Addition Of Nitrate Research Articles

Photodegradation of Azithromycin in Aqueous System Under VIS/UV Irradiation

Antibiotics, such as azithromycin, have become one major group of emerging contaminants in aquatic systems. It is urgent to explore efficient, safe, and economic methods to removal azithromycin in aquatic environment. This paper described the photolysis of azithromycin and its affecting factors (initial concentration of azithromycin, pH, nitrate and Fe (III)-oxalate complexes) under visible and UV light irradiation. The results indicated ultraviolet has stronger ability to degrade azithromycin than visible light. The photodegradation efficiencies of azithromycin decreased with the increase of its initial concentration under UV irradiation, as well as pH value. The maximum degradation rates occurred in the initial concentration of 10 mg∙L-1 and pH value of 4, which was 53.1% and 82.6%, respectively. The addition of nitrate can promote the photodegradation of azithromycin but Fe (III)-oxalate complexes had the opposite effect. The achievements proved photodegradation is a promising technology to remove azithromycin from water environment.

氮添加对黄河三角洲滨海湿地芦苇养分再吸收效率的影响

大气氮沉降增加能改变土壤养分可利用性，影响滨海湿地植物的养分再吸收。目前研究多关注氮沉降量对养分再吸收过程的影响，且研究集中于叶片，鲜有研究区分不同形态氮素对植物不同器官养分再吸收过程的影响。通过两年的野外控制实验，研究硝态氮、铵态氮添加对黄河三角洲滨海湿地芦苇（Phragmites australis）叶、茎养分再吸收效率的影响。结果表明：两类氮添加均显著增加叶、茎的氮、磷含量（P<0.001），增幅达32.74%-43.22%（氮）、30.91%-36.51%（磷）。叶片氮的再吸收效率为54.14%-67.66%，茎氮的再吸收效率为50.60%-62.85%。叶片磷的再吸收效率为56.80%-70.38%，茎磷的再吸收效率为77.43%-84.95%。两类氮添加均显著降低氮、磷的再吸收效率（P<0.001），但两类氮添加处理下的养分再吸收效率无差异。叶、茎氮的再吸收效率无差异，但茎磷的再吸收效率明显高于叶（P<0.01）。总之，氮添加降低芦苇对氮、磷的再吸收效率，且茎对养分的再吸收也具有不可忽略的贡献。;Increased atmospheric nitrogen (N) deposition may adjust the nutrient resorption efficiency of the plant species in the coastal wetlands due to the changing of soil nutrients availability. Most studies concentrated on the nutrient resorption of the leaf, whereas the nutrient resorption of the non-leaf organs, such as culm, is still less known. Moreover, little attention is concentrated on differentiating the effects of nitrate and ammonium additions on nutrient resorption. In this study, an in situ experiment was conducted to investigate the effects of nitrate and ammonium additions on the nutrient resorption efficiency of leaf and culm for reed (Phragmites australis) in the coastal wetlands of the Yellow River Delta, China. Results showed that N additions increased the concentrations of N and phosphorus (P) in senesced organs, ranging from 32.71% to 43.22% for N, and ranging from 30.91% to 36.51% for P. The N resorption efficiency (NRE) ranged from 54.14% to 67.66% for the leaf and ranged from 50.60% to 62.85% for the culm. The P resorption efficiency (PRE) ranged from 56.80% to 70.38% for the leaf and ranged from 77.43% to 84.95% for the culm. Both two types of N addition had similar and negative effects on nutrient resorption efficiency (P<0.001). The NRE of leaf was similar to that of culm, whereas the culm had larger PRE than leaf (P<0.01). Overall, both N additions decreased the NRE and PRE of reed. Furthermore, the culm of reed had a non-negligible contribution to nutrient resorption.

Generation and Characterization of Silver Nanoparticles in Mentha pulegium Extract and Evaluation of Biological Activities of the Prepared Extract

The aim of the present study was to synthesize silver nanoparticles (AgNPs) using Saudi Mentha pulegium leaves, to characterize the physicochemical properties of the resulting AgNPs, and to evaluate the biological activities of the resulting AgNP‐containing extract. The formation of AgNPs in M. pulegium extract was indicated by a change in color following the addition of silver nitrate and was confirmed using UV‐visible spectroscopy with a maximum absorbance at 425 nm. Energy dispersive X‐ray spectroscopy (EDX) indicated that the anisotropic AgNPs were spherical, and Fourier transform infrared spectroscopy (FTIR) spectral analysis indicated that the aqueous M. pulegium extracts were responsible for reducing Ag+ to Ag0. The secondary metabolite contents of the methanolic M. pulegium extract corresponded to 17 mg GAE/g DW. DPPH and ABT radical‐scavenging assays indicated that the M. pulegium extracts possessed antioxidant activity (IC50 = 6 and 3 μg/mL, respectively). Disc and broth dilution assays revealed that the extracts exerted significant antibacterial activity, with the inhibition zone diameters and minimal inhibition concentrations of 17–24 mm and 0.08–0.62 mg/mL, respectively. These findings clearly indicate that modified plant extracts have high biological importance and potential use as preservatives in the pharmaceutical and food industries.

58 - Experimental Silver-Infiltrated Glass on Biofilm Formation in Monolithic Zirconia

The aim of this study was to evaluate the effect of different coating applications of experimental glass with silver particles on surface properties, biofilm formation and inhibition of microbial adhesion to yttria-stabilized tetragonal zirconia (Y-TZP). 105 YZ T zirconia samples (VITA Zahnfabrik, Germany) with dimensions of 5.0 ×5.0 ×2.0 mm were divided into 7 groups: Polished YZ (P), Glazed YZ (G), YZ with infiltration glass (INF), YZ + 4% Ag (Ag4), YZ + 5% Ag (Ag5), YZ with glass + 4% silver (IAg4) and YZ with glass + 5% silver (IAg5). The experimental infiltration glass was made from silicic acid, which was obtained when sodium meta silicate (Na 2 SiO 3 5H 2 O) passed through aqueous solution (10% m / m) and an ion exchange resin (IR120 - Rohm and Haas). The glass with was obtained through a similar protocol, which was then followed by the addition of silver nitrate (AgNO 3 ) and silicon (SiO 2 ), aluminum (Al 2 O 3 ), calcium (CaO), sodium (Na 2 O), and potassium (K 2 O) oxides. The product upon completion comprised 5% AgNO 3 , 65% SiO 2 , 1.1% Al 2 O 3 , 0.59% K 2 O, 14.54% Na 2 O, 8.93% CaO and 3.41% MgO. Specimens were submitted to the following tests: surface roughness, colony-forming unit count (CFU) of Candida albicans, Streptococcus mutans and Streptococcus sanguinis, and Scanning Electron Microscopy (SEM). The different coating exhibited notable differences, both in relation to surface roughness, and bacterial and fungal adhesion. Regarding surface roughness, the Ag5 and IAg5 had a rougher profile when compared to the other groups, that were smoother and statistically similar to each other. However, in the CFU tests of Candida albicans and Streptococcus mutans groups P, G, and INF showed higher adherence of microorganisms, while all silver groups had less biofilm adherence, being statistically similar to each other. In the SEM it was possible to observe that all the groups of glass with silver (Ag4, IAg4, Ag5 and IAg5) presented silver particles anchored to the zirconia-glass system. The application of silver coating made the surface of the monolithic Vita HT zirconia resistant to the tested oral pathogens, causing inhibition of bacterial growth in the nearby surrounding region and also preventing the formation of biofilm on the ceramic surface.

Insights on “nitrate salt” in lithium anode for stabilized solid electrolyte interphase

AbstractA Li/KNO3 composite (LKNO), with KNO3 uniformly implanted in bulk metallic Li, is fabricated for battery anode via a facile mechanical kneading approach, which exhibits high Coulombic efficiency and prolonged cycle life. The mechanism behind the enhanced electrochemical performance of the “salt‐in‐metal” composite is investigated, where KNO3 in metallic Li composite electrode would be sustainably released into the electrolyte. The presence of NO3– stabilizes the solid electrolyte interphase by producing functional Li3N, LiNxOy, and Li2O species. K+ from KNO3 also helps to form an electrostatic shield after its adsorption on the electrode protrusions, which suppresses the dendritic growth of metallic Li. With the above advantages, uniform Li plating with dense and planar structure is realized for the LKNO electrode. These findings reveal a deep understanding of the effect of the “salt‐in‐metal” anode and provide new insights into the use of nitrate additives for high‐energy‐density Li metal batteries.

The effect of silver nitrate addition on the properties of electrospun polycaprolactone membranes with potential application for electrical stimulation in tissue engineering

The effect of silver nitrate addition on the properties of electrospun polycaprolactone membranes with potential application for electrical stimulation in tissue engineering

Influence of Nitrogen Sources Applied by Fertigation to an Enriched Soil with Organic Compost on Growth, Mineral Nutrition, and Phytochemicals Content of Coriander (Coriandrum sativum L.) in Two Successive Harvests.

The aim of the present study was to evaluate the effects of nitrogen source applied by fertigation to an enriched soil with organic compost on plant growth, mineral nutrition, and phytochemical contents in two successive harvests in coriander. The treatments were as follows: unfertilized soil, soil enriched with organic compost, and soil enriched with organic compost to which 60 kg N ha−1 as ammonium nitrate and as ammonium sulfate applied by fertigation were added. Ammonium nitrate addition allowed to obtain a high total fresh yield (3.6 kg m−2) with a low inorganic nitrogen input. Ammonium nitrate increased plant shoot dry weight; fresh yield; and shoot N, K, and Ca uptake in the first harvest. Ammonium nitrate relative to organic compost and to ammonium sulfate increased fresh yield by approximately 57 and 25%, respectively. However, ammonium sulfate in the first harvest greatly increased shoot total phenols, from 137 mgGAE/100 g FW in ammonium nitrate to 280.4 mgGAE/100 g FW. Coriander’s fresh yield, in the second harvest, was unaffected by nitrogen addition. However, ammonium nitrate increased shoot total phenols and FRAP activity. Overall, the shoot phytochemical accumulation in the second harvest was lower than in the first. The combined application of ammonium nitrate and organic compost is a strategy to reduce inorganic nitrogen application.

Efficient reductive and oxidative decomposition of haloacetic acids by the vacuum-ultraviolet/sulfite system

Haloacetic acids (HAAs), as a representative category of halogenated disinfection byproducts, are widely detected in disinfected water. In this work, the vacuum ultraviolet (VUV)/sulfite process under N2 saturated conditions was proposed to eliminate a series of HAAs (i.e., monochloroacetic acid (MCAA), difluoroacetic acid (DFAA), trifluoroacetic acid (TFAA), dichloroacetic acid (DCAA), etc.). The in situ generated hydrated electron (eaq−) demonstrated to be the main species to fulfill the initial degradation and dechlorination of MCAA, while hydroxyl radicals (˙OH) were in charge of the mineralization of MCAA. This means that the VUV/sulfite system is a combination of advanced reduction and oxidation processes (ARPs and AOPs). A significant enhancement of MCAA removal was observed with increasing pH values from 6.0 to 10.0, and surprisingly, kobs correlated well with the proportion of SO32- as the pH changed. This can be explained by the production of eaq− from VUV irradiation of SO32− rather than HSO3− and also due to eaq− being more stable under alkaline conditions. Increasing the sulfite dosage also elevated the degradation of MCAA. However, the addition of certain anions (i.e., chloride (Cl−), bicarbonate (HCO3−), and nitrate (NO3−)) and dissolved organic matter (DOM) inhibited the removal of MCAA to varying degrees. The VUV/sulfite system was effective toward various types of halogenated disinfection byproducts, supporting its broad applicability. Nevertheless, even in real waters, the VUV/sulfite system was also promising for the simultaneous abatement of HAAs and other oxyanions.

Production of Gynogenic Plants of Red Beet (Beta vulgaris L.) in Unpollinated Ovule Culture In Vitro

The unique and balanced components of the biochemical composition, together with high antioxidant activity, make the red beet necessary a dietary vegetable crop, much contributing to healthy food ration. The application of the technology for producing gynogenic plants in vitro increases the genetic diversity and significantly reduces the period of time required to obtain the appropriate homozygous lines used to create the F1 hybrids that are demanded in the market. For induction of gynogenesis, we used IMB medium developed by us with the addition of 55 g/L sucrose, 3 g/L phytogel, 200 mg/L ampicillin, and 0.4 mg/L thidiazuron (TDZ) and cultured at 28 °C in the dark for 4–6 weeks. Shoot regeneration from embryoids and callus was performed on MS medium with 20 g/L sucrose, 3 g/L phytogel, 1 mg/L 6-benzylaminopurine (BAP), and 0.1 mg/L gibberellic acid (GA3). Immersion of the obtained microshoots with 5–7 well-developed leaves for 10–15 s into concentrated sterile indole-3-butyric acid (IBA) solution (50 mg/L) followed by their cultivation on solid medium ½ IMB with 2% sucrose and 3 g/L phytogel was the most efficient method for root formation. The addition of silver nitrate (22 mg/L) to the nutrient medium provoked an increase in the number of induced ovules up to nine per Petri dish (up to 25% of induced ovules). Gynogenic development was produced in six out of 11 genotypes studied, and the plants that were then acclimatized to ex vitro conditions were obtained in three genotypes (Nezhnost’, Dobrynya, b/a 128). The evaluation of ploidy of gynogenic plants that was carried out by flow cytometry and direct counting of chromosomes stained with propion-lacmoide revealed that all obtained gynogenic plants were haploids (2n = x = 9).

Formation of Zn-protoporphyrin during the elaboration process of non-nitrified serrano dry-cured hams and its relationship with lipolysis

This study assessed the ZnPP content, heme content, salt content, and instrumental color in the biceps femoris and semimembranosus muscles during the elaboration of Serrano dry-cured ham manufactured without the addition of nitrate and nitrite for 15 months. The effects of lipolysis and lipid oxidation on the content of Zn-protoporphyrin were also investigated in the biceps femoris. We found that the maximum formation of Zn-protoporphyrin occurred between end of resting and 6 months of processing, which coincides with temperature increase during processing and the end of salt equalization. Zn-protoporphyrin further increased in the biceps femoris until 9 months of processing but remained unchanged in the semimembranosus. Free fatty acid content increased till 6 months and then remained unchanged until the end of the process. These findings and those from an in vitro study reinforced the idea that the release of free fatty acids can promote the activity of the endogenous enzyme ferrochelatase and contribute to the formation of Zn-protoporphyrin from heme. However, the content of Zn-protoporphyrin decreased at the end of the processing, which may be due to the progression of lipid oxidation.

Exothermic synthesis of ceramic materials based on barium and strontium aluminosilicates

Ceramic materials were synthesized in the RO(R=Ba, Sr)–Al2O3–SiO2 system using exothermic synthesis from solutions containing barium and strontium nitrates, silica and organic reducing agents (glycine and carbamide). It was shown that only the use of a mixture of glycine and carbamide as well as the addition of ammonium nitrate allows carrying out a complete exothermic synthesis with the formation of an X-ray amorphous product with a small fraction of the crystalline phase. It was established that monophase materials based on barium and strontium aluminosilicates (BaAl2Si2O8 and SrAl2Si2O8) are formed when the obtained X-ray amorphous product is heat-treated at the temperatures above 10000C. Ceramics from synthesized materials sintered at 15500C has a high refractoriness, open porosity of 0–1.0%, compressive strength of 115–120 MPa; dielectric constant of 3.25–6.0 (at the frequency of 1 MHz) and the loss tangent of (1.5–5.2)10–3. The results shows that the exothermic synthesis ensures the preparation of nano- and sub-microcrystalline powders in the system RO(R=Ba, Sr)–Al2O3–SiO2. Materials based on the obtained aluminosilicates can be used in the manufacture of protective structures for devices operating in the radio frequency band, in radar installations of aviation and rocket technology, in microwave elements, etc.

Assessment of Calcium Nitrate Addition on the AVS Removal, Phosphorus Locking, and Pb Release in Sediment

Assessment of Calcium Nitrate Addition on the AVS Removal, Phosphorus Locking, and Pb Release in Sediment

In situ arsenic immobilisation for coastal aquifers using stimulated iron cycling: Lab-based viability assessment

Arsenic (As) is one of the most harmful and widespread groundwater contaminants globally. Besides the occurrence of geogenic As pollution, there is also a large number of sites that have been polluted by anthropogenic activities, with many of those requiring active remediation to reduce their environmental impact. Cost-effective remedial strategies are however still sorely needed. At the laboratory-scale in situ formation of magnetite through the joint addition of nitrate and Fe(II) has shown to be a promising new technique. However, its applicability under a wider range of environmental conditions still needs to be assessed. Here we use sediment and groundwater from a severely polluted coastal aquifer and explore the efficiency of nitrate-Fe(II) treatments in mitigating dissolved As concentrations. In selected experiments >99% of dissolved As was removed, compared to unamended controls, and maintained upon addition of lactate, a labile organic carbon source. Pre- and post-experimental characterisation of iron (Fe) mineral phases suggested a >90% loss of amorphous Fe oxides in favour of increased crystalline, recalcitrant oxide and sulfide phases. Magnetite formation did not occur via the nitrate-dependent oxidation of the amended Fe(II) as originally expected. Instead, magnetite is thought to have formed by the Fe(II)-catalysed transformation of pre-existing amorphous and crystalline Fe oxides. The extent of amorphous and crystalline Fe oxide transformation was then limited by the exhaustion of dissolved Fe(II). Elevated phosphate concentrations lowered the treatment efficacy, indicating joint removal of phosphate is necessary for maximum impact. The remedial efficiency was not impacted by varying salinities, thus rendering the tested approach a viable remediation method for coastal aquifers.

Fabrication of Fe3O4@Ag magnetic nanoparticles for highly active SERS enhancement and paraquat detection

Fe3O4 magnetic nanoparticles with a particle size of ∼ 250 nm were synthesized by the thermal solvent method, and then modified with polyethyleneimine (PEI) as the intermediate layer on the Fe3O4 surface to form ultra-thin polymer interlayer to replace the traditional carbon shell and silicon shell interlayer. The seeding of Fe3O4 magnetic particles was completed thanks to the strong positive charge of the amino group of PEI-adsorbed 3–5 nm colloidal gold on the surface of magnetic beads, and the addition of silver nitrate and reducing agent to the magnetic microsphere enabled the silver shell to be coated on the surface of the magnetic microspheres almost without affecting their magnetism. Moreover, the effects of the additive amount of colloidal gold, silver nitrate and ultrasonic time on the magnetic nanoparticles were systematically studied. Morphology and characterization analysis showed that the prepared Fe3O4@Ag magnetic nanoparticles (MNPs) had uniform particle size, good dispersibility, strong magnetic response, and powerful SERS performance. Furthermore, the SERS performance of the composite nanometer material was investigated by using 4-aminophenol and pesticide paraquat as active targets, with the molecular concentration down to 10-8 M and 10-10 M, respectively, confirming that the functional composite had a good SERS activity and Fe3O4 magnetic core.

Effect of dissolved oxygen on N2O release in the sewer system during controlling hydrogen sulfide by nitrate dosing

Nitrate dosing is commonly used for controlling hydrogen sulfide in sewer systems. However, it may potentially facilitate N2O emission due to the denitrification process promoted by nitrate addition. In this study, lab-scale sewer reactors were operated to investigate the impact of nitrate addition on N2O production in sewer systems. Results showed that the N2O flux even increased by six times with the addition of nitrate when dissolved oxygen (DO) in the wastewater exceeded 0.4 mg/L. Principal component analysis showed that the N2O concentration was notably affected by DO and oxidation-reduction potential (ORP) in the wastewater. Furthermore, it was founded that N2O flux had a strong linear relationship with the DO concentration in the batch test. The microbial analysis found that the nosZ possessing organisms decreased significantly in the micro-aerobic condition and the copy numbers of nosZ gene declined consequently. It indicated that the inhibition of N2O reduced to N2 was responsible for significant accumulation and emission of N2O in the micro-aerobic condition. Given the gravity sewers are not completely anaerobic, the DO concentration is ranged from 0.1 to 2.4 mg/L in gravity sewers with the partially filled flow. Therefore, more attention should be paid to the N2O production when nitrate dosing for hydrogen sulfide controlling in gravity sewers.

Demethylation of the Antibiotic Methylarsenite is Coupled to Denitrification in Anoxic Paddy Soil.

Arsenic (As) biomethylation is an important component of the As biogeochemical cycle, which produces methylarsenite [MAs(III)] as an intermediate product. Its high toxicity is used by some microbes as an antibiotic to kill off other microbes and gain a competitive advantage. Some aerobic microbes have evolved a detoxification mechanism to demethylate MAs(III) via the dioxygenase C-As lyase ArsI. How MAs(III) is demethylated under anoxic conditions is unclear. We found that nitrate addition to a flooded paddy soil enhanced MAs(III) demethylation. A facultative anaerobe Bacillus sp. CZDM1 isolated from the soil was able to demethylate MAs(III) under anoxic nitrate-reducing conditions. A putative C-As lyase gene (BcarsI) was identified in the genome of strain CZDM1. The expression of BcarsI in the As-sensitive Escherichia coli AW3110 conferred the bacterium the ability to demethylate MAs(III) under anoxic nitrate-reducing condition and enhanced its resistance to MAs(III). Both Bacillus sp. CZDM1 and E. coli AW3110 harboring BcarsI could not demethylate MAs(III) under fermentative conditions. Five conserved amino acid resides of cysteine, histidine, and glutamic acid are essential for MAs(III) demethylation under anoxic nitrate-reducing conditions. Putative arsI genes are widely present in denitrifying bacteria, with 75% of the sequenced genomes containing arsI, also possessing dissimilatory nitrate reductase genes narG or napA. These results reveal a novel mechanism in which MAs(III) is demethylated via ArsI by coupling to denitrification, and such a mechanism is likely to be common in an anoxic environment such as paddy soils and wetlands.

Production of nanopowders of bismuth oxide doped with silver by pulsed electron beam evaporation in vacuum

Various bismuth containing compounds are promising in many applications, including for creating photocatalysts based on them using a visible range of light. However, strong polymorphism (9 polymophic phases of Bi2O3), thermal instability and changes in the properties of bismuth oxide during long-term storage significantly complicate work with it. One way to increase stability and improve photocatalytic properties is by doping Bi2O3 with various metals. Ag doped Bi2O3 nanoparticles (NPs) are typically produced using chemical techniques often associated with the presence of toxic chemicals. The present paper used an environmentally friendly method of producing NPs using the method of pulsed electron beam evaporation in vacuum. The evaporation target was obtained by solid phase synthesis in an electric furnace on air using silver nitrate additives (1 and 5 wt.%). Textural, thermal and magnetic properties of the obtained NPs have been studied. Was found that the Ag-Bi2O3 NPs have a specific surface area (SSA) of 23.7 m2/g, which was almost 2 times bigger than the SSA of the pure Bi2O3 (13.2 m2/g) obtained previously. The thermal stability of the Ag-doped Bi2O3 samples was maintained to the temperature 350°C. While further heating on air took place the phase transition β → α

The potential of nitrate supplementation for modulating the fermentation pattern and mitigating methane emission in ruminants: A meta-analysis from in vitro experiments

The aim of this study was to evaluate the potential of nitrate supplementation as an in vitro feed additive for modulating the rumen fermentation pattern and mitigating the enteric methane emission by using a meta-analysis method. A database was built from the previously published articles regarding the effectiveness of nitrate as a feed additive in the in vitro rumen fermentation system. Different doses or forms of nitrate supplementations were identified in the database. A total of thirteen studies containing 47 data sets were obtained from ten published research papers. The obtained data were subjected to the mixed model methodology. The doses or the different forms of nitrate were treated as a fixed factor, while the different studies were considered as a random effect. Results showed that nitrate addition decreased significantly (P<0.05) the total gas production, methane production, the TVFAs, and the acetic acid, and increased significantly (P<0.05) ammonia concentration in a linear pattern. However, nitrate did not affect significantly the rumen pH and the population of methanogenic archaea. In conclusion, nitrate is an effective additive for modulating the rumen fermentation by altering the fermentation process resulting in a lower methane production.

Storage without nitrite or nitrate enables the long-term preservation of full-scale partial nitritation/anammox sludge

Bioaugmentation with summer harvested sludge during winter could compensate for bacterial activity loss but requires that sludge activity can be restored after storage. This study assesses the effect of temperature and redox adjustment during the storage over 180 days of partial nitritation/anammox (PN/A) granular resp. floccular sludge from potato processing resp. sludge reject water treatment. Anoxic storage conditions (in the presence of nitrite or nitrate and the absence of oxygen) resulted in a loss of 80–100% of the anammox bacteria (AnAOB) activity capacity at 20 °C and 4 °C, while anaerobic conditions (without oxygen, nitrite, and nitrate) lost only 45–63%. Storage at 20 °C was more cost-effective compared to 4 °C, and this was confirmed in the sludge reactivation experiment (20 °C). Furthermore, AnAOB activity correlated negatively with the electrical conductivity level (R2 > 0.85, p < 0.05), so strong salinity increases should be avoided. No significant differences were found in the activity capacity of aerobic ammonia-oxidizing bacteria (AerAOB) under different storage conditions (p > 0.1). The relative abundance of dominant AnAOB (Candidatus Brocadia) and AerAOB genera (Nitrosomonas) remained constant in both sludges. In conclusion, preserving PN/A biomass without cooling and nitrite or nitrate addition proved to be a cost-effective strategy.

The Effect of Cobalt Incorporation into Nickel–Iron Oxide/(oxy)hydroxide Catalyst on Electrocatalytic Performance Toward Oxygen Evolution Reaction

This work presents a study on the influence of the addition of cobalt into state‐of‐the‐art nickel–iron (NiFe) mixed oxides/hydroxides/(oxy)hydroxides on their structural and morphological properties, and oxygen evolution reaction (OER) catalytic activity. A one‐step electrodeposition process is performed without any additives to fabricate NiFe and x cobalt‐doped nickel/iron (xCoNiFe) layer‐double‐hydroxide catalysts directly on nickel foam. The addition of cobalt nitrate in the synthesis solution significantly affects the final form of the catalyst: the addition of 2 mm cobalt nitrate into the aqueous solution of 4 mm nickel and iron nitrate stabilizes the electrochemical synthesis of the catalyst, which leads to the formation of a homogenously spread 3D interconnected structure with a high electroactive surface area (0.07 cm2, 1.1 m2 cm−2: including nickel foam substrate); it induces the formation of Ni3+ desirable for the formation of the catalytically active (oxy)hydroxides, which is not observed for the state‐of‐the‐art NiFe. The significant role of the addition of cobalt translates into improved preliminary OER catalytic stability and activity of the catalyst with an onset potential of 1.40 V, overpotential of 224 mV determined at 10 mA cm−2, and only 0.7% loss in stability after 22 h working in alkaline conditions compared with the initial parameters.