Search Results (125)

Rice bran protein (RBP) is an important plant protein, but its functional properties are reduced due to the presence of disulfide bonds in the structure. Polyphenol modification is an effective strategy to improve protein functional properties. However, the interactions between quercetin (Que) and RBP have not been well-studied. In this study, we explored the mechanism of non-covalent interactions between RBP and Que and systematically evaluated the improvement of functional properties of the RBP–Que complex. The results revealed that the addition of Que can significantly affect the particle size, ζ-potential and protein flexibility of the RBP–Que complex, and the non-covalent interactions significantly altered the secondary structure (α-helix content decreased to 20.28%, β-sheet decreased to 22.02%, β-turn increased to 29.30% and random coil increased to 28.40%) and the tertiary conformation of RBP. Spectroscopic data showed that static quenching occurred. Thermodynamic parameters showed that ΔG, ΔH, and ΔS were negative, revealing that the binding process was spontaneous and exothermic and the main reactive bonds were the hydrogen bond and the van der Waals force. When the Que concentration was 120 μmol/g, the emulsifying and foaming properties were improved by 57.72% and 71.88% compared with the RBP, respectively. The study will expand the application of RBP in the food and beverage processing industry. Full article

This study examines the environmental challenges posed by azo-dye pollutants and aluminum industrial waste. Aluminum oxide nanoparticles (P/Al₂O₃-NPs) were produced using a green method that utilized pharmaceutical packaging waste as an aluminum source and marine algae extract (Padina pavonica) as reducing and stabilizing agents and that was characterized by XRD, EDX, SEM, TEM, and zeta potential. Batch biosorption studies were performed to assess the effectiveness of P/Al₂O₃-NPs in removing CR dye from aqueous solutions. The results demonstrate that the particle sizes range from 58.63 to 86.70 nm and morphologies vary from spherical to elliptical. FTIR analysis revealed Al–O lattice vibrations at 988 and 570 cm⁻¹. The nanoparticles displayed a negative surface charge (−13 mV) and a pH_zpc of 4.8. Adsorption experiments optimized parameters for CR dye removal, achieving 97.81% efficiency under native pH (6.95), with a dye concentration of 30 mg/L, an adsorbent dosage of 0.1 g/L, and a contact time of 30 min. Thermodynamic studies confirmed that the process is exothermic and spontaneous. Kinetic data fit well with the pseudo-second-order model, while equilibrium data aligned with the Langmuir isotherm. The adsorption mechanism involved van der Waals forces, hydrogen bonding, and π–π interactions, as supported by the influence of pH, isotherm data, and FTIR spectra. Overall, the study demonstrates the potential of eco-friendly P/Al₂O₃-NPs to efficiently remove CR dye from aqueous solutions. Full article

Herein, a novel super-hygroscopic material, steam-exploded modified corn stalk pith (SE-CSP), was developed from corn stalk pith (CSP) via the steam explosion (SE) method, and its hygroscopic properties and mechanisms were evaluated. The results confirmed that SE effectively removed lignin and hemicellulose, disrupted the thin cell walls of natural CSP, and formed an aligned porous structure with capillary channels. SE changed the bonding distribution and surface morphology, and enhanced the crystallinity and thermal stability of CSP. The equilibrium hygroscopic percentage of SE-CSP (62.50%) was higher than that of CSP (44.01%) at 25 °C and 80% relative humidity (RH), indicating significantly greater hygroscopicity. The hygroscopic process of SE-CSP followed a Type III isotherm and fitted the Guggenheim–Anderson–de Boer (GAB), Peleg, and pseudo-first-order kinetic models. This process exhibited multi-layer adsorption with enthalpy-driven, exothermic behavior, primarily through physical adsorption involving hydrogen bonds and van der Waals forces. This work offered a new approach for advancing sorption dehumidification technology. Full article

An outstanding adsorbent, such as the metal–organic framework (MOF) MIL-101 (Cr), was employed to study the adsorption of two dyes, namely reactive red 2 (RR2) and reactive blue 19 (RB19). Experimental adsorption data were retrieved at T = 25, 35 and 45 °C and analyzed to define the adsorption mechanism of these dyes. A modeling approach based on a double-layer model derived from statistical physics was used. The maximum adsorption capacity (MAC) was found to be 875, 954 and 1002 mg/g for RR2 and 971, 1093 and 1148 mg/g for RB19, at T = 25, 35 and 45 °C, respectively. These values indicate that MIL-101 (Cr) exhibits outstanding performance in removing potential water pollutants such as the RR2 and RB19 dyes. The possible orientations of the RR2 and RB19 dyes upon adsorption were determined by analyzing the number of dye molecules bound per MIL-101 (Cr) active sites during the adsorption process. It was found that the RR2 dye was removed via a mixed parallel and non-parallel orientation on MIL-101 (Cr), while RB19 was removed via an inclined orientation at higher temperatures. The adsorption mechanism suggested that MIL-101 (Cr) site density was reduced due to an exothermic effect, which decreases the number of active sites participating in dye adsorption, even though the reduction in water adsorption may be attributed to the overall endothermic behavior. From the adsorption energy (AE) and the chemical structure of MIL-101 (Cr) and both dyes, it was concluded that hydrogen bonds, Van der Waals forces and π-π stacking are involved in the dye removal process. This research provides new physical insights into the adsorption mechanism of two relevant dyes on an outstanding adsorbent such as the MIL-101 (Cr) MOF. Full article

Apricot kernel shells were evaluated as a sustainable activated carbon precursor for wastewater treatment using experimental and theoretical methods. Two adsorbents were synthesized: physically activated with CO₂ (AKS-CO₂) and chemically activated with H₃PO₄ (AKS-H₃PO₄). Comprehensive materials characterization and adsorption tests using Pb²⁺ ions and Rhodamine B dye (RhB) as model pollutants revealed that AKS-H₃PO₄ significantly outperformed its physically activated counterpart. With an exceptionally high specific surface area (1159.4 m²/g) enriched with phosphorus-containing functional groups, the chemically activated carbon demonstrated outstanding removal efficiencies of 85.1% for Pb²⁺ and 80.3% for RhB. Kinetic studies showed Pb²⁺ adsorption followed pseudo-second-order kinetics, indicating chemisorption, while RhB adsorption fitted pseudo-first-order kinetics, suggesting intra-particle diffusion control. The thermodynamic analysis confirmed the spontaneity of both processes: Pb²⁺ adsorption was exothermic under standard conditions with positive isosteric heat at higher concentrations, reinforcing its chemisorption nature, whereas RhB adsorption was endothermic, consistent with physisorption. Density Functional Theory (DFT) calculations further elucidated the mechanisms, revealing that Pb²⁺ preferentially binds to oxygen-containing functional groups, while RhB interacts through hydrogen bonding and π–π stacking. These findings establish chemically activated apricot kernel shell carbon as a high-performance adsorbent, exhibiting exceptional removal capacity for both ionic and molecular contaminants through distinct adsorption mechanisms. Full article

Industrial hemp (Cannabis sativa L.) was investigated as a sustainable biosorbent for removing Congo Red (CR) and Remazol Brilliant Blue R (RBBR) from wastewater. The unmodified hemp biosorbent exhibited moderate but practically relevant sorption capacities (4.47 mg/g for CR; 2.44 mg/g for RBBR), outperforming several agricultural waste materials. Kinetic studies revealed rapid uptake, with CR following pseudo-first-order kinetics (t₁/₂ < 15 min) and RBBR fitting the Elovich model, indicating heterogeneous surface interactions. Equilibrium data showed CR adsorption was best described by the Temkin isotherm (R² = 0.983), while RBBR followed the Langmuir model (R² = 0.998), reflecting their distinct binding mechanisms. Thermodynamic analysis confirmed spontaneous (ΔG° < 0), exothermic (ΔH° ≈ −2 kJ/mol), and entropy-driven processes for both dyes. Molecular docking elucidated the structural basis for performance differences: CR’s stronger binding (−7.5 kcal/mol) involved weak noncovalent interaction arising from partial overlap between the π-electron cloud of an aromatic ring and σ-bonds C-C or C-H (π-σ stacking) and hydrogen bonds with cellulose, whereas RBBR’s weaker affinity (−5.4 kcal/mol) relied on weak intermolecular interaction between a hydrogen atom (from a C-H bond) and the π-electron system of an aromatic ring (C-H∙∙∙π interactions). This work establishes industrial hemp as an eco-friendly alternative for dye removal, combining renewable sourcing with multi-mechanism adsorption capabilities suitable for small-scale water treatment applications. Full article

In this study, an effective composite material, manganese-modified magnetic dual-sludge biochar (Mn@MDSBC), was developed for the adsorption of ciprofloxacin hydrochloride (CIP). This composite was prepared by means of a simple one-pot method, which involved the pyrolysis of iron-based waterworks sludge (IBWS) and paper mill sludge (PMS) loaded with manganese (Mn) under controlled conditions in a nitrogen atmosphere. The synthesized Mn@MDSBC was subjected to a comprehensive suite of characterization approaches, which included N₂ adsorption–desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Subsequently, static adsorption tests were conducted to investigate how different factors, including the initial solution pH, reaction time and temperature, CIP concentration, and ionic strength influence the adsorption of CIP by Mn@MDSBC. Mn@MDSBC had the maximum CIP adsorption capacity of 75.86 mg/g at pH 5, among the pH values ranging from 3 to 9. The pseudo-second order model provided the best description of the adsorption process, while the experimental data aligned more closely with the Langmuir equation than with the Freundlich model, indicating monolayer adsorption. The adsorption process was found to be non-spontaneous and exothermic according to thermodynamic analysis. The presence of Cl⁻ and SO₄²⁻ enhanced CIP adsorption, while PO₄³⁻ weakened it. After five cycles of reuse, Mn@MDSBC experienced a 17.17% loss in CIP adsorption capacity. The primary mechanisms for CIP removal by Mn@MDSBC were identified as physical and chemical adsorption, hydrogen bonding, and π-π stacking interactions. In summary, the study underscores the high efficiency of Mn@MDSBC as a composite material for CIP adsorption, highlighting its potential for application in wastewater treatment processes. Full article

Composite hydrogels with improved mechanical and chemical properties can be formed by non-covalently decorating the nanofibrillar structures formed by the self-assembly of peptides with fucoidan. Nevertheless, the precise interactions, and the electrochemical and thermodynamic stability of these composite materials have not been determined. Here, we present a thermodynamic analysis of the interacting forces that drive the formation of a composite fucoidan/9-fluorenylmethoxycarbonyl-phenylalanine-arginine-glycine-aspartic acid-phenylalanine (Fmoc-FRGDF) hydrogel. The results showed that the co-assembly of fucoidan and Fmoc-FRGDF was spontaneous and exothermic. The melting point increased from 87.0 °C to 107.7 °C for Fmoc-FRGDF with 8 mg/mL of added fucoidan. A complex network of hydrogen bonds formed between the molecules of Fmoc-FRGDF, and electrostatic, hydrogen bond, and van der Waals interactions were the main interactions driving the co-assembly of fucoidan and Fmoc-FRGDF. Furthermore, the sulfate group of fucoidan formed a strong salt bridge with the arginine of Fmoc-FRGDF. This study provides useful biomedical engineering design parameters for the inclusion of other highly soluble biopolymers into these types of hydrogel vectors. Full article

Arsenic is a highly toxic element, and excessive levels can affect human health. Composites possess a larger specific surface area and better adsorption performance than single-MOF materials. In this paper, a simple novel nanocomposite (MnFe₂O₄@Fe-UiO-67) was synthesized by the one-pot method for the removal of arsenic from industrial wastewater. The synthesis and adsorption mechanism of the adsorbent were analyzed by a series of characterizations. The results showed that the adsorption behavior of MnFe₂O₄@Fe-UiO-67 was consistent with the pseudo-secondary kinetics and Langmuir isotherm model, i.e., it is a monomolecular layer chemisorption. Characterization by Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) showed that the active site formed a strong coordination bond (As-O bond) with As ions to achieve efficient adsorption. At 298 K and pH = 10, the arsenic removal rate can reach 98.43%, and the adsorption capacity is 600.25 mg/g, which is more than most of the existing reported adsorbents. Through thermodynamic analysis, it is found that the adsorption of As ions by the adsorbent is a spontaneous exothermic process. It can exhibit excellent adsorption performance at room temperature without the need for additional energy consumption. This adsorbent has great development prospects in the treatment of wastewater. Full article

The efficient removal of pharmaceuticals and personal care products (PPCPs) from aqueous solutions using conventional adsorbents is hindered by low adsorption capacity, insufficient selectivity, poor regeneration performance, and limited stability. In this study, a multilayer β-CD/GO membrane was successfully prepared via layer-by-layer coating with β-cyclodextrin (β-CD) and graphene oxide (GO). The multilayer β-CD/GO membrane combines the host–guest complexation ability of β-CD with the abundant oxygen-containing functional groups of GO to enhance the targeted removal of PPCPs (CTD, SMZ, and DCF) from aqueous solutions. The prepared multilayer β-CD/GO membrane adsorbent overcomes the separation difficulties and poor regeneration performance of powdered adsorbents, and the multilayer structure can significantly enhance structural stability and increase the number of adsorption sites. Batch adsorption experiments showed that the optimal adsorption performance of the multilayer β-CD/GO membrane for PPCPs occurred at pH 4 and in the absence of coexisting ions. With increasing pH values in the range of 4–9, the adsorption capacities of CTD, SMZ, and DCF slightly decreased to 14.37, 13.69, and 13.01 mg/g, respectively, and the adsorption capacities decreased slowly to 4.88, 3.51, and 3.26 mg/g as the coexisting ion concentrations increased from 0 to 0.20 mol/L. The adsorption mechanism of the multilayer β-CD/GO membrane for PPCPs was systematically investigated through adsorption kinetics, isotherms, and thermodynamics. The adsorption processes of CTD, SMZ, and DCF by the multilayer β-CD/GO membrane were well described by both pseudo-first-order and pseudo-second-order kinetic models (R² > 0.984), suggesting a hybrid adsorption mechanism involving both physisorption and chemisorption. The isotherm results indicated that the adsorption of CTD by the multilayer β-CD/GO membrane followed the Langmuir model (R² = 0.923), whereas the adsorption of SMZ and DCF was better described by the Freundlich model (R² = 0.984–0.988). The multilayer β-CD/GO membrane exhibited high adsorption capacities for CTD, SMZ, and DCF with maximum capacities of 35.56, 43.29, and 39.49 mg/g, respectively. Thermodynamic analyses indicated that the adsorption of PPCPs was exothermic ($\Delta H^0$ = −86.16 to −218.49 J/mol/K) and non-spontaneous ($\Delta G^0$ = 9.84–11.56, 9.50–12.54, and 10.09–14.46 kJ/mol). The multilayer β-CD/GO membrane maintained a removal efficiency of over 58.45–71.73% for CTD, SMZ, and DCF after five consecutive regeneration cycles, demonstrating high reusability for practical applications. The adsorption mechanisms of the multilayer β-CD/GO membrane include electrostatic interactions, hydrogen bonding, hydrophobic interactions, and π-π EDA interactions. This study offers a promising and environmentally friendly adsorbent for the efficient removal of PPCPs from aqueous solutions. Full article

This study addresses the dual challenges of water pollution and waste management by exploring the valorization of chicken bone biomass in native (NBio) and calcined (CBio) forms as biosorbents for dye removal. Basic fuchsine (BF) and methylene blue (MB) were selected as model pollutants, and adsorption was assessed under varying operational conditions. Characterization using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) showed that calcination improved crystallinity, eliminated organic impurities, and increased surface area (247 m²/g for NBio vs. 370 m²/g for CBio). Adsorption tests revealed higher performance for CBio, with maximum adsorption capacities of 100 mg/g (BF) and 142.85 mg/g (MB) based on the Langmuir isotherm, while NBio with maximum adsorption capacities of 111 mg/g (BF) and 111.11 mg/g (MB) followed the Freundlich model. Adsorption kinetics indicated pseudo-second-order behavior, suggesting chemisorption. The possible interactions between dyes and the biosorbent are hydrogen bonding, electrostatic interactions, and Lewis acid–base interactions. Thermodynamic analysis highlighted exothermic behavior for NBio and endothermic, entropy-driven adsorption for CBio, with both processes being spontaneous. A decision tree with Least Squares Boosting (DT_LSBOOST) provided accurate predictions (R² = 0.9999, RMSE < 0.003) by integrating key parameters. These findings promote chicken bone biomass as a cost-effective, sustainable biosorbent, offering promising potential in wastewater treatment and environmental remediation. Full article

The application of wide-bandgap semiconductors in next-generation power modules requires cost-effective Cu particles and a reduced bonding time in the die attachment process to enable efficient industrial-scale manufacturing. Therefore, this study aimed to analyze the effect of Cu particle size variation on pressure-assisted sinter-bondability and bond line shear strength. Cu particles were synthesized through a simple wet-chemical process, in which pH variation was employed to obtain submicrometer-sized Cu particles with average diameters of 500, 300, and 150 nm. The synthesized particles exhibited pure Cu composition, forming only a native oxide layer on their surfaces. In pastes containing these Cu particles, smaller particle sizes led to the delayed evaporation of the reducing solvent, which in turn delayed the exothermic reactions associated with particle sintering and oxidation. However, the sintering-induced exothermic peak became more pronounced as the particle size decreased, confirming that smaller particles improved sinterability. Pressure-assisted sinter bonding performed in air at 300 °C indicated that a decreased particle size contributed to the densification of the bond line structure and an increase in shear strength. Specifically, the paste containing 150 nm Cu particles achieved a highly dense microstructure and an exceptional shear strength of 36.7 MPa within just 30 s of sinter bonding. These findings demonstrate that reducing the particle size is essential for enhancing the sinter-bondability of cost-effective Cu particle-based sinter-bonding pastes. Full article

Coffee silverskin, a by-product of coffee processing, was studied using microscopic (SEM), spectroscopic (FTIR), and thermogravimetric (TGA, DSC) methods to assess its use as a substitute filler in the manufacturing of plywood. TGA showed that the material was compatible with plywood hot pressing temperatures (140 °C) and that it was thermally stable up to 50 °C, with a notable decomposition event at 335 °C. Functional groups like hydroxyl and carbonyl were detected by FTIR analysis, indicating possible hydrogen bonds and chemical adaptability. DSC analysis confirmed structural alterations by highlighting endothermic processes associated with dehydration and an exothermic transition over 150 °C. Coffee silverskin substituted rye flour in plywood adhesive compositions at different concentrations (0%, 1%, 5%, 10%, and 20%). Due to the structural and chemical constraints of the filler, larger concentrations (10% and 20%) dramatically lowered bonding strength, whereas low silverskin amounts (1% and 5%) attained strengths equivalent to rye flour, reaching up to 5 N mm⁻², according to internal bond strength tests. SEM images revealed smaller, more fragmented, and porous silverskin particles than larger, compact rye flour particles, which affected mechanical interlocking and adhesion. The findings point to coffee silverskin as an environmentally friendly and performance-balancing substitute for conventional fillers, especially at medium levels. Full article

Industrial textile wastewater containing both heavy metals and dyes has been massively produced. In this study, semi-interpenetrating polymer network structures of sodium alginate (SA)/polyvinyl alcohol (PVA)/κ-carrageenan (CG) aerogel beads were synthesized for their simultaneous reduction. The SA/PVA/CG aerogel beads were synthesized through a cost-effective and environmentally friendly method using naturally abundant biopolymers without toxic cross-linkers. The SA/PVA/CG aerogel beads were spheres with a size of 3.8 $\pm$ 0.1 mm, exhibiting total pore areas of 15.2 m²/g and porous structures (pore size distribution: 0.04–242.7 μm; porosity: 93.97%) with abundant hydrogen bonding, high water absorption capacity, and chemical resistance. The adsorption capacity and mechanisms of the SA/PVA/CG aerogel beads were investigated through kinetic and isotherm experiments for heavy metals (Cu(II), Pb(II)), cationic dye (methylene blue, MB), and anionic dye (acid blue 25, AB)) in both single and binary systems. The maximum adsorption capacities of the SA/PVA/CG aerogel beads based on the Langmuir model of Cu(II), Pb(II), and MB were 85.17, 265.98, and 1324.30 mg/g, respectively. Pb(II) showed higher adsorption affinity than Cu(II) based on ionic properties, such as electronegativity and hydration radius. The adsorption of Cu(II), Pb(II), and MB on the SA/PVA/CG aerogel beads was spontaneous, with heavy metals and MB exhibiting endothermic and exothermic natures, respectively. Full article

A novel β-cyclodextrin–graphene oxide (β-CD/GO) composite adsorbent was synthesized via a hydrothermal method. Removal efficiency and mechanisms of typical pharmaceutical and personal care products (PPCPs) by the β-CD/GO composite were investigated in aqueous solutions. The results demonstrated that the β-CD/GO composite was successfully formed through cross-linking between β-CD and GO nanosheets, exhibiting enriched hydroxyl groups, a porous layered structure, and good thermal stability. The adsorption of cimetidine (CTD), sulfamethazine (SMZ), and diclofenac (DCF) onto the β-CD/GO composite was well described by pseudo-first-order and pseudo-second-order kinetic models, and Langmuir isotherm. The maximum adsorption capacities of CTD, SMZ, and DCF onto the β-CD/GO composite were 58.86, 35.62, and 29.11 mg g⁻¹ at 298 K, respectively. The adsorption process was rapid and reached equilibrium after 6 h. The adsorption followed a monolayer mechanism and was an exothermic process. The adsorption capacity decreased with increasing pH values and ion concentrations. The β-CD/GO composite exhibited maximum adsorption capacities of 17.69, 16.96, and 16.23 mg g⁻¹ for CTD, SMZ, and DCF, respectively, under a pH of 4 with a dosage of 1.0 g/L at 298 K for 6 h. Due to the combined impacts of electrostatic interaction, hydrogen bonding, and host–guest interaction, the adsorption of PPCPs onto β-CD/GO composite was fast and efficient. β-CD/GO composite exhibited superior adsorption efficacy and structural stability, which highlighted its promising application in the elimination of micropollutants from aqueous solutions. Full article