K2 SO4 Research Articles

Dual Activation for Tuning N, S Co-Doping in Porous Carbon Sheets Toward Superior Sodium Ion Storage.

Porous carbon has been widely focused to solve the problems of low coulombic efficiency (ICE) and low multiplication capacity of Sodium-ion batteries (SIBs) anodes. The superior energy storage properties of two-dimensional(2D)carbon nanosheets can be realized by modulating the structure, but be limited by the carbon sources, making it challenging to obtain 2D structures with large surface area. In this work, a new method for forming carbon materials with high N/S doping content based on combustion activation using the dual activation effect of K2SO4/KNO3 is proposed. The synthesized carbon material as an anode for SIBs has a high reversible capacity of 344.44mAhg-1 at 0.05Ag-1. Even at the current density of 5Ag-1, the capacity remained at 143.08mAhg-1. And the ICE of sodium-ion in ether electrolytes is ≈2.5 times higher than that in ester electrolytes. The sodium storage mechanism of ether/ester-based electrolytes is further explored through ex-situ characterizations. The disparity in electrochemical performance can be ascribed to the discrepancy in kinetics, wherein ether-based electrolytes exhibit a higher rate of Na+ storage and shedding compared to ester-based electrolytes. This work suggests an effective way to develop doubly doped carbon anode materials for SIBs.

Benzylic C(sp3 )-H Bond Oxidation with Ketone Selectivity by a Cobalt(IV)-Oxo Embedded in a β-Barrel Protein.

Artificial metalloenzymes have emerged as biohybrid catalysts that allow to combine the reactivity of a metal catalyst with the flexibility of protein scaffolds. This work reports the artificial metalloenzymes based on the β-barrel protein nitrobindin NB4, in which a cofactor [CoII X(Me3 TACD-Mal)]+ X- (X=Cl, Br; Me3 TACD=N,N' ,N''-trimethyl-1,4,7,10-tetraazacyclododecane, Mal=CH2 CH2 CH2 NC4 H2 O2 ) was covalently anchored via a Michael addition reaction. These biohybrid catalysts showed higher efficiency than the free cobalt complexes for the oxidation of benzylic C(sp3 )-H bonds in aqueous media. Using commercially available oxone (2KHSO5 ⋅ KHSO4 ⋅ K2 SO4 ) as oxidant, a total turnover number of up to 220 and 97 % ketone selectivity were achieved for tetralin. As catalytically active intermediate, a mononuclear terminal cobalt(IV)-oxo species [Co(IV)=O]2+ was generated by reacting the cobalt(II) cofactor with oxone in aqueous solution and characterized by ESI-TOF MS.

A redox additive electrolyte boosted supercapacitive energy density of wrinkled RGO sheets

Redox additive (RA)-based electrolytes have emerged as a promising approach to enhance the performance of carbon-based supercapacitors (SCs) as they bestow the additional pseudocapacitance to carbon and enhance its energy density (Ed). The present study demonstrates the enhanced supercapacitive Ed of reduced graphene oxide (RGO) electrodes by employing an RA of 0.05 M K4[Fe(CN)6] (KFC) in 0.5 M K2SO4 (K2) electrolytes. To enhance the active surface area (confirmed by N2 absorption- desorption) with minor agglomeration (confirmed by morphological analysis) and less defective (confirmed by Raman analysis) wrinkled RGO sheets were synthesized through thermal reduction of GO. The RGO electrode obtained 3 times higher specific capacitance (CS) in K2+ KFC as compared to the K2 electrolyte. The assembled RGO-based symmetric aqueous device shows CS of 79.5 F/g and 66 mAh/g of specific capacity (CPS) at 5 mV/s with 36.8 Wh/kg Ed, 1.2 kW/kg of Pd at 15 mA, and 134 % capacitance retention over 5000 galvanostatic charge-discharge cycles in K2 + KFC electrolyte. The obtained results demonstrated the incorporation of a tiny amount of RA in supporting electrolytes can significantly enhance the electrochemical performance and pave the way for future advanced energy storage technology.

Tuning Main Group Element-based Metal-Organic Framework to Boost Electrocatalytic Nitrogen Reduction Under Ambient Conditions.

Main group element-based materials are emerging catalysts for ammonia (NH3 ) production via a sustainable electrochemical nitrogen reduction reaction (N2 RR) pathway under ambient conditions. However, their N2 RR performances are less explored due to the limited active behavior and unclear mechanism. Here, an aluminum-based defective metal-organic framework (MOF), aluminum-fumarate (Al-Fum), is investigated. As a proof of concept, the pristine Al-Fum MOF is synthesized by the solvothermal reaction process, and the defect engineering method namely solvent-assisted linker exchange, is applied to create the defective Al sites. The defective Al sites play an important role in ensuring the N2 RR activity for defective Al-Fum. It is found that only the defective Al-Fum enables stable and effective electrochemical N2 RR, in terms of the highest production rate of 53.9µg(NH3 ) h-1 mgcat -1 (in 0.4m K2 SO4 ) and the Faradaic efficiency of 73.8% (in 0.1m K2 SO4 ) at -0.15V vs reversible hydrogen electrode) under ambient conditions. Density functional theory calculations confirm that the N2 activation can be achieved on the defective Al sites. Such sites also allow the subsequent protonation process via the alternating associative mechanism. This defect characteristic gives the main group Al-based MOFs the ability to serve as promising electrocatalysts for N2 RR and other attractive applications.

Potential of plant-growth regulators and nutrients sprays on yield and yield components in lucerne (Medicago sativa)

An experiment was conducted at the Punjab Agricultural University, Ludhiana, during the winter (rabi) seasons of 2017–18 and 2018–19, to evaluate the effects of different plant-growth regulators and nutrients applied as foliar sprays on yield and yield components of lucerne (Medicago sativa L.). The treatments comprised foliar applications of 0.25% ZnSO4 , 1.0% K2 SO4 , 1.0% (monoammonium phosphate) MAP, 100 ppm salicylic acid, 500 ppm mepiquat chloride and 1.0 ppm brassinolide at pre-flowering stage and 10 days after the first spray along with the control. Plant-growth regulators and nutrient sprays significantly increased the seed yield of lucerne over control by 22.4 to 31.0% in 2017–18 and by 5.5 to 17.8% in 2018–19. The highest seed yield of 122.4 and 167.5 kg/ha in 2017–18 and 2018–19 respectively, was obtained with application of 1.0 ppm brassinolide. The significant increase in yield was obtained mainly owing to increase in number of pods/plant and number of seeds/pod. None of the foliar applications showed any effect on lucerne seed quality, i.e. 1,000-seed weight and seed germination. The monetary returns were also significantly higher with 1.0 ppm brassinolide application. Hence, plant-growth regulators may be used to enhance lucerne seed production while maintaining its seed quality.

Metal-Catalyst-Free One-Pot Aqueous Synthesis of trans-1,2-Diols from Electron-Deficient α,β-Unsaturated Amides via Epoxidation Using Oxone as a Dual Role Reagent.

In organic synthesis, incorporating two functional groups into the carbon-carbon double bond of α,β-unsaturated amides is challenging due to the electron-deficient nature of the olefin moiety. Although a few examples of dihydroxylation of α,β-unsaturated amides have been demonstrated, producing cis-1,2-diols using either highly toxic OsO4 or other specialized metal reagents in organic solvents, they are limited to several specific amides. We describe herein a general and one-pot direct synthesis of trans-1,2-diols from electron-deficient α,β-unsaturated amides through dihydroxylation using oxone as a dual-role reagent in water. This reaction does not require any metal catalyst and produces non-hazardous and nontoxic K2SO4 as the sole byproduct. Moreover, epoxidation products could also be selectively formed by adjusting the reaction conditions. By the strategy, the intermediates of Mcl-1 inhibitor and antiallergic bioactive molecule can be synthesized in one pot. The gram-scale synthesis of trans-1,2-diol which is isolated and purified by recrystallization further shows the potential applications of this new reaction in organic synthesis.

Environment to Store Alginate at its Best: An In-vitro Study

Introduction: Irreversible hydrocolloid alginate impressions are among the widely used impression materials in dentistry but they suffer from one major drawback, i.e., dimensional change after setting. Because of clinical limitations, impressions are poured to make cast after a time delay which is so long as compared to the recommended period. This can be reduced by storing the impression material in different storage environments. Aim: To assess the impact of the storage environment on the dimensional accuracy of alginate impression material. Materials and Methods: In this in-vitro study, 70 samples were made with chromatic alginate impression material according to the manufacturer’s guidelines and divided into seven groups (Exposed to atmosphere, Airtight container in the refrigerator, 2% NaCl Solution, Air-tight container, Distilled water, 1% K2 SO4 Solution and Mixture of 2% NaCl and 1% K2 SO4 Solution). Samples were made with stainless steel die fabricated according to ADA specification 18 and dimensions were noted after 24 hours of storage. Distance between the cross lines was calculated using are profile projector. ANOVA Test and Tukey Test were applied to compare the mean dimensional change of seven groups and to compare the difference in mean dimensional change between the groups. Results: Samples kept in a solution of 1% K2 SO4 and 2% NaCl solution had no significant dimensional change (F-value 2026.0, p-value <0.001), whereas samples stored in open-air resulted in the greatest dimensional change (Group 7 > Group 6 > Group 3 >Group 4 >Group 2 >Group 5 >Group 1). Conclusion: The impressions which are kept in a combined solution of 1% K2 SO4 and 2% NaCl have shown the best impact on the dimensional accuracy of alginate impression materials. However, these can also be seen in 1% K2 SO4 or in 2% NaCl solutions respectively

EVALUATION OF FIREWORKS RESIDUE OBTAINED FROM THE FLASH POWDER CONTAINING ALUMINIUM AND BORON

Herein, we report the characteristics of residues obtained after igniting the flash powder mixture consisting of varying amounts of Aluminium (Al) and Boron (B) with other energetic materials like potassium nitrate (KNO3 ) and sulphur (S). The nature of particulate matter collected after combustion was characterized through FESEM-EDX, FTIR, STA (TGA/DSC) and ICP spectrometer. FTIR spectra analysis reveals about the presence of various metal oxides, K2 S and K2 SO4 . On replacing aluminum by boron, more alkaline K2 S present in the residue was converted into the neutral K2 SO4 . FESEM with EDX confirm the presence of the elements like Al, B, K, S, O, etc., and the size of the particles formed after combustion is about 400 nm. The gradual replacement of aluminum by boron is substantiated from the analysis of residue through ICP Spectrometer. Boron blended fireworks mixture on ignition produces excellent performances and the residues generated do not have any hazardous nature.

Kinetic Salt Effect on Base-Catalyzed Isomerization of d-Glucose into d-Fructose.

Isomerization of d-glucose (Glc) into d-fructose (Fru) is of great importance for food sector as well as for valorization of lignocellulosic biomass. Soluble and solid bases exhibit high catalytic activity for the isomerization. Here, we report a salt effect on the base-catalyzed aqueous-phase Glc-Fru isomerization. Addition of soluble salts (Na2 SO4 , NaNO3 , K2 SO4 , and NaCl) results in an increased apparent reaction rate (factors of 1.5 to 6). The salt effect was observed both in the presence of soluble base NaOH at constant pH value and solid bases MgO, Li3 PO4 , and Mg-Al hydrotalcite. Apparent activation energy and UV absorption spectra were not significantly influenced by addition of salts. Potentiometric titration showed that the acidity constants of the saccharides increase in the presence of electrolytes. Since the rate of the isomerization depends on the thermodynamic acidity constant of Glc, the isomerization is accelerated by the presence of electrolytes.

Enhancing drought stress tolerance in Camelina (Camelina sativa L.) through exogenous application of potassium.

The current study was performed under controlled conditions to study the effects of exogenous potassium application on carotenoid contents and drought tolerance in Camelina. Water deficit levels such as 100% FC (control) and 40% FC (drought stress) were imposed after germination of Camelina plants grown to maturity, and different treatments of exogenous K+ were applied at the vegetative stage. We have reported 17 traits of plant growth, physiology, antioxidant enzyme activity, focusing on carotenoids in Camelina to explore their potential yield and yield components. For this purpose, we used multivariate analysis techniques (descriptive statistics, correlation matrix, analysis of variance [ANOVA] and principal components analysis [PCA] to determine the best relation between potassium and studied traits). The results showed a large number of variations in the studied trait under control and water deficit condition. Plant fresh weight (g) was negatively correlated with shoot length and SOD insignificantly correlated with plant fresh weight (g) under water deficit conditions. Potassium loading predicted that foliar application (3 mM K2 SO4 ), foliar application (6 mM KNO3 ), foliar application (12 mM KNO3 ) and foliar application (12 mM K2 SO4 ) are the important doses that contribute the most to enhance the growth, physiological and biochemical activities and carotenoids to improve the Camelina yield under water deficit condition. These doses should be considered in the future to improve the Camelina yield under semi-arid conditions with increased genetic diversity (varietal selection).

The Role of Alkali Cation Intercalates on the Electrochemical Characteristics of Nb2 CTX MXene for Energy Storage.

The intercalation of cations into layered-structure electrode materials has long been studied in depth for energy storage applications. In particular, Li+ -, Na+ -, and K+ -based cation transport in energy storage devices such as batteries and electrochemical capacitors is closely related to the capacitance behavior. We have exploited different sizes of cations from aqueous salt electrolytes intercalating into a layered Nb2 CTx electrode in a supercapacitor for the first time. As a result, we have demonstrated that capacitive performance was dependent on cation intercalation behavior. The interlayer spacing expansion of the electrode material can be observed in Li2 SO4 , Na2 SO4 , and K2 SO4 electrolytes with d-spacing. Additionally, our results showed that the Nb2 CTx electrode exhibited higher electrochemical performance in the presence of Li2 SO4 than in that of Na2 SO4 and K2 SO4 . This is partly because the smaller-sized Li+ transports quickly and intercalates between the layers of Nb2 CTx easily. Poor ion transport in the Na2 SO4 electrolyte limited the electrode capacitance and presented the lowest electrochemical performance, although the cation radius follows Li+ >Na+ >K+ . Our experimental studies provide direct evidence for the intercalation mechanism of Li+ , Na+ , and K+ on the 2D layered Nb2 CTx electrode, which provides a new path for exploring the relationship between intercalated cations and other MXene electrodes.

Optically stimulated luminescence decay and dosimetric properties of cerium-doped potassium sulfate phosphor.

Optically stimulated luminescence (OSL) is used for dating in archaeology and geology, and in dosimetry of ionizing radiation. Some crystalline wide band-gap insulators may be used as OSL radiation detectors. Recently it was found that cerium-doped potassium sulfate crystals have promising luminescence properties. This paper presents some OSL properties of K2 SO4 :Ce crystals that were prepared in the form of pellets. The crystals exhibited a strong luminescence signal, good measurement repeatability, and high sensitivity for ionizing radiation. Best results were obtained after annealing at 1000°C. Dose-dependence characteristics were determined in the range 10 mGy to 11.2 Gy. OSL decay curves consisted of several components. Fast and slow OSL components of the phosphor had different properties. The slow component was quite stable and obeyed power law dependence. It decayed in the 55 days after irradiation. Its luminescence properties depended on sample preparation and the storage time after irradiation.

Influence of mineral fertilizers on potash nutrition and productivity of columnar apple

The columnar form of apple tree is promising for growing in super-intensive orchards. The mineral nutrition study of apple tree with columnar crown is relevant due to high density of tree planting. The article presents the study results on the effect of mineral fertilizers on potash nutrition and the yield of columnar apple tree. The experiments were carried out in an experimental orchard located in the forest-steppe zone of the Central Russian Upland (Oryol region). The soil of the orchard is loamy haplic Luvisol with a high content of organic matter. Fruit plantations are represented by columnar apple trees of Poezia variety on 62-396 rootstock planted in 2016. Urea ((NH2)2CO) and potassium sulfate (K2 SO4) were used as fertilizers in doses of N60K80; N90K120; N120K160 which were introduced in early spring. The content of exchange potassium in the soil was determined annually in layers (0-20 cm and 20-40 cm), the concentration of potassium in leaves and fruits, yield. The use of fertilizers contributed to an increase in the exchange potassium content in the soil both in the 0-20 cm layer (45 - 53%) and in the 20-40 cm layer (18-31%). The amount of potassium in leaves and fruits also increased. However, potassium concentration in the leaves (0.77 … 0.95% dry matter) remained significantly below the optimum (1.5% dry matter). A significant increase in the average fruit weight was revealed in options N90K120 and N120K160.

Phosphorus and Sulfur Co-Doped Cobaltous Oxide Synthesized by an Inorganic-Salt-Assisted Method: Reaction Mechanism and Electrocatalytic Application.

An inorganic-salt-assisted synthesis of non-metallic heteroatom (phosphorus and sulfur) co-doped cobaltous oxide (P/S-CoO) has been reported. Potassium sulphate (K2 SO4 ) was used as inorganic source of sulfur (S), while triphenyl phosphine (PPh3 ) was used as phosphorus (P) source. A stepwise mechanistic investigation into the doping process revealed that the decomposition of PPh3 triggered the release of both the elemental sulfur and phosphorus because of the reducing reaction environment. The transformation of cobalt-PPh3 complex into cubic cobalt (II) oxide along with the successful co-doping (P and S) was achieved by high temperature calcination at 800 °C but preserved the bulk CoO crystalline structure. The as synthesized P/S-CoO demonstrated an unprecedented enhancement on the oxygen evolution activity compare to that of pristine CoO with the current density of 10 mA/cm2 at the overpotential of 293 mV in 1.0 M KOH electrolyte and profound stability at different current densities.

Effect of Potassium Nitrate on Anti-Caking Performance of AN-based NPK Granular Compound Fertilizer

Agricultural ammonium nitrate(ANP) is one of the main raw materials for the production of AN-based compound fertilizer. The IV-III phase transition of ammonium nitrate(AN) is one of the main reasons for the caking of AN-based compound fertilizer(NPK). Potassium salts used for the production of compound fertilizers are usually K2SO4(KS). In this paper KNO3(KN) was added to improve the anti-caking properties of AN-based NPK. The IV-III phase transition of ANP and the effects of KN, KS, NH4SO4(NS), and NH4H2PO4(NP) on the solid phase transitions of ANP was investigated by differential scanning calorimetry (DSC) and powder X-ray diffractometer(XRD). The results showed that the phase transformation inhibition effect of KN and KS on ANP was better than that of NS and NP. In this experiment, KN was used to replace part of KS in the formula of AN-based NPK, and the granular fertilizer with different contents of KN were prepared, the anti caking properties and hygroscopicity of the fertilizer were tested. The results showed that although the content of potassium in the compound fertilizer remained unchanged, with the increase of the content of KN and the decrease of the content of KS in the formula, the anti-caking performance and hygroscopicity of the AN-based NPK were obviously improved.

Effect of foliar fertilization on the yield, sugar contents and improving resistance of cercospora leaf spot on sugar beet

In this study six mineral elements; Copper sulfate (Cu SO₄), Potassium sulfate (K2 SO₄), Micron Sulfure (S), Boric acid (H3 BO3), Copper sulfate + Micron Sulfure (Cu SO₄ + S) and Potassium sulfate + Boric acid (K2 SO₄ + H3 BO3) as well as fungicide; Montoro 30% were used as foliar spraying. These elements were evaluated against Cercospora, leaf spot disease on sugar beet under field conditions during two season; 2017/18 and 2018/19. All foliar applications were significantly reduced the disease severity % compared to untreated treatment during the two seasons. Potassium and combined application of Potassium and Boron treatments recorded the high value of sugar beet leaf dry weight over the control. Sulfure application led to an increase the fresh weight of sugar beet root, while Boron application increased the total soluble solid (TSS), sucrose % and purity %. Results obtained showed significant increasing (%) in catalase (CAT), peroxidase (POX) and polyphenolosxidase (PPO) activities in the case of mineral application and Montoro 30% fungicide compare with untreated treatment. However, the present study showed that foliar application of mineral elements tested in increased yield components of sugar beet, and thus is recommended to increase root yield and quality as well as can reduce disease severity.

Efficient Electrochemical Nitrogen Fixation over Isolated Pt Sites.

Recently, ambient electrochemical N2 fixation has gained great attention. However, the commercial Pt-based electrocatalyst hardly shows its potential in this field. Herein, it is found that the isolated Pt sites anchored on WO3 nanoplates exhibit the optimum electrochemical NH3 yield rate (342.4 µg h-1 mg-1 Pt ) and Faradaic efficiency (31.1%) in 0.1 m K2 SO4 at -0.2 V versus RHE, which are about 11 and 15 times higher than their nanoparticle counterparts, respectively. The mechanistic analysis indicates that N2 conversion to NH3 follows an alternating hydrogenation pathway, and positively charged isolated Pt sites with special Pt-3O structure can favorably chemisorb and activate the N2 . Furthermore, the hydrogen evolution reaction can be greatly suppressed on isolated Pt sites decorated WO3 nanoplates, which guarantees the efficient going-on of nitrogen reduction reaction.

Study of adsorption isotherms and physicochemical characterization of natural food colourants

Abstract Synthetic colourants are widely used for colouring foods. However, their safety has been questioned. Due to this limitation and the global trend of consuming healthy foods, the industry is faced with the need to replace artificial colourings, which has given rise to a growing interest in colourants from natural sources. Thus, this work obtained the moisture adsorption isotherms of the natural food dyes of anthocyanins, betalains and curcumin and evaluated the humidity, water activity (aw), hygroscopicity, colour and antioxidant capacity in vitro. Isotherms were determined by the static gravimetric method with saturated salt solutions (LiCl. H2O, MgCl2.6H 2O, Mg(NO3)2.6H2O, NaCl, KCl and K2 SO4) at 25 °C. Experimental data were adjusted by GAB, BET, Halsey, Oswin and Henderson models. All models, except Henderson's for Curcumin, fitted the data and BET was used to represent the moisture adsorption isotherm. All the isotherms were type sigmoidal, characteristic of most foods. The observed water content (<0.3%) and a w (<0.03) can be considered favourable to stability. Colour analysis indicated a high colouring strength and the antioxidant capacity suggested that, in addition to representing a source of colour in food products, natural dyes may have an additional function, with possible health benefits.

Pulsed Electrodeposition of Co3 O4 Nanocrystals on One-Dimensional ZnO Scaffolds for Enhanced Electrochemical Water Oxidation.

Pulsed electrodeposition has been introduced to deposit ultrathin flakes of Co3 O4 nanocrystals on ZnO nanorods. By fixing the seeding process, the scaffolding function of ZnO nanorods was studied by varying deposition times (30 s, 60 s, and 90 s) of Co3 O4 at a nucleation current of -1.0 mA cm-2 . The amount of deposited Co3 O4 has a strong influence on the oxygen evolution performance with ZnO scaffolds. To deliver a current density of 10.0 mA cm-2 in neutral solutions (0.5 M K2 SO4 ), the presence of ZnO scaffold electrodes negatively shifted the overpotential by ∼200 mV. In particular, the Co3 O4 /ZnO hybrid nanostructured electrode (60 s) exhibits the lowest onset potential of 1.5 V (vs. reversible hydrogen electrode, RHE). Electrochemical impedance spectra and double layer capacitance showed that the enhanced oxygen evolution activities originated from the improved charge transfer capability and the increased electrochemically active interface between Co3 O4 and ZnO.

Biochemical composition and antioxidant activity affected by spraying potassium sulfate in black grape (Vitis vinifera L. cv. Rasha).

The physiological and metabolic processes involved with grapevine growth and production are influenced by key macro- and micronutrients. Potassium is an essential plant nutrient that affects growth and fruit quality. In this study, the impact of foliar spraying of potassium sulfate (K2 SO4 ) on qualitative characteristics of grape berries was evaluated in the cultivar 'Rasha', a commonly cultivated cultivar in Kurdistan province of Iran. Leaves of the fully grown vines were sprayed with each of the 1.5 and 3 g L-1 K2 SO4 solutions once (1 month after petal senescence) and twice (15 days after first spraying). The control plants were sprayed with distilled water. Various biochemical contents and enzyme activities on the ripe berries were analyzed. Significant increases in anthocyanin, total protein content, and antioxidant enzyme activities were observed in the berries treated twice with 3 g L-1 K2 SO4 . Concentrations of total carbohydrate, phenol, and antioxidant activity in berries sprayed with K2 SO4 were higher than in the controls. We observed a strong correlation between antioxidant activity and different phenolic compounds. These findings suggest that K2 SO4 treatment influences biosynthesis of phenolic compounds and antioxidant enzymes. Thus, treatment by K2 SO4 could improve nutritional and qualitative attributes of grape. © 2018 Society of Chemical Industry.