Zero Charge Research Articles

Ultrasound Activated Clay: Preliminary Study of PB And as Removal in Aqueous Media

Objective: The objective of this study was to evaluate the removal of Pb and As in aqueous media by activated clay (AC). Theoretical Framework: Heavy metals in water represent a risk to health and ecosystems, their removal through new materials is a challenge for the industry. Method: The methodology adopted for this research comprises in that natural clay (NC) was activated with sodium chloride and phosphoric acid followed by sonication. A synthetic solution of Pb and As was prepared at different pH. Results and Discussion: The zero charge point was found to be 7.10 for AC and 8.02 for NC, the ζ potential was found to be between - 41.15 and - 45.43 mV in the pH range of 4 to 12, with degree of crystallinity of 97.24% and crystal size of 2.85 nm determined by XRD. FTIR analysis allowed the identification of functional groups with chelating capacity. Was observed As removal of 75.51% (110.40 mg/g) and 23.23% (58.13 mg/g) and 97.75% (106.41 mg/g) and 100.0% (206.53 mg/g) for Pb with AC and NC respectively at pH 6 and 8. Research Implications: Los reaultadoe encontrados sugieren que la arcilla activada se convierte en un material alta capacidad de adsorción de metales pesados en sistemas multimetal. Esta cualidad se debe al incremtno de grupos funionales en su superficie y al tamaño nanométrico que incrementa el área de contacto. Originality/Value: Activation of the clay with sodium chloride and weak acid followed by sonication is an environmentally friendly process that produces a material with high heavy metal removal capacity in aqueous media.

Biosynthesis of calcium oxide nanoparticles by employing Mulberry (Morus nigra) leaf extract as an efficient source for Rhodamine B remediation

Green processes for synthesizing nanocomposites are a hot area of research today as traditional processes are expensive, inefficient, harmful for synthesizing organic and inorganic molecules, and unsuitable for large-scale operations. The present study investigates the capacity of green synthesized Calcium oxide nanoparticles (CaO NPs) for efficiently removing Rhodamine B. Chemical reduction was replaced with Mulberry (Morus nigera) leaf extract as an environmentally friendly reaction mechanism. CaO NPs are characterized by various analytical techniques including EDX, BET, SEM, FTIR, TGA, Zeta Potential, Point of Zero Charge (PZC), and XRD. Maximum adsorption of Rhodamine B by CaO NPs is revealed at an initial concentration of Rhodamine B of 80 ppm, a temperature of 343 K, and contact time of 60 min, 0.4 g of adsorbent at a pH value of 7. Maximum removal of Rhodamine B by CaO NPs was found to be 98.2% which is promising with this small amount of adsorbent (0.4 g). Diverse Kinetic and adsorption isotherms are employed in this study to determine the requirement and significance of the adsorption process. Various adsorption isotherms such as Freundlich, Temkin, Dubinin–Radushkevich (D–R), and Langmuir models have been employed. Among the kinetic adsorption isotherms Elovich, Intraparticle kinetic model, pseudo 1st order, and pseudo 2nd order models were applied. The current study investigates the thorough understanding of the Rhodamine B adsorption process including the mechanism of adsorption using condition optimization, characterization, and model applications. The proposed adsorbent can be employed for the green removal of Rhodamine B from wastewater of industry with maximum efficiency and favorable regeneration properties.

Ibuprofen removal by modified natural zeolite: characterization, modeling, and adsorption mechanisms

AbstractBACKGROUNDDeveloping robust technologies to remove emerging pollutants from water is urgent since conventional treatments are not technically prepared to remove them. This paper investigated the ibuprofen (IBU) adsorption capacity onto natural zeolite (NZ) and hydrothermally modified zeolite in an acidic medium followed by impregnation with the cationic surfactant cetyltrimethylammonium bromide (CTAB) (MZHT‐CTAB). The materials characterization included scanning electron microscopy (SEM), X‐ray diffraction (XRD), atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTG), N2 adsorption/desorption isotherm (BET), Zeta Potential (ZP), and Point of Zero Charge (pHPZC). The adsorptive capacity studies were carried out by varying the pH solution, a kinetic study at three concentrations (25, 50, and 100 mg L−1), and the contaminant concentration influence (5–100 mg L−1).RESULTSThe results showed that the MZHT‐CTAB obtained both the highest removal efficiency (~ 37%) and the highest adsorption capacity (~ 14 mg g−1) at pH 5.0. The Pseudo Second‐Order (PSO) model, which showed the best fit to the experimental data, is significant as it indicates the reliability of our results. The maximum adsorption capacity for the concentration of 100 mg L−1 was 11.93 mg g−1. According to Giles's classification, the isotherm was classified as S‐3 type, indicating the competition between the adsorbate and water molecules for the active sites on the adsorbent surface.CONCLUSIONThe adsorption studies demonstrate that the novel adsorbent (MZHT‐CTAB) is highly effective in removing IBU, presenting a significant removal capacity and feasibility. This promising result contributes to the ongoing search for alternative materials for water treatment. © 2024 Society of Chemical Industry (SCI).

Biodegradable Acid-Based Fe2MnO4 Nanoparticles for Water Remediation.

This study demonstrated the synthesis of Fe2MnO4 modified by citric acid, a biodegradable acid, using a simple co-precipitation method. Characterization was performed using qualitative analysis techniques such as Fourier-transformed infrared spectroscopy, scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, X-ray diffraction, selected-area electron diffraction, N2 adsorption-desorption, and zero-point charge. The prepared nanoparticles had a rough and porous surface, and contained oxygenous (-OH, -COOH, etc.) functional groups. The specific surface area and average pore size distribution were 83 m2/g and 5.17 nm, respectively. Net zero charge on the surface of the prepared nanoparticles was observed at pH 7.5. The prepared nanoparticles were used as an adsorbent to remove methylene blue dye from water under various conditions. Using small amounts of the adsorbent (2.0 g/L), even a high concentration of MB dye (60 mg/L) could be reduced by about ~58%. Exothermic, spontaneous, feasible, and monolayer adsorption was identified based on thermodynamics and isotherm analysis. Reusability testing verified the stability of the adsorbent and found that the reused adsorbent performed well for up to three thermal cycles. Comparative analysis revealed that the modified adsorbent outperformed previously reported adsorbents and unmodified Fe2MnO4 in terms of its partition coefficient and equilibrium adsorption capacity under different experimental conditions.

Engineering Bis-Pyridine N-Functionalized Cellulose Aerogel for Efficient Extraction of Cu2+ from High-Acidity Wastewaters: Coupling Molecular Scale Interpretation with Experiment.

In order to address the issue of protonation of functional groups and structural instability on the surface of aerogel due to strong acidic wastewater, a three-dimensional bis-pyridine N cellulose aerogel [PEIPD/carboxymethyl cellulose (CMC)] with protonation resistance was prepared in this paper by grafting pyridine onto polyethylenimine. The adsorption capacity for Cu2+ of the as-prepared aerogel is as high as 1.64 mmol/g (pH 5) and is maintained well in high-acidity solutions (1.15 mmol/g at pH = 2). It reveals high selectivity, splendid anti-interference ability, and also reliable on the recycle performance. Through the zeta potential tests, this adsorbent reveals a rather low zero charge point (pHpzc = 2.2). The adsorption of Cu2+ on the adsorbent is consistent with the pseudo-second-order kinetic model and the Langmuir model, suggesting that the adsorption process is dominated by chemisorption in a monolayer. The characterizations by Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy proved pyridine N as responsible binding sites, based on which two possible mechanisms are proposed, including chelation and cation-π interaction. Density functional theory calculations are further used to precisely investigate the pathway. By comparing the binding energies, molecular electrostatic potentials, electron densities, and differential charge densities, the bis-pyridine N functional group is finally determined to be of much higher affinity to Cu2+ following chelation reaction as designated. By integrating bis-pyridine N with the CMC and understanding their crucial roles, this will provide significant insights into the rational design of aerogel adsorbents to enhance the recovery of Cu from strongly acidic wastewaters.

Synthesis and characterisation of novel beta-cyclodextrin based Fe3O4 nanocomposite: adsorption behaviour and photocatalytic dye degradation studies

ABSTRACT Novel Beta-Cyclodextrin-based Fe3O4 nanocomposite has been synthesised through copolymerisation by incorporating Fe3O4 nanoparticles into the polymer matrix. Ultraviolet-Visible (UV-Visible) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Thermogravimetric (TGA) analysis, Point of Zero Charge, X-ray diffraction (XRD), and Scanning electron microscopy (SEM) analysis have been used to characterise the Fe3O4 Nanoparticles and β-CDHs@Fe3O4 nanocomposite. The synthesised β-CDHs@Fe3O4 nanocomposite has been utilised for the adsorption of methylene blue (MB) dye from aqueous solutions. The maximum percentage removal of MB dye at optimum pH 7 and was found to be 98.51%. The adsorption capacity (qe) of β-CDHs@Fe3O4 nanocomposite has been found to be 268.09 mg/g at optimum dosages 1.2 g/L, pH 7, temperature 25°C, concentration 100 mg/L and an agitation speed of 200 rpm. Adsorption data have been fitted with three isotherm models namely Langmuir, Freundlich, and Temkin, and it was found to be the best fit with the Langmuir isotherm model. Kinetic studies like the pseudo-first order, pseudo-second order, and intra-particle diffusion model were also performed to study the adsorption mechanism. Further, thermodynamic studies demonstrate that the reaction was exothermic and spontaneous. Photocatalytic degradation of MB dye under visible light has also been studied, and 79.01% degradation of the dye was observed. Also, desorption of the nanocomposite was performed, and it was found to be reusable up to 5 times with 90% dye-desorption in the fifth cycle.

Guar gum, Ulva lactuca L. biomass, and xanthan gum-based copolymer novel biosorbent for adsorptive removal of acid orange 10

The textile industry's wastewater discharge into water bodies has become a significant environmental concern due to its toxicity and adverse impact on the ecosystem. In response, this study presents the development of a highly effective adsorbent (GG@ULB@XG composites) by employing guar gum (GG), Ulva lactuca L. biomass (ULB), and xanthan gum (XG), using the ionic gelation method. Various characterization techniques including XRD, SEM, TGA, Zeta Sizer, Zeta Potential, BET, FTIR, and Point of Zero charge (pHPZC) were utilized to analyze the properties of the GG@ULB@XG composites. The removal efficiency of the composite for Acid Orange 10 dye was found to be exceptional, achieving a remarkable 93% removal rate. Optimal adsorption parameters were determined, including initial AO10 concentration (100 ppm), temperature (298K), pH (3), adsorbent concentration (100 mg), and contact time (15 min) at 480 λmax. The thermodynamic analysis provided valuable insights into the thermal stability of the adsorbent. Additionally, a comprehensive investigation of adsorption isotherms (linear and non-linear), such as Elovich, Freundlich, D-R, Langmuir, and Temkin Isotherms, was conducted to better understand the adsorption behavior. Various linear and non-linear adsorption kinetics models, including Elovich, first-order, interparticle diffusion, and second-order kinetic models, were employed to gain deeper insights into the chemistry of the adsorption process. This study highlights the potential of GG@ULB@XG composites as an effective and environmentally friendly solution for water treatment and dye removal in industrial wastewater and sets a foundation for future studies in the field of environmental remediation.

Use of a Clay from Southern Ivory Coast (Bingerville) for the Adsorption of Methyl Orange in Aqueous Media

Increasing levels of textile dyes being discharged into the environment as industrial waste represent a serious threat to human health, life, resources and ecological systems. It is therefore necessary to treat wastewater from textile industries before discharging it into the environment. The aim of this project is to eliminate methyl orange (MO) from textile industry wastewater using clay from Bingerville (Ivory Coast). The clay used was characterized by Scanning Electron Microscopy, Brunauer-Emmett-Teller and pH of Zero Charge. MO concentration was monitored using a UV-visible spectrophometer. Characterization of the clay by SEM and BET showed that our clay is microporous. The study showed that the surface of our clay has a pH of zero. Adsorption of methyl orange on our clay reaches adsorption equilibrium in 60 minutes. The adsorption model corresponds to the pseudo-order 2 kinetic model. Two adsorption isotherm models (Langmuir and Freundlich) are applicable to the adsorption of our dye on clay. This implies that the dye adsorption process on our clay is governed by a bimolecular process involving a collision between an active site on the clay and a dye molecule. Bingerville clay can be used to effectively treat dye-contaminated wastewater, since the maximum adsorbed quantity is equal to 58.139 mg g<sup>-1</sup>. The best adsorption rate was obtained in acid medium (pH = 2.26) with an adsorption rate of 91.84%.

Active recharge biphasic stimulation for the intraoperative monopolar review in deep brain stimulation.

Charge balancing is used in deep brain stimulation (DBS) to avoid net charge accumulation at the tissue-electrode interface that can result in neural damage. Charge balancing paradigms include passive recharge and active recharge. In passive recharge, each cathodic pulse is accompanied by a waiting period before the next stimulation, whereas active recharge uses energy to deliver symmetric anodic and cathodic stimulation pulses sequentially, producing a net zero charge. We sought to determine differences in stimulation induced side effect thresholds between active vs. passive recharge during the intraoperative monopolar review. Sixty-five consecutive patients undergoing DBS from 2021 to 2022 were retrospectively reviewed. Intraoperative monopolar review was performed with both active recharge and passive recharge for all included patients to determine side effect stimulation thresholds. Sixteen patients with 64 total DBS contacts met inclusion criteria for further analysis. Intraoperative monopolar review results were compared with the monopolar review from the first DBS programming visit. The mean intraoperative active recharge stimulation threshold was 4.1 mA, while the mean intraoperative passive recharge stimulation threshold was 3.9 mA, though this difference was not statistically significant on t-test (p = 0.442). Mean stimulation threshold at clinic follow-up was 3.2 mA. In Pearson correlation, intraoperative passive recharge thresholds had stronger correlation with follow-up stimulation thresholds (Pearson r = 0.5281, p < 0.001) than intraoperative active recharge (Pearson r = 0.340, p = 0.018), however the difference between these correlations was not statistically significant on Fisher Z correlation test (p = 0.294). The mean difference between intraoperative passive recharge stimulation threshold and follow-up stimulation threshold was 0.8 mA, while the mean difference between intraoperative active recharge threshold and follow-up threshold was 1.2 mA. This difference was not statistically significant on a t-test (p = 0.134). Both intraoperative active recharge and passive recharge stimulation were well-correlated with the monopolar review at the first programming visit. No statistically significant differences were observed suggesting that either passive or active recharge may be utilized intraoperatively.

Effective solid–solid and microwave-assisted formation of folic acid@titanium oxide nanoparticles for enhanced batch adsorptive uptake of toxic Cd(II) and Cu(II) pollutants

Synthesis of complicated multi-constituent nanocomposites for adsorption, removal and photocatalytic decomposition of miscellaneous pollutants is a tedious process with respect to the cost of synthesis, methodology and characterization of the produced materials. To find out a simple, short, and direct approach for preparation of an efficient nanomaterial from only two components is a challenging target. Therefore, it is aimed in this investigation to design and generate a potential nanosorbent by only combination of folic acid (Fol-Ac) with titanium oxide nanoparticles (TiO2NPs) via simple solid–solid and microwave-assisted formation of a novel Fol-Ac@TiO2NPs nanosorbent in less than 15 min. The assembled nanosorbent was confirmed by determination of the surface coverage using thermal gravimetric analysis 187.4 mg/g (425.6 µmol g−1), homogenous particles distribution with average particle size (56.92–96.74 nm) based on the TEM imaging. The surface was loaded with several effective and related functional groups to Fol-Ac and TiO2NPs as detected from the FT-IR analysis. The characterized Fol-Ac@TiO2NPs was then used as a novel nanosorbent to capture Cd(II) as a highly toxic divalent metal ion and Cu(II) as a moderately toxic ion via batch mode under the contribution of numerous experimental parameters. Zero charge point of Fol-Ac@TiO2NPs was identified at pHPZC = 6.6 to match with the optimum capture at pH 6.0–7.0 for both Cd(II) plus Cu(II) pollutants. Other parameters as reaction time and temperature as well as metal concentration were also performed and modeled to characterize the possible mechanisms via evaluation of the kinetic, thermodynamic and adsorption isotherm investigations, respectively. Fol-Ac@TiO2NPs nanosorbent was efficiently recycled providing 96.67–97.03 % and 91.34–92.47 % stability after the first and fifth cycles, respectively. Moreover, the efficient usage of Fol-Ac@TiO2NPs for uptake of Cd(II) plus Cu(II) pollutants from contaminated water samples was successfully performed providing 98.32–83.97 % and 93.45–83.39 %, respectively.

Applicability and characterization of the natural Moroccan clay for cationic dye removal: Kinetic, isotherms studies, and application on effluent treatment for textile dyeing

The aim of this study was to investigate the adsorption of methylene blue (MB) using Natural Moroccan clay (NMC). The NMC was characterized by, Brunauer-Emmett-Teller (BET), Point of Zero Charge (pHPZC), Fourier-Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). Adsorption key variables, including dosage of adsorbent dose, solution pH, and initial concentrations, effect of ionic strength, contact time and temperature were inspected for determining their impacts on MB dye removal. The adsorption process of MB onto NMC was examined using various isotherm models, such as Langmuir, Temkin and Freundlich. The results indicate that the adsorption process is characterized by the Langmuir isotherm, which is confirmed by the fitting data and the comparison of the correlation coefficient (R2). This suggests the highest adsorption capacity of 32.14 mg/g. The pseudo-second order kinetic model provides a good fit for the kinetic data, achieving an R2 value of 0.997. From these results, the method is employed for textile wastewater treatment primarily composed of methylene blue.

Pseudomonas sp. Bacteria: potentially toxic metal-contaminated soil remediation potentials - minimum inhibitory concentration investigation and application

Agricultural inputs used for correction or nutrition in agriculture have a composition that, in addition to containing desirable elements, often includes potentially toxic metals that contaminate the soil. Faced with this scenario, one can observe the appearance of various remediation techniques, amongst them, bio-remediation. This technique has been shown to be highly promising, as there is a wide variety of genera and species of microorganisms. In this study, the application of Pseudomonas sp. bacteria in soil from bean cultivation was investigated, with the aim of removing Zn2+ and Ni2+ ions. Analyzes were carried out of soil parameters, pH in water and KCl, Zero Charge Point, exchangeable acidity, quantity of organic matter in soil and initial concentrations of ions. To evaluate the tolerance of bacteria to metal concentrations in the soil, studies of Minimum Inhibitory Concentration were conducted. A bioremediation experiment was then carried out, applying the bacteria to the soil and monitoring the process over 21 days. The results showed that Pseudomonas sp. bacteria showed good resistance to high metal concentrations, as well as remarkable capacity and efficiency in the absorption of metals, reaching 0,063 mg kg-1 and 90.5% efficiency in the removal of Ni2+ ions, and 0,012 mg kg-1 capacity and 47.9% efficiency in the removal of Zn2+ ions. These results suggest that the Pseudomonas sp. bacteria are promising for the bioremediation of soils contaminated with potentially toxic metals.

Canonical Ensemble vs. Grand Canonical Ensemble in the Description of Multicomponent Bosonic Systems

The thermodynamics of a system of interacting bosonic particles and antiparticles in the presence of the Bose–Einstein condensate is studied in the framework of a Skyrme-like mean-field model. It is assumed that the total charge density (isospin density) is conserved at all temperatures. Two cases are explicitly considered: the zero or nonzero isospin charge of the system. A comparative analysis is carried out using the Canonical Ensemble or the Grand Canonical Ensemble. It is shown that the Grand Canonical Ensemble is not suitable for describing the bosonic systems of particles and antiparticles in the presence of a condensate, but an adequate study can be carried out within the framework of the canonical ensemble, where the chemical potential is a thermodynamic quantity that depends on the canonical free variable.

Understanding the impact of kaolinite/muscovite ratio in natural clays on oxide contents, physisorbed water, and structural water fractions

The objective of the present work, is to comprehend the impact of two naturals non-swelling phyllosilicates, namely kaolinite/muscovite ratio, denoted as f(K/M), on the physicochemical properties of the sample. This includes oxide content as well as the fractions of physisorbed and the structural water. To achieve this, the adsorbed amount on the clay sample was assessed using the cationic surfactant (cetyltrimethyl ammonium chloride CTACl) by measuring the Streaming Induced Potential (SIP) at the Point of Zero Charge (PZC). Further, the physisorbed water and structural water losses present in the clay sample, were determined through DTA/TGA thermal analysis. In addition, the kaolinite/muscovite ratios, denoted as f(K/M), characterizing the samples, were calculated using the elemental compositions of various metal oxides as obtained via X-ray fluorescence (XRF) analysis.

Methods for Determining the Potential of Zero Charge

Methods for Determining the Potential of Zero Charge

Origin of Solvent Dependency of the Potential of Zero Charge.

Fundamental properties of the Au(111)-KPF6 interface, particularly the potential of zero charge (PZC), exhibit pronounced variations among solvents, yet the origin remains largely elusive. In this study, we aim to link the solvent dependency to the microscopic phenomenon of electron spillover occurring at the metal-solution interface in heterogeneous dielectric media. Addressing the challenge of describing the solvent-modulated electron spillover under constant potential conditions, we adopt a semiclassical functional approach and parametrize it with first-principles calculations and experimental data. We unveil that the key variable governing this phenomenon is the local permittivity within the region approximately 2.5 Å above the metal edge. A higher local permittivity facilitates the electron spillover that tends to increase the PZC on the one hand and enhances the screening of the electronic charge that tends to decrease the PZC on the other. These dual effect lead to a nonmonotonic relationship between the PZC and the local permittivity. Moreover, our findings reveal that the electron spillover induces a capacitance peak at electrode potentials that are more negative than the PZC in concentrated solutions. This observation contrasts classical models predicting the peak to occur precisely at the PZC. To elucidate the contribution of electron spillover to the total capacitance, we decompose the total capacitance into a quantum capacitance of the metal Cq, a classical capacitance of electrolyte solution Cc, and a capacitance Cqc accounting for electron-ion correlations. Our calculations reveal that Cqc is negative due to the promoted electron spillover at more negative potentials. Our work not only reveals the importance of local permittivity in tuning the electron spillover but also presents a viable theoretical approach to study solvent effects on electrochemical interfaces under operating conditions.

Preparation of chemically and thermally modified water caltrop epicarp (Trapa natans L.) adsorbent for enhanced adsorption of Ni(II) from aqueous solution

The present study aims to prepare waste water caltrop (Trapanatans L.) epicarp (WCS)-based adsorbents such as raw WCS (WCS-Raw), citric acid-grafted WCS (WCS-CA), acrylamide-grafted WCS (WCS-AM), and calcined WCS (WCS–Si) for Ni(II) removal from aqueous solution in batch adsorption process. The physical and chemical properties of the prepared adsorbents were investigated by different characterization techniques such as scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, nitrogen adsorption-desorption analyses, and pH at the Point of Zero Charge (pHpzc) in order to assess the suitability and effectiveness of the adsorbents for the removal of Ni(II) by understanding their surface morphology, chemical composition, porosity, and surface charge properties. The experimental Ni(II) adsorption data followed both the Langmuir isotherm and the pseudo-second-order kinetic model suggesting the adsorption process on the prepared adsorbents is well-described by these models. The modified adsorbents WCS-CA, WCS-AM, and WCS-Si exhibited a maximum adsorption capacity of 52.08, 40.32, and 158.73 mg/g, respectively, while WCS-Raw had a capacity of 29.06 mg/g. The thermodynamic study revealed that the adsorption process was feasible, spontaneous, and endothermic. The desorption study demonstrated that the adsorbents could be reused for multiple cycles with minimal loss of activity. The present work evidenced the potential practical applicability and sustainability of the WCS-based adsorbents as promising adsorbents in treating and removing Ni(II) from wastewater.

Point of Zero Charge of Soils - It’s Dynamics under Fertilizer Management Practices and Nutrient Availability

Aims: To study the dynamics of point of zero charge of different soil types and determine the availability of nutrients under the influence of specific fertilizer management practices.&#x0D; Study Design: Completely Randomized Design.&#x0D; Place and Duration of Study: Department of Soil Science, Assam Agricultural University, Jorhat, Assam; between March 2020 and December 2021.&#x0D; Methodology: We estimated the point of zero charge (PZC) components, i.e., the point of zero salt effect (PZSE) and point of zero net charge (PZNC) in six surface soil samples [black soil (Vertisol), laterite soil (Alfisol), red soil (Alfisol) of Odisha, and alluvial soils belonging to Entisol, Inceptisol, and Alfisol of Assam, India] through potentiometric titration and ion retention methods respectively. The soils were subjected to four specific fertilizer management practices under laboratory incubation, viz., FYM @ 5 t ha-1 (T1), NPK @ 80:40:40 for Odisha soils and 60:20:40 for Assam soils (T2), T1 + T2 (T3) and T3 + Lime requirement/ Gypsum requirement (T4). The PZC components and availability of nutrients were determined at 15 and 30 days after incubation.&#x0D; Results: The PZSE values of the soils ranged from 2.18 to 4.70, while PZNC values were achieved at relatively lower pH ranging from 2.03 to 4.10. Highest values of PZSE and PZNC were recorded under treatment T2 followed by T3, T4 and T1 for all the incubated soil samples, however there was a decrease in the PZC values with increase in days of incubation. Comparatively, the treatment T4 resulted as the most ideal fertilizer management practice. Besides providing optimum amount of primary and maximum amount of secondary nutrients, T4 regulated the PZC values favouring minimal loss of nutrients and enhanced nutrient use efficiency. The availability of nutrient ions is influenced by the difference between soil solution pH and PZC values of the soil, which recorded to be highest for Vertisol (OS1), followed by Entisol (AS1), Inceptisol (AS2), and Alfisol (AS3, OS2, OS3) soil orders.&#x0D; Conclusion: The exchange and availability of cationic nutrients get enhanced due to higher CEC in soils with high clay and organic matter percentage. The pH of these soils must therefore be regulated for better availability of anionic nutrients. Highly weathered soil of Alfisol order exhibit optimal CEC over a narrow pH range, favouring better availability of anionic nutrients and hence simultaneously require frequent fertilizer application along with organic manures for the enhanced retention, mobility and availability of nutrients in soil.

Acidic Hydrogen Evolution Electrocatalysis at High-Entropy Alloys Correlates with its Composition-Dependent Potential of Zero Charge.

The vast possibilities in the elemental combinations of high-entropy alloys (HEAs) make it essential to discover activity descriptors for establishing rational electrocatalyst design principles. Despite the increasing attention on the potential of zero charge (PZC) of hydrogen evolution reaction (HER) electrocatalyst, neither the PZC of HEAs nor the impact of the PZC on the HER activity at HEAs has been described. Here, we use scanning electrochemical cell microscopy (SECCM) to determine the PZC and the HER activities of various elemental compositions of a Pt-Pd-Ru-Ir-Ag thin-film HEA materials library (HEA-ML) with high statistical reliability. Interestingly, the PZC of Pt-Pd-Ru-Ir-Ag is linearly correlated with its composition-weighted average work function. The HER current density in acidic media positively correlates with the PZC, which can be explained by the preconcentration of H+ in the electrical double layer at potentials negative of the PZC.

Die Elektrokatalyse der Wasserstoffentwicklung im Sauren an Hochentropielegierungen korreliert mit dem von der Zusammensetzung abhängigen Nullladungspotential

AbstractAufgrund der enormen Variation möglicher Elementkombinationen von Hochentropielegierungen (HEAs) ist es von entscheidender Bedeutung, Aktivitätsdeskriptoren zu finden, um rationale Prinzipien für die Entwicklung von Elektrokatalysatoren zu entwickeln. Trotz der zunehmenden Beachtung des Nullladungspotentials (PZC) bei Elektrokatalysatoren für die Wasserstoffevolutionsreaktion (HER), wurden weder das PZC von HEAs noch die Auswirkungen des PZC auf die HER‐Aktivität bei HEAs beschrieben. Hier verwenden wir die rasterelektrochemische Zellmikroskopie (SECCM), um das PZC und die HER‐Aktivitäten verschiedener Elementzusammensetzungen einer Pt−Pd−Ru−Ir−Ag‐Dünnfilm‐HEA‐Materialbibliothek (HEA‐ML) mit hoher statistischer Zuverlässigkeit zu bestimmen. Interessanterweise ist das PZC von Pt−Pd−Ru−Ir−Ag linear mit seiner zusammensetzungsgewichteten durchschnittlichen Austrittsarbeit korreliert. Die HER‐Stromdichte in sauren Medien korreliert positiv mit dem PZC, was durch die Anreicherung von H+ in der elektrochemischen Doppelschicht bei negativen Potentialen relativ zum PZC erklärt werden kann.