Search Results (282)

Synthetic gypsum (SG) is produced in massive quantities, yet hazardous impurities limit its reuse. This review summarized the impurity types in various SGs and the corresponding removal methods. Physical methods, such as washing, screening, magnetic separation, and others, exploit solubility and size/density differences to remove soluble salts and particulates. Chemical methods, including acid leaching, precipitation/solidification, and so on, can dissolve or immobilize phosphates, fluorides, and heavy metals. Flotation utilizes the differences in the physicochemical properties of solid surfaces to remove insoluble impurities. The thermal treatment is mainly used to decompose organics and improve whiteness. Microbial methods achieve environmentally friendly cleanup through metabolic leaching or microbially induced carbonate precipitation. The phase-transformation method is a recently developed method that can achieve synergistic effects of deep impurity removal and high-value utilization by reconstructing gypsum crystals to release co-crystallized impurities. Most impurity-removal methods target only a single type of impurity. At present, purifying SG requires a combination of multiple methods, which is not recommended from a cost perspective. Subsequent research on removing impurities from SG should focus on simultaneously removing multiple major impurities in a single process, as well as the synergistic effects between impurity removal and the high-value utilization of gypsum. Full article

Tungsten is a critical metal for advanced industrial applications, yet its supply is challenged by the depletion of high-grade ores. This study presents a comprehensive optimization and mechanistic analysis of the alkaline fusion process for extracting tungsten from wolframite ((Fe,Mn)WO₄) using sodium carbonate (Na₂CO₃). Experimental investigations systematically evaluated the effects of alkali-to-ore ratio, reaction temperature (650–1000 °C), and reaction duration (30–270 min). Optimal conditions were established at a 2:1 Na₂CO₃-to-ore molar ratio, a reaction temperature of 750 °C, and a holding time of 30 min, achieving a tungsten extraction efficiency exceeding 99.9%. This represents a significant improvement in energy and process efficiency over conventional methods. A novel kinetic analysis reveals a two-stage reaction mechanism, transitioning from a slow, diffusion-controlled solid-state reaction (E_a = 243 kJ/mol) to a rapid, autocatalytic liquid-phase reaction (E_a = 212 kJ/mol) upon the formation of a Na₂WO₄–Na₂CO₃ eutectic above approximately 590 °C. The optimal temperature of 750 °C is rationalized as the point that ensures operation within this kinetically favorable liquid-phase regime. Furthermore, a thermochemical analysis of ore impurities indicates that silicon, lead, sulfur, and calcium are effectively sequestered into the slag phase as stable silicates, insoluble lead compounds, and sulfates, highlighting an intrinsic purification benefit. X-ray fluorescence (XRF) and X-ray diffraction (XRD) analyses confirmed minimal residual tungsten in the processed slag. This streamlined process, supported by a robust mechanistic understanding, reduces alkaline consumption, shortens reaction times, and maintains high yields, offering a sustainable and efficient pathway for leveraging declining wolframite resources. Full article

Coal gangue, a major industrial solid waste from coal mining and processing, requires efficient alumina and silica separation for high-value utilization. This study focused on mineral reaction mechanisms and characteristics of coal gangue during calcination and alkaline leaching. Results showed calcination at 900–1200 °C altered its phase composition, affecting silica separation efficiency, with the optimal calcination range being 960–1120 °C. Poorly crystallized mullite and Al₂O₃ in calcined gangue were insoluble under low-alkaline and low-temperature conditions. On the contrary, amorphous silica is soluble and forms a sodium silicate solution in the proper alkaline conditions. This characteristic facilitates the efficient separation of alumina and silica. It was determined that the suitable conditions for silica removal from coal gangue are as follows: 1080 °C calcination for 90 min, leaching at 75 °C with 200 g/L NaOH (solid–liquid ratio of 1:4) for 4 h. Under these selected conditions, the silica leaching efficiency was 77.31%, the alumina leaching efficiency was 12.21%, the Na₂O content in the leached residue was 1.94%, and the mass ratio of alumina to silica (A/S) in the leached residue increased from 0.88 to 3.42. A potential desilication mechanism was also analyzed. Full article

Efficient oxidation of refractory sulfides, such as dibenzothiophene (DBT) and its derivatives, provides a promising strategy to produce fuel oils with ultra-low sulfur content, or even completely sulfur-free. In this study, a series of non-stoichiometric molybdenum oxides (MoO_x) were synthesized via a facile procedure and employed as efficient catalysts. These catalysts can effectively oxidize DBT and its derivatives into insoluble sulfones, which subsequently precipitate from the oil phase, achieving efficient sulfur removal. In this system, molecular oxygen from air can be activated by the MoO_x catalysts with oxygen vacancies into superoxide radicals, which act as active oxygen species to efficiently oxidize refractory sulfides. Under atmospheric pressure at 120 °C, complete sulfur removal (100%) was achieved for both DBT and its derivatives, representing significantly milder conditions compared to conventional hydrodesulfurization. The aerobic oxidation system could be reused for up to 12 consecutive cycles without any significant decline in sulfur removal. And complete desulfurization (100%) was regained after a simple washing of the separated solid phase. Then, a possible reaction procedure was subsequently proposed to describe the desulfurization route. The remarkable catalytic performance, together with the facile synthesis strategy, indicates the potential of this approach for constructing other transition metal oxides used in various advanced aerobic oxidation reactions. Full article

Hierarchically porous polyaniline (PANI) was synthesized by oxidative copolymerization of tetrakis(4-aminophenyl)methane (TA) and aniline. Mixing TA with ammonium persulfate (APS) followed by aniline addition generated both tetra-arm star-shaped and linear PANIs; their insolubility in the reaction medium led to aggregation into solid precipitates. During assembly, linear PANI formed nanofibers, while star-shaped PANI created short branches on the nanofiber surfaces. The TA molar fraction in the feed governed morphology and properties: higher TA increased specific surface area and the mesopore fraction but decreased electrical conductivity. Balancing this porosity–conductivity trade-off identified PANI (TA 3%) as optimal, exhibiting the highest CV current response with pseudocapacitive profiles, with a specific capacitance of 556 F g⁻¹ versus 380 F g⁻¹ for pristine PANI. Device-level galvanostatic charge–discharge yielded 239 F g⁻¹ at 0.1 A g⁻¹ (vs. 199 F g⁻¹), while high-rate performance was limited by conductivity. These results show that introducing a small comonomer fraction to promote star-chain growth can produce hierarchical porosity and enhance pseudocapacitive behavior; further conductivity enhancement is expected to improve high-rate capacitance. Full article

Due to the presence of insoluble dietary fibre (IDF), DF-enriched products have a lower consumer acceptance compared to those prepared using a regular formulation. The objective of this review was to focus on a comprehensive utilization of enzymes for improving the DF-enriched dough rheology and bubble dynamics via the regulation of intermolecular interactions between DF, starch granules, and gluten proteins. Xylanase was used to promote the interactions between water-extractable arabinoxylan (WEAX) and gluten proteins, leading to a stronger gluten network and dough liquid film around gas bubbles. Cellulase was applied to promote the breakdown of cellulose, mitigating the adverse impacts of IDF on the gluten structure. Glucose oxidase (GOx) was utilized to facilitate disulfide bond (S-S) formation between gluten proteins, thereby enhancing the gluten strength, gas retention capacity, and bubble stability of dough during processing. Amylase incorporation promoted bubble expansion of high-fibre dough. In conclusion, the review established a solid theoretical framework on how an unpredictable evolution for the rheological behaviour and bubble dynamics of dough during processing could be modified via the complicated interactions involving enzymes and biopolymers. This will contribute to a high-quality development for the fibre-enriched product industry, and also a sustainable promotion of regular DF consumption. Full article

Fats, oils, and grease (FOG) deposits are hardened, sticky, insoluble solids that accumulate in sewage systems globally. These deposits contribute to pipe blockages and sanitary sewer overflows, releasing pathogens and pollutants into the environment, posing significant environmental and public health risks. Current removal methods are labor-intensive and costly, emphasizing the need for alternatives. While biological strategies offer a viable alternative, the microbial breakdown of FOG is poorly understood. In this study, we evaluated the potential of individual microbial strains and synthetic microbial communities to biodegrade wastewater-derived FOG deposit samples. These biological agents were applied to a range of FOG samples, and biodegradation was assessed through visual observations such as color change or gas bubbles, particle size, cell counts, pH, weight loss, and changes in fatty acid profile. Results demonstrate that microbial augmentation can enhance FOG degradation, offering an alternative or complementary approach for reducing maintenance burdens and preventing sewer blockages. Full article

Elastin is the principal protein found in the elastic fibers of vertebrate tissues, and the water within these fibers plays a crucial role in preserving the structure and function of this hydrophobic protein. Soluble elastin was successfully obtained by repeatedly treating insoluble elastin, extracted from pig aorta, with oxalic acid. Solid-state NMR analysis was performed on the soluble elastin, focusing on conformation-dependent chemical shifts of alanine residues. This analysis revealed that cross-linked alanine residues exhibited both α-helix and random coil structures in the dry state. In contrast, the hydrated state favored random coil structures, with some distorted helices possibly present, indicating that the cross-linked configuration is relatively unstable. Similar conformational changes were observed in insoluble elastin, mirroring those found in the soluble form. Additionally, when the soluble elastin was re-cross-linked using 1,12-dodecanedicarboxylic acid and 4-hydroxyphenyl dimethylsulfonium methylsulfate, it retained a mixture of α-helix and random coil structures in the dry state. Remarkably, in the hydrated state, α-helix structures were more prominently preserved alongside random coils. These structural changes corresponded with increased stiffness of molecular chains in the hydrophobic regions compared to their state prior to re-cross-linking, even under hydrated conditions. Full article

Background/Objectives: Prodrug strategies are a vital aspect of drug development, with ester prodrugs particularly notable for modifying parent drug properties through ester functional groups to enhance oral absorption. However, ester prodrugs are prone to hydrolysis by water and enzymes, making stability in the gastrointestinal (GI) tract prior to absorption a key challenge. Few formulation strategies effectively address this degradation issue. We recently introduced binary lipid systems (BLS), comprising a lipid and a water-soluble surfactant only that form stable microemulsions. This study aimed to explore the application of BLS for enhancing the oral absorption of ester prodrugs by coating drug crystals with BLS in solid granules and study the impact of the compositions of BLS on oral absorption. Methods: Olmesartan medoxomil (OLM), a methyl ester prodrug of olmesartan (OL), was selected as a model drug. Various lipids were combined with TPGS to form BLS and used to prepare OLM solid granules containing OLM crystals. Results: Among the tested formulations, OLM MCM-TPGS granules significantly enhanced drug release and protected OLM from enzyme-mediated degradation in two-step dissolution studies with esterase. Pharmacokinetic and tissue distribution studies in rats confirmed that OLM MCM-TPGS granules improved oral absorption by 145% and increased tissue uptake compared to OLM powder. Conclusions: This approach overcomes solubility limitations when using lipids and surfactants as excipients, enabling high drug loading in solid dosage forms and expanding the utility of lipids and surfactants for water-insoluble drugs. This novel formulation strategy holds great potential for enhancing oral absorption of ester prodrugs, representing a significant advancement in formulation technologies and offering more effective and versatile drug delivery solutions. Full article

Water-reducing admixtures are of enormous importance to adjust the workability of alkali-activated materials. Especially in geopolymers activated by highly concentrated alkaline solutions, the polycarboxylate ether (PCE) superplasticizers are less effective than in conventional cementitious systems. The aim of this study was to clarify the reasons for the lower dispersing performance of PCE and the synthesis of alternative dispersing agents based on the biopolymer starch to improve the workability of highly alkaline geopolymers. Furthermore, the focus of investigations was on the role of activator type and concentration as key parameters for geopolymer reaction and interaction of water-reducing agents. Therefore, in this study the conformation of three different types of PCE (MPEG: methacrylate ester, IPEG: isoprenol ether, and HPEG: methallyl ether) and synthesized starch admixtures in sodium and potassium hydroxide solutions (1 mol/L up to 8 mol/L) were studied. Furthermore, the dispersing performance, adsorption behavior, and influence on reaction kinetics in metakaolin-based geopolymer pastes were investigated in dependence on activator type and concentration. While the PCE superplasticizers show coiling and formation of insoluble aggregates at activator concentrations of 3 mol/L and 4 mol/L, the synthesized starch admixtures show no significant change in conformation. The cationic starch admixtures showed a higher dispersing performance in geopolymer pastes at all activator concentrations and types. The obtained adsorption isotherms depend strongly on the activator type and the charge density of the starch admixtures. The reaction kinetics of geopolymer pastes were not significantly influenced using the synthesized starch admixtures. Especially the cationic starch admixtures allow the reduction of liquid/solid ratios, which leads to higher flexural and compressive strengths. Full article

Background/Objectives: Betulin is a promising agent in many areas of medicine and is being investigated, particularly in the field of cancer. However, in in vivo experiments, its water insolubility becomes a significant obstacle. This study describes a promising method for the administration of betulin in in vivo experiments and the determination of betulin levels in organ samples. Methods: Betulin was first dissolved in ethanol, and this solution was then mixed with acylglycerols, followed by evaporation of the ethanol. Olive oil and food-grade lard were determined to be suitable lipids for noninvasive application per os. A method for processing the organs of experimental animals for betulin determination was developed. Determination of betulin levels in blood is also likely the only viable option for use in future clinical studies and practice. Results: The maximum amount of betulin usable (i.e., absorbable by organisms) in olive oil (10 mg/mL), suppository mass (6 mg/mL), food lard (4 mg/mL), and cocoa butter (2 mg/mL) carriers was found microscopically. A specific distribution of betulin concentration in the organs of experimental animals (Wistar rats) after a weekly diet containing betulin was discovered. The blood was shown to be particularly advantageous, as it allows continuous monitoring of betulin levels in the body. In these pilot experiments, a statistically significant (p < 0.001) synergistic effect of betulin on solid Ehrlich adenocarcinoma tumors was observed when betulin was combined with cytostatic Namitecan (NMRI mice). The high-purity betulin used in this study is very stable even under fluctuating storage conditions. Conclusions: Our study suggests that both the method of betulin administration and the proposed analytical procedure could greatly increase the reliability and reproducibility of in vivo studies, as well as future preclinical and clinical studies on the effects of betulin and potentially other similar water-insoluble triterpenoids on living organisms. Full article

An ultrasonic-enhanced hydrogen peroxide water-washing process was developed to recover lead from raw flue dust (RFD) under neutral conditions. At optimal parameters (40 °C, 30 min, 4 mL H₂O₂, liquid-to-solid ratio 2:1, 240 W ultrasound), the Pb mass fraction in the solid residue increased from 41.68% in the RFD to 68.11%, accompanied by a Pb recovery rate of 97.1%. These values are significantly higher than those obtained under identical conditions without ultrasound (64.07% and 95.93%, respectively). Ultrasound promotes de-agglomeration and generates •OH radicals that accelerate the oxidation of PbSO₃ to insoluble PbSO₄ while concurrently removing impurity cadmium. This research offers a green and efficient alternative to traditional lead recovery methods, fostering sustainable development in the metallurgical industry. Full article

The present article aims to develop a technological scheme for processing zinc ferrite residue, which typically forms during the leaching of zinc calcine. This semi-product is currently processed through the Waelz process, the main disadvantage of which is the loss of precious metals with the Waelz clinker. The experimental results of numerous experiments and analyses have verified a technological scheme including the following operations: sulfuric acid leaching of zinc ferrite residue under atmospheric conditions; autoclave purification of the resulting productive solution to obtain hematite; chloride leaching of lead and silver from the insoluble residue, which was produced in the initial operation; and cementation with zinc powder of lead and silver from the chloride solution. Utilizing such an advanced methodology, the degree of zinc leaching is 98.30% at a sulfuric acid concentration of 200 g/L, with a solid-to-liquid ratio of 1:10 and a temperature of 90 °C. Under these conditions, 96.40% Cu and 92.72% Fe form a solution. Trivalent iron in the presence of seeds at a temperature of 200 °C precipitates as hematite. In chloride extraction with 250 g/L NaCl, 1 M HCl, and a temperature of 60 °C, the leaching degree of lead is 96.79%, while that of silver is 84.55%. In the process of cementation with zinc powder, the degree of extraction of lead and silver in the cement precipitate is 98.72% and 97.27%, respectively. When implementing this scheme, approximately 15% of the insoluble residue remains, containing 1.6% Pb and 0.016% Ag. Full article

Agriculture and its related industries produce annually a vast amount of byproducts and waste which comprise a large proportion of global waste. Only a small percentage is managed with environmentally acceptable procedures, while a large proportion is either incinerated or discarded into nearby open fields, causing serious environmental burdens. Since these byproducts exhibit a rich nutritional and phytochemical content, they may be considered as raw materials for various industrial applications, initiating the need for the development of sustainable and eco-friendly methods for their valorization. Among the various methods considered, Solid-State Fermentation (SSF) constitutes an intriguing eco-friendly bioprocess, being suitable for water-insoluble mixtures and providing products with improved stability and depleted catabolic suppression. Thus, there are several literature studies highlighting the aspects and efficacy of SSF for improving the nutritional and phytochemical contents of diverse agro-industrial waste. The review herein aspires to summarize these literature results with a special focus on the enhancement of their antioxidant potency. For this purpose, specific keywords were used for searching multiple scientific databases with an emphasis on the most recent studies and higher impact journals. The presented data establish the usefulness and efficacy of the SSF bioprocess to obtain fermentation products with enhanced antioxidant profiles. Full article

Background: The growing demand for nutritionally balanced, gluten-free products has encouraged the development of innovative formulations that deliver both sensory quality and functional benefits. Combining rice and legume flours offers promising alternatives to mimic gluten-like properties while improving nutritional value. This study aimed to develop a gluten-free fusilli noodle using extruded flours based on mixtures of Japanese rice (JR) and chickpea (CP) particles. Methods: A 2³ factorial design with augmented central points was applied to evaluate the effects of flour ratio (X₁, CP/JR, 20–40%), feed moisture (X₂, 24–30%), and extrusion temperature (X₃, 80–120 °C) on responses from process properties (PPs), extruded flours (EFs), and noodle properties (NPs). Results: Interaction effects of X₃ with X₁ or X₂ were observed on responses. On PP, X₁ at 120 °C reduced the mechanical energy input (181.0 to 136.2 kJ/kg) and increased moisture retention (12.0 to 19.8%). On EF, X₁ increased water-soluble solids (2.3 to 4.2 g/100 g, db) and decreased water absorption (8.6 to 5.7 g/g insoluble solids). On NP, X₁ also affected their cooking properties. The mass increase was greater at 80°C (140 to 174%), and the soluble-solids loss was greater at 120 °C (9.3 to 4.5%). The optimal formulation (X₁–X₂–X₃: 40–30%–80 °C) yielded noodles with improved elasticity, augmented protein, and enhanced textural integrity. Conclusions: Extruded flours derived from 40% chickpea flour addition and processed under mild conditions proved to be an effective strategy for enhancing both the nutritional and technological properties of rice-based noodles and supporting clean-label alternative products for gluten-intolerant and health-conscious consumers. Full article