Search Results (498)

This article aims to investigate the effects of operational factors on methylene blue (MB) decolorization in a visible light advanced oxidation process (AOP). Response surface methodology was applied to evaluate variable interactions and identify the best operational conditions of the process. The response surface analysis of the expected increase in methylene blue decolorization at different levels of the variable parameters was employed. The experiment evaluated the influence of the following parameters: pH, glucose dose, Na₂S₂O₈ (SPS) concentration, and initial dye concentration. The model confirmed that the optimal conditions for MB decolorization in the visible light-driven advanced oxidation process were: SPS dose = 30 mM, glucose dose = 230 mM, pH = 4. The highest decolorization level was obtained at a concentration of C_0[MB] = 5 ppm (R = 63%). The kinetics of the process followed pseudo-first-order (R² = 97–99%). The radical scavenger test showed that both sulfate and hydroxy radicals are involved in MB decolorization. The test confirmed that the proposed method is effective even at a broad range of MB concentrations (1–10 ppm). The analysis showed that the proposed method is highly efficient across various dye concentrations, which is particularly significant from a practical perspective. Summarizing, this study fills a research gap in the optimization of methylene blue decolorization within the scope of advanced oxidation processes driven by visible light and glucose, demonstrating high efficiency across a range of different environmental variables. The study showed that the SPS/Vis/glucose process can serve as a valuable alternative to conventional decolorization methods. Full article

This study analyzes a low-cost potassium feldspar mineral from Chihuahua, Mexico, for removing cationic dyes (methylene blue and rhodamine 6G) from water. The raw mineral, characterized by Rietveld refinement as a polymineralic composite of sanidine (49 vol%), muscovite (27 vol%), calcite (16 vol%), and anorthoclase (7 vol%), demonstrated significant dual functionality. In darkness, it acted as an effective adsorbent, achieving 98% and 76% removal of MB and R6G, respectively, after 120 min, with adsorption behavior fitting the Langmuir isotherm. Under solar irradiation, the mineral facilitated photocatalytic degradation, evidenced by a faster intensity decrease and a shift in the absorption bands, and the near-complete decolorization of the dyes. The degradation kinetics were significantly accelerated in a synergistic advanced oxidation process (AOP) with added hydrogen peroxide (H₂O₂), achieving 98% degradation for MB and 93% degradation for R6G within 15 min, compared with 97% for MB and 65% for R6G under sunlight irradiation alone. Kinetic analysis revealed that the process consistently followed a pseudo-second-order model, indicating a surface-controlled mechanism dependent on dye concentration and the availability of active sites. Additional fitting with the Elovich and Avrami models suggested heterogeneous surface behavior and multistep degradation pathways, implying that the overall process involved concurrent adsorption, surface-mediated catalytic reactions, and oxidative degradation driven by photogenerated reactive species. Additionally, the scavenger tests revealed that the dominant reactive species depended on the presence of ${\mathrm{H}}_2{\mathrm{O}}_2$: ${\mathrm{O}}_2^{•-}$ radicals prevailed in the peroxide-free system, whereas $•\mathrm{OH}$ radicals dominated under ${\mathrm{H}}_2{\mathrm{O}}_2$- assisted conditions. Photoluminescence spectroscopy analysis provided mechanistic insights, tracking the evolution of dye monomers, dimers, and aggregates, confirming structural degradation of the dyes and revealing the formation of specific fluorescent intermediates. Together, these findings highlight the mineral’s potential as an abundant, eco-friendly material for solar-driven wastewater treatment. Full article

Dye wastewater pollution has become a critical environmental issue, while conventional silica adsorbents are often limited by high production costs and the use of chemical silicon sources. In this study, a black-liquor-derived silica-based adsorbent was prepared from bamboo alkaline black liquor through calcium hydroxide precipitation, acid leaching, washing, and calcination. The obtained product was systematically characterized by ICP-OES, XRD, SEM, and BET analysis. Phase analysis showed that the product was mainly composed of amorphous SiO₂, together with a small amount of residual CaSiO₃. The product was semi-quantitatively estimated to contain approximately 64.6 wt.% total SiO₂ and 14.7 wt.% total CaSiO₃, and the estimated SiO₂ yield was about 4.6 wt.% based on dry black liquor solids. The adsorbent exhibited a mesoporous structure with a specific surface area of 60.04 m²/g, a pore volume of 0.23 cm³/g, and an average pore diameter of 7.5 nm. The effects of adsorbent dosage, initial methylene blue concentration, solution pH, and temperature on adsorption performance were investigated. Under the selected conditions of 0.5 g adsorbent, 50 mg/L methylene blue, pH 7, and 20 °C, the removal efficiency reached 82.94%. Adsorption isotherm analysis showed that the Langmuir equation provided the best fit among the tested models over the studied concentration range, and the linear Langmuir fit gave an apparent capacity parameter of 840.3 mg/g. However, this fitted value should not be interpreted as a physically realizable ideal monolayer uptake. This work provides a feasible route for converting silicon-containing bamboo alkaline black liquor into a mesoporous silica-based adsorbent for dye removal. Full article

Synthetic dyes released from industrial effluents represent an important environmental challenge due to their persistence and toxicity. In this study, for the first time, a crude extracellular laccase preparation from Bjerkandera adusta TMF1 produced by solid-state fermentation on a wheat/barley bran mixture was immobilized onto glutaraldehyde-activated alginate beads and applied for mediator-free Bromophenol Blue (BPB) decolorization. The produced laccase showed high activity (51.51 IU/mL; 128.77 IU/g dry substrate), while immobilization efficiency reached 98.84% with 88.39% residual activity under optimal immobilization conditions. FTIR and SEM analyses indicated successful enzyme immobilization and structural changes in the alginate matrix. Under optimal conditions (50 mg/L BPB, pH 5, 30 °C), free and immobilized crude extracellular laccase preparation achieved 73.02% and 78.12% decolorization within 1 h, respectively, without the addition of synthetic redox mediators. The immobilized preparation retained decolorization ability during repeated use, maintaining more than 50% decolorization efficiency after the third cycle. HPLC analysis indicated changes in the chromatographic profile of BPB after enzymatic treatment, while phytotoxicity and antimicrobial assays suggested reduced toxicity of the treated samples toward the tested organisms. These results demonstrate that a crude extracellular laccase preparation produced by B. adusta TMF1 can serve as an efficient immobilized biocatalyst for Bromophenol Blue decolorization while supporting the sustainable valorization of agro-industrial residues for low-cost enzyme production. Full article

Industrial wastewater containing synthetic dyes is difficult to treat because many dyes are chemically stable, highly colored, and resistant to natural degradation. In this study, a Ag₂CO₃/montmorillonite (Ag₂CO₃/MMT) composite photocatalyst was synthesized by an in situ precipitation method using acid-activated MMT as a low-cost clay support. The prepared material was characterized by XRD, FTIR, SEM, BET, and UV–Vis diffuse reflectance spectroscopy to evaluate its structural, morphological, textural, and optical properties. XRD and FTIR confirmed the formation of crystalline Ag₂CO₃ on the MMT support, while SEM analysis showed dispersed Ag₂CO₃ surface particles/deposits on the clay sheets. BET analysis indicated that the composite retained mesoporosity after Ag₂CO₃ deposition, which is beneficial for dye adsorption and diffusion. The photocatalytic performance was evaluated using methylene blue (MB) and methyl orange (MO) under visible-light irradiation. The Ag₂CO₃/MMT composite showed efficient dye decolorization, with faster degradation of cationic MB than anionic MO, mainly due to stronger electrostatic interaction between MB and the negatively charged catalyst surface. Kinetic analysis followed a pseudo-first-order model, with apparent rate constants of 0.036 min⁻¹ for MB and 0.021 min⁻¹ for MO. Operational parameters, including solution pH, irradiation time, and catalyst dosage, strongly influenced photocatalytic efficiency. Reactive species trapping experiments indicated that superoxide radicals (•O₂⁻) and photogenerated holes (h⁺) were the dominant oxidative species. The catalyst retained more than 91% activity after four cycles, indicating good recyclability under the tested conditions. These results suggest that Ag₂CO₃/MMT is a promising visible-light-responsive photocatalyst for dye-contaminated wastewater treatment. Full article

Although polylactic acid (PLA) filaments are currently the leading biodegradable polymer in three-dimensional (3D) printing due to their excellent printability, good mechanical properties, and environmental friendliness, they possess low thermal resistance and limited flexibility, which restricts their use in applications requiring enhanced material performance. PLA filaments were reinforced with carboxymethyl cellulose (CMC) derived from durian husk using a single-screw extrusion technique to produce PLA/CMC filaments. CMC was obtained via carboxymethylation of durian husk-derived cellulose using monochloroacetic acid (MCA) in the presence of NaOH. The incorporation of CMC improved the thermal and mechanical properties of the PLA filaments. The presence of carboxylate (–COO–) groups from CMC makes the filaments promising as an adsorbent for a dye pollutant, namely, methylene blue (MB). Adsorption tests showed that the performance of PLA/CMC filaments for MB removal was influenced by the CMC loading, with 0.1 wt.% CMC (PLA/CMC-30 (0.1)) being the optimal one for achieving a higher adsorption rate. Over the filaments, the removal of MB followed a pseudo-first-order kinetic model, with a k₁ of 0.020 min⁻¹. Overall, this work demonstrates that PLA/CMC filaments derived from agricultural waste offer a sustainable and multifunctional material with enhanced performance for environmental remediation applications. Full article

In this study, olive mill leaves (OMLs), a waste generated during the olive cleaning at the mill, were used as an adsorbent for removing methylene blue (MB) from aqueous solution. An Olive Leaf-based Adsorbent (OLA) was prepared from OMLs with minimal processing. The maximum adsorption capacity experimentally measured for OLA was q_e = 12.8 mg∙g⁻¹. The adsorption of MB by OLA, primarily governed by electrostatic attraction, pore diffusion and weak interactions with functional groups of the leaves, is well described by the Koble–Corrigan isotherm model and pseudo-second-order kinetic model. The performance of OLA under practical environmental conditions, such as in synthetic wastewater, remained unchanged compared to tests carried out in ideal conditions. The possibility of regenerating OLA with methanol, HCl and NaCl solutions was demonstrated, allowing the material to be reused for at least three cycles with unchanged performance. A life cycle assessment was conducted to compare the impacts of OLA production with those of activated carbon, a benchmark for adsorbent materials. Overall, despite its moderate adsorptive performance, OLA stands out as a highly sustainable material for dye removal from polluted waters, owing to its exceptional cost-effectiveness, reusability, and minimal environmental impact. Full article

Photocatalytic degradation of organic pollutants has emerged as a promising approach for wastewater treatment due to its environmental friendliness and high efficiency under mild conditions. This study focuses on evaluating materials for the decolorization of methylene blue (MB) and methyl orange (MO), which are commonly used cationic and anionic dyes, respectively, known for their persistence and toxicity in aquatic environments. The research investigates the synthesis of a Mott–Schottky junction at the interface of two materials using MXene as a dopant. We synthesized three MXene-containing Porous Organic Polymers (POP-2MX, POP-6MX, and POP-10MX), incorporating 2%, 6%, and 10% MXene, respectively. UV–Vis spectroscopy tests revealed that all polymers exhibited high degradation efficiency; however, POP-6MX demonstrated the best overall activity. Under illumination of a 500 W Xenon lamp (λ > 420 nm) with a catalyst loading of 1 mg/mL, POP-6MX achieved complete adsorption-corrected degradation of MB and MO within 10 and 45 min, respectively. This research also investigated the influence of pH on photocatalytic performance under homogeneous aqueous conditions, revealing that neutral pH provides the optimal environment for degradation activity. The photocatalytic mechanism follows a reactive oxygen species (ROS)-dominated pathway, primarily driven by superoxide radicals (•O₂⁻) and hydroxyl radicals generated through photochemical reactions. These results demonstrate the potential of POP-1/MXene composites as efficient and recyclable photocatalysts for sustainable dye wastewater treatment applications. Full article

Synthetic food dyes represent an important category of chemical contaminants with potential phytotoxic, genotoxic, and ecotoxic effects on living organisms and natural ecosystems. The present study aimed to evaluate the physiological effects induced by three commercial food dyes on the model organism Allium cepa, using the Allium test under hydroponic conditions. A total of 105 bulbs were exposed for 48 h to two different concentrations of each dye, for which gravimetric and physiological parameters, such as biomass, water content, mineral and organic composition, growth inhibition index, tolerance index, and relative growth rate, were subsequently analyzed. Statistical analyses revealed significant differences between batches for all evaluated parameters, indicating effects mainly dependent on the type of dye applied. The results suggest that exposure to synthetic food dyes causes disturbances in water balance, biomass accumulation and mineral homeostasis, confirming the phytotoxic potential of these compounds and the utility of the Allium test in the biomonitoring of chemical contaminants. Full article

Hemp plants are precious resources for the textile industry, being considered a sustainable and more economical alternative to cotton. Sustainable dyeing processes should minimize the consumption of water, energy, and chemicals while ensuring high color intensity and reducing the pollution load of residual baths. Black carrot (Daucus carota L. ssp. sativus) is a valuable source of dyes for dyeing hemp materials because it is rich in anthocyanins and anthocyanidins, which generate colors ranging from red-orange and muted magenta to blue, depending on the pH. In this article, the dye extraction process was colorimetrically monitored for 26 days to determine the optimal fermentation/storage period that generates the most intense color during the dyeing process. The dyeing parameters tested were temperature (40–100 °C), pH (4.33–9.15), duration (1–24 h), concentration (2.5–10%), and the presence of organic acids (ascorbic and citric acids). Virgin baths and the first three residual baths were used in the dyeing process. While the results of FTIR, SEM, and EDX analyses confirmed the dyeing process, the CIEL*a*b* measurements quantified the characteristics of the colors obtained using virgin and residual baths. The 12 principles of green chemistry were also discussed, together with their implementation in hemp dyeing. Full article

This study investigates the potential of several sustainable agricultural by-products—including olive stones, cork, and almond shells, which are locally available in Alentejo, Portugal—as low-cost adsorbents for the removal of methylene blue (MB) from synthetic wastewater. The biomass residues were evaluated both in their raw form and after conversion into activated carbons (ACs) through chemical activation with KOH at 973 K. The produced ACs exhibited well-developed surface areas (760–1103.5 m² g⁻¹) and porous structures (0.31–0.51 cm³ g⁻¹). The adsorbents were characterised in terms of their chemical and textural properties. Raw biomass materials presented acidic surface groups, whereas the ACs presented neutral or basic groups. Batch adsorption experiments were conducted to assess the effects of adsorbent particle size, solution pH, initial MB concentration, stirring speed, contact time, and temperature on dye removal efficiency. Among all tested materials, the ACs achieved superior MB adsorption capacities, ranging from 244.2 to 317.6 mg g⁻¹, compared to the untreated biomass adsorbents, which showed capacities between 34.1 and 46.4 mg g⁻¹. The adsorption data were best described by the Langmuir isotherm model, while the kinetic data closely followed the pseudo-second-order (PSO) model. Thermodynamic analysis revealed that MB adsorption was spontaneous and endothermic; however, the relatively low enthalpy values indicated that physical interactions contributed significantly, particularly in the case of the raw biomass adsorbents. This suggests that the PSO model may also be applicable when physical adsorption is the dominant mechanism. This work demonstrates the novel use of cork, olive stone, and almond shell biomasses and their derived ACs as sustainable adsorbents, highlighting an integrated approach that simultaneously promotes efficient wastewater treatment, waste valorisation, and circular economy-driven socio-economic development. Full article

Berberine, curcumin, biochanin A, cucurbitacin E, and caffeic acid phenethyl ester (CAPE) are plant-derived compounds with long histories of use in traditional medicine for inflammatory and proliferative conditions. Their known capacity to modulate NF-κB signaling makes them candidates for anticancer investigation, particularly in mesenchymal malignancies such as fibrosarcoma, which arise in muscle-rich environments shared with normal myogenic tissue. To evaluate the selective anticancer potential of these compounds in fibrosarcoma (WEHI-164) and normal muscle (L6) cells, with focus on mitochondrial function, mitophagy, cellular senescence, and NF-κB-related metabolic pathways, alongside preliminary in vivo toxicity assessment. IC₅₀ values were determined using MTT and PrestoBlue^® assays. Mitochondrial membrane potential was assessed using JC-1 and normalized to the matched untreated control for each cell line, and mitophagy by PINK1/PARKIN immunofluorescence colocalisation together with a mitophagy dye assay. Cellular senescence was measured using a β-galactosidase assay, and ATP levels by a luminescence-based method. Gene expression of NF-κB pathway components and PFKFB3 was analyzed by RT-qPCR. In vivo–like toxicity was assessed using the Galleria mellonella model, including PBS handling, DMSO vehicle, and 70% ethanol utility controls, with survival data analyzed by Kaplan–Meier curves and the log-rank test. The compounds differentially affected normal and cancer cells, indicating selectivity toward malignant phenotypes. Decreased ATP and mitochondrial depolarization suggest disruption of bioenergetic homeostasis, supported by modulation of mitophagy. Stronger effects in WEHI-164 cells indicate higher susceptibility to mitochondrial dysfunction. Increased cellular senescence suggests inhibition of tumor proliferation. These findings indicate that natural NF-κB modulators may exert anticancer effects by targeting mitochondrial and metabolic homeostasis. Differential sensitivity between normal and tumor cells highlights therapeutic potential. In the G. mellonella model, berberine and curcumin did not differ significantly from the PBS or DMSO controls, whereas CAPE, CurE, and particularly biochanin A produced significantly greater larval mortality. The G. mellonella assay should be regarded only as a preliminary acute toxicity screen, and further in vivo studies in mammalian models are required to clarify mechanisms and clinical relevance. Full article

This work reports the synthesis, characterization, and photocatalytic performance of multifunctional spheres based on AgNP-doped TiO₂-Fe₃O₄ embedded in an alginate–chitosan biopolymeric matrix for the removal of organic contaminants from water. The composite powders exhibited a nanocrystalline structure composed of anatase TiO₂ (~20 nm) and magnetite (~25 nm), with homogeneously dispersed Ag nanoparticles, as observed by SEM. The spheres presented a mainly submicrometric particle size distribution (0.55–0.92 µm), favoring high surface area and colloidal stability. Under simulated solar irradiation, the material achieved efficient photocatalytic degradation of methylene blue, with a pseudo-first-order rate constant of 0.112 h⁻¹ and ~46% decolorization after 5 h. UV-Vis spectra showed progressive attenuation of the dye absorption band without accumulation of intermediates. Magnetic recovery tests confirmed rapid separation and reuse without performance loss. The enhanced activity is attributed to the synergistic interaction among plasmonic Ag, photocatalytic TiO₂, redox-active Fe₃O₄, and the adsorptive carbon–biopolymer matrix. The material exhibited strong antibacterial activity, achieving over 90% removal of fecal coliforms after 5 h of irradiation. Therefore, the developed AgNP-doped TiO₂-Fe₃O₄ spheres represent a sustainable, reusable, and efficient material for solar-assisted water sanitation. Full article

This study presents the synthesis and use of a novel bamboo-derived magnetic activated carbon (BMAC) for the effective removal of cationic and anionic dyes, specifically methylene blue (MB), methyl orange (MO), and sunset yellow (SY), from aqueous solutions. The adsorbent was synthesized using thermal carbonization and subsequent inclusion of magnetic oxide, yielding a porous structure with improved adsorption and magnetic separation properties. Thorough characterization utilizing SEM, EDX, BET, FTIR, XRD, and TGA/DTA validated the creation of a highly porous material including uniformly dispersed magnetic particles and several surface functional groups. Batch adsorption tests were performed to examine the influences of contact time, adsorbent dosage, initial dye concentration, pH, and temperature. The findings indicated rapid adsorption kinetics, with equilibrium reached in around 60–70 min, and adsorption capacity ranked as MB > MO > SY. Augmenting adsorbent dosage enhanced removal efficiency but diminished adsorption capacity per unit mass due to site unsaturation. The maximum adsorption capacities (q_m) of BMAC were 58.9, 56.3, and 32.7 mg/g for MB, MO, and SY, respectively, as determined from the Langmuir isotherm model, indicating superior performance compared with other reported magnetic activated carbon. The adsorption process was determined to be exothermic and spontaneous, as evidenced by thermodynamic characteristics. The equilibrium data were optimally characterized by the Langmuir isotherm model, indicating monolayer adsorption, whereas the kinetic studies conformed to the pseudo-second-order model, signifying that chemisorption is predominant. The adsorption mechanism encompasses electrostatic interactions, π–π stacking, hydrogen bonding, van der Waals forces, pore filling, and surface complexation with magnetic oxides. The findings indicate that BMAC is an efficient, sustainable, and magnetically recoverable adsorbent for the elimination of both cationic and anionic dyes from wastewater. Full article

This study explores the natural dyeing of banana pseudo-stem (BSS) fibers as a sustainable material for plant-based leather applications through low-energy processes. Two dye types, lac dye and indigo blue, were applied, and the optimal dyeing parameters were systematically determined. Optimal lac dyeing was achieved using pre-mordanting with a binary mordant system comprising tannic acid and aluminum potassium sulfate (5 g L⁻¹ each), a dye concentration of 10% owf, a pH of 4.23, and a dyeing duration of 6 h. For indigo dyeing, the optimal conditions involved 500 g L⁻¹ wet indigo, 30 g L⁻¹ sodium hydroxide, and 40 g L⁻¹ thiourea dioxide, with a reduction step at 30 °C for 30 min. The dyed samples exhibited good to excellent perspiration fastness in terms of staining, while color change ratings remained low due to the intrinsic sensitivity of natural dyes. Light fastness was rated fair. The dyed BSS was subsequently laminated onto a polypropylene (PP) nonwoven substrate and coated with natural rubber (NR) latex, yielding bursting strengths of 51.8–54.8 psi. Moisture management testing confirmed inherent waterproof properties. Overall, this study presents a resource-efficient approach to transforming agricultural residues into sustainable, plant-based leather alternatives. Full article