Preparation and characterization of a novel functionalized agricultural waste-based adsorbent for Cu2+ removal: Evaluation of adsorption performance using response surface methodology

In this study, it was aimed to the improvement of adsorption capability with a novel modification method based on increasing surface activity of flaxseed waste (FW), an agricultural waste product, and the investigation of its usability as an effective adsorbent for Cu²⁺ removal. The modification method involves functionalization of FW with iron by adding FeCl₃ to medium in presence of N, N-Dimethyl-formamide, poly (N-vinyl-pyrrolidone), and hexamethylenetetramine. The effect of parameters was investigated by conventional univariate analysis. In addition, Response Surface Methodology (RSM) based on multivariate analysis was used to improve the performance of Cu²⁺ adsorption onto iron-modified flaxseed waste (M ? FW). Cu²⁺ removal efficiency was achieved as 91.46% ± 2.34 (N = 2) at an equilibrium time of only 15 min under determined optimum conditions as Co: 75 ppm, pH: 4.7, and m: 0.23 g. RSM was successfully applied for the prediction of adsorption. Adsorption nature was as a single-layer adsorption with a maximum adsorption capacity (Q_max) of 7.64 mg/g. The adsorption mechanism, determined to be chemically controlled, an exothermic and non-spontaneous process. Furthermore, pH-dependent adsorption showed that electrostatic interactions between M ? FW and Cu²⁺ ions play an important role in adsorption mechanism. The results of characterization studies showed that a large surface area was provided with increased porosity of structure and desired changes occurred in target functional structures with modification. Moreover, modification and reusability of M ? FW were evaluated in terms of overall sustainability and waste management. The results indicated that M ? FW has potential for usability to remove heavy metals like Cu²⁺ in environmental remediation applications.     

Adsorptive removal of Bisphenol A by biomass activated carbon and insights into the adsorption mechanism through density functional theory calculations

Activated carbon was synthesized from Tithonia diversifolia biomass using potassium hydroxide as the chemical activating reagent. Taguchi's experimental design approach was applied to determine the best preparation conditions. An optimum 2:1 impregnation ratio and 700 °C activation temperature produced the best carbon with a high 854.44 m²g^-1 surface area, 0.445 cm³g^-1 total pore volume and 18.3% yield. From the analysis of variance (ANOVA), the impregnation ratio was found to be the most influential factor in preparing activated carbon with the maximum surface area. SEM and XRD studies revealed the porous microcrystallite structure of the obtained activated carbon. Batch adsorption studies were performed to test the efficiency of Tithonia diversifolia activated carbon for the removal of Bisphenol A (BPA) from aqueous solution. A maximum 98.2% removal percentage was attained at optimum conditions of 0.2 g adsorbent dose, pH 7, 80 min contact time and 40 mg L^?1 initial BPA concentration. The Langmuir isotherm model described the equilibrium adsorption of BPA well with a maximum adsorption capacity(q_m) of 15.69 mg g^?1 while the kinetic adsorption study indicated a pseudo second order model. A theoretical investigation suggested that the adsorption of BPA onto the activated carbon mainly proceeds via chemisorption and the presence of a carboxyl functional group on the activated carbon surface yielded a greater adsorptive impact on BPA. This study indicates that Tithonia diversifolia could be used as a potential raw material for preparing activated carbon for removing of BPA from water.     

Performance assessment and statistical modeling of modification and adsorptive properties of a lignocellulosic waste modified using reagent assisted mechanochemical process as a low-cost and high-performance method

In this study, olive stone (OS), one of the largely-gathered agricultural wastes, was investigated as an adsorbent in modified and less efficient raw form in order to remove trace elements that have negative effects on human health and environment. Citric acid (CA) assisted mechanochemical modification method (MCM) proposed as an alternative to traditional chemical modification was presented as an innovative approach with advantages of being an easy-to-use, low-cost and eco-friendly technology. As an effective adsorbent, modified olive stone (M-OS) was used for removing Cu²⁺, Pb²⁺ and Zn²⁺ metals from aqueous solutions. Kinetic analysis was fitted with Pseudo-second-order model and equilibrium data with Langmuir model. Adsorption capacities were found as 3.49, 4.67, 2.50 mg/g with OS, and 10.10, 21.28, 18.18 mg/g with M-OS for Cu²⁺, Pb²⁺ and Zn²⁺ respectively. The removal efficiencies of all metals were above 94% for modified adsorbent in optimum conditions (C_o: 0.30 mM, pH: 5.40, and m: 0.300 g). According to thermodynamic parameters, adsorption process was spontaneous and endothermic for both adsorbents. Activation energy values indicated that nature of adsorption process was physical for OS and chemical for M-OS. In desorption and reusability studies, removal efficiencies were found as 40% and below in third cycle. In addition, financial advantages of method were revealed by cash flow and alternative selection cost analysis methods. As a result, the applied modification method was proposed as an effective, economical and green technology for modification of similar materials in today's conditions, where it is important to achieve high efficiency with lower cost.     

Nickel adsorption from aqueous solution using lemon peel biomass chemically modified with TiO2 nanoparticles

Adsorption technique has attracted considerable attention as a promising alternative for reducing heavy metal ions in water sources. This work is focused on the adsorption of nickel ions using lemon peel biomass chemically modified with titanium dioxide (TiO₂) nanoparticles through siloxane bonds. The biomass was characterized by FT-IR and compositional analyses to identify functional groups and elemental composition. From these measurements, it was observed peaks at 1741, 1328, and 1229 cm^?1, characteristics of CO, C–O, and C–H stretching bands, respectively. These organic bonds can be related to the existence of cellulose, lignin, and pectin biopolymers, which are present in the lemon peel biomass, as observed from the compositional analyses. After grafting TiO₂ nanoparticles onto lemon peel biomass surface, it was observed from FTIR the presence of vibrational bands at 1524, 1054, and 943 cm^?1, characteristics of –Ti-O-C, –Si-O-Si, and –Ti-O-Si functional groups. Additionally, the morphology and elemental composition of the lemon peel biomass modified with the titanium dioxide (TiO₂) nanoparticles were determined by SEM microscope, observing the presence of C, O, Ti, and Si atoms from the EDS mapping. Batch adsorption experiments were carried out to determine the effect of pH and biomass particle size on adsorption of Ni (II) ions from aqueous solution. From these experiments, maximum adsorption of Ni (II) ions of 78 ± 0.2% was obtained at pH 6.0, while no significant effects were observed for biomass particle size. Furthermore, the modification of biomass with TiO₂ nanoparticles increased up to 90 ± 0.1% the Ni (II) ions adsorption, suggesting the potential of the biomass modified with metal oxide nanoparticles for removal of heavy metal ions.     

Cadmium removal from water by green synthesized nanobioadsorbent [SiO2@DOPP]: Mechanism,isotherms, kinetics and regeneration studies

In this study, dried orange peel powder [DOPP] is chemically modified with nanosilica (SiO₂) employing sonication technique to produce nanobioadsorbent [SiO₂@DOPP]. [SiO₂@DOPP] This nanoadsorbent was evaluated for Cd²⁺ removal from aqueous systems. Successful functionalization of [DOPP] into nanosilica was confirmed by various analytical techniques like XRD, FTIR, SEM, EDX, TEM, DLS, pH_zpc and TGA. XRD, FTIR and EDX confirmed the emergence of new peaks after modification of [DOPP] by nanosilica and adsorption of Cd²⁺ onto [SiO₂@DOPP]. Further, TGA spectrum suggested that [SiO₂@DOPP] nanoadsorbent is thermally more stable than [DOPP]. pH plays a major role to Cd²⁺ adsorption onto [SiO₂@DOPP]. The optimum conditions for Cd²⁺ removal include pH = 6.5 and 0.03g adsorbent dose with 100 min contact time. Different adsorption isotherms models [best fitted-(Langmuir adsorption model)], adsorption kinetics [best fitted–(Pseudo second order and Intraparticle diffusion)] were examined for the removal of Cd²⁺. The maximum monolayer adsorption capacity [q_max] was 142 mg/g. Thermodynamic evaluation indicates the endothermic and spontaneous nature of Cd²⁺ adsorption onto [SiO₂@DOPP]. Furthermore complexation mechanism of Cd²⁺ onto [SiO₂@DOPP] is discussed in detail. The results indicate involvement of functional group interactions, π–metal interactions, proton exchange, chelate complexes and electrostatic interactions during adsorption of Cd²⁺ onto [SiO₂@DOPP]. Based on the results it has been inferred that [SiO₂@DOPP] is a promising nanobioadsorbent to manage environment burden of Cd²⁺ from aqueous systems.     

Adsorptive removal of lead from aqueous solutions by amine–functionalized magMCM-41 as a low–cost nanocomposite prepared from rice husk: Modeling and optimization by response surface methodology

Amorphous silica that was extracted from rice husk was used to synthesize the magMCM-41 mesoporous silica. This was then functionalized by the APTMS group in order to produce NH₂-magMCM-41 as a novel and low–cost adsorbent. The XRD, VSM, N₂ adsorption–desorption, FT–IR, TGA, SEM and TEM analyses were utilized to characterize the produced materials. In order to optimize the adsorption of the Pb(II) ions, the RSM (response surface methodology) was applied by using the synthesized adsorbent in aqueous solutions. A rotatable CCD (central composite design) was adopted to carry out the experiments and RSM was used to analyze them. Three independent factors namely, initial solution pH (3–7), adsorbent dosage (0.1–2 g L^?1), and initial Pb(II) concentration (15–150 mg L^?1) were used to investigate the removal procedure. According to the obtained results, the initial solution pH of 5.22, adsorbent dosage of 0.1 g L^?1, and initial Pb(II) concentration of 150 mg L^?1 were considered as the optimum conditions with 64.32% removal of Pb(II) and an adsorption capacity of 540.64 mg g^?1. The maximum removal efficiency of Pb(II) ions was found to be 96.76%. The Sips isotherm model represents a better correlation with equilibrium data. It was reported by the kinetic study that data taken from the experiments fitted better to the pseudo–second–order model compared to the pseudo–first–order and intraparticle diffusion models. Finally, according to the thermodynamic study, the removal process strongly depends on temperature, which indicates an exothermic behavior and spontaneous nature of the adsorption.     

Doxorubicin complexes with copper ions of the active center of ceruloplasmin

Features of the interaction of doxorubicin (DR) with Cu²⁺ ions of the active center of ceruloplasmin (CP) have been studied by electronic spectroscopy. It is established that DR · Cu²⁺ CP and DR complexes with inorganic copper salts (Cu(CH₃COO)₂ and CuSO₄) have the same chromophore. An equation establishing a relationship between the electronic absorption at 540 nm (chromophore absorption region) and the concentration of DR involved in the complex formation is proposed. Using this dependence in accordance with the Benesi-Hildebrand theory, the complex formation constant was approximately evaluated as K_p = 4.5 × 10⁶. Effective complex formation between DR and Cu²⁺ ions of the CP active center creates prerequisites for the removal of Cu²⁺ ions from CP and, consequently, for a decrease in CP oxidase activity. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 5, pp. 49–53, May, 2006.     

Tetracycline adsorption on kaolinite: pH,metal cations and humic acid effects

Contamination of environmental matrixes by human and animal wastes containing antibiotics is a growing health concern. Because tetracycline is one of the most widely-used antibiotics in the world, it is important to understand the factors that influence its mobility in soils. This study investigated the effects of pH, background electrolyte cations (Li⁺, Na⁺, K⁺, Ca²⁺ and Mg²⁺), heavy metal Cu²⁺ and humic acid (HA) on tetracycline adsorption onto kaolinite. Results showed that tetracycline was greatly adsorbed by kaolinite over pH 3–6, then decreased with the increase of pH, indicating that tetracycline adsorption mainly through ion exchange of cations species and complexation of zwitterions species. In the presence of five types of cations (Li⁺, Na⁺, K⁺, Ca²⁺ and Mg²⁺), tetracycline adsorption decreased in accordance with the increasing of atomic radius and valence of metal cations, which suggested that outer-sphere complexes formed between tetracycline and kaolinite, and the existence of competitor ions lead to the decreasing adsorption. The presence of Cu²⁺ greatly enhanced the adsorption probably by acting as a bridge ion between tetracycline species and the edge sites of kaolinite. HA also showed a major effect on the adsorption: at pH < 6, the presence of HA increased the adsorption, while the addition of HA showed little effect on tetracycline adsorption at higher pH. The soil environmental conditions, like pH, metal cations and soil organic matter, strongly influence the adsorption behavior of tetracycline onto kaolinite and need to be considered when assessing the environmental toxicity of tetracycline.     

Fabrication of porous polyethyleneimine-functionalized chitosan/Span 80 microspheres for adsorption of diclofenac sodium from aqueous solutions

Porous surface-modified microspheres can have widespread applications in the removal of wastewater pollutants. In this study, using a nonionic surfactant (Span80) as the pore-forming agent and Zr⁴⁺ as the cross-linking agent, polyethyleneimine (PEI)-modified porous CYCTS/Span80 microspheres ((CYCTS/Span80)-@-PEI) were successfully prepared for the adsorptive removal of diclofenac sodium (DS) from wastewater. The adsorbent was characterized using Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectrometry, scanning electron microscopy, and X-ray diffractometry. The activity of the porous (CYCTS/Span80)-@-PEI microspheres as adsorbents of DS was investigated by varying the experimental parameters (i.e., adsorbent dosage, adsorbent ratio, pH, contact time, temperature, and pollutant concentration). A possible adsorption mechanism was also discussed. The experimental results showed that the adsorption process followed a pseudo-second order kinetic model and the Langmuir adsorption isotherm model, in addition to the Freundlich isotherm model, indicating that the porous structure allowed multi-layer adsorption. Adsorption equilibrium was reached after 240 min at pH 5 and 303 K, yielding a maximum adsorption capacity of 572.67 mg/g. After five adsorption cycles, the removal rate of DS remained >80%, and the recovery rate was high. Therefore, we concluded that the porous (CYCTS/Span80)-@-PEI microspheres are efficient and inexpensive candidates for the removal of DS from wastewater.     

Application of novel metal organic framework,MIL-53(Fe) and its magnetic hybrid: For removal of pharmaceutical pollutant,doxycycline from aqueous solutions

As a pharmaceutical pollutant, doxycycline causes contamination when enters into the environment. In this research MIL-53(Fe), and its magnetic hybrid MIL-53(Fe)/Fe₃O₄ were synthesized and employed for removal of doxycycline from aqueous solutions. The adsorbents were characterized by XRD, SEM, BET, FTIR, EDAX, VSM and TG-DTG technique. The effect of different variables such as DOC concentration, pH, contacting time, and adsorbent dose on the removal efficiency was studied and under optimized conditions the adsorption capacity of 322 mgg⁻¹ was obtained. The adsorption process was kinetically fast and the equilibration was attained within 30 min. The used adsorbent was easily separated from the solution by applying external magnetic field. The regenerated adsorbent retained most of its initial capacity after six regeneration steps. The effect of ionic strength was studied and it was indicated that removal of doxycycline from salt-containing water with moderate ionic strengths was quite feasible. Langmuir, Freundlich, Tempkin and Dubinin–Redushkevich isotherms were employed to describe the nature of adsorption process. The sorption data was well interpreted by the Longmuir model.     

Adsorptive removal of Safranin-O dye from aqueous medium using coconut coir and its acid-treated forms: Adsorption study,scale-up design,MPR and GA-ANN modeling

Coconut coir (Cocos nucifera L.), particle size 300–850 μm, has been identified as an adsorbent for safranin-O dye removal from aqueous solution. Bioadsorption efficiency is improved by modifying untreated coconut coir (UCC) with 1 N phosphoric acid (PCC) and 1 N sulphuric acid (SCC). The acid treatment enhances the surface area of adsorbents and accelerates more dye uptake. The adsorption process is optimized by varying the physicochemical conditions like initial pH, adsorbent amount, contact time, initial dye concentration, and temperatures. The adsorption process's optimum pH is 4, 6, and 6, respectively, using UCC, PCC, and SCC adsorbents.In contrast, more than 98% of dye removal has been observed at the lower concentration of dyes up to 200 mg/L at 303 K. Maximum dye removal is possible at 75 mg/L of dye concentration. UCC, PCC, and SCC adsorbents’ adsorption capacity is 80.32 mg/g, 96.81 mg/g, and 89.53 mg/g, respectively, at 303 K temperature. Langmuir and Tempkin model and the pseudo-second-order model are the best-fitted models for isotherm and kinetic study. Thermodynamic parameters indicate the adsorption process is viable, spontaneous, exothermic. 75% glacial acetic acid is the most potent solvent for safranin-O dye extraction from dye loaded biomass. The functional groups and different interactions are identified to establish the adsorption mechanism. The PCC adsorbent has been used for scale-up design. The multiple polynomial regression (MPR) successfully predicts the dye removal efficiency for individual adsorbents. The modeling of the Genetic Algorithm has also been done successfully.     

Antibiotics adsorption from aqueous solutions using carbon nanotubes: a systematic review

Abstract

Over the past few years, antibiotics are considered as an emerging environmental and health challenges due to their genotoxic and mutagenic effects and persistence in natural ecosystems. Adsorption materials are widely used for water purification. Among them carbon nanotubes (CNTs) have attracted the attention of many researchers for removing water contaminants, especially antibiotics. CNTs have many advantages such as lower cost, and energy, less chemical mass and impact on the environment, large surface area and, greater chemical reactivity that make them suitable materials for water and wastewater treatment. Therefore, this review discussed the environmental and health impacts of antibiotics, the physical and chemical characteristics of CNTs, as well as parameters that influenced the efficiency of antibiotics removal using CNTs. Based on this review nanotubes in different forms of a walled nanotubes, double-walled, multi-walled and in combination are used. Most studies investigated the application of CNTs to remove antibiotics in the modified form or by other factors assistant that make them superior than other adsorbents for antibiotics removal. Review results also showed the maximum removal (100%) related to Metronidazole by multi-walled carbon nanotubes and contact time = 60?min, pH = 7, temperature = 30?±?2?°C and adsorbent dosage 0.1?g/L and ionic strength 0.2 NaCl. Also comparison of adsorption capacity showed the highest absorption capacity related to MWCNTS (1100?mg/g for Cephalexin). Adsorption isotherms study showed the best fitness relate to the Langmuir isotherm (R²= 0.999) and higher adsorption reaction rate in the nanotubes is because of better adsorption in the intermediate levels of CNTs.     

Photometric Determination of Cu²⁺ Ion Using Octabromo-tetrakis(4-methylpyridyl)porphine

Octabromo-tetrakis(4-methylpyridyl)porphine (OBTMPyP), an octabromonated compound with 4 pyrole rings of tetrakis(4-methylpyridyl)porphine, selectively forms a complex with Cu²⁺ ions at pH 2.0. When 3.6×10^-5 mol/L OBTMPyP was added to the reaction mixture, the calibration curve showed good linearity for Cu²⁺ ions ranging from 0.01-2.2 μg (addition of 1.0 mL). A good coefficient of variation (Cu²⁺ions=1.5 μg (addition of 1.0 mL), n=10, 0.8%) was obtained. The molar absorption coefficient (ε) based on Cu²⁺ ions was 8.5×10⁴ L/mol?cm. This value was 6-fold greater than that determined with a clinical chemical analysis kit using the bathocuproine sulfonic acid method, which is a well-known method for spectrophotometric determination of the Cu²⁺ ion concentration. A deproteination method was successfully applied in the clinical analysis kit for determination of Cu²⁺ ion concentrations in control serum I, and the values determined using this method and the bathocuproine sulfonic acid method were almost the same.     

Suppression of epimerization by cupric (II) salts in peptide synthesis using free amino acids as amino components

An epimerization-free system for coupling N-protected peptides with free amino acids was developed. A number of inorganic substances were tested as epimerization suppressant additives during the coupling by various methods (carbodiimide plus additives, uronium salts, Woodward’s reagent-K, isobutyl-chloroformate, etc.). Some of them (ZnCl₂, RbClO₄, LiCl, SnCl₄, AlCl₃, etc.) in combination with some coupling methods can guarantee coupling with minimal epimerization (D -epimer < 1%). But only a simultaneous use of 1-hydroxybenzotriazole and Cu²⁺ ions as additives in carbodiimide-mediated peptide couplings appeared to give a standard result (D -epimer < 0.1%). There was no epimerization even in the case when N-methyl amino acid (sarcosine) was used as an amino component, while in the absence of Cu²⁺ ions an unacceptable level of epimerization was observed (D -epimer, 22% for carbodiimide with the 1-hydroxybenzotriazole method). So far it has been considered that Cu²⁺ ions prevent obtaining peptides in high yields (< 90%) by various coupling methods. We have found that the use of 1-hydroxybenzotriazole, CuCl₂ and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide instead of dicyclohexylcarbodiimide provides a possible method for obtaining the desired peptides in 90–99% yields without epimerization. All these results were shown by employing several model peptide couplings with free amino acids as amino components dissolved in an effective solvent system which readily dissolved them.     

Synthesis and characterization of metal oxide based ion exchanger from chicken egg shell biomass for the removal of arsenic from water

A new metal oxided-based high capacity biosorbent for As(III) was designed and synthesized from egg shell biomass and characterized using FTIR, FE-SEM, EDX, XRD, chemical analysis. For this, raw egg shell (RES) powder was first dissolved with HCl and mixed with ZrOCl₂18H₂O solution then precipitated to obtain hydrated double oxide precipitate (HDOP), which was employed for As(III) removal. As(III) biosorption onto HDOP is fast, depends on pH and As(III) concentration. Pseudo second order kinetics and Langmuir isotherm models successfully described the As(III) biosorption mechanism. HDOP provided exchangeable hydroxide/or chloride ligands for improved biosorption of As(III). Maximum biosorption capacity of HDOP for As(III) from Langmuir isotherm modelling was found to be 40 mg g^?1 at optimum pH 10. Chloride and nitrate cause negligible interference whereas sulphate and phosphate significantly reduced As(III) biosorption capacity of HDOP. HDOP completely removed arsenic from contaminated ground water and the remaining concentration was reached below the safe drinking water standard (10 μg L^?1) set by WHO. Moreover, HDOP exhibited effective regeneration and high stability with As(III) removal up to 8 cycles. Thus, HDOP synthesized from egg shell biomass can be used as a low cost, environmentally benign and high capacity biosorbent for the treatment of arsenic polluted water.     

Synthesis and characterization of MOF-5 incorporated waste-derived siliceous materials for the removal of malachite green dye from aqueous solution

The synthesis of MOF-5 and its modification have been investigated towards malachite green (MG) dye removal. The modified MOF-5 adsorbents have been prepared using waste-derived siliceous materials, i.e., rice husk ash (RHA) and/or coal fly ash (CFA) at different ratio. The MOF-5/RHA&CFA/2:1 has been chosen as the best adsorbent for MG dye removal from the aqueous solutions. The adsorption characteristics of the modified MOF-5 for MG dye removal was studied varying various parameters. The MG adsorption efficiency increases with increasing the shaking rate and contact time, but remained constant after 300 rpm and 4 h, respectively. The maximum adsorption capacity of 39.47 mg/g was obtained at adsorbent amount of 0.3 g, initial dye concentration of 150 mg/L, temperature of 30 °C, shaking rate of 200 rpm, contact time of 2 h, and original solution pH. The optimum temperature, pH, and amount of adsorbent for effective MG dye adsorption were 40 °C, 11.5, and 0.2 g, respectively. XRD analysis indicated the presence of crystalline materials has become reduced when RHA and CFA were being incorporated in MOF-5. FTIR analysis showed significant functional groups in the spectrum for both prepared and spent adsorbents. The SEM micrograph results revealed the rough surface morphology with many pores on the MOF-5/RHA&CFA/2:1 before MG adsorption and became smooth and less porous after MG adsorption. While BET analysis indicated that the surface area does not affect the MG dye adsorption efficiency. This study showed that modified MOF-5 adsorbents were successfully used for the removal of MG dye.     

金属离子Cu2+和Zn2+诱导β-淀粉样蛋白的聚集

为探讨金属离子Cu²⁺和Zn²⁺对β-淀粉样蛋白 (Αβ) 聚集的影响, 用紫外光谱、荧光光谱和透射电镜等方法, 从Aβ40聚集体的形态、大小和细胞毒性等多个角度研究了Cu²⁺和Zn²⁺对Aβ40聚集的作用。结果表明, Cu²⁺和Zn²⁺都能促进Aβ40的聚集, 并且两者能改变Aβ40聚集体的形态和大小。Zn²⁺诱导Aβ40聚集产生纤维状聚集体, 而Cu²⁺诱导Αβ40聚集产生纤维状和无定形聚集体。此外, Aβ40还原Cu²⁺产生了H₂O₂。本研究结果分析了金属离子与Αβ40聚集的关系, 阐明了金属离子在阿尔兹海默病 (AD) 中的作用。     

Protective mechanism of quercetin and rutin on 2,2′-azobis(2-amidinopropane)dihydrochloride or Cu-induced oxidative stress in HepG2 cells

Protective effects of quercetin and rutin against oxidative stress were evaluated using in vitro and intracellular antioxidant assay. Quercetin showed higher peroxyl and hydroxyl radical-scavenging activity in a dose-dependent manner than did rutin in oxygen-radical absorbance capacity (ORAC). At 10 and 100 μM, quercetin had higher metal-chelating activity than rutin carrying rutinose at position C-3 and was also more efficient than rutin in reducing intracellular oxidative stress caused by peroxyl radicals and Cu²⁺. The protective activities of 10 and 100 μM quercetin against Cu²⁺-induced intracellular oxidation were 13.8% and 44.8%, respectively. Rutin showed no protective activity against Cu²⁺-induced oxidative stress. Quercetin showed significantly lower intracellular Cu²⁺-chelating activity than did 1,10-phenanthroline but offered greater protection from Cu²⁺-induced oxidative stress. Thus, quercetin may diffuse through the cell membrane more efficiently than rutin because quercetin does not carry rutinose, is hydrophilic, and reduces Cu²⁺-induced oxidative stress by scavenging radicals instead of chelating with metal ions.     

Adsorptive removal of Cd (II) using oil palm empty fruit bunch-based charcoal/chitosan-EDTA film composite

Oil palm empty fruit bunch (OPEFB) is a solid waste abundantly produced by the palm oil industry. This study aimed to prepare a film adsorbent from OPEFB-based charcoal (OC), embedded into chitosan-ethylenediaminetetraacetic acid (EDTA) matrix (OC/Chi-EDTA) through a simple phase inversion technique for Cd (II) removal. Based on the tensile strength (20.4 kgf/mm²) and adsorption capacity (66.6 mg/g), the material with 0.85 : 0.1: 0.15 was selected as the best film adsorbent using simple additive weighting. Further, the sample was characterized for its functional group, morphology, crystallinity, and thermal behavior. The characterizations revealed the successful preparation of OC/Chi-EDTA with advantageous properties for Cd (II) adsorptive removal such as rough surface morphology and amorphous structure (crystallinity = 41.02). Good thermal stability of OC/Chi-EDTA was also suggested by the T_peak of the first composite degradation at 298.97°C. At equilibrium, the adsorption isotherm best fitted with the Langmuir isotherm model (R² = 0.992; root-mean-square error = 2.75), where the maximum adsorption capacity was 283.33 mg/g. Investigation on the adsorption mechanisms found that electrostatic attraction and complexation were responsible for the Cd (II) uptake. At the optimum conditions (contact time = 120 min; pH 7), the adsorption capacity was recorded to be 67.2 mg/g with a removal efficiency of 99.56%. Regeneration studies suggested that OC/Chi-EDTA can be used up to four cycles (removal efficiency > 75%). In conclusion, the OC has been successfully embedded into chitosan-EDTA matrix resulting in a film adsorbent that could perform a high Cd (II) uptake.