High Concentrations Of Phenol Research Articles

Cold-acclimation effect on cadmium absorption and biosynthesis of polyphenolics, and free proline and photosynthetic pigments in Spirogyra aequinoctialis

Abstract Herein, a link has been established between cold acclimation and Cd uptake in Spirogyra aequinoctialis. The water samples supplemented with cadmium (0.1, 0.5, and 1.0 mg/L) were used for plant growth at two different temperatures. Cold-acclimated plants accumulated high concentrations (0.40 ± 0.02 µg/dry biomass) of Cd as compared to non-acclimated plants (0.30 ± 0.08 µg/dry biomass). The negative effects of Cd on the biomass, carotenoids, and chlorophyll contents in non-acclimated plants were more pronounced in non-acclimated plants as compared to the cold-acclimated plants. High concentrations of free proline and total phenolics in cold-acclimated plants were observed as compared to the non-acclimated plants. About 13 different phenolic compounds were identified using high-pressure liquid chromatography. Cold acclimation as well as the presence of Cd in water highly increased the concentrations of polyphenolics, while synergistic increase was recorded with the combination of cold acclimation and Cd treatments. The highest increase in the concentration of polyphenolics was recorded for syringic acid. Significant positive correlations of total phenolics were noted with dry biomass (R 2 = 0.51) and Cd accumulation (R 2 = 0.59) in plant tissues. Free proline concentration also showed positive correlations with dry biomass, Cd accumulation, and chlorophyll contents (R 2 = 0.80).

Phytochemical and Nutritional Profile, Mineral Ratio and Mineral Safety Index of Young and Matured Corn Silk Collected from Ekiti State, Nigeria

Corn silk is an agricultural waste material from corn cultivation. The need for a supplement feed material that would be readily available, affordable and has nutritional qualities prompted this study. Fresh and dry corn silk were collected from a farm land in Ado Ekiti, Ekiti State, Nigeria and evaluated for phytochemical and nutritional composition using standard techniques. The phytochemical analysis revealed that both the young and matured corn silk contained alkaloids, tannins, saponins, flavonoids, phenols, steroids and reducing sugar. The qualitative phytochemical estimates showed high concentration of flavonoids and total phenols while tannins were found in moderate quantities. The proximate estimation (%) revealed high values of carbohydrate and crude fiber, moderate crude protein and ash, low crude fat, low moisture as well as high energy content in young and matured corn silk respectively. Both samples contained high K, P, Ca, Mg, moderate Na, Fe, Mn, Zn and Cu while Pb and Ni, toxic metals, were absent. The results showed low mineral CV% which ranged from 1.32-38.92. The results of the mineral safety index were lower than the standard, an indication that there would be no mineral overload. The two corn silk samples were rich in active secondary metabolites which could offer protective health benefits, also safe and contained nutritional qualities that could make them suitable to be incorporated into man’s diet and domestic feed.

Elucidated potential of immobilized Janibacter sp. for saline wastewater phenol removal.

Phenolic compounds are commonly found in industrial effluents and can be hazardous to organisms even at low concentrations. Over the years, researchers have demonstrated that bioremediation is a cost-effective and environmentally friendly alternative to physicochemical approaches used to remove phenol. The aim of this study was to investigate the removal of phenol from saline wastewaters by a halotolerant strain of the genus Janibacter. For this purpose, bacterial cells were immobilized on different supports, from which mica and zeolite were ultimately chosen due to their higher removal efficiency. The wet weight of immobilized cells per 1g of mica and zeolite was 0.51 and 0.48g, respectively. Free cells consumed 100mg/L of phenol in 88h, while immobilized cells used it in 40h. Immobilized cells revealed a higher thermostability and could operate over a wider pH range and salinity. Unlike free cells, immobilized cells could remove 700mg/L of phenol and could be reused for at least nine cycles. Interestingly the phenol removal efficiency of zeolite-immobilized cells remained unchanged after 4months of storage at 4 and - 20°C, which could be of great advantage for industrial applications. Complete destruction of phenol was observed through the meta pathway comprising phenol hydroxylase and catechol 2,3-dioxygenase enzymes. KEY POINTS: • Mica- and zeolite-immobilized cells were able to consume high concentrations of phenol. • Cells immobilized on mica and zeolite had considerable operational and storage stability. • Immobilized cells could be a good candidate for phenol removal in saline environments.

Phytochemical studies on Arecaceae growing in Al-Madinah Al-Munawarah, Saudi Arabia

ABSTRACT Arecaceae belongs to monocotyledons with around 217 genera. In Saudi Arabia, two genera of Arecaceae are recorded, namely, Hyphaena and Phoenix. Al-Madinah Al-Munawarah is an important region in the western part of Saudi Arabia. This study aimed to investigate the significance of phytochemical traits in Arecaceae plants growing in the region of Al-Madinah Al-Munawarah. Plant specimens were collected in September 2021 from the Al-Madinah Al-Munawarah region. Leaves and fruit samples were screened using standard techniques for the presence of phytochemical groups. For the estimation of antioxidants, extracts were obtained from leaves and the concentration of phenolics and flavonoids was determined by LC-DAD at 335 nm and characterized by LTQ-XL linear Ion Trap LC-MS. In statistical analyses, all data obtained from phytochemical investigations were transferred to numerical characters and used in the multivariate statistical package (MVSP). In phytochemical screening, the phytochemical groups of leaves were useful to differentiate between cultivars of date palms. The presence or absence of tannin and saponin in fruits was useful to distinguish between Ph. dactylifera and H. thebaica. The leaves of Ph. dactylifera cultivars and H. thebaica contained flavonoid compounds with different concentrations. The leaves of Phoenix dactylifera cultivars and Hyphaena thebaica can be a valuable source of natural antioxidants and protect against several diseases because of the abundance of flavonoids. The high concentration of phenolics and flavonoids among date palm cultivars was in Altaibat (5.88 mg/g) while the lowest concentration was found in Safawi (1.54 mg/g). The concentration of phenolics and flavonoids in H. thebaica was 5.02 mg/g.

Phenolics profile, anti-nephrolithiasis, and antioxidant activities of Monodora myristica seed: impact of endogenous proteins and lipids

The bioactive compounds in a food matrix can exist either in their free form or bound to other endogenous compounds, which may affect their bioactivities. This study investigated the impact of endogenous proteins and lipids on the phenolics profile, anti-nephrolithiasis, and antioxidant activities of Monodora myristica (African nutmeg) seed. Endogenous proteins and lipids in M. myristica seed flour were removed by deproteinization and defatting, to obtain the deproteinized, defatted, and deproteinized-defatted flours. The native flour served as a control. Phenolics compounds in the flours were quantified using HPLC-DAD, while nephrolithiasis-associated enzymes (xanthine oxidase and urease) inhibitory and antioxidant activities were determined using a spectrophotometer. Nine phenolic compounds (gallic, chlorogenic, caffeic, p-coumaric, ellagic acids, catechin, rutin, quercetin and luteolin) were detected in the native flour, with quercetin as the most abundant. The concentrations of the phenolic compounds, nephrolithiasis-associated enzymes inhibitory, and antioxidant activities of the flour decreased significantly due to deproteinization and defatting. Overall, the native flour had the highest concentrations of phenolics and the most potent enzymes inhibitory and antioxidant activities, followed by the defatted, deproteinized, and deproteinized-defatted flours. Hence, endogenous proteins and lipids may enhance the phenolics profile, anti-nephrolithiasis and antioxidant activities of M. myristica seed. This could have application in the development of functional food products and nutraceuticals targeting nephrolithiasis.Graphical

Selective Removal of Organic Pollutants in Groundwater and Surface Water by Persulfate-Assisted Advanced Oxidation: The Role of Electron-Donating Capacity.

The efficiency of persulfate-assisted advanced oxidation processes (PS-AOPs) in degrading organic pollutants is affected by the electron-donating capability of organic substances present in the water source. In this study, we systematically investigate the electron-donating capacity (EDC) difference between groundwater and surface water and demonstrate the dependence of removal efficiency on the EDC of target water by PS-AOPs with carbon nanotubes (CNTs) as a catalyst. Laboratory analyses and field experiments reveal that the CNT/PS system exhibits higher performance in organic pollutant removal in groundwater with a high concentration of phenols, compared to surface water, which is rich in quinones. We attribute this disparity to the selective electron transfer pathway induced by potential difference between PS-CNT and organic substance-CNT intermediates, which preferentially degrade organic substances with stronger electron-donating capability. This study provides valuable insights into the inherent selective removal mechanism and application scenarios of electron transfer process-dominated PS-AOPs for water treatment based on the electron-donating capacity of organic pollutants.

Contaminated Perry in Patagonia Argentina: A Case Study.

Perry is a beverage obtained by fermentation of pear juice, popular in the North Hemisphere. In Argentina it is an emerging market, particularly in the Patagonian region. The aim of this work is to describe and to evaluate the spoilage yeasts associated to six perry samples showing signs of microbiological contamination from a local craft perry company in North Patagonian region. Eighteen yeasts were isolated from four of the six perry samples where Brettanomyces custersianus, Brettanomyces bruxellensis and Zygosaccharomyces parabailii were identified. The growth capacity of these isolates in the presence of antimicrobial agents (sulfite and potassium sorbate) was analyzed in solid media. Growth parameters in sterile perry must was evaluated and the production of undesirable compounds were evaluated, products were characterized in terms of their aromatic and physicochemical features. The yeasts Z. parabailii NPCC1791 was able to grow on plates containing sulfite concentrations of up to 4mM and produced high methanol concentrations in perry. Additionally, B. bruxellensis NPPC1792 was able to produce methanol as well as high concentrations of volatile phenols including 4-ethylphenol and 4-ethylguaiacol. These results demonstrate the potential of these species as perry contaminants. Given the lack of studies describing the contaminating yeasts in perry production, this work represents the first report about perry spoilage yeasts in Argentina, with this knowledge, control strategies can be developed to prevent microbiological contamination and minimize product loss.

Advantages of residual phenol in coal chemical wastewater as a co-metabolic substrate for naphthalene degradation by microbial electrolysis cell

The use of co-metabolic substrates is effective for polycyclic aromatic hydrocarbons (PAHs) removal, but the potential of the high phenol concentrations in coal chemical wastewater (CCW) as a co-metabolic substrate in microbial electrolysis cell (MEC) has been neglected. In this study, the efficacy of varying phenol concentrations in comparison to simple substrates for degrading naphthalene in MEC under comparable COD has been explored. Results showed that phenol as a co-metabolic substrate outperformed sodium acetate and glucose in facilitating naphthalene degradation efficiency at 50 mg-COD/L. The naphthalene removal efficiency from RP, RA, and RG was found to be 84.11 ± 0.44 %, 73.80 ± 0.27 % and 72.43 ± 0.34 %, respectively. Similarly, phenol not only enhanced microbial biomass more effectively, but also exhibited optimal COD metabolism capacity. The addition of phenol resulted in a stepwise reduction in the molecular weight of naphthalene, whereas sodium acetate and glucose led to more diverse degradation pathways. Some bacteria with the potential ability to degrade PAHs were detected in phenol-added MEC, including Alicycliphilus, Azospira, Stenotrophomonas, Pseudomonas, and Sedimentibacter. Besides, phenol enhanced the expression of ncrA and nmsA genes, leading to more efficient degradation of naphthalene, with ncrA responsible for mediating the reduction of the benzene ring in naphthalene and nmsA closely associated with the decarboxylation of naphthalene. This study provides guidance for the effective co-degradation of PAHs in CCW with MEC, demonstrating the effectiveness of using phenol as a co-substrate relative to simple substrates in the removal of naphthalene.

Influence of Grape Polysaccharide Extracts on the Phenolic Compounds and Color Characteristics of Different Red Wines.

Polysaccharides have an important role in the technological and sensory characteristics of wines. The aim of this work was to study the effects of the addition of four polysaccharide extracts obtained from grape products and byproducts to red wines during storage for 2 months on their phenolic composition and color. The four extracts rich in polysaccharides were obtained from grape must, white grape pomace, red grape marc, and red wine, and they were compared with a commercial inactivated yeast. These products were studied in three wines selected for their highest astringency and acidity characteristics. The highest differences were found in the red wines with high initial phenolic concentrations, which reduced their values. The addition of polysaccharide extracts from grape pomace or marc, must, or yeast can mainly be interesting in wines with high phenolic content since they may be useful to modulate the astringency of red wines. This is the first work that studies the effect of polysaccharide extracts obtained from grape byproducts in red wines, showing great possibilities of these products.

Dietary Fruit By-Products Improve the Physiological Status of Nile Tilapias (Oreochromis niloticus) and the Quality of Their Meat.

By-products from fruit industrialization retain nutritional and functional components; thus, they may find use in animal feeding. This study aimed to assess the effects of dietary fruit industrial by-products on the tilapias blood biochemical and oxidative parameters and on the composition and lipid peroxidation of their fillets. Four diets were supplied to the tilapias: a C-control diet, with no fruit meal, and three diets containing 5% of either acerola (ACM), apple (APM) or grape (GRM) meal. The phenolic compounds and the carotenoids in the meals and their antioxidant capacities were measured. Fish were weighed and measured for the calculation of the growth performance data, their blood was analyzed for health and oxidative status biomarkers and their fillets were analyzed for proximal composition and lipid peroxidation. Grape meal had the highest concentration of phenolics and carotenoids and the highest antioxidant activity, followed by acerola and apple meals. The productive performance was similar among the treatments. The fruit by-product diets either maintained or improved the biochemical biomarkers of health and improved the oxidative status of the fish. The fruit by-product diets increased the concentration of lipids in the fillets and slowed down the onset of the lipid peroxidation during frozen storage.

Ericoid shrub encroachment shifts aboveground-belowground linkages in three peatlands across Europe and Western Siberia.

In northern peatlands, reduction of Sphagnum dominance in favour of vascular vegetation is likely to influence biogeochemical processes. Such vegetation changes occur as the water table lowers and temperatures rise. To test which of these factors has a significant influence on peatland vegetation, we conducted a 3-year manipulative field experiment in Linje mire (northern Poland). We manipulated the peatland water table level (wet, intermediate and dry; on average the depth of the water table was 17.4, 21.2 and 25.3 cm respectively), and we used open-top chambers (OTCs) to create warmer conditions (on average increase of 1.2°C in OTC plots compared to control plots). Peat drying through water table lowering at this local scale had a larger effect than OTC warming treatment per see on Sphagnum mosses and vascular plants. In particular, ericoid shrubs increased with a lower water table level, while Sphagnum decreased. Microclimatic measurements at the plot scale indicated that both water-level and temperature, represented by heating degree days (HDDs), can have significant effects on the vegetation. In a large-scale complementary vegetation gradient survey replicated in three peatlands positioned along a transitional oceanic-continental and temperate-boreal (subarctic) gradient (France-Poland-Western Siberia), an increase in ericoid shrubs was marked by an increase in phenols in peat pore water, resulting from higher phenol concentrations in vascular plant biomass. Our results suggest a shift in functioning from a mineral-N-driven to a fungi-mediated organic-N nutrient acquisition with shrub encroachment. Both ericoid shrub encroachment and higher mean annual temperature in the three sites triggered greater vascular plant biomass and consequently the dominance of decomposers (especially fungi), which led to a feeding community dominated by nematodes. This contributed to lower enzymatic multifunctionality. Our findings illustrate mechanisms by which plants influence ecosystem responses to climate change, through their effect on microbial trophic interactions.

Synergistic removal performance and mechanism in denitrification system under phenol stress

Based on the principle of heterotrophic denitrification, the synergistic removal mechanism of phenol and NO3--N in denitrification system under phenol stress was investigated. The denitrification process with phenol as the only carbon source was successfully achieved by running the UASB reactor for 119 days, which had excellent phenol and NO3--N removal efficiency (over 99.5%). Results showed that phenol stress enhanced the ATP level, key enzyme activities to increase denitrification and phenol degradation. Phenol stress also stimulated improvement of cell membrane permeability, which led to the increase of electron transport system activity. Meanwhile, phenol stress promoted the secretion of N-acylhomoserine lactones (AHLs), which increased bacterial activity by modulating EPS to mitigate the external environmental shock. Besides, AHLs-mediated quorum sensing (QS) might regulated the changes of microbial structural, resulting in the optimization of microbial communities within the whole denitrification system. Therefore, a synergistic removal mechanism was proposed to elucidate the excellent performance of the denitrification system under phenol stress. This work provided serviceable information for treatment of high concentration phenol wastewater and the synergistic removal mechanism.

Isolated Fraction of Gastric-Digested Camel Milk Yogurt with Carao (Cassia grandis) Pulp Fortification Enhances the Anti-Inflammatory Properties of HT-29 Human Intestinal Epithelial Cells.

Functional foods have recently generated a lot of attention among consumers looking for healthy options. Studies have examined yogurt with carao to increase health benefits and probiotic characteristics. It has been determined that carao fruit and camel milk have high phenolic compound and antioxidant activity concentrations. The objective of this study was to examine if carao (0, 1.3, 2.65, and 5.3 g/L) incorporated into yogurt enhances anti-inflammatory stimulus and antioxidant activity and impacts the physio-chemical and sensory properties of camel milk yogurt. HT-29 cells were used as a model of anti-inflammatory response, including cytokine responses of IL-8 and mRNA production of IL-1β and TNF-α in gastric digested isolated fraction. In addition, pH, titratable acidity, Streptococcus thermophilus counts and Lactobacillus bulgaricus counts of camel yogurts were examined during the fermentation process in 0, 2.5, 5, and 7 h whereas viscosity, syneresis, and radical scavenging assay evaluations were determined at hour 7. Furthermore, a consumer study was performed. Compared to control samples, the incorporation of carao into yogurts did not lead to a significant (ρ > 0.05) difference in the pH. In contrast, titratable acidity (TA), viscosity, syneresis, and antioxidant capacity significantly increased with the inclusion of 2.65 and 5.3 g/L carao, while 5.3 g/L carao significantly (ρ < 0.05) increased the counts of both bacteria. The inflammatory response of IL-8 and the level of mRNA production of IL-1β and TNF-α was significantly (ρ < 0.05) lower with 2.65 and 5.3 g/L carao yogurt compared to control camel yogurt. Sensory attributes were not impacted by the addition of 1.3 and 2.65 g/L carao. Carao could be a possible ingredient to consider when improving the nutrition value of yogurt.

Nutritional Assessment of Lactarius drassinus and L. controversus from the Cold Desert Region of the Northwest Himalayas for Their Potential as Food Supplements.

Kargil is a cold desert with hostile ecological conditions such as low temperature and precipitation, as well as difficult terrains. However, several wild mushrooms thrive well under such an extreme environment. Despite their abundance, the chemical composition of indigenous mushrooms has not been explored. This study aimed to assess the potential of two wild edible mushrooms from Kargil, Lactarius drassinus and Lactarius controversus, as food supplements by evaluating their nutritional and nutraceutical properties. Nutritional attributes such as total protein, available carbohydrates, soluble sugars, and vitamins were found to be high in the mushroom species. Furthermore, high mineral accumulation and relatively lower antinutrient concentrations resulted in higher bioavailabilities of Zn, Fe, Ca, and Mg. Gas-chromatography-mass-spectrometry-based metabolite profiling revealed that although the two mushroom species showed similar metabolite compositions, their relative concentrations differed. Sugars were the predominant compounds identified in both the species, with sugar alcohols being the major contributor. The second most abundant class of compound in L. drassinus was amino acids, with 5-oxoproline as the major contributor. On the other hand, fatty acids were the second most abundant compounds in L. controversus, with high oleic and linoleic acid concentrations. In the ultra-performance-liquid-chromatography-based quantification of phenolic compounds, chlorogenic acid was found to be highest in in terms of its concentration in both the mushrooms studied, followed by quercetin dihydrate and gallic acid in L. drassinus and L. controversus, respectively. Moreover, high antioxidant activities attributable to their high phenol, flavonoid, and carotenoid concentrations were observed. Overall, the two mushrooms offer well-balanced sources of nutritional and nutraceutical compounds, making them healthy foods.

Extraordinary photooxidation properties of ZnO nanosheets with surface oxygen vacancies of low density

Surface defect engineering strategies are critical for catalytic activity, especially in the photodegradation of organic pollutants. However, the exact function of the oxygen vacancies for the photooxidation performance of ZnO is unclear. Oxygen vacancies might act as electron donors to encourage carrier separation and then boost catalytic efficiency; besides, excessive oxygen vacancies might act as recombination centers for photogenerated electron–hole, which impairs photocatalytic performance. Therefore, the specific effect of the amount of oxygen vacancies in ZnO needs to be investigated. We developed a facile method, which is inspired by the aforementioned strategy, to adjust the amount of oxygen vacancies in ZnO nanosheets for exploring its photocatalytic activity. ZnO nanosheets with oxygen vacancies of low density exhibit a greatly enhanced photooxidation ability and can rapidly and stably degrade high concentration (4 × 10−4 mol/L) of phenol compared with nearly inactivity of the ZnO nanosheets with plentiful oxygen vacancies. This mechanism of the improved photocatalytic activity is proposed to be mainly due to the significant reduction in oxygen vacancies as carrier recombination centers and the increase in photogenerated electron–hole mobility. This research presents a new idea for the surface defect engineering design of regulated photocatalysts to enhance photocatalytic activity.

Effect of CQDs doping on the properties of RuO2–TiO2/Ti anode

Phenol is a harmful substance that can cause pathological changes in animals or human body, and its degradation has become a research hotspot at present. This paper innovatively proposed the preparation of carbon quantum dots by microwave enhancement technology, the preparation of RuO2–TiO2-CQDs/Ti composite coating anode by thermal decomposition method, and studied the electrocatalytic degradation process of organic wastewater containing phenol. The surface morphology of the anode was observed by XPS, TEM and SEM. Electrochemical workstation was used to characterize the electrocatalytic performance of the anode, and high performance liquid chromatography was used to determine the degradation process. The results show that the doping of CQDs can produce a large number of vacancy defects on the surface of the composite coating, and the addition of CQDs can increase the loading of Ru element on the surface of the coating during anode preparation. With the increase of CQDs content, the crack width and depth of coating surface decrease gradually, and the crystal size decreases. Doping of CQDs can effectively improve the surface charge capacity and corrosion resistance of anode. Compared with the traditional RuO2–TiO2/Ti anode, the removal efficiency of phenol and COD at the RuO2–TiO2-CQDS/Ti composite coating electrode was increased by 102% and 55.7% respectively within 1 h. This study makes full use of the high specific surface area and excellent electrocatalytic performance of carbon quantum dots, which provides a new idea for the mineralization of high concentration phenol in Ru–Ti electrode.

AGS Gastric Cells: Antioxidant Activity and Metabolic Effects of Phenolic Extracts from Different Monocultivar Virgin Olive Oils.

The effects of the phenolic compounds of extra virgin olive oil (EVOO) on AGS cells have never been studied so far, which is the aim of this study. The profiles of the main phenolic components in EVOOs, mainly secoiridoid compounds derived from the transformation of oleuropein during the olive milling process, were evaluated and compared. Oils of different origins were evaluated aiming at verifying whether chemical differences in the phenolic composition of the dry extracts played a role in the metabolism and in maintaining the cellular redox state of AGS cells. The following key enzymes of some metabolic pathways were studied: lactate dehydrogenase, enolase, pyruvate kinase, glucose 6-phosphate dehydrogenase, citrate synthase, 3-Hydroxyacyl-CoA dehydrogenase and hexokinase. As confirmed through PCA analysis, pretreatments with the dry extracts of EVOOs at different concentrations appeared to be able to counteract the enzymatic activity alterations due to oxidative stress induced by H2O2 1 mM and 2 mM. The studied phytocomplexes showed the ability to protect AGS cells from oxidative damage and the secoiridoid derivatives from both oleuropein and ligstroside contributed to the observed effects. The results suggested that EVOOs with medium to high concentrations of phenols can exert this protection.

Phenolic compounds, antioxidant and antibacterial activities of the methanolic extracts of Euphorbia resinifera and Euphorbia echinus

Euphorbia resinifera and Euphorbia echinus are Moroccan endemic plants that are used in traditional medicine for their therapeutic properties. The aim of this research is to study the phenolic compounds content, the antioxidant and the antibacterial activities of two Euphorbiaceae species: Euphorbia resinifera and Euphorbia echinus, which were collected in Béni-Mellal and Agadir regions, respectively. The current study involved determining the concentration of phenolics, flavonoids, and tannins of our spieces using spectrophotometry. To test the antioxidant activity of the two methanolic extracts, the DPPH° technique was used.Also, the antibacterial activity against three microorganisms was tested in vitro. The quantification of phenolic compounds revealed that Euphorbia resiniferamethanolic extract had the highest concentration of phenolics. The methanolic extract of Euphorbia resinifera and Euphorbia echinus showed a higher antioxidant activity than Ascorbic acid.The antibacterial analysis showed a positive correlation between antioxidant activity and total phenolic content. Our extracts exhibited antibacterial activity against Staphylococcus aureus and Bacillus subtilis. In contrast, it had no inhibitory effect on Escherichia coli.

The efficient degradation of high concentration phenol by Nitrogen-doped perovskite La2CuO4 via catalytic wet air oxidation: Experimental study and DFT calculation

Herein, N-doped perovskite La2CuO4 (LCO) (N-LCO(M)) was fabricated by sol–gel rapid calcination method using melamine (M) as N source/ligand, and applied for the catalytic wet air oxidation (CWAO) to degrade high-concentration phenol-containing simulated wastewater. The experimental results exhibited that N-LCO(M) illustrated enhanced phenol degradation efficiency. Thereinto, 87.9% COD degradation efficiency was achieved in simulated wastewater containing 8000 mg/L phenol, while for undoped LCO prepared with citric acid (CA) as ligand (LCO(CA)) was only 43.8%. The systematic characterizations and density functional theory (DFT) calculations were utilized to verify the above results. The results revealed that N doping favored the formation of more oxygen vacancies (*) and facilitated the charge transfer between Cu and O. More oxygen vacancies (*) reinforced the ability of N-LCO(M) to adsorb O2 to form reactive oxygen species (O*), and meanwhile, the charge transfer between Cu and O was manifested as the redox cycle of the catalytic active metal Cu2+/Cu1+. The redox cycle also promoted the formation of O2− and HO, making the more exhaustive degradation of phenol. This successfully proved that N doping was core to improving the activity and stability of N-LCO(M). Moreover, a possible mechanism of phenol degradation was proposed based on the experimental results and DFT calculations. Eventually, the toxicity of the intermediate products was further evaluated by quantitative structure–activity relationship (QSAR) analysis, showing the significantly reduced toxicity of the intermediate products. Overall, the proposed CWAO technique is a green and promising wastewater treatment method.

Assessing the impact of increasing phenol loads on the performance and stability of an aerobic granular sludge system

This work evaluated the impact of phenol on the performance and stability of an aerobic granular sludge (AGS) sequencing batch reactor (SBR) operated under alternating anaerobic-aerobic conditions for simultaneous organic matter, nitrogen, and phosphorus removal. The reactor was fed with synthetic wastewater whose phenol concentration was gradually increased from 2 to 200 mg L−1, while the other carbon source (acetate) was reduced proportionally to keep the organic loading rate invariable. Up to 20 mg L−1 of phenol, the average COD removal was above 90%, while practically full ammonium, phosphorus, and phenol removal was achieved. However, at higher phenol concentrations, the activity of polyphosphate-accumulating organisms and nitrifiers was affected. Although the overall COD removal was only slightly affected by increasing phenol loads, replacing the main carbon source from acetate to phenol changed the organic matter removal profile over the cycle, with the latter being converted mainly within the aerated stage of the SBR. As a result, there was filamentous growth that deteriorated the settling properties of the granules. The establishment of an anaerobic feast-aerobic famine regime over the non-aerated and aerated phases of the AGS SBR and the presence of a readily biodegradable substrate (such as acetate) proved to be crucial for maintaining granules stability. Having phenol as the sole organic carbon source led to complete process failure regarding nutrient removal capability.