Search Results (2,440)

The oxidation of multi-walled carbon nanotubes (MWCNTs) using cold plasma was investigated for their subsequent use as adsorbents for the removal of dyes from aqueous solutions. The properties of MWCNTs after plasma modification and their adsorption capacities were compared with pristine and chemically oxidized nanotubes. The modification process employed a reactor where plasma was generated through dielectric barrier discharges (DBD) powered by high-voltage nanosecond pulses. Various modification conditions were examined, such as processing time and pulse voltage amplitude. The degree of oxidation and the impact on the chemistry and structure of the nanotubes was investigated through various physicochemical and morphological characterization techniques (XPS, BET, TEM, etc.). Maximum oxidation (O/C = 0.09 from O/C = 0.02 for pristine MWCNTs) was achieved after 60 min of nanopulsed-DBD plasma treatment. Subsequently, the modified nanotubes were used as adsorbents for the removal of the dye methylene blue (MB) from water. The adsorption experiments examined the effects of contact time between the adsorbent and MB, as well as the initial dye concentration in water. The plasma-modified nanotubes exhibited high MB removal efficiency, with adsorption capacity proportional to the degree of oxidation. Notably, their adsorption capacity significantly increased compared to both pristine and chemically oxidized MWCNTs (~54% and ~9%, respectively). Finally, the kinetics and mechanism of the adsorption process were studied, with experimental data fitting well to the pseudo-second-order kinetic model and the Langmuir isotherm model. This study underscores the potential of plasma technology as a low-cost and environmentally friendly approach for material modification and water purification. Full article

Combining ionic liquids (ILs) and metal–organic frameworks (MOFs) can be an intriguing opportunity to develop advanced materials with different adsorption capabilities for environmental applications. This study reports the preparation and characterization of a 3D pillared-layered compound, namely, [Zn₂(tz)₂(bdc)] (CIM91), formed by 1,2,4-triazole (Htz) and 1,4-benzenedicarboxylic acid (H₂bdc) ligands. Then, various loadings of the water-stable and hydrophobic IL, 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]), and the water-soluble 1-n-butyl-3-methylimidazolium chloride ([BMIM][Cl]) were incorporated into CIM91. Detailed characterization by X-ray powder diffraction (XRD), FT-IR spectra, scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) analysis, N₂ adsorption measurements, and thermogravimetric analysis confirmed the formation of [BMIM][X]/CIM91 composites and the structural stability of the MOF after the incorporation of the ionic liquids. CO₂ adsorption–desorption analysis was experimentally carried out for all the materials at 298 K and 318 K, demonstrating a great enhancement in the CO₂ adsorption properties of the sole MOF CIM91, particularly by including [BMIM][PF₆] species in its structure with a double isosteric heat of CO₂ adsorption. The composites were also tested for the adsorption of methylene blue (MB) dye. The results indicate that the incorporation of [BMIM][X] into CIM91 can substantially modify the adsorption properties of the MOF. The influence of the nature of the [BMIM][X] anions on these properties has also been analyzed. Full article

Cancer cells are known to create an acidic microenvironment (the Warburg effect). At the same time, fluorescent dyes can be sensitive to pH, showing a sharp increase or decrease in fluorescence depending on pH. However, modern applications, such as confocal laser scanning microscopy (CLSM), set additional requirements for such fluorescent markers to be of practical use, namely, high quantum yield, low bleaching, minimal quenching in the cell environment, and minimal overlap with auto-fluorophores. R6G could be the perfect match for these requirements, but its fluorescence is not pH-dependent. We have attempted to develop an R6G conjugate with its FRET or PeT pair that would grant it pH sensitivity in the desired range (5.5–7.5) and enable the selective targeting of tumor cells, thus improving CLSM imaging. Covalent conjugation of R6G with NBD using a spermidine (spd) linker produced a pH-sensitive FRET effect but within the pH range of 7.0–9.0. Shifting this effect to the target pH range of 5.5–7.5 appeared possible by incorporating the R6G-spd-NBD conjugate within a “smart” polymeric micelle based on chitosan grafted with lipoic acid. In our previous studies, one could conclude that the polycationic properties of chitosan could make this pH shift possible. As a result, the micellar form of the NBD-spd-R6G fluorophore demonstrates a sharp ignition of fluorescence by 40%per1 pH unit in the pH range from 7.5 to 5. Additionally, “smart” polymeric micelles based on chitosan allow the label to selectively target tumor cells. Due to the pH sensitivity of the fluorophore NBD-spd-R6G and the selective targeting of cancer cells, the efficient visualization of A875 and K562 cells was achieved. CLSM imaging showed that the dye actively penetrates cancer cells (A875 and K562), while minimal accumulation and low fluorophore emission are observed in normal cells (HEK293T). It is noteworthy that by using “smart” polymeric micelles based on polyelectrolytes of different charges and structures, we create the possibility of regulating the pH dependence of the fluorescence in the desired interval, which means that these “smart” polymeric micelles can be applied to the visualization of a variety of cell types, organelles, and other structures. Full article

Nanotechnology, a rapidly growing field, holds tremendous promise as it harnesses the unique properties and applications of nanoparticulate materials on a nanoscale. In parallel, the pressing global environmental concerns call for the development of sustainable chemical processes and the creation of new materials through eco-friendly synthesis methods. In this work, zero-valent iron nanoparticles (nZVI) were synthesized using an innovative and environmentally friendly approach as an alternative to conventional methods. This method leverages the antioxidant capacity of natural plant extracts to effectively reduce dissolved metals and produce nZVI. The chosen extract of green tea plays a pivotal role in this process. With the extract in focus, this study delves into the remarkable capability of nZVI in degrading two dyes commonly used in medicine, chrysoidine G and methylene blue, in aqueous solutions. Additionally, Fenton-type oxidation processes are explored by incorporating hydrogen peroxide into the nanoparticle mixture. By applying the statistical design of experiments and Response Surface Methodology, the influence of four key parameters—initial concentrations of Fe²⁺, Fe³⁺, H₂O₂, and polyphenols—on dye elimination efficiency in aqueous solutions is thoroughly analyzed. The obtained results demonstrate that advanced oxidation technologies, such as Fenton-type reactions in conjunction with nanoparticles, achieve an excellent efficiency of nearly 100% in eliminating the dyes. Moreover, this study reveals the synergistic effect achieved by simultaneously employing nZVI and the Fenton process, showcasing the potential for further advancements in the field. Full article

Acid mine drainage (AMD) is one of the main environmental problems associated with mining activity, whether the mine is operational or abandoned. In this work, several precipitates from this mine drainage generated by the oxidation of sulfide minerals, when exposed to weathering, were used as adsorbents. Such AMD precipitates from abandoned Portuguese mines (AGO, AGO-1, CF, and V9) were compared with two raw materials from Morocco (ClayMA and pyrophyllite) in terms of their efficiency in wastewater treatment. Different analytical techniques, such as XRD diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), N₂ adsorption isotherms, and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) were used to characterize these natural materials. The adsorption properties were studied by optimizing different experimental factors, such as type of adsorbent, adsorbent mass, and dye concentration by the Box–Behnken Design model, using methylene blue (MB) and crystal violet (CV) compounds as organic pollutants. The obtained kinetic data were examined using the pseudo-first and pseudo-second order equations, and the equilibrium adsorption data were studied using the Freundlich and Langmuir models. The adsorption behavior of the different adsorbents was perfectly fitted by the pseudo-second order kinetic model and the Langmuir isotherm. The most efficient adsorbent for both dyes was AGO-1 due to the presence of the cellulose molecules, with q_m equal to 40.5 and 16.0 mg/g for CV and MB, respectively. This study confirms the possibility of employing AMD precipitates to adsorb organic pollutants in water, providing valuable information for developing future affordable solutions to reduce the wastes associated with mining activity. Full article

Water pollution caused by dyes is a significant environmental issue, necessitating the development of effective, cost-efficient decolorization methods suitable for industrial use. In this study, a Chitosan-Fe polymeric gel was synthesized, characterized, and tested for removing the azo dye Direct Red 83:1 from water. The polymeric magnetic chitosan was analyzed using various techniques: Field Emission Scanning Electron Microscopy (FE-SEM) revealed a porous structure, Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA) demonstrated the thermal stability, Infrared Spectrophotometry (IR) indicated the successful coordination of iron at the C3 position, and X-ray Powder Diffraction (XRD) confirmed the crystalline nature of the polymeric structure. Optimal conditions for kinetic and isotherm models were found at 1 g and pH 7.0. Adsorption behavior of Direct Red 83:1 onto magnetic chitosan gel beads was studied through kinetic tests and isotherm curves. The maximum adsorption capacity was 17.46 mg/g (qmax). The adsorption process followed pseudo-second-order kinetics (R² = 0.999) and fit the Temkin isotherm (R² = 0.946), suggesting heterogeneous surface adsorption. The newly synthesized Chitosan-Fe polymeric gel demonstrated good adsorption properties and facilitated easy separation of purified water. Full article

This project studied the use of lentil protein (LP) and quinoa protein (QP) in their native and modified states as carrier material in the encapsulation process by the ionic gelation technique of annatto seed extract. Soy protein (SP) was used as a model of carrier material and encapsulated bioactive compounds, respectively. The plant proteins were modified by enzymatic hydrolysis, N acylation, and N-cationization to improve their encapsulating properties. Additionally, the secondary structure, differential scanning calorimetry (DSC), solubility as a function of pH, isoelectric point (pI), molecular weight (MW), the content of free thiol groups (SH), the absorption capacity of water (WHC) and fat (FAC), emulsifier activity (EAI), emulsifier stability (ESI), and gelation temperature (Tg) were assessed on proteins in native and modified states. The results obtained demonstrated that in a native state, LP (80.52% and 63.82%) showed higher encapsulation efficiency than QP (73.63% and 45.77%), both for the hydrophilic dye and for the annatto extract. Structural modifications on proteins improve some functional properties, such as solubility, WHC, FAC, EAI, and ESI. However, enzymatic hydrolysis on the proteins decreased the gels’ formation, the annatto extract’s encapsulated efficiency, and the hydrophilic dye by the ionic gelation method. On the other hand, the modifications of N-acylation and N-cationization increased but did not generate statistically significant differences (p-value > 0.05) in the encapsulation efficiency of both the annatto extract and the hydrophilic dye compared to those obtained with native proteins. This research contributes to understanding how plant proteins (LP and QP) can be modified to enhance their encapsulating and solubility properties. The better encapsulation of bioactive compounds (like annatto extract) can improve product self-life, potentially benefiting the development of functional ingredients for the food industry. Full article

Chemiluminescence in solution-based systems has been extensively studied for the chemical analysis of biomolecules. However, investigations into the control of chemiluminescence reactions in gel-based systems, which offer flexibility in reaction conditions (such as the softness of the reaction environment), have only recently begun in polymer materials, with limited exploration in low-molecular-weight gelator (LMWG) systems. In this study, we investigated the chemiluminescence behaviors in the gel states using LMWG systems and evaluated their applicability to fluorescent-dye-containing molecular organogel systems/oxidant-containing aqueous systems. Using diethyl succinate organogels composed of 12-hydroxystearic acid as a molecular organogelator, we examined the fluorescent properties of various fluorescent dyes mixed with oxidant aqueous solutions. As the reaction medium transitioned from the solution to the gel state, the emission color and chemiluminescence duration changed significantly, and distinct characteristics were observed, for each dye. This result indicates that the chemiluminescence behavior differs significantly between the solution and gel states. Additionally, visual inspection and dynamic viscoelastic measurements of the mixed fluorescent dye-containing molecular gels and oxidant-containing aqueous solutions confirmed that the chemiluminescence induced by the mixing occurred within the gel phase. Furthermore, the transition from the solution to the gel state may allow for the modulation of the mixing degree, thereby enabling control over the progression of the chemiluminescence reaction. Full article

Industrial discharge of hazardous organic and synthetic chemicals, such as antibacterials and dyes, poses severe risks to human health and the environment. This study was conducted to address the urgent need for efficient and stable zinc-oxide-based photocatalysts to degrade such pollutants. A novel approach to synthesizing silver-loaded zinc oxide (Ag@Z) catalysts was introduced by using a simple and efficient combination of hydrothermal and precipitation methods. Comprehensive characterization of Ag@Z photocatalysts was performed using XRD, XPS, Raman, UV–vis adsorption, FTIR, and SEM, revealing an enhancement of structural, optical, and morphological properties in comparison to pure zinc oxide. Notably, the 5%Ag@Z catalyst exhibited the highest degradation efficiency among the other synthesized catalysts under UV-C light irradiation, and enhanced the degradation rate of pure zinc oxide (Z) by 1.14 and 1.64 times, for Triclosan (TCS) and Methylene Blue (MB), respectively. the effect of catalyst dose and initial concentration was studied. A mechanism of degradation was proposed after investigating the effect of major reactive species. The 5%Ag@Z catalyst increased the photostability, which is a major problem of zinc oxide due to photocorrosion after reusability. We found that 50% and 74% of energy consumption for the photocatalytic degradation of TCS and MB by 5%Ag@Z, respectively, was saved in compassion with zinc oxide. The remarkable photocatalytic performance and the good recovery rate of Ag@Z photocatalysts demonstrate their high potential for photocatalytic degradation of organic contaminants in water. Full article

This study reported the synthesis of ZnO nanoparticles (ZnO NPs) using Cucurbita pepo L. seed extract and explored their multifunctional properties such as anti-corrosion, photocatalytic, and adsorption capabilities. The synthesized ZnO NPs were characterized by Fourier-transform infrared spectroscopy (FTIR) to identify their functional groups, thermogravimetric analysis (TGA) to assess their thermal stability, transmission electron microscopy (TEM), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) to determine their size, morphology, and elemental composition. The characterization of biofabricated ZnO NPs revealed an average particle size of 32.88 nm; however, SEM displayed a tendency for the particles to agglomerate. Furthermore, the X-ray diffraction (XRD) and EDX analysis confirmed the NPs as ZnO, matching patterns reported in the literature. In this study, the potential of the biogenic ZnO NPs was explored for multifunctional applications. Zinc oxide nanoparticles exhibited a higher capacity for adsorbing hydrogen sulfide (H₂S) compared to bulk zinc oxide, mostly because of their larger surface area. In addition, electrochemical studies demonstrated a substantial enhancement in the corrosion resistance of mild steel in a 1.0 M HCl solution. ZnO NPs also demonstrated remarkable photodegradation effectiveness, reducing 75% of methyl orange in 60 min under sun-light irradiation. This implies that they could be used to remediate organic pollutants (organic dyes) from wastewater. Full article

The art of dyeing fabrics is one of the oldest human activities. In order to improve the fastness properties of dyeing products, various additives are added to optimize the uniformity of fibers and surfaces and improve dye distribution. Unfortunately, these additives can be harmful and very often are not biodegradable. This article reports on the possibility of using a natural additive for dyeing textiles: a polysaccharide extracted from the prickly pear cactus (Opuntia ficus indica). One type of fabric was tested, silk, with different colors. Several samples were prepared and dyed for each color, adding the same additives but also a commercial chemical aid for one of them and the mucilage of Opuntia for another. The fastness of the applied dyes was evaluated by washing at different temperatures with a common liquid detergent. All samples were analyzed before and after washing with a colorimeter to evaluate the color changes. The results of the analyses reported and compared indicate the potential of prickly pear mucilage as an additive for dyeing silk, which is easily accessible, safe, and sustainable compared to other commonly used additives. Full article

Na-kenyaite materials are available in nature and can easily be prepared in the laboratory. These materials exhibit interesting adsorption properties; therefore, they can be invested in the new wastewater treatment technologies. This study investigates the removal of basic blue-41 (BB-41) dye from artificially contaminated water using Na-kenyaite materials in batch mode. Firstly, Na-kenyaites were prepared by the hydrothermal process at a temperature of 150 to 170 °C for a period of 2 to 7 days using different silica sources and ratios of SiO₂/NaOH/H₂O. The prepared materials were characterized by different techniques such as XRD, FTIR, ²⁹Si MAS NMR, TGA/DTA, SEM, and nitrogen adsorption isotherms. A pure Na-kenyaite phase was successfully obtained using a fumed silica source and 5SiO₂/Na₂O/122H₂O ratio. The removal experiments of basic blue-41 estimated the effectiveness of Na-kenyaites in removing properties, investigating the influence of the solid dosage, initial basic blue-41 concentration, and solution pH or Na-kenyaite solid. Results showed optimal dye removal of around 99% at pH levels above 7. Furthermore, the estimated maximum removal capacity from the Langmuir isotherm was between 124 and 165 mg/g. The results demonstrated efficient removal by Na-kenyaites and its prominence for wastewater treatment. Finally, this study explored the regeneration and reuse of Na-kenyaites through seven cycles and reported a design of a batch adsorber system to reduce the initial concentration of 200 mg/L at different percentages. Full article

A binary Fe₂O₃/Fe₃O₄ mixed nanocomposite was prepared by phyto-mediated avenue to be suited in the photo-Fenton photodegradation of methylene blue (MB) in the presence of H₂O₂. XRD and SEM analyses illustrated that Fe₂O₃ nanoparticles of average crystallite size 8.43 nm were successfully mixed with plate-like aggregates of Fe₃O₄ with a 15.1 nm average crystallite size. Moreover, SEM images showed a porous morphology for the binary Fe₂O₃/Fe₃O₄ mixed nanocomposite that is favorable for a photocatalyst. EDX and elemental mapping showed intense iron and oxygen peaks, confirming composite purity and symmetrical distribution. FTIR analysis displayed the distinct Fe-O assignments. Moreover, the isotherm of the developed nanocomposite showed slit-shaped pores in loose particulates within plate-like aggregates and a mesoporous pore-size distribution. Thermal gravimetric analysis (TGA) indicated the high thermal stability of the prepared Fe₂O₃/Fe₃O₄ binary nanocomposite. The optical properties illustrated a narrowing in the band gab (Eg = 2.92 eV) that enabled considerable absorption in the visible region of solar light. Suiting the developed binary Fe₂O₃/Fe₃O₄ nanocomposite in the photo-Fenton reaction along with H₂O₂ supplied higher productivity of active oxidizing species and accordingly a higher degradation efficacy of MB. The solar-driven photodegradation reactions were conducted and the estimated rate constants were 0.002, 0.0047, and 0.0143 min⁻¹ when using the Fe₂O₃/Fe₃O₄ nanocomposite, pure H₂O₂, and the Fe₂O₃/Fe₃O₄/H₂O₂ hybrid catalyst, respectively. Therefore, suiting the developed binary Fe₂O₃/Fe₃O₄ nanocomposite and H₂O₂ in photo-Fenton reaction supplied higher productivity of active oxidizing species and accordingly a higher degradation efficacy of MB. After being subjected to four photo-Fenton degradation cycles, the Fe₂O₃/Fe₃O₄ nanocomposite catalyst still functioned admirably. Further evaluation of Fe₂O₃/Fe₃O₄ nanocomposite in photocatalytic remediation of contaminated water using a mixture of MB and pyronine Y (PY) dyestuffs revealed substantial dye photodegradation efficiencies. Full article

The presented study was focused on the simple, eco-friendly synthesis of composite hydrogels of crosslinked carboxymethyl cellulose (CMC)/alginate (SA) with encapsulated g-C₃N₄ nanoparticles. The structural, textural, morphological, optical, and mechanical properties were determined using different methods. The encapsulation of g-C₃N₄ into CMC/SA copolymer resulted in the formation of composite hydrogels with a coherent structure, enhanced porosity, excellent photostability, and good adhesion. The ability of composite hydrogels to eliminate structurally different dyes with the same or opposite charge properties (cationic Methylene Blue and anionic Orange G and Remazol Brilliant Blue R) in both single- and binary-dye systems was examined through adsorption and photocatalytic reactions. The interactions between the dyes and g-C₃N₄ and the negatively charged CMC/SA copolymers had a notable influence on both the adsorption capacity and photodegradation efficiency of the prepared composites. Scavenger studies and leaching tests were conducted to gain insights into the primary reactive species and to assess the stability and long-term performance of the g-C₃N₄/CMC/SA beads. The commendable photocatalytic activity and excellent recyclability, coupled with the elimination of costly catalyst separation requirements, render the g-C₃N₄/CMC/SA composite hydrogels cost-effective and environmentally friendly materials, and strongly support their selection for tackling environmental pollution issues. Full article

This work aims to present the results of evaluating the coloristic properties of polylactic acid (PLA) fibers. PLA is common nowadays in much research, as it is a biodegradable plastic from renewable sources. However, little research is devoted to PLA fibers, and even less to applied research of colored fibers. The prepared color masterbatches, created using inorganic pigments, such as titanium dioxide and carbon black, were subsequently used to prepare dyed PLA fibers in mass. The fibers were drawn to the maximum drawn ratio. The properties of the pure and dyed fibers were investigated before and after accelerated light aging using Q-SUN equipment. The changes were recorded by Fourier Transform Infrared (FTIR) spectroscopy and colorimetric properties were recorded using a device spectrometer from TECHKON SpectroDens. We also evaluated thermal properties from the first heating via differential scanning calorimetry (DSC). The measurements were taken before and after the aging of the PLA fibers, in order to see the effect of aging on the supermolecular structure, excluding the influence of the preparation process and the influence of the kind of PLA. Using inorganic pigments showed sufficient color stability even after accelerated light aging, which is beneficial for using colored fibers in practice. Full article