Search Results (1,004)

As a non-volatile diterpenoid, oridonin represents the major bioactive compound in the medicinal plant Isodon rubescens (Hemsl.) Hara. This compound exhibits a broad range of pharmacological activities, including potent anticancer effects against various tumor types, as well as antibacterial and anti-inflammatory properties. Although the pharmacological properties of oridonin have been extensively characterized, its exact tissue-level distribution in leaves has yet to be elucidated. In this study, histochemical staining, desorption electrospray ionization mass spectrometry imaging (DESI–MSI), and dichloromethane-targeted extraction coupled with high-performance liquid chromatography (HPLC) were employed to determine the cellular distribution of oridonin in I. rubescens leaves. Histochemical staining with Hydrochloric acid–vanillin (HCl–vanillin) revealed intense fluorescence signals exclusively in peltate glandular trichomes, with no detectable fluorescence in mesophyll cells. DESI–MSI analysis showed that the characteristic ion signal of oridonin (m/z = 387.15) exhibited a punctate distribution pattern closely matching the spatial arrangement of glandular trichomes. Quantitative HPLC analysis demonstrated that oridonin content in glandular trichome extracts accounted for 77.44% of that in whole-leaf extracts, whereas mesophyll extracts contained only 10.20%, suggesting that glandular trichomes serve as the primary storage site. Furthermore, bioactivity assays revealed that glandular trichome-enriched extracts exhibited significant antibacterial activity against Bacillus subtilis, Micrococcus luteus, and Staphylococcus aureus, and showed cytotoxic effects on A549 human lung adenocarcinoma cells, with activity levels positively correlated with oridonin content. These convergent lines of evidence provide evidence that glandular trichomes are the main accumulation and storage sites of oridonin in I. rubescens leaves, and that trichome-stored oridonin constitutes the primary material basis for the antibacterial and cytotoxic activities of this plant. This study provides a cellular-level basis for the quality evaluation and breeding of high-oridonin I. rubescens varieties. Full article

Oxidative stress-induced macrophage activation and vascular injury are major contributors to atherosclerosis, a chronic inflammatory disease associated with approximately 20 million deaths worldwide. This study investigated the antioxidant and anti-inflammatory activities of structurally characterized low-molecular-weight chitosan oligosaccharides (COS) derived from mud crab (Scylla olivacea) shell waste by hydrochloric acid hydrolysis and explored their molecular interactions with inflammation-related targets. Structural characterization by ¹³C-NMR and MALDI-TOF confirmed the identity of COS, while DPPH and ABTS analysis demonstrated concentration-dependent antioxidant activity. In LPS-induced RAW 264.7 macrophages, COS showed no cytotoxicity and significantly reduced nitric oxide production at 80 and 160 µg/mL. Molecular docking predicted favorable interactions of COS with several inflammation-associated proteins, with iNOS and COX-2 exhibiting the most favorable docking scores and extensive hydrogen-bonding and polar interactions. Transcriptomic profiling further revealed broad transcriptional remodeling and enrichment of pathways related to inflammation and atherosclerosis, including TNF, NF-κB, MAPK, Toll-like receptor, and lipid-and-atherosclerosis signaling. COS markedly suppressed inflammatory mediators, particularly Nos2 (iNOS) and Ptgs2 (COX-2) together with multiple cytokines and chemokines, consistent with reduced nitric oxide production and modulation of macrophage activation and foam cell-associated processes. Integration of docking and transcriptomic analyses identified iNOS and COX-2 as convergent candidate anti-inflammatory targets of COS, supporting its ability to attenuate inflammatory signaling through relevant pathways. These findings suggest that COS may modulate macrophage inflammatory responses through coordinated regulation of oxidative stress and inflammation-related signaling pathways. Full article

The reuse of expired pharmaceuticals as corrosion inhibitors offers a sustainable strategy for reducing pharmaceutical waste while providing environmentally friendly alternatives to conventional inhibitors. In this work, the corrosion inhibition performance of expired ibrutinib (EIB) for P110 carbon steel in 1.0 M HCl was investigated using electrochemical techniques, mass loss measurements, surface characterization, and computational approaches. Electrochemical impedance spectroscopy (EIS) revealed a progressive increase in charge-transfer resistance with increasing inhibitor concentration, while potentiodynamic polarization (PDP) measurements demonstrated that EIB acts as a mixed-type inhibitor with a predominant anodic effect. At 1000 mg L⁻¹, inhibition efficiencies of 88.7%, 96.8%, and 93.3% were obtained from EIS, PDP, and mass loss measurements, respectively. SEM analysis confirmed the formation of a compact and homogeneous protective film on the steel surface, significantly reducing corrosion damage and surface roughness. Density functional theory (DFT), Natural Bond Orbital (NBO), Monte Carlo (MC), and molecular dynamics (MD) simulations demonstrated strong adsorption of EIB on the Fe(110) surface through nitrogen- and oxygen-containing active centers, while radial distribution function analysis confirmed the contribution of chemisorption. The excellent agreement between the experimental and theoretical results demonstrates that expired ibrutinib is an efficient and sustainable corrosion inhibitor for P110 carbon steel in acidic environments and represents a promising approach for the valorization of expired pharmaceutical products. Full article

Spent titanium chlorinator melt is a potential technogenic source of scandium, but its recovery is complicated by high contents of iron, aluminium and alkali and alkaline-earth chlorides. This study assessed a sequence of hydrochloric acid leaching, Fe(III) reduction with ascorbic acid, sorption on the strong-acid cation exchanger Lewatit MonoPlus SP112H, desorption with acidified ammonium sulfate solution, oxalate precipitation, calcination and an additional column purification. In a scaled-up test, leaching of 4 kg of the spent melt with 5% HCl produced 25.5 L of filtrate containing 475.30 mg Sc. Two-stage sorption recovered 90.9% of the scandium, and the overall desorption degree reached 94.8%. The kinetic data were better described by the non-linear pseudo-second-order model (R² = 0.890–0.938). Precipitation and calcination gave 0.60 g of an intermediate oxide product with 65.0 wt% Sc, and the additional purification 0.45 g of a final oxide product in which X-ray diffraction identified cubic Sc₂O₃ as the predominant crystalline phase; the elemental analysis gave a purity close to 98 wt%. Recovery into the final oxide reached 61.92% of the scandium in the filtrate. Iron co-sorption and scandium losses during the additional purification remained the principal limitations of the process. Full article

The occurrence characteristics of impurities and the precise technologies used for their removal are the main factors limiting the high-end applications of quartz sand. To simultaneously achieve ultrahigh purity and a high yield while incorporating a sustainable waste acid treatment strategy, quartz sand (SP1) from India was selected as the research material. A stepwise experimental scheme involving single-acid and mixed-acid treatments was adopted to optimize the purification conditions, incorporating a complete process of pretreatment, acid leaching, and post-treatment along with a defined waste liquid management method. The raw SP1 quartz samples and samples treated under the optimal acid-washing conditions were characterized through qualitative and quantitative analyses, including X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and inductively coupled plasma mass spectrometry. The optimal result for the single-acid system was obtained by treating quartz sand with 70 mL of hydrofluoric acid at 120 °C for 2 h, resulting in a purity of 99.9963%. For the mixed-acid system, the volume ratio of hydrofluoric acid, hydrochloric acid, and nitric acid was maintained at 1:6:2, and acid leaching was performed at a constant temperature of 120 °C for 5 h. Under these conditions, the aluminum and iron contents were reduced to 15.23 and 0.15 μg/g, respectively, while the purity and production yield of the acid-washed quartz sand reached 99.9964% and 82.11%, respectively. Based on comprehensive consideration of the purification effectiveness and process economy, an HF:HCl:HNO₃ volume ratio of 1:6:2 and an acid-washing reaction time of 5 h were selected, providing a stable purity exceeding 99.996%. This study provides a theoretical and technical basis for the standardized and sustainable production of high-purity quartz sand. Full article

The durability of alkali-activated materials (AAMs) in acidic environments is a key factor governing their suitability as sustainable alternatives to ordinary Portland cement (OPC). This study investigates the acid resistance of fly ash–slag alkali-activated mortars prepared with either seawater-based or distilled water-based activator solutions, thereby addressing the feasibility of substituting potable water in activator preparation. Eleven binder blends were tested, ranging from 100% fly ash (F100G0) to 100% ground granulated blast furnace slag (GGBS, F0G100) in 10% replacement increments, each prepared with both distilled-water (D-series) and seawater-based (M-series) activator solutions. Mortar cubes were exposed to hydrochloric acid (HCl) and sulphuric acid (H₂SO₄) after curing for 28, 60, 90, and 180 days. Durability was assessed through mass change, compressive strength retention, and ultrasonic pulse velocity (UPV), complemented by X-ray diffraction (XRD) analysis to elucidate mineralogical transformations. Results showed that acid resistance was governed primarily by binder composition: calcium-rich slag (C–A–S–H) systems deteriorated mainly by decalcification under acid exposure, whereas low-calcium fly ash (N–A–S–H) systems degraded more slowly by dealumination. Seawater activation did not significantly compromise acid resistance relative to distilled-water systems, with the two-activator series performing comparably under both HCl and H₂SO₄. Paired comparisons of the reported blend values showed small, age-dependent differences between the two-activator series: seawater activation modestly delayed strength loss under HCl at intermediate ages, while under H₂SO₄ it carried a small late-age penalty attributable to reaction of activator-derived chloride compounds with the acid; at most ages, the two series were statistically indistinguishable. X-ray diffraction showed essentially identical phase assemblages in the two series: no crystalline products formed under HCl, where an amorphous silica-rich residue accumulates on fly-ash-rich blends, whereas gypsum was the sole crystalline product under H₂SO₄, enhanced in seawater-activated fly-ash-rich blends. The findings clarify the role of marine ions in influencing acid degradation and provide guidance for designing sustainable binder systems for chloride- and sulphate-rich service environments. Overall, seawater is shown to be a viable substitute for potable water in activator preparation, retaining acid resistance comparable to distilled-water systems and supporting the development of more sustainable alkali-activated binders. Full article

Hydrochloric acid is conventionally used to pre-hydrolyse starch before periodate oxidation into dialdehyde starch (DAS), which may generate chloride-containing waste. This study proposes a sustainable one-step hydrolysis–oxidation route using acetic acid, a biodegradable organic acid, evaluating reaction time (24–72 h) to maximise aldehyde content while minimising acid hazard. Acetic-acid-derived DAS (24 h) achieved a significantly higher aldehyde content than the HCl route (59.57 ± 0.55% vs. 49.91 ± 1.00%; p < 0.001). This DAS was applied as a covalent crosslinker in chitosan/poly(vinyl alcohol) films loaded with Artemisia herba-alba extract, benchmarked against a non-crosslinked film. Crosslinking increased tensile strength (67.1 vs. 51.5 MPa) and crystallinity (40.83% vs. 17.04%), reduced porosity, and slowed extract release in phosphate-buffered saline (27.5% vs. 41.9% at 168 h; Weibull model, Adj. R² ≥ 0.97) while preserving predominantly Fickian diffusion. Despite releasing less extract, the crosslinked film retained significantly higher DPPH radical-scavenging activity, consistent with hemiacetal interactions between residual aldehydes and extract phenolics. Antibacterial testing against six clinical strains suggested that crosslinking modulates rather than suppresses activity. These findings support acetic-acid-mediated DAS synthesis as a low-hazard, waste-reducing route toward bioactive, controlled-release biopolymer films as promising candidates for future biomedical or active-packaging applications. Full article

Background: With the growing popularity of golf, the wood consumption and white pollution caused by traditional wooden and plastic golf tees create an urgent need for green, degradable, high-performance alternatives. Materials and Methods: To address this, a novel approach for the green fabrication of high-performance composites was developed utilizing a single agricultural solid waste (chestnut shells) bridged by an extremely low proportion (4 wt%) of a thermoplastic agent (polylactic acid, PLA). A mild dilute hydrochloric acid hydrothermal pretreatment selectively removed hemicellulose to expose active hydroxyl groups, followed by a wet hot-pressing process optimized at 80 °C, 4 h, 15 MPa, and 180 mesh. Results: Under these conditions, the resulting CS-APLA composite tees exhibited a bending strength of 86.32 ± 6.46 MPa and a dynamic impact toughness of 104.89 ± 5.26 kJ/m², representing significant increases of 64.86% and 41.69%, respectively, compared to the pure biomass material, and outperforming conventional commercial wooden tees. A 75-day soil burial test demonstrated a weight loss of approximately 45.42%, confirming a balanced degradation rate. Conclusions: Multi-scale characterization confirmed that the synergistic reinforcement relies objectively on an acid-treatment-induced hydrogen-bonding network coupled with in situ polymer-bridged microdomains formed by PLA flow filling during hot-pressing. This study provides a sustainable route for the high-value utilization of agricultural solid waste. Full article

Lignocellulosic fruit peel waste represents an abundant, carbon-neutral feedstock for green biohydrogen production via dark fermentation, yet its rigid compact structure and high cellulose crystallinity severely restrict saccharification and fermentative hydrogen yield. In this study, a hydrothermal acidification pretreatment strategy was proposed to boost dark fermentative biohydrogen generation from navel orange peel waste, and systematic investigations were conducted to reveal the regulating mechanisms of key pretreatment parameters (hydrochloric acid concentration, pretreatment temperature, duration) on reducing sugar release and hydrogen-producing performance. Multiscale characterizations including SEM, XRD, FTIR, and TG were integrated to unravel the microstructural and chemical compositional evolution of raw and pretreated substrates. The results demonstrated that hydrothermal acidification effectively disrupted the dense lignocellulosic network of navel orange peel, lowered cellulose crystallinity, and greatly improved substrate accessibility for hydrolytic reactions and microbial adhesion. Under the optimal pretreatment condition (1.0 mol/L HCl, 120 °C, 1 h), the concentration of released reducing sugars reached 10.2 g/L, which was 67.2% higher than that of untreated raw peel. The corresponding maximum cumulative hydrogen yield attained 36.5 mL H₂/g TS, representing a 67.4% improvement relative to the untreated control group. Pearson correlation analysis verified that pretreatment temperature, acid concentration, and duration exhibited strong positive correlations with hemicellulose and cellulose removal efficiencies, while excessive pretreatment (HCl > 1.0 mol/L, temperature > 120 °C, duration > 1 h) generated inhibitory by-products that suppressed microbial hydrogen evolution. This study comprehensively clarifies the structural modification and biohydrogen promotion mechanism of hydrothermal acidification pretreatment on pectin-rich biomass, and delivers a cost-effective, facile technical route for high-value energy valorization and harmless disposal of fruit processing solid wastes. Full article

Pectin is a naturally occurring biopolymer extensively used for applications in the pharmaceutical, biotechnology, and food industries, and is abundantly present in lemon by-products. Although lemon peels represent a highly promising raw material, the structure of pectin is strongly influenced by extraction and drying processes, and the resulting attributes remain insufficiently understood. The present study systematically investigates the impact of conventional hot acid extraction using three different acidifying agents (citric, sulphuric, and hydrochloric) in combination with two drying techniques (oven-drying and freeze-drying) on the physicochemical, structural, thermal, and viscosity–shear rate properties of pectin obtained from lemon by-products (Citrus limon, Portuguese Eureka variety) following the prior recovery of bioactive compounds (essential oils and phenolic compounds). The results demonstrated that citric acid extraction followed by freeze-drying yielded the highest pectin recovery, at approximately 26.7%, highlighting the suitability of this approach for efficient by-product valorisation. Oven-dried pectins exhibited higher moisture contents (8.5–10%) and lower lightness values (L* = 57.02–65.67), indicating darker colouration compared to freeze-dried pectins (L* = 78.82–83.75). All extracted pectins presented a degree of esterification (DE ≥ 50%), classifying them as high-methoxyl pectins. The galacturonic acid (GalA) content ranged from 37.6 to 48.9% for oven-dried samples and increased to 44.1–58.6% for freeze-dried samples. Furthermore, pectin obtained from lemon by-products exhibited a well-defined structural organisation and enhanced thermal stability, especially for freeze-dried pectin samples, and suitable rheological properties, with no statistically significant variations observed between different acids or drying conditions, supporting its technological suitability for applications in the food, cosmetic, and pharmaceutical industries. Full article

This study evaluated the chemical and mechanical stability of recycled polyethylene terephthalate (rPET) fibers produced by rotary die extrusion under selected aqueous exposure conditions. The rPET fibers, natural wool, cotton batting, and a polyester and cotton apparel fabric were exposed to powder detergent, liquid soap, bleach, and dilute hydrochloric acid for periods ranging from 2 h to 7 days. Mass retention was assessed for all materials, whereas tensile properties were evaluated only for rPET. The rPET fibers retained between 99.92 and 100% of their initial mass and more than 95% of their initial tensile strength after 7 days of exposure. Wool showed its greatest mass loss in bleach, while cotton batting and apparel fabric showed measurable mass losses under specific exposure conditions. These reference materials differed in composition and physical form and were therefore used only to provide descriptive context. Overall, the results indicate high mass retention and tensile property retention of the investigated rPET fibers under static exposure at 25 °C. The findings support their potential use in textile applications requiring resistance to the tested aqueous environments but do not establish molecular chain integrity or equivalence with virgin PET. Full article

The uptake of textile dyes from water using activated carbon has become a key topic because of its fast sorption capacity, easy handling, and high removal efficiency. Biomass-based activated carbon is a good adsorbent because of its easy accessibility and renewability. In this study, the adsorption capacity of activated carbon from potato peel waste was investigated. The potato peels were carbonized at 550 °C and activated with three different acids, namely hydrochloric acid (HCl), nitric acid (HNO₃), and sulfuric acid (H₂SO₄). The prepared adsorbents were analyzed for their adsorption capacity to remove methylene blue (MB) and methyl orange (MO) from water. Although chemical activation by various acids has already been explored by other researchers, there are few studies in which potato peel waste has been converted to carbon and used for the uptake of MO dye. The adsorbents were characterized using XRD, FTIR, and SEM. Effects of pH, time, temperature, and dye concentration were investigated. The data from the isotherms indicated that the uptake of MB takes place on heterogeneous surfaces and MO on homogeneous surfaces. The thermodynamic parameters for both dyes showed that both the ΔS° and ΔH° values were negative, indicating that the sorption process of MB and MO on all adsorbents was exothermic and that the randomness increased during the removal process. ΔG° values indicated that physisorption was important during the sorption process. This work shows a great possibility of activated carbon from potato peels for the uptake of dyes. Full article

NdFeB waste is an important rare earth secondary resource, and the current industrial practice primarily employs a hydrochloric acid preferential dissolution method to recover rare earth elements (REEs). However, approximately 1% of REEs (e.g., cerium oxide, neodymium oxide, praseodymium oxide, and dysprosium oxide) remain in the leaching residue, resulting in low recovery efficiency. This work puts forward mechanochemical leaching (integrating mechanical activation and acid leaching) to replace traditional agitated leaching, which realizes synchronous mechanical activation and acid leaching within a stirred ball mill. A systematic comparison is conducted between these two leaching technologies, and the influences of operational variables on rare earth leaching efficiency are explored. The experimental results reveal that sustained mechanical grinding can pulverize particles down to the submicron level, induce substantial lattice distortion and amorphous transformation, destroy the physical coating of rare earth-bearing phases by iron oxides, and thereby drastically improve the extraction efficiency of REEs. The optimal conditions were determined as follows: stirring speed of 700 r/min, leaching temperature of 85 °C, HCl concentration of 1 mol/L, leaching time of 180 min and solid–liquid ratio of 100 g/L. Furthermore, this study reveals the synchronous evolution mechanism of particle refinement and phase transformation during mechanochemical leaching, providing an alternative and more economical recycling route for NdFeB waste. Full article

AISI 316L austenitic stainless steel is extensively used in petrochemical storage and processing equipment because of its excellent corrosion resistance. However, exposure to concentrated hydrochloric acid severely destabilizes its passive film, promoting active dissolution and localized corrosion. This work investigates the corrosion behavior of AISI 316L stainless steel in hydrochloric acid solutions of 7.2, 9.6, and 12 M at room temperature. Cyclic potentiodynamic polarization (CPP) tests were performed according to ASTM G61, and the corrosion morphology was characterized using optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and metallographic cross-sections. The electrochemical results revealed an active dissolution regime characterized by the absence of a stable passive region and positive hysteresis loops in all HCl solutions, indicating irreversible surface damage and poor repassivation. The corrosion current density increased from the order of 10⁻¹ mA cm⁻² in 7.2 and 9.6 M HCl to the order of 10¹ mA cm⁻² in 12 M HCl, demonstrating a significant acceleration of the corrosion kinetics. SEM and cross-sectional analyses confirmed the development of localized pitting corrosion, with pit depths reaching approximately 0.87 mm. The results demonstrate that concentrated hydrochloric acid promotes the coexistence of generalized active dissolution and localized pitting corrosion, while increasing HCl concentration modifies the morphology and propagation mode of the pits. Full article

Isolating rhenium and molybdenum selectively from multicomponent acidic hydrometallurgical solutions remains problematic because of the abundance of competing cations and the low concentration of target oxoanions. This study investigates the sorption of Re(VII) and Mo(VI) oxoanions by an interpolymer system (IPS) comprising a cellulose–polyethyleneimine–glutaraldehyde (Cellulose-PEI-GA) weak-base anion exchanger and a sulfonated styrene–divinylbenzene cation-exchange resin (Lewatit MonoPlus SP112H), operating as spatially separated but solution-coupled phases. The industrial feed, a sulfuric acid leach liquor from electrostatic precipitator dust at the Zhezkazgan copper smelter, Kazakhstan (pH 1.25), was pretreated by liquid–liquid extraction with a trialkylamine-2-ethylhexanol–kerosene system followed by ammonia stripping to give an alkaline re-extract (pH 11.98) used for sorption. At the optimal 1:1 mass ratio of the two components (3:3), the IPS achieved a rhenium recovery of 77.7% (Kd = 3678 mL g⁻¹, q = 4.51 mg g⁻¹) against a markedly lower molybdenum recovery of 24.0% (Kd = 333 mL g⁻¹), giving a Re/Mo separation factor β of 8.8–15.5 across the studied compositions; this uptake exceeded the value predicted from the individual sorbents by a factor of ~2.6, indicating a cooperative rather than purely additive effect. Sorption kinetics (pseudo-first-order, pseudo-second-order and Elovich models) and diffusion mechanisms (Weber–Morris and Boyd models) were consistent with mixed film- and intraparticle-diffusion control. Desorption with hydrochloric acid recovered 91.4% of the sorbed rhenium and 89.1% of the molybdenum, and FTIR, TGA, and BET analyses (surface area increasing from 1.93 to 8.62 m² g⁻¹ for the cellulose component and from 7.21 to 8.46 m² g⁻¹ for the resin) confirmed sorbate-induced textural and compositional changes consistent with the proposed complementary anion-/cation-exchange mechanism. Full article