Search Results (74)

Spent coffee grounds (SCG) are a widely available agro-industrial residue rich in carbon and phenolic compounds, presenting significant potential for biotechnological valorization. This study evaluated the use of SCG as a suitable substrate for fungal laccase production and the application of the resulting fermented biomass (RFB), a mixture of fermented SCG and fungal biomass as a biosorbent for textile dye removal. Two fungal strains, namely Lentinus crinitus UCP 1206 and Trametes sp. UCP 1244, were evaluated in both submerged (SmF) and solid-state fermentation (SSF) using SCG. L. crinitus showed superior performance in SSF, reaching 14.62 U/g of laccase activity. Factorial design revealed that a lower SCG amount (5 g) and higher moisture (80%) and temperature (30 °C ± 0.2) favored enzyme production. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analyses confirmed significant structural degradation of SCG after fermentation, especially in SSF. Furthermore, SCG and RFB were chemically activated and evaluated as biosorbents. The activated carbon from SCG (ACSCG) and RFB (ACRFB) exhibited high removal efficiencies for Remazol dyes, comparable to commercial activated carbon. These findings highlight the potential of SCG as a low-cost, sustainable resource for enzyme production and wastewater treatment, contributing to circular bioeconomy strategies. Full article

The authentication of high-value spices such as paprika and cinnamon is critical due to increasing food fraud. This study explored the potential of a multi-analytical approach, combined with chemometric tools, to differentiate 45 paprika and 46 cinnamon samples from the Slovenian market based on their geographic origin, production methods, and possible adulteration. The applied techniques included stable isotope ratio analysis (δ¹³C, δ¹⁵N, δ³⁴S), multi-elemental profiling, FTIR, and antioxidant compound analysis. Distinct isotopic and elemental markers (e.g., δ¹³C, δ³⁴S, Rb, Cs, V, Fe, Al) contributed to classification by geographic origin, with preliminary classification accuracies of 90% for paprika (Hungary, Serbia, Spain) and 89% for cinnamon (Sri Lanka, Madagascar, Indonesia). Organic paprika samples showed higher values of δ¹⁵N, δ³⁴S, and Zn, whereas conventional ones had more Na, Al, V, and Cr. For cinnamon, a 95% discrimination accuracy was achieved between production practice using δ³⁴S and Ba, as well as As, Rb, Na, δ¹³C, S, Mg, Fe, V, Al, and Cu. FTIR differentiated Ceylon from cassia cinnamon and suggested possible paprika adulteration, as indicated by spectral features consistent with oleoresin removal or azo dye addition, although further verification is required. Antioxidant profiling supported quality assessment, although the high antioxidant activity in cassia cinnamon may reflect non-phenolic contributors. Overall, the results demonstrate the promising potential of the applied analytical techniques to support spice authentication. However, further studies on larger, more balanced datasets are essential to validate and generalize these findings. Full article

Global industrialization has intensified the emission of emerging contaminants (ECs), posing a serious threat to the environment and human health. Persulfate-based advanced oxidation processes (PS-AOPs) have become a research hotspot due to their efficient degradation capability and environmentally friendly features; carbon-based materials are ideal catalysts for activating persulfate (PS) due to their tunable electronic structure, abundant active sites, and low cost. This study summarizes the application of carbon-based materials (graphene, single-atom catalysts (SACs), etc.) in PS-AOPs, and provides insights into the degradation mechanisms of radicals (e.g., sulfate radical (SO₄^−·), hydroxyl radical (·OH)) and non-radicals (e.g., ¹O₂(singlet oxygen), electron transfer). The removal efficacy of carbon-based catalysts for antibiotics, phenols, and dyes was compared, and the key degradation pathways were elucidated. In addition, the activation of PS can be accelerated, and catalytic efficiency can be improved by synergizing with ancillary technologies (e.g., light, electricity). Despite the great potential of carbon-based catalysts, their large-scale application is limited by the complexity of the catalyst preparation process and the lack of selectivity for complex water qualities. Future studies can accelerate the practical application of PS-AOPs in wastewater treatment through the precise design of SACs and the construction of multi-mechanism synergistic activation systems. Full article

The residual emerging pollutants in secondary effluent from a chemical industry park contain potential risks for natural waters. Herein, the cobalt ferrite/peracetic acid system was employed to destroy aniline, a typical emerging pollutant, with a reaction rate of 0.0147 min⁻¹ at pH 7.0. Singlet oxygen (¹O₂) served as the predominant reactive species for aniline degradation, with superoxide radicals (O₂⁻) and organic radicals (R-O) acting in secondary roles. The valence transition between Co(II) and Co(III) on the CoFe₂O₄ surface played a determining role in the reaction progression. The presence of anions and humic acids with low concentrations had minimal impact on aniline removal. Additionally, the CoFe₂O₄ catalyst demonstrated excellent recyclability, maintaining a pollutant removal rate above 93% over five consecutive cycles. Lastly, the CoFe₂O₄/PAA system demonstrates effective treatment of typical pollutants, including phenolic compounds, pesticides, antibiotics, and dyes, achieving removal rates of 77.48% to 99.99%. Furthermore, it significantly enhances water quality in the treatment of actual secondary effluent, offering a novel theoretical foundation and practical insights for applying this catalytic system in wastewater treatment. Full article

Maghemite nanoparticles (NPs) were successfully developed using phenolic-rich extracts (cyanidin) from Citrus reticulata peel residues. The 11 nm maghemite NPs, obtained at 3% w/v and at 353 K, presented the optimal synthesis conditions. To improve dye adsorption performance, the synergetic adsorption behavior between these 11 nm NPs and multiwall carbon nanotubes was demonstrated. Prior to the adsorption tests, the aging effect on NPs was carefully assessed using various analytical techniques, which clearly showed the magnetite–maghemite phase transition. However, this had no impact on the cyanidin coating or adsorption properties. A remarkable percentage removal of (93 ± 3)% for methylene blue and (84 ± 3)% for methylene green was achieved in short equilibrium times of 10 and 25 min, respectively, with an optimum pH value of 5.5. Reuse experiments revealed that 90% removal for both dyes was achieved between the second to seventh regeneration cycles. Organic loading during these cycles was effectively confirmed by X-ray photoelectron spectroscopy and magnetic measurements. Dye adsorption involves a two-step mechanism: (i) electrostatic adsorption by the negative surface groups of the adsorbent (isoelectric point of 5.2) and the dye cationic groups and (ii) π–π stacking interactions between the aromatic benzene rings of the dyes, the hexagonal skeleton of the multiwall carbon nanotubes, and the phenolic ring groups of the biosynthesized sample. These results suggest that the low-cost modified phenolic adsorbent can be successfully applied to dye removal from water with promising recycling properties. Full article

This manuscript explores the removal of eosin yellow dye, a toxic color substance contributing to water pollution, from aqueous solutions. For this purpose, iron-zirconia binary oxide (Fe₂O₃-ZrO₂) was functionalized with eugenol oil, a natural phenolic aromatic compound extracted from the clove plant. The functional groups developed in the binary oxide were confirmed by Fourier transform infrared spectroscopy (FT-IR), and its crystal structure was determined via X-ray diffraction (XRD). The grain size analyzed by the XRD pattern was found to be 45 nanometers. The morphological analysis revealed nanoparticles of quasi-spherical type with a size ranging from 4 to 5 nanometers. The consistency between SEAD and XRD further confirmed that the material formed was iron-zirconia binary oxide. The obtained material, which was insoluble in water, was used as an adsorbent. Through the adsorption study of eosin yellow dye, the maximum monolayer adsorption capacity of approximately 91.0 mg/g at 27 °C and pH = 7.0 for the functionalized adsorbent was determined. The process was exothermic, feasible, and spontaneous. At a dose of 1.0 g/L, the adsorbent was responsible for removing more than 90% of eosin yellow with 10–70 mg/L initial concentration, while about 56% removal was achieved at a higher concentration of 150 mg/L at 27 °C and pH = 7.0. These results highlight the potential of functionalized Fe₂O₃-ZrO₂ as an effective adsorbent for water purification applications. Full article

The escalating issue of phenol-containing wastewater necessitates the development of efficient and sustainable treatment methods. In this context, we present a novel composite photocatalyst comprising ZnFe₂O₄ (ZFO) nanoparticles supported on nanocellulose (NC), aimed at addressing this environmental challenge. The synthesis involved a facile hydrothermal method followed by the impregnation of ZFO nanoparticles onto the NC matrix. The morphology and structure of ZFO, NC, and ZFO/NC were investigated by TEM, SEM-EDX, UV–vis, FT-IR, XRD, and XPS analyses. ZFO, as a weakly magnetic semiconductor catalytic material, was utilized in photocatalytic experiments under magnetic field conditions. By controlling the electron spin states through the magnetic field, electron–hole recombination was suppressed, resulting in improved photocatalytic performance. The results demonstrated that 43% and 76% degradation was achieved after 120 min of irradiation due to ZFO and 0.5ZFO/NC treatment. Furthermore, the composite 0.5ZFO/NC demonstrated the highest photocatalytic efficiency, showing promising recyclability by maintaining its activity after three cycles of use. This study underscores the potential of the ZFO/NC composite for sustainable wastewater treatment, offering a promising avenue for environmental remediation. Full article

The use of sewage sludge activated carbon (thickened samples ACS1 and non-thickened samples ACS2) in a variety of applications and simple environmentally friendly production techniques are attracting more and more attention. We offer here a novel environmentally friendly method based on the green synthesis of activated carbons (ACS1/ACS2) using sewage sludge (SS). These activated carbons are then used to effectively remove the water-based reactive dye phenol red (PR). The ACS1 and ACS2 produced are porous materials with an average diameter of 20.72–13.30 and 6.20–7.34 nm, respectively. These ACS1/ACS2 were analyzed using a range of characterization techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) analysis. Elimination of toxic PR dye was investigated using several operational factors, including ACS1/ACS2 dose, initial PR dye concentration, pH and temperature. Under the best experimental conditions, the ACS1 and ACS2 adsorbents absorbed nearly 89.58% and 97.69% of the PR dye, respectively. It was found that both ACS1 and ACS2 adsorption corresponded to pseudo-first-order kinetics (R = 0.996 and 0.980) and fulfilled Langmuir’s (ACS1) and Freundlich’s (ACS2) models well, with maximum adsorption capacities of 65.35 and 122.72 mg/g, respectively. It was found that the adsorption processes are basically exothermic. The results suggest that sewage sludge can be effective as a low-cost and environmentally beneficial synthesis of ACS1 and ACS2 in the purification of water sources contaminated with hazardous dyes. Full article

The oxidation of organic pollutants in water is the most reported application of a Titanium dioxide (TiO₂) photocatalyst. During the last decade, photoreduction with TiO₂ has also been explored but simultaneous capabilities for unmodified TiO₂ have not been reported yet. Here, we reported on the fabrication of TiO₂ nanorods using hydrothermal treatment and compared the effect of two different TiO₂ powders as the starting material: P-25 and TiO₂ sol–gel (N-P25 and N-TiO₂, respectively) which were further calcined at 400 °C (N-P25-400 and N-TiO₂-400). XPS and XRD analyses confirmed the presence of sodium and hydrogen titanates in N-P25, but also an anatase structure for N-TiO₂. The specific surface area of the calcined samples decreased compared to the dried samples. Photocatalytic activity was evaluated using phenol and methyl orange for degradation, whereas 4-nitrophenol was used for photoreduction. Irradiation of the suspension was performed under UV light (λ = 254 nm). The results demonstrated that the nanorods calcined at 400 °C were more photoactive since methyl orange (20 ppm) degradation reached 86% after 2 h, when N-TiO₂-400 was used. On the other hand, phenol (20 ppm) was completely degraded by the presence of N-P25-400 after 2 h. Photoreduction of 4-nitrophenol (5 ppm) was achieved by the N-TiO₂-400 during the same period. These results demonstrate that the presence of Ti³⁺ and the source of TiO₂ have a significant effect on the photocatalytic activity of TiO₂ nanorods. Additionally, the removal of methylene blue (20 ppm) was performed, demonstrating that N-TiO₂ exhibited a high adsorption capacity for this dye. Full article

The single-atom catalyst (SAC) activated persulfate process has emerged as a highly efficient technology for eliminating refractory organic compounds in aqueous environments. This review delves into the intricacies of utilizing SACs for the effective removal of various contaminants in water. The common supports and the preparation procedures of SACs are summarized at first. The synthesis methods of SACs (i.e., wet chemical method, one-pot hydrothermal method, and high-temperature pyrolysis method) are also described. Then, a comprehensive overview of the diverse reaction mechanisms in SAC-activated persulfate systems is presented, including a radical oxidation process via sulfate or hydroxyl radicals and superoxide radicals, or a nonradical process via single oxygen, surface active complex, and high-valent metal-oxo species oxidation. The impact of key factors such as peroxides concentration, SAC dosage, reaction pH, inorganic anions, organic matter, operando stability, and real water is also delved. The removal of various pollutants (i.e., azo dyes, phenolic compounds, pharmaceuticals, and bacteria) by this process is further summarized. Finally, the challenges and perspectives in the field of water treatment utilizing SACs are discussed. Full article

Worldwide, populations face issues related to water and energy consumption. Water scarcity has intensified globally, particularly in arid and semiarid regions. Projections indicate that by 2030, global water demand will rise by 50%, leading to critical shortages, further intensified by the impacts of climate change. Moreover, wastewater treatment needs further development, given the presence of persistent organic pollutants, such as dyes and pharmaceuticals. In addition, the continuous increase in energy demand and rising prices directly impact households and businesses, highlighting the importance of energy savings through effective building insulation. In this regard, tannin-furanic foams are recognized as promising sustainable foams due to their fire resistance, low thermal conductivity, and high water and chemical stability. In this study, tannin and lignin rigid foams were explored not only for their traditional applications but also as versatile materials suitable for wastewater treatment. Furthermore, a systematic approach demonstrates the complete replacement of the tannin-furan foam phenol source with two lignins that mainly differ in molecular weight and pH, as well as how these parameters affect the rigid foam structure and methylene blue (MB) removal capacity. Alkali-lignin-based foams exhibited notable MB adsorption capacity (220 mg g⁻¹), with kinetic and equilibrium data analysis suggesting a multilayer adsorption process. The prepared foams demonstrated the ability to be recycled for at least five adsorption-desorption cycles and exhibited effective flame retardant properties. When exposed to a butane flame for 5 min, the foams did not release smoke or ignite, nor did they contribute to flame propagation, with the red glow dissipating only 20 s after flame exposure. Full article

Novel sorbents were produced using sustainable and eco-friendly methods, aimed at minimizing environmental impact while utilizing industrial by-products and natural minerals. Olive stones and molasses derived from olive mill and sugar industries, respectively, and an abundant, natural and low-cost mineral, clinoptilolite, were combined in the following proportions: 80/20 clinoptilolite/stone, 80/10/10 clinoptilolite/stone/molasses, 50/50 stone/molasses, w/w. Then, physical carbonization (CL80OL20C, CL80OL10M10C, OL50M50C) or chemical activation (CL80OL20A, CL80OL10M10A, OL50M50A) took place. The adsorbents were characterized through Raman, FT-IR, BET and SEM-EDS analysis. The CL80OL20A material presents the highest ratio of C/O in EDS analysis and the lowest I_D/I_G in Raman spectroscopy. The increase in the specific surface area is as follows: OL50M50C < OL50M50A < CL80OL10M10C < CL80OL20C < CL80OL20A < CL80OL10M10A. Three applications were conducted: two with dyes (methylene blue and methyl red) in aqueous means and one in olive mill wastewaters for the removal of total phenols and their addition to rice, increasing the total phenolic content and producing novel foods. The well-fitted application of the pseudo-second order kinetic model to the experimental data has shown that chemisorption is the prevailing mechanism. The adsorbed amount of the recovered phenols to rice ranges from 0.14 to 0.93 mg/g. Consequently, olive and sugar by-products can be used as filters either to adsorb dangerous organic compounds or to recover bioactive compounds from wastewater, preventing their disposal in the environment, which could otherwise lead to severe negative effects on the ecosystems. Full article

Currently, water pollution caused by dyes is a serious problem since they are toxic and carcinogenic to living beings. To reduce the presence of these contaminants, natural adsorbents have been considered as they are easy to obtain, inexpensive, and have high removal efficiency. In this work, the adsorption process using natural brushite (nDCPD) was studied for the removal of phenol red (PR), achieving a removal rate of 99.15% and an adsorption capacity of 82.24 mg/g, and gentian violet (GV), achieving a removal rate of 97.03% and an adsorption capacity of 74.22 mg/g. Equilibrium adsorption occurs for both dyes in multiple layers on the surface. The adsorption process is spontaneous for both dyes. The kinetics of the adsorption process involve using a single active site on the surface for PR adsorption, while for GV, two active sites on the surface are required. Analysis via FTIR, EDS, and XRD revealed various mechanisms that intervene in the adsorption process of both dyes on the surface of nDCPD, such as electrostatic forces, functional groups, physisorption, and ion exchange. Full article

In this work, a meso-macroporous analcime/sodalite zeolite composite was produced by a hybrid synthesis process between a complex template method and hydrothermal treatment at 220 °C of naturally abundant kaolinitic-rich clay, using dodecyltrimethylammonium bromide as an organic soft template to enhance the mesoporous structure. The chemical and morphological properties of the developed zeolites composite were characterized using powder X-ray diffraction (PXRD), attenuated total Reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), N₂ adsorption/desorption; and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) methods were used to study the morphology, chemical composition and structure of the product. Two types of zeolite particles were obtained:(1) hollow microsphere with an attached analcime icositetrahedron of 30–40 µm in size and (2) sodalite microsphere with a ball-like morphology of 3–4 µm in size. Both N₂ adsorption/desorption and surface area data confirmed the high potentiality of the produced zeolite composite to act as an excellent adsorbent to remove inorganic pollutants such as Cu, Cd, Cr, Ni, Zn, and Pb ions, organic pollutants such as dyes, phenolic compounds, and surfactants from water; and their high catalytic activity, especially in the oxidation reaction of volatile organic compounds. The catalytic activity and adsorption ability of the produced analcime/sodalite composite will be tested experimentally in future work. Full article

Papaya contains high amounts of vitamins A, C, riboflavin, thiamine, niacin, ascorbic acid, potassium, and carotenoids. It is confirmed by several studies that all food waste parts such as the fruit peels, seeds, and leaves of papaya are potential sources of phenolic compounds, particularly in the peel. Considering the presence of numerous bioactive compounds in papaya fruit peels, the current study reports a rapid, cheap, and environmentally friendly method for the production of gold nanoparticles (AuNPs) employing food biowaste (vegetable papaya peel extract (VPPE)) and investigated its antioxidant, antidiabetic, tyrosinase inhibition, anti-inflammatory, antibacterial, and photocatalytic degradation potentials. The phytochemical analysis gave positive results for tannins, saponins, steroids, cardiac steroidal glycoside, protein, and carbohydrates. The manufactured VPPE-AuNPs were studied by UV–Vis scan (with surface plasmon resonance of 552 nm), X-ray diffraction analysis (XRD) (with average crystallite size of 44.41 nm as per the Scherrer equation), scanning electron microscopy–energy-dispersive X-ray (SEM-EDS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), particle size, zeta potential, etc. The mean dimension of the manufactured VPPE-AuNPs is 112.2 d.nm (PDI—0.149) with a −26.1 mV zeta potential. The VPPE-AuNPs displayed a significant antioxidant effect (93.24% DPPH scavenging and 74.23% SOD inhibition at 100 µg/mL); moderate tyrosinase effect (with 30.76%); and substantial α-glucosidase (95.63%) and α-amylase effect (50.66%) at 100 µg/mL. Additionally, it was found to be very proficient in the removal of harmful methyl orange and methylene blue dyes with degradation of 34.70% at 3 h and 24.39% at 5 h, respectively. Taken altogether, the VPPE-AuNPs have been proven to possess multiple biopotential activities, which can be explored by the food, cosmetics, and biomedical industries. Full article