limited sulfur; in conditions of normal heating the cross section is vitreous, shiny dark color. When cooled, the vitreous and luster of cross section of such slags disappears — the chip becomes stone-like gray or black with some difference in the formation of macropores in the sample mass. Common for slag samples with В1&gt;1,1 is a decrease in the vitreous amorphous part with increasing modulus of basicity. The difference for such slags in comparison with those known for melting in other raw material conditions is the lack of clear delimitation of layers in the cross section of the samples, especially noticeable for half-slags. It is established that the macrostructure of slag samples apart from the main В1 and furnace heating is influenced by the magnitude of the alumina-magnesium modulus; this fact should be taken into account in the operational control of the blast furnace for external conditions. It was also found that the deviation of the basicity towards acidic or highly basic slags was accompanied by the absorption of coal dust particles by slag melt. The properties of samples in terms of fluidity and desulfurizing ability of corresponding slags are considered.

Miscibility and rigid amorphous phase in blends of polypropylene with poly(propylene‐co‐ethylene)

AbstractThermal and mechanical properties of binary blends of polypropylene (PP) with a statistical copolymer (85 wt% propylene and 15 wt% ethylene, abbreviated here as VM) have been investigated. Both components were found to be miscible in the melt in the whole range of compositions. No separate domains of VM have been detected by polarizing optical microscopy, and the size of spherulites is going down with increasing VM content. The crystallization temperature of PP as detected by DSC, is going down to 83°C, for PP/VM blends 10:90. This is another evidence for miscibility in the melt. Viscoelastic properties of the melt were measured. Regarding the solid state, the melting enthalpy is exactly proportional to the PP content in the blend. The DSC step height at the glass transition is exactly proportional to the VM content. These results are suggesting a three‐phase model (crystalline, rigid amorphous, and mobile amorphous phase), where the VM component is mainly located in the mobile amorphous regions, while the amorphous part of PP is in the rigid amorphous regions. Stress–strain curves show a systematic increase of elongation at break with increasing VM%, to be extended from 7.8% to more than 550%.

Towards a better understanding of synergistic enzyme effects during refining of cellulose fibers

Refining of cellulose fibers is essential for reaching desired paper properties, yet highly energy demanding. Enzymes like endoglucanases (e.g. EndoC) are increasingly used to reduce energy consumption during pulp refining. However, prediction of the enzyme effect is still a major concern, considering the high variety of commercially available enzyme formulations, containing a range of different enzymes. In this study, synergisms of xylanases and β-glucosidases in combination with endoglucanases purified from enzyme formulations were studied and related to their refining performance. Size exclusion chromatography with multi-angle laser light scattering (SEC-MALLS) of carboxymethylcellulose revealed that a narrow size distribution and a high reduction in molecular weight are beneficial characteristics for refining. SEC-MALLS of hardwood pulp resulted in pronounced formation of low molecular weight fractions (log MW 4.3) for most efficient refining enzymes. Application of enzyme formulations and combinations of endoglucanase EndoC with β-glucosidase or xylanase using Fourier-transform infrared spectroscopy (FTIR) revealed synergistic effects that promoted degradation of amorphous parts of cellulose. Laboratory refining trials on hardwood pulp confirmed the increase in degree of refining and tensile index after addition of xylanase and β-glucosidase. Surface plasmon resonance (SPR) analysis resulted in strong binding of endoglucanases to regenerated cellulose, which correlated to refining performance.

Unraveling Water-Mediated 31P Relaxation in Bone Mineral.

Bone is a dynamic tissue composed of organic proteins (mainly type I collagen), inorganic components (hydroxyapatite), lipids, and water that undergoes a continuous rebuilding process over the lifespan of human beings. Bone mineral is mainly composed of a crystalline apatitic core surrounded by an amorphous surface layer. The supramolecular arrangement of different constituents gives rise to its unique mechanical properties, which become altered in various bone-related disease conditions. Many of the interactions among the different components are poorly understood. Recently, solid-state nuclear magnetic resonance (ssNMR) has become a popular spectroscopic tool for studying bone. In this article, we present a study probing the interaction of water molecules with amorphous and crystalline parts of the bone mineral through 31P ssNMR relaxation parameters (T1 and T2) and dynamics (correlation time). The method was developed to selectively measure the 31P NMR relaxation parameters and dynamics of the crystalline apatitic core and the amorphous surface layer of the bone mineral. The measured 31P correlation times (in the range of 10–6–10–7 s) indicated the different dynamic behaviors of both the mineral components. Additionally, we observed that dehydration affected the apatitic core region more significantly, while H–D exchange showed changes in the amorphous surface layer to a greater extent. Overall, the present work provides a significant understanding of the relaxation and dynamics of bone mineral components inside the bone matrix.

Influence of ice formation on the dynamic and thermodynamic properties of aqueous solutions

Water dynamics in solutions with biological or non-biological solutes has been intensely studied when both components (solvent and solute) are amorphous. Here, we apply broadband dielectric spectroscopy combined with calorimetric measurements to analyze the dynamics of the aqueous solutions tri-propylene glycol (3PG) and ε-poly (lysine) (ε-PLL), after their water becomes semi-crystalline. Various crystallization levels were explored by conducting experiments with different annealing times at temperatures above the glass transition temperature (Tg). We find that the amount of ice depends on both the time and temperature of the annealing, and that this, in turn, affects Tg and dynamics of the amorphous part of the samples. However, it should be noted that the observed differences are relatively small for the degrees of crystallinity we have studied (up to about 26 wt% of the water). This also implies that the dynamic crossover of the water relaxation from a high temperature non-Arrhenius behavior to a low temperature Arrhenius dependence is unaffected by the partial crystallization and still occurs as a single crossover at the calorimetric Tg. Thus, we cannot detect two different crossovers, as commonly observed for other types of two-component systems, such as two glass formers.

Influence of precursor materials on the fresh state and thermo-chemo-mechanical properties of sodium-based geopolymers

Aluminosilicates are the base precursors that combined with alkali solutions manufacture geopolymers. A wide variability of aluminosilicate precursors can be found in the market worldwide, which may be an issue when proposing single designs. The goal of this study is to compare the use of different precursors in the hardening mechanisms of geopolymers. For this, two types of metakaolin (a low (MKLR) and a high-reactive (MKHR) one), and partial replacements made with fly-ash (FA) and blast furnace slag (BFS) are used in SiO2/Al2O3 = 4.00, Na2O/SiO2 = 0.25, and H2O/Na2O = 11.00 fixed design ratios. Fresh state (viscosity and squeeze flow), transient state (Vicat needle and sonic strength), and hardening measurements (compression tests under room and high temperature conditions), were used, supported by chemical analysis (calorimetry and SAM/HCl extraction) and materials characterization (particle analysis, density, BET and XRD). In general, the reactivity, chemical composition, and morphology of each precursor, as well as solid/liquid portions of each mix were major factors influencing the hardening process. The use of MKLR achieved shorter setting times and enhanced viscosities due to its particles larger surface area, solid/liquid ratios, and unreactive portions, reaching the highest values of strength and diminished thermomechanical performance. Partial substitutions made with FA and BFS increased the amorphous part of the binder, increasing also its flowability, setting time, and its stability to thermal exposure. The geopolymer made with MKHR presented the lowest viscosity and longer setting time due to its almost constant dissolution rate, attributed to its enhanced reactivity from highly amorphous parts and diminished solid-to-liquid ratio mixture. Therefore, the use of varied aluminosilicates significantly modifies the materials properties, leading to different potential applications that should be considered when designing geopolymers.

Response Surface Methodology Modeling, Experimental Validation, and Optimization of Acid Hydrolysis Process Parameters for Nanocellulose Extraction

Nanocellulose is one of the most significant nanomaterials that can be derived from lignocellulosic materials. The properties of nanocellulose make it a promising material for a variety of applications, including paper and paperboard production, antibacterial agents, coatings, cosmetics, drug delivery, soft tissue transplant, blood vessel replacements, and others. This study focuses on the extraction of nanocellulose from teff straw, which is an agricultural residue and locally available in Ethiopia. Nanocellulose was extracted by acid-chlorite delignification, alkali, and acid hydrolysis method. The effect of acid hydrolysis process parameters, sulfuric acid concentration, time, and the temperature was studied using response surface methodology. The central composite design was used to screen and adjust the design matrix with three factors and five levels. The optimum yield was 62.2% when acid concentration, time, and temperature were 44.4%v/v, 32 min, and 40.5 ° C respectively. The Analysis of variance (ANOVA) was carried out to identify the most significant factors that influence the percentage of nanocellulose yield. The Fourier-transform infrared (FTIR) result confirms the reduction and total removal of lignin, and the amorphous parts in straw. The average particle size determined by dynamic light scattering (DLS) was 101.6 nm with a polydispersity index of 0.047. From the X-ray diffractometer (XRD) result crystallinity index of straw and nano-cellulose was 47.7% and 77.1% respectively. The thermogravimetry analysis demonstrates the maximum temperature of nanocellulose and cellulose was 270 °C and 360 °C respectively. The Scanning electron microscopy (SEM) result implies the surface of nano-cellulose was improved by the chemical treatments.

Improving inner structure and properties of additive manufactured amorphous plastic parts: The effects of extrusion nozzle diameter and layer height

Material extrusion is an efficient additive manufacturing process for thermoplastic materials in the field of rapid prototyping, rapid tooling, rapid manufacturing and rapid repair. Parts to be additive manufactured of acrylonitrile butadiene styrene (ABS Terluran GP 35) with mechanical properties close to the data sheet specification of injection molded parts are in the focus of this study. An in-house process chain from the plastic pellets to the finished additive manufactured product is developed to monitor and to define the process parameters for each individual processing step using the terpolymer. By varying the parameters extrusion nozzle diameter and layer height, the production-related internal part structure and the surface topography of the additive manufactured tensile test specimens are improved in such a way that the mechanical property yield strength rises from 55% to 75% of the data sheet specification for injection molded ABS parts. The elongation at break increases from 42% up to 70% of the specified data. The smallest extrusion nozzle diameter in connection with the smallest layer height provide the densest internal part structure, the lowest surface roughness and the best mechanical properties. Especially the ductility was controlled by the manufacturing parameters since the number of pores introduced in the internal part structure determine the number of crazes. Apart from ductility, even with low layer height but larger extrusion nozzle diameter, the resistance to failure of the material extrusion manufactured parts improves significantly and saves manufacturing time by a factor of 10.

Dynamic organic mechanoluminescence (ML): The roles of Mechano-induced conformational isomer and energy transfer from ML to photoluminescence (PL)

Organic mechanoluminescence (ML), especially dynamic ML with color change along continuously grinding, is promising for mechano-dependent applications of lighting, imaging and sensors. Here, new insights for fine tuning ML feature from no, stable to dynamic characteristic, are reported by simply changing the substituted position of bromine atom on isomers of phenothiazine (PTZ) derivative (Br-BPZ). Additionally, three key factors, including mechano-induced conformation transformation, mixture formation of crystal and amorphous powders after ground as well as the energy transfer from ML of crystal part to photoluminescence (PL) of amorphous part inside, have been experimentally confirmed for promoting dynamic ML (an extremely rare kind of ML) of organic materials. These findings not only provide a strategy for design of organic ML but also develop a new application of colorful ML display without doping based on dynamic ML materials.

Amorphous-Crystalline Composite Microstructure Formation in Zr&lt;sub&gt;46&lt;/sub&gt;Cu&lt;sub&gt;46&lt;/sub&gt;Al&lt;sub&gt;8&lt;/sub&gt; Alloy at the Conditions of Selective Laser Melting

Amorphous alloys are promising structural materials because of their high mechanical strength. Their drawbacks are low ductility and severe size restrictions for components obtained by casting. Additive manufacturing by selective laser melting (SLM) consists in successive fusion of small portions of material to add to a growing part. Each portion is subjected to a short thermal cycle favorable for amorphization. Thus, one can build an amorphous part as large as necessary. We study the microstructure of cast samples of a zirconium-based bulk metallic glass after laser processing with the parameters typical for SLM. Scanning electronic microscopy has shown partial crystallization in the heat affected zone of the laser beam. The spatial distribution and the volume fraction of the crystalline phase can be controlled by laser processing parameters. The obtained amorphous-crystalline structures are promising to increase the ductility of bulk metallic glasses.

Molecular dynamics simulation of size dependent plastic deformation mechanism of CoCrFeNiMn crystalline/amorphous dual-phase high-entropy alloys

Recently proposed crystalline/amorphous dual-phase high-entropy alloy is an effective strategy to obtain high-entropy, high-strength and high-toughness alloys. And the relative plastic deformation mechanism is dependent on the size of component phases. The effect of component phase size on the plastic deformation mechanism of CoCrFeNiMn crystalline/amorphous dual-phase high-entropy alloy is investigated by molecular dynamics simulation. The results indicate that the size of amorphous phase has a significant effect on the mechanical behavior and plastic deformation mechanism of high entropy alloy. For the sample with small thickness of amorphous phase, the plastic deformation is dominated by dislocation slip and phase transformation of face-centered-cubic structure to hexagonal-close-packed structure. Especially, the deformation twins and Lomer-Cottrell locks are observed in the sample with amorphous layer spacing of 1 nm. When the thickness of the amorphous layer is moderate, the plastic deformation of the dual-phase high-entropy alloy is realized mainly through the dislocation slip, phase transformation of face-centered-cubic structure to hexagonal-close-packed structure in crystalline part and shear band multiplication in amorphous part. If the amorphous layer spacing is larger, the plastic deformation of the high-entropy alloy is dominated by the formation of uniform shear bands in the amorphous phase. In addition, the amorphous phase in the dual-phase high-entropy alloy structure can stabilize the crystalline grains. The results of this study can provide a guidance for designing and preparing high entropy alloy with high performance.

Magnetocaloric effect in amorphous-crystalline microcircuits PrDyFeCoB

In amorphous-crystalline PrDyFeCoB microconductors obtained by ultrafast melt cooling, a negative magnetocaloric effect was detected at 200-250 K (with heat release when the magnetic field is turned on), as well as a positive magnetocaloric effect in the temperature range of 300-340 K (with heat absorption when the magnetic field is turned on). It is established that there are no phase transitions of the first kind in the studied temperature range, which indicates that both of the detected effects are associated with a change in the magnetic part of the entropy. The transition at 200-250 K is due to the presence of metamagnetic states induced by a magnetic field in the spin-glass state of the amorphous part of the PrDyFeCoB alloy, and with their transition to the ferrimagnetic state. The transition at 300-340 K is spin-reorientation, and it occurs in crystalline inclusions identified in the amorphous matrix. Keywords: spin-reorientation transition, spin glass, magnetocaloric effect, entropy. Keywords: spin-reorientation transition, spin glass, magnetocaloric effect, entropy.

THE EFFECT OF MECHANICAL PROCESSING ON THE STRUCTURE OF CELLULOSE FROM HEMP

In the course of the research work, the influence of mechanical processing on the structural specificity of cellulose obtained by organo–solvent oxidation from cannabis, an annualraw material common in the East region, is considered. The features of the chemical structure and crystal structure of the modified cellulose were studied by the methods of IR-Fourier spectroscopy and X-ray diffractometry and surface morphology by the optical microscopy method. One solution to the widespread use of mechanical processing is to consider a new habit. The method of mechanical processing using a natural polymer modification is environmentally and cost-effective. Cellulose obtained by organo-solvent oxidation from a hemp was machined in a ball mill, using balls with a diameter of 10 mm, at room temperature, at a rotation speed of 300 rpm. It was confirmed that the chemical structure of the obtained cellulose has not changed using the IR spectrum. The results of X-ray diffractometry were processed by the Segal method, making sure that the crystallinity index (CI) increased from 58.6% to 65.2%. As a result, it turned out that mechanical activation using a ball mill increases the crystallinity index due to the destruction of amorphous parts without changing the chemical structure of cellulose. This result opens the way for the selective production of the really desired crystalline degree of cellulose by mechanical processing.

Extracting lithium from the H2SO4 leaching solution of bauxitic claystone via co-precipitation methods without addition of Al source

Newly mined bauxitic claystone resources have received attention due to the rapidly growing demand for lithium. However, existing methods for extracting lithium from bauxitic claystone are still difficult and costly. This study proposed a novel aluminum hydroxide precipitation method to improve the extraction rate of Li by cleverly utilizing Al from bauxitic claystone. First, the ball-milled and calcined bauxitic claystone samples were leached by sulfuric acid to obtain a leaching solution with a high concentration of Al3+. Then, a NaOH solution was added to form amorphous aluminum hydroxide to adsorb Li+. The precipitation rate of Li+ reached 97.2% under the suitable precipitation conditions. Lastly, the precipitate was calcined and leached with deionized water to extract lithium. Li+ reached a water-leaching rate of 86.13%. According to the X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) results, the prepared precipitate was mainly amorphous aluminum hydroxide and part was composed of a gibbsite phase. The elution experiment showed that the amorphous aluminum hydroxide had good adsorption selectivity for Li+. In addition, Al2O3 could be recovered from the solid phase after water-leaching, which can significantly reduce the cost.