Search Results (32)

The treatment of contaminants from road infrastructure poses significant challenges due to their variable composition and the high concentrations of chloride ions, heavy metals, and oil-derived substances. Traditional methods for protecting groundwater environments are often insufficient. A promising alternative is permeable reactive barrier (PRB) technology, which utilizes recycled materials and construction waste as reactive components within the treatment zone of the ground. This paper delves into the potential of employing a composite (MIX) consisting of modified construction aggregate (as recycled material) and activated carbon (example of reactive material) to address environmental contamination from a mixture of heavy metals and chloride. The research involved chemical modifications of the road aggregate, activated carbon, and their composite, followed by laboratory tests in glass reactors and non-flow batch tests to evaluate the kinetics and chemical equilibrium of the reactions. The adsorption process was stable and conformed to the pseudo-second-order kinetics and Langmuir, Toth, and Redlich–Peterson isotherm models. Studies using MIX from a heavy metal model solution showed that monolayer adsorption was a key mechanism for removing heavy metals, with strong fits to the Langmuir (R² > 0.80) and Freundlich models, and optimal efficiencies for Cd and Ni (R² > 0.90). The best fit, at Cd, Cu, Ni = 0.96, however, was with the Redlich–Peterson isotherm, indicating a mix of physical and chemical adsorption on heterogeneous surfaces. The Toth model was significant for all analytes, fitting Cl and Cd well and Pb and Zn moderately. The modifications made to the composite significantly enhanced its effectiveness in removing the contaminant mixture. The test results demonstrated an average reduction of chloride by 85%, along with substantial removals of heavy metals: lead (Pb) by 90%, cadmium (Cd) by 86%, nickel (Ni) by 85%, copper (Cu) by 81%, and zinc (Zn) by 79%. Further research should focus on the removal of other contaminants and the optimization of magnesium oxide (MgO) dosage. Full article

In the waste oil recycling industry, large amounts of oil-containing sludge are still generated, thus posing a resource depletion issue when disposed of or incinerated without energy recovery or residual oil utilization. In this work, chemical activation experiments using phosphoric acid (H₃PO₄) were performed at a low temperature (600 °C) for 30 min to produce porous carbon products. From the results of the pore property analysis, an increasing trend with an increasing impregnation ratio from 0.5 to 2.0 was observed. Based on the Brunauer–Emmett–Teller (BET) model, the maximal BET surface area was about 70 m²/g, which was indicative of the hysteresis loop and the type IV isotherms in the resulting carbon product. In addition, the enhancement in the pore properties of the carbon products obtained through acid-washing was superior to that achieved through water-washing and without post-washing. From observations made using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), the carbon products featured a porous structure and inherent magnetism due to their richness of iron oxides. In this regard, they can be used as efficient adsorbents or catalyst supports due to their simple recovery (or separation) when exhausted. Full article

In this research work, the catalytic performances of two manganese-based catalysts, manganese (III) acetylacetonate (Mn(acac)3) and manganese tallate (Mn-TO), were studied during the process of Ashalcha heavy oil oxidation under in situ combustion conditions. DSC analysis shows distinct thermal behavior of both ligated catalysts during low- and high-temperature oxidation phases (LTO and HTO); for example, the shifting in peak temperature (Tp) in the HTO at a heating rate of 10 °C/min was reduced by approximately 5.3% for Mn-TO and 2.24% for Mn(acac)3 when compared with uncatalyzed heavy oil. Combined isothermal kinetic analyses using the Friedman and Kissinger–Akahira–Sunose analytic methods have provided insights about activation energies and frequency factors over the whole conversion range, where the catalytic performance of Mn-TO showed low activation energies in both LTO and HTO (E_α of Mn-TO was approximately 13.33% (LTO) and 7.68% (HTO) less than with the heavy oil alone). In addition, calculations of the effective rate constant confirmed the increased oxidation rate trend of both catalysts, with Mn-TO exhibiting the highest values. The findings highlight the potential of these manganese-based catalysts, the Mn-TO catalyst in particular, in optimizing heavy oil oxidation processes. The overall results further contribute to developing more efficient ligand catalyst complexes for sustainable heavy oil recovery while continuously improving their efficient application during in situ combustion in the petroleum industry. Full article

The encapsulation of fish oil by monoaxial electrospraying using kafirin or zein proteins as hydrophobic wall materials was investigated. Kafirin resulted in spherical fish oil-loaded nanocapsules (>50% of capsules below 1 µm), whereas zein led to fish oil-loaded nanocapsules with non-spherical morphology (>80% of capsules below 1 µm). Both hydrophobic encapsulating materials interacted with fish oil, successfully entrapping the oil within the protein matrix as indicated by Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy results. FTIR also suggested hydrogen bonding between fish oil and the proteins. Trapped radicals in the encapsulation matrix that were detected by electron paramagnetic resonance (EPR), indicated oxidation during electrospraying and storage. Results from isothermal (140 °C) differential scanning calorimetry (DSC) denoted that the encapsulation of fish oil by electrospraying using both kafirin or zein as wall materials protected fish oil from oxidation. In particular, the zein-based nanocapsules were 3.3 times more oxidatively stable than the kafirin-based nanocapsules, which correlates with the higher oil encapsulation efficiency found for zein-based capsules. Thus, this study shows that kafirin might be considered a hydrophobic wall material for the encapsulation of fish oil by electrospraying, although it prevented lipid oxidation to a lower extent when compared to zein. Full article

(1) Background: Safety problems associated with aflatoxin B₁ (AFB₁) contamination have always been a major threat to human health. Removing AFB₁ through adsorption is considered an attractive remediation technique. (2) Methods: To produce an adsorbent with a high AFB₁ adsorption efficiency, a magnetic reduced graphene oxide composite (Fe₃O₄@rGO) was synthesized using one-step hydrothermal fabrication. Then, the adsorbent was characterized using a series of techniques, such as SEM, TEM, XRD, FT-IR, VSM, and nitrogen adsorption–desorption analysis. Finally, the effects of this nanocomposite on the nutritional components of treated foods, such as vegetable oil and peanut milk, were also examined. (3) Results: The optimal synthesis conditions for Fe₃O₄@rGO were determined to be 200 °C for 6 h. The synthesis temperature significantly affected the adsorption properties of the prepared material due to its effect on the layered structure of graphene and the loading of Fe₃O₄ nanoparticles. The results of various characterizations illustrated that the surface of Fe₃O₄@rGO had a two-dimensional layered nanostructure with many folds and that Fe₃O₄ nanoparticles were distributed uniformly on the surface of the composite material. Moreover, the results of isotherm, kinetic, and thermodynamic analyses indicated that the adsorption of AFB₁ by Fe₃O₄@rGO conformed to the Langmuir model, with a maximum adsorption capacity of 82.64 mg·g⁻¹; the rapid and efficient adsorption of AFB₁ occurred mainly through chemical adsorption via a spontaneous endothermic process. When applied to treat vegetable oil and peanut milk, the prepared material minimized the loss of nutrients and thus preserved food quality. (4) Conclusions: The above findings reveal a promising adsorbent, Fe₃O₄@rGO, with favorable properties for AFB₁ adsorption and potential for food safety applications. Full article

Origanum vulgare is recognized worldwide for its numerous applications, in the food industry and beyond. However, the extraction of its essential oils generates a significant amount of waste. The aim of this research was to achieve the valorization of solid waste from oregano hydro-distillation, by (i) optimizing the ultrasound extraction of antioxidants, (ii) evaluating the effect of spray and freeze drying on the extract’s physicochemical properties, and (iii) characterizing the obtained powder by its antioxidant capacity. A central composite design of experiments was used to optimize the sample/solvent ratio, ethanol/water ratio, and extraction time. The extract was analyzed for its antioxidant potential by determining the percentage of DPPH inhibition, FRAP, and total phenolic content (TPC). The GAB model best fit the data for the moisture sorption isotherm of the resulting powder. The antioxidant activity of the powders was tested in a ground-beef food system. The TPC was maximized at times longer than 58 min, a sample/solvent ratio between 0.058 and 0.078, and a ratio of ethanol/water around 1. Neither drying method significantly affected the antioxidant properties of the extract, even though the resulting powders from each showed a different morphology (determined using SEM). Encapsulation with maltodextrin protected the spray-dried extract during a 6-month storage period. Powders from both drying methods equally retarded lipid oxidation, and were comparable to the synthetic antioxidant BHT. It is concluded that oregano processing waste is a potent source of antioxidants, and that its dried extract, via an ultrasound-assisted process, can potentially be used as a natural alternative to synthetic antioxidants. Full article

Drying Pickering o/w emulsions has been considered as a promising strategy to produce oil microcapsules, as long as their quality parameters can be preserved over storage. In this sense, it is shown as an interesting alternative to preserve the quality of roasted coffee oil, a valuable agroindustrial byproduct. Thus, freeze- and spray-dried chitosan-based Pickering emulsions of roasted coffee oil were evaluated over 30 days of storage at 25 °C together with the non-encapsulated oil as a control. Water sorption isotherms were determined, whereas color, oxidative stability (peroxide value and conjugated dienes) and volatile compounds were assessed over the storage period. Type II isotherms and Guggenheim–Anderson–Boer (GAB) model parameters showed that water binding was impaired by the surface oil in freeze-dried samples. Oxidation was maintained under acceptable values over the storage for all samples, with slightly higher protection also observed for volatile compounds in the spray-dried particles. The powdered emulsions were able to suitably preserve the oil’s quality over 30 days of storage, enabling its commercialization and application as a food ingredient and potential flavoring. Full article

The susceptibility of polyunsaturated fatty acids to oxidation severely limits their application in functional emulsified foods. In this study, the effect of sesamol concentration on the physicochemical properties of WPI-stabilized fish oil emulsions was investigated, focusing on the relationship between sesamol–WPI interactions and interfacial behavior. The results relating to particle size, zeta-potential, microstructure, and appearance showed that 0.09% (w/v) sesamol promoted the formation of small oil droplets and inhibited oil droplet aggregation. Furthermore, the addition of sesamol significantly reduced the formation of hydrogen peroxide, generation of secondary reaction products during storage, and degree of protein oxidation in the emulsions. Molecular docking and isothermal titration calorimetry showed that the interaction between sesamol and β-LG was mainly mediated by hydrogen bonds and hydrophobic interactions. Our results show that sesamol binds to interfacial proteins mainly through hydrogen bonding, and increasing the interfacial sesamol content reduces the interfacial tension and improves the physical and oxidative stability of the emulsion. Full article

Mediterranean countries experience a large production of olive oil, thus generating huge quantities of non-biodegradable vegetation waters. The discharge of these effluents into aquatic environments seriously affects the quality of surface waters. This study investigated the potential use of carbon steel slag (SS) as an adsorbent and improver for reducing olive mill wastewater (OMWW) toxicity. The elemental and structural characterization of SS was carried out using inductively coupled plasma-optical emission spectrometry (ICP/EOS), X-ray fluorescence (XRF), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analysis. OMWW characterization indicated that the effluent was acidic in nature, with a pH of 4.8, a higher conductivity reaching 14.92 mS/cm, higher COD of 157.31 g/L, rich in organic matter 112.33 g/L, and total phenolic compounds of 11.13 g/L. The neutralization capacity of SS was demonstrated by reducing the OMWW’s acidic character. Afterward, the adsorption of tannic acid (TA) was investigated using SS. Parameters such as contact time, initial TA concentration, adsorbent dosage, pH, and temperature were investigated. The kinetic study indicated that the adsorption of TA onto SS fitted well with the second pseudo-order (r = 0.99) and Elovich (r = 0.98) models, indicating that the adsorption of TA was mainly chemical and depends on the reactions of oxide hydrolysis and hydroxides dissolution. Moreover, Langmuir isotherm has greatly described the adsorption of TA on SS (R = 0.997), suggesting that the surface of SS is homogenous, and the adsorption occurs mainly in monolayer. The maximum adsorption capacity reached 714.28 mg/g, indicating the higher capacity of SS to reduce the polyphenolic compounds in OMWW. This study demonstrated that SS residue from the steelmaking industry could present a highly interesting material for OMWW remediation. Full article

Hexagonal SBA-15 mesoporous material was used as a catalytic template for impregnation, with the transition metals Fe, Co, and Ni as catalysts for chemical transformation. Nitrogen adsorption/desorption isotherms, scanning electron microscopy, and transmission electron microscopy were conducted to better understand the physicochemical properties of the metal oxide-impregnated SBA-15. The specific surface area of the original SBA-15 was approximately 680 m²/g, and the abundances of the catalysts impregnated ranged from 2 to 8%, corresponding to specific surface areas of 560–470 m²/g for Fe-SBA-15, 440–340 m²/g for Ni-SBA-15, and 410–340 m²/g for Co-SBA-15. The increase in impregnated metal loadings filled the pores and collapsed the silica walls during the metal oxides impregnation on SBA-15 and calcination procedures, resulting in a decrease in the specific surface area and pore volume of the templates. The results showed that the order of nitrogen adsorbed was SBA-15 > Fe-SBA-15 > Ni-SBA-15 > Co-SBA-15 when the metal loading was 5%. In addition, the metal oxides on SBA-15 increased the wall thickness compared with raw SBA-15. Based on the XRD spectrum analysis, Fe₂O₃, Co₃O₄, and NiO were the stable crystals on the Fe-SBA-15, Co-SBA-15, and Ni-SBA-15, respectively. The sequence of the average grain size of metal oxides on SBA-15 was Co-SBA-15 > Fe-SBA-15 > Ni-SBA-15, according to XRD spectra and Scherrer’s equation. Isopropanol could be decomposed by metal oxide-impregnated SBA-15 to form carbon filament materials. Therefore, these materials have the potential to be employed for pollutant removal, catalytic reactions for organic solvent and bio-oil/biomass reforming, and recycling waste into high-value materials. Full article

The use of biobased heterogeneous catalysts made from agricultural waste for producing biodiesel has gained attention for its potential to create a sustainable and low-cost process. The blending of two or more biomass residues to create more viable biobased catalysts is still in its early stages. In this study, a Biobased Composite Heterogeneous Catalyst (CHC) was made by blending the shells of periwinkle (PWS), melon seed-husk (MSH), and locust bean pod-husk (LBP) at a mixing ratio of 67:17:17 using Simplex Lattice Design Mixture, that was then calcined for 4 h at 800 °C. The chemical, structural, and morphological components of the CHC were characterized via XRF, XRD, SEM-EDX, BET, TGA/DSC, and FTIR to assess its catalytic potential. The CHC was employed to synthesize biodiesel from palm kernel oil, and the process optimization was conducted using the Taguchi approach. The XRF analysis showed that the catalyst had 69.049 of Calcium (Ca) and 9.472 of potassium (K) in their elemental and oxide states as 61.592% calcium oxide and 7.919% potassium oxide. This was also supported by the EDX result, that showed an appreciable value of 58.00% of Ca and 2.30% of magnesium, that perhaps provided the active site in the transesterification reaction to synthesize biodiesel. The morphological and physisorption isotherms via SEM and BET showed mesoporous structures in the CHC that were made up of nanoparticles. A high maximum biodiesel yield of 90.207 wt.% was attained under the optimized process conditions. The catalyst could be reused for up to four cycles, and the biodiesel produced met both ASTM D6751 and EN 14214 standards for biodiesel. This study demonstrates that blending PWS, MSH, and LBP waste materials can produce high-quality biodiesel without the need for additional catalysts. Full article

To overcome the issues in the traditional deacidification processes of peony seed oil (PSO), such as losses of neutral oil and trace nutrients, waste discharge, and high energy consumption, adsorption deacidification was developed. The acid removal capacity of adsorbent-alkali microcrystalline cellulose was evaluated using the isothermal adsorption equilibrium and the pseudo-first-order rate equation. The optimized adsorption deacidification conditions included adsorbent-alkali microcrystalline cellulose at 3%, a heating temperature of 50 °C, and a holding time of 60 min. The physicochemical, bioactive properties, antioxidant capacities, and oxidative stabilities of PSO processed by alkali refining and oil-hexane miscella deacidification were compared under the same operating conditions. Fatty acid content was not significantly different across all three methods. The deacidification rates were 88.29%, 98.11%, and 97.76%, respectively, for adsorption deacidification, alkali refining, and oil-hexane miscella deacidification. Among the three deacidification samples, adsorption deacidification showed the highest retention of tocopherols (92.66%), phytosterols (91.96%), and polyphenols (70.64%). Additionally, the obtained extract preserved about 67.32% of the total antioxidant activity. The oil stability index was increased 1.35 times by adsorption deacidification. Overall, adsorption deacidification can be considered a promising extraction technology in terms of quality as compared to alkali refining and oil-hexane miscella deacidification. Full article

Cold-pressed hemp (Cannabis Sativa L.) seed oil has become very popular amongst consumers and researchers, due to its manifold application in food and medicine industry. In this study, oils pressed from stored and fresh hemp seeds of the Henola cultivar were analyzed. Determination of the acid value (AV) and color of oil (a* parameter) revealed significant differences between the two groups of oils (fresh and stored seeds) in contrast to the peroxide value (PV), p-anisidine value (p-AV), and fatty acid composition. On the other hand, isothermal and non-isothermal assessments of the thermo-oxidative stability by differential scanning calorimetry (DSC) showed no significant differences in oxidation induction time (OIT) as well as in onset temperature (T_on) between two groups of oils (p > 0.05). The DSC isothermal test (OIT 160) showed significant correlations with mono- and polyunsaturated fatty acids as well as with values of AV and a* (p ≤ 0.05), in contrast to the non-isothermal test, for which correlations were not significant (p > 0.05). However, the best distinction of both groups of oils was obtained analyzing all results together (DSC, fatty acid and tocochromanols composition, color, and oxidative stability results) by principal component analysis (PCA). Full article

We report the synthesis of reduced graphene oxide (rGO)-α-Fe₂O₃ nanocomposite and its application to remove and recover dissolved oil from a high-salinity oil–water emulsion in batch and column/breakthrough setups. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and nitrogen adsorption characterized the synthesized nanocomposite’s structure, morphology, and surface properties. Both batch and continuous breakthrough adsorption studies were investigated. The effect of the adsorption parameters on the adsorption capacity and removal efficiency was analyzed. The rGO-Fe₂O₃ nanocomposite (rGO-Fe₂O₃-NC) demonstrated a superior adsorption capacity, both when measured experimentally (1213 mg/g) and predicted using the Freundlich isotherm (1301 mg/g). The adsorption process followed pseudo-second-order kinetic, and the rGO-Fe₂O₃-NC exhibited a very rapid removal, with more than 60% of oil being removed within 10 min. Breakthrough confirmed the exceptional removal capacities with good regeneration and cycling ability under a short contact time. Moreover, the adsorption capacity was enhanced with an emulsion salinity of up to 100,000 ppm, confirming the suitability for high-salinity wastewater. Full article

Bioactive collagen–chitosan–lemongrass (COL–CS–LG) membranes were prepared by casting method and analyzed for potential biomedical applications. For COL–CS–LG membranes, LG essential oil release, antioxidant properties, in vitro cytotoxicity and antimicrobial assessments were conducted, as well as free radical determination after gamma irradiation by chemiluminescence, and structural characteristics analysis through Attenuated Total Reflection–Fourier Transform Infrared Spectroscopy (ATR–FTIR) and Differential Scanning Calorimetry (DSC). The evaluation of non-isothermal chemiluminescence after gamma radiation exposure to COL–CS–LG membranes revealed a slowing down of the oxidation process at temperatures exceeding 200 °C, in correlation with antioxidant activity. Antimicrobial properties and minimum inhibitory concentrations were found to be in correlation with cytotoxicity limits, offering the optimum composition for designing new biomaterials. Full article