Ion Concentration Research Articles

Effect of non-covalent binding of tannins to sodium caseinate on the stability of high-internal-phase fish oil emulsions

In this study, we designed the noncovalent binding of sodium caseinate (SC) to tannic acid (TA) to stabilize high internal phase emulsions (HIPEs) used as fish oil delivery systems. Hydrogen bonding was the dominant binding force, followed by weak hydrophobic interaction and weak van der Waals forces, as demonstrated by FTIR, fluorescence spectroscopy, and molecular docking experiments, with a binding constant of 3.25 × 106, a binding site of 1.2, and a static quenching of the binding. Increasing SC:TA from SC to 2:1 decreased the particle size from 107.37 ± 10.66 to 76.07 ± 2.77 nm and the zeta potential from −6.99 ± 2.71 to −22 ± 2.42 mV. TA increased the interfacial tension of SC, decreased the surface hydrophobicity from 1.3 × 104 to 1.6 × 103 and improved the oxidation resistance of SC. The particle size of high internal phase emulsions stabilized by complexes with different mass ratios (SC:TA from 1:0 to 2:1) increased from 4.9 ± 0.02 to 12.9 μm, the potential increased from −32.37 ± 2.7 to −35.07 ± 2.58 mV, and the instability index decreased from 0.75 to 0.02. Thicker interfacial layers could be observed by laser confocal microscopy, and an increase in the storage modulus indicated a formation of a stronger gel network. SC:TA of 1:0 showed emulsion breakage after 14 d of storage at room temperature. SC:TA of 2:1 showed the lowest degree of oil-water separation after freeze-thaw treatment. Especially, the most stable high endo-phase emulsion (at SC:TA of 2:1) prepared at each mass ratio was selected for further stability exploration. The emulsion particle size increased only from 15.63 ± 0.06 to 22.27 ± 0.35 μm at salt ion concentrations of 50–200 mM and to 249.33 ± 31.79 μm at 300 mM. The instability index and storage modulus of the high endo-phase emulsions increased gradually with increasing salt ion concentrations. At different heating temperatures (55–85 °C), the instability index of the high internal phase emulsion gradually decreased and the storage modulus gradually increased. Meanwhile, at 50 °C for 15 d of accelerated oxidation, the content of hydroperoxide decreased from 53.32 ± 0.18 to 37.48 ± 0.77 nmol/g, about 29.7 %, and the thiobarbituric acid value decreased from 1.06 × 103 to 0.8 × 103, about 24.5 %, in the high endo-phase emulsions prepared by 2:1 SC:TA compared to the fish oils, and the SC-stabilized high endo-phase only emulsion broke at the sixth day of oxidation. From the above findings, it was concluded that the high internal phase emulsion prepared with SC:TA of 2:1 can be used as a good delivery system for fish oil.

Interaction of aluminum alloys with MKPC and Portland-based cements on the metal-matrix interface

Cementitious matrices are considered for the immobilisation of radioactive aluminium. The processes occurring at the interface between both materials are relevant for the long-term stability of the repository. The present study compares Ordinary Portland cement (OPC), CEM I-type, with alternative Portland blended cement (CEM IV and CEM I + 50% silica fume) and magnesium potassium phosphate cement (MKPC). Al A1050 and Al AA5754, with 3.5% Mg, have been used as reactive metal alloys. Two exposure conditions were employed: (1) water immersion and (2) isolated in sealed plastic films. Long-term corrosion monitoring (Ecorr, icorr and Vcorr) was evaluated to understand the effect of Al reactivity in the matrix. The associated H2 release was quantified to understand the changes at the metal/matrix interface. Furthermore, pore ion concentrations and the pore microstructure were evaluated. The metal/matrix interface alterations were analysed at the end of the tests. The study revealed that after 300 days of water immersion, the CEM I + 50% of silica fume matrix had reduced the pore solution pH down to 10.5 compared to CEM I, which remained high alkaline (pH 12.9), and CEM IV with no significant decreases (pH 12.3). In contrast, MKPC showed the lowest pH (7–9.8). Low Al corrosion rates were found with MKPC, followed by CEM I + 50% SF according to their lower pH. A corrosion product layer of 90-50 μm thickness was observed at the Al/CEM I matrix interface constituted of aluminium and oxygen. Furthermore, enrichment in Al was detected in the matrix (around 1 mm depth), causing the formation of ettringite nodules. Voids were detected at the interface level associated with the high volume of H2 released. The MKPC matrix showed no alteration at the metal/matrix interface due to the lower reactivity of the matrix and lower H2 release. A homogeneous and dense region (30 μm) rich in phosphorous, potassium and magnesium was observed near the metal surface.

Investigation on Luminescence Properties of Dy3+ Ions Doped NaBaB9O15 Phosphors for Optoelectronic Applications.

A series of Dy3+ ions doped NaBaB9O15 phosphors with different dopant concentration was synthesized by solid state reaction. The phase purity was checked by X-ray diffraction analysis and the functional groups present in as prepared phosphors was investigated with the help of FTIR spectral analysis. Under 386nm excitation, the photoluminescence spectra exhibit three emission bands around 482nm, 574nm and 664nm due to 4F9/2→6HJ/2 (J = 15, 13, 11) transions respectively. The optimum doping concentration of Dy3+ ions was found to be 5mol%. The color coordinates are estimated from the emission spectra to check the dominant emission color and the color coordinates of the studied phosphors are fall on white region of CIE 1931 diagram. The decay curve analysis was made to determine the lifetime of excited state of Dy3+ ions and the decay curves are exhibited bi-exponential behavior irrespective of Dy3+ ion concentration. All these measurents are done in room temperature and the results obtained from these studies are discussed in detail to claim their usage in light emitting devices.

SYNTHESIS OF NEW ADSORBENTS VIA FUNCTIONALIZED MCM-41 FOR THE REMOVAL OF SOME IONS FROM AQUEOUS SOLUTION

Background: Mesoporous materials like MCM-41 silica are highly regarded for their structural features and applications in adsorption and catalysis. This study enhances MCM-41's ability to adsorb cobalt and copper ions by introducing amine and Schiff-base groups, boosting its affinity for these pollutants and aiding in their removal from water solutions. Aims: To prepare MCM-41@NTPE and MCM-41@NTPE-BSAL and use them to adsorb heavy pollutants like cobalt and copper divalent ions from aqueous solutions. Methods: Mesoporous materials (MCM-41@NTPE and MCM-41@NTPE-BSAL) derived from rice husk were used as low-cost adsorbents for the adsorption of Co(II) and Cu(II) ions from aqueous solutions. Uptake experiments were performed to determine adsorption parameters like ion concentration, pH, exposure time, and adsorbent mass. Results: MCM-41@NTPE and MCM-41@NTPE-BSAL were characterized by FT-IR, FESEM-EDX, TEM, N2-adsorption–desorption, XRD,AFM and TGA/DTA. FT-IR confirmed the presence of silanol and siloxane groups. XRD and TEM indicated highly ordered hexagonal arrangements. N2–adsorption–desorption analysis revealed average pore diameters of 42.468 nm and 40.417 nm, total pore volumes of 0.094 cm3g?1 and 0.3384 cm3g?1, and specific surface areas of 8.873 m2g?1 and 37.802 m2g?1 for MCM-41@NTPE and MCM-41@NTPE-BSAL, respectively. TGA showed three mass reduction steps. Adsorption assessment showed pH 6 and 5 were optimal for Co(II) and Cu(II) uptake, respectively, and uptake increased with initial concentration and exposure time. Discussion: XRD confirmed the hexagonal mesoporous structure, while BET analysis displayed amorphous natures. TGA suggested MCM-41@NTPE and MCM-41@NTPE-BSAL have potential for stability, although decomposing between 15-900°C. Electron microscopy revealed ordered hexagonal arrangements. The materials demonstrated high efficacy in extracting copper and cobalt ions from aqueous solutions. Conclusions: Two mesoporous silica materials (MCM-41@NTPE and MCM-41@NTPE-BSAL) were prepared from rice husk by functionalizing MCM-41. Adsorption assessment showed uptake depended on exposure time, pH, initial concentration, and adsorbent mass. MCM-41@NTPE-BSAL exhibited better ion uptake than MCM-41@NTPE.

Cation valency in water-in-salt electrolytes alters the short- and long-range structure of the electrical double layer

Highly concentrated aqueous electrolytes (termed water-in-salt electrolytes, WiSEs) at solid-liquid interfaces are ubiquitous in myriad applications including biological signaling, electrosynthesis, and energy storage. This interface, known as the electrical double layer (EDL), has a different structure in WiSEs than in dilute electrolytes. Here, we investigate how divalent salts [zinc bis(trifluoromethylsulfonyl)imide, Zn(TFSI)2], as well as mixtures of mono- and divalent salts [lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) mixed with Zn(TFSI)2], affect the short- and long-range structure of the EDL under confinement using a multimodal combination of scattering, spectroscopy, and surface forces measurements. Raman spectroscopy of bulk electrolytes suggests that the cation is closely associated with the anion regardless of valency. Wide-angle X-ray scattering reveals that all bulk electrolytes form ion clusters; however, the clusters are suppressed with increasing concentration of the divalent ion. To probe the EDL under confinement, we use a Surface Forces Apparatus and demonstrate that the thickness of the adsorbed layer of ions at the interface grows with increasing divalent ion concentration. Multiple interfacial layers form following this adlayer; their thicknesses appear dependent on anion size, rather than cation. Importantly, all electrolytes exhibit very long electrostatic decay lengths that are insensitive to valency. It is likely that in the WiSE regime, electrostatic screening is mediated by the formation of ion clusters rather than individual well-solvated ions. This work contributes to understanding the structure and charge-neutralization mechanism in this class of electrolytes and the interfacial behavior of mixed-electrolyte systems encountered in electrochemistry and biology.

Determination of nutrient concentration in liquid culture of cyanobacteria Nostoc sp. by capillary electrophoresis and inductively coupled plasma mass spectrometry

In this work, we demonstrate the use of capillary electrophoresis and inductively coupled plasma mass spectrometry, as competitive methods primarily for ion chromatography, to determine changes in the concentration of small inorganic ions in the Nostoc sp. culture medium. Although macronutrients were analyzed by capillary electrophoresis with conductivity detection, micronutrients were analyzed by inductively coupled plasma mass spectrometry. The different light settings (light intensity and spectral composition) had a visible effect on the culture growth and depletion of calcium, magnesium, and phosphate ions, and iron and manganese elements when comparing the behavior under red or violet light with that under blue light.

A Performance-Based Test for Mitigating the Risk of Geopolymer Concrete Surface Efflorescence Due to Alkali Leaching

Geopolymer concretes are considered to be a potential sustainable, low-embodied carbon alternative for Ordinary Portland Cement (OPC) concrete. Alkali leaching is considered to be a major esthetic concern for Na-silicate-based geopolymers as it can lead to the formation of efflorescence products on the surfaces of concrete members exposed to humidity. In this context, this research aims to investigate the effect of the alkali content and the FA/GGBS mass ratio on the alkali leaching and formation of the efflorescence products. Paste cylinders were fabricated and cured in ambient conditions. Samples were submerged in deionized water and the concentration of the leached-out ions was measured. Efflorescence potential was also investigated by partial immersion of the samples in deionized water. The results highlight the complexity of the interacting parameters governing the formation of efflorescence products in geopolymer materials. Establishing relationships between the concrete mix variables and the risk of efflorescence seems unfeasible particularly because of the wide range of possible precursors and activators available to design geopolymer concrete mixes. To overcome this barrier, a practical performance-based testing method is developed. For the first time, by testing a wide range of geopolymer materials, performance-based requirements associated with the risk of efflorescence for geopolymer concrete surfaces exposed to humidity are calibrated. Four categories of risk are proposed and typical suitable exposure conditions for geopolymer concrete surfaces are suggested for each risk category.

The sealing ability of different endodontic biomaterials as an intra-orifice barrier: evaluation with high-performance liquid chromatography.

This study evaluated the sealing ability of different biomaterials as intra-orifice barriers in the internal bleaching of discolored teeth with the walking bleaching technique. The release of hydroxyl ions from the bleaching materials can cause cervical root resorption, making it necessary to use intra-orifice barrier materials to prevent this issue. In the current study, the high-performance liquid chromatography (HPLC) method was used to measure the released hydroxyl ions. The study included 90 single-rooted and single-canal premolars, which were divided into four groups based on the intra-orifice barrier materials used (mineral trioxide aggregate [MTA], calcium-enriched mixture [CEM], Biodentine, and MTA+PG) and the type of bleaching material (sodium perborate + water or sodium perborate + hydrogen peroxide 30%). Two control groups were also considered in this study: a positive control group, where sodium perborate and hydrogen peroxide were placed inside the pulp chamber without any intra-orifice barriers; and a negative control group, where no bleaching agent or surgical obstruction was used, and the root surface was covered with wax up to the cemento-enamel junction (CEJ) level. The results showed that there was a significant difference in the concentration of hydroxyl ions released among the studied groups. The amount of hydroxyl ion released was highest in the positive control group and lowest in the CEM group. Among the intra-orifice barrier materials used, CEM cement was found to be the most appropriate material for use in the step-by-step internal bleaching method. The study highlights the importance of using appropriate intra-orifice barrier materials to prevent root cervical resorption in internal bleaching procedures.

Investigation of Operational Parameters for Nanoelectrokinetic Purification and Preconcentration.

This work reports on experimental investigations into the operational parameters of nanoelectrokinetic purification and preconcentration, especially utilizing on ion concentration polarization (ICP). ICP as a nanoscale electrokinetic phenomenon has demonstrated promising advances in various fields utilizing an ion depletion zone (IDZ) with a steep electric field gradient inside the ICP layer. However, the inevitable electrokinetic instability occurring within the IDZ has posed a challenge in operating the ICP system stably. To address the need for a stable and efficient ICP operation in various devices and applications, we propose an operational strategy along with conducted research to determine optimal operating ranges. In order to investigate the operational parameters, a unit voltage (VTH) is introduced as the threshold for initiating ICP. We examined the applicability of VTH across various operating ranges to ensure its effectiveness and versatility. In ICP purification, we categorize three modes (steady, burst, and unsteady) based on IDZ expansion and stability under varying VTH and flow rate conditions, presenting optimal operational conditions that minimize the voltage margin. In ICP preconcentration, a systematic investigation is conducted to observe the influence of background electrolyte concentration and voltage conditions on preconcentration efficiency, offering insights into the correlation between preconcentration factor, electrical conditions, and preconcentration time. Therefore, this research would contribute to the practical understanding of nanoelectrokinetics, providing insight into experimental designs. These findings are expected to offer valuable guidance to researchers aiming to utilize ICP's potential across a spectrum of applications, from purification to preconcentration, in the realm of micro/nanofluidic systems.

Electrospun Cellulose Acetate/Maleic Acid Functionalized Gold Nanoparticles as Pb(II) Ions Colorimeter Senser Strip

This study investigates the synthesis of gold nanoparticles and surface modifications to enable their utilization as a colorimetric sensor strip on electrospun nanofibrous. Additionally, it utilizes cellulose acetate electrospun fiber preparations as substrates for loading the gold nanoparticles. In order to produce gold nanoparticles, citrate reduction was employed, followed by modification with maleic acid (MA-GNPs). MA-GNPs were significantly more selective for Pb2+ than for other ions (Co2+, Cu2+, Hg2+, Ni+), according to the results. Following the introduction of Pb2+, the solutions exhibited a color change from red to blue or purple, which was attributed to the aggregation of nanoparticles, as determined by UV-Vis spectrometry. An optical band indicative of GNPs and MA-GNPs was detected at an estimated wavelength of 520 nm. Approximately 600 nanometers after the addition of Pb2+, the intensity of the solution progressively decreased to 520 nanometers, and a new band emerged. To fabricate cellulose acetate nanofibrous via electrospinning, the impact of solvent ratios, polymer concentrations, and process conditions were investigated. The ideal parameters for the fabrication of the substrate were as follows: 15%w/w polymer solution, 15 kV electrospinning voltage, 15 cm needle-to-collector distance, and 48 hours of collecting time. In order to examine the color change of the prepared strip, it is observed that the strip transforms from red to blue upon exposure to Pb2+ ions of varying concentrations, just as it does in solution form. An examination of water samples indicated that the strip remained colorless when tested with DI water. However, testing with wastewater sourced from a battery facility identified a transformation of the strip from red to purplish blue. This is equivalent to an estimated lead concentration of 40 parts per million. The outcomes showcased the capacity of the discolored strips to identify the preliminary concentration of lead ions, suggesting potential for future advancements in this area.

Anthropogenic Drivers of Spatial Trends in Groundwater Quality in the Upper Athi River Basin of Kenya, East Africa

Rapid urbanization and population growth in the upper Athi River basin in Kenya have increased the strain on the sub catchments water supply and sanitation situation. Due to increasing demand, inadequate supply of drinking water and lack of sanitation facilities, people in the sub-catchment are increasingly reliant on groundwater as a primary or supplementary water source. However, the use of on-site wastewater systems and agricultural pollution, mainly from runoff containing fertilizers, pesticides, herbicides, and faeces, pose a threat to groundwater in the sub catchment. Subsequently, the current study was conducted in the Thiririka sub catchment, Kiambu County, Kenya, to determine the safety of groundwater sources and to examine the factors influencing groundwater quality in the catchment area. This study assessed the influence of anthropogenic activities on the physical, chemical, and bacteriological quality of groundwater in the Upper Athi River basin of Kenya between April and June 2022. Twenty variables were analyzed and compared with water quality standards to determine hydro chemical characteristics, evidence of contamination, and suitability of groundwater. Shallow wells (SW) had higher concentrations of major ions and key parameters than boreholes (BH), such as alkalinity (7%), turbidity (96%), nitrates (92%), sulfates (48%), phosphates (93%), chlorides (77%), potassium (84%), sodium (30%) and fecal coliforms (99%) significant at p < 0.01. Concentrations of eleven water quality variables however were comparable in both systems. Farming, animal husbandry, and pit latrines were negatively but significantly correlated with the water quality of SW explaining substantial amounts of variation (≤ 45%) in concentrations of water quality variables. Ionic and coliform levels increased with decreasing distance and vice versa. IDW interpolation maps were generated in ArcGIS software to determine the spatial variability of groundwater quality in the basin. Anthropogenic activities such as pit latrines and animal husbandry impaired the quality of groundwater which in most cases was not potable.

Magnesium-enriched deep-sea water inhibits NLRP3 inflammasome activation and dampens inflammation

The NLRP3 inflammasome is an essential component of the innate immune system, but excessive activation can lead to inflammatory diseases. Ion fluxes across the plasma membrane or from intracellular stores are known to regulate NLRP3 inflammasome activation. Deep-sea water (DSW) contains high concentrations of many mineral ions, which could potentially influence NLRP3 inflammasome activation. However, the impact of DSW on NLRP3 inflammasome activation has not been investigated. Here, we demonstrated that DSW with water hardness levels up to 500 mg/L did not affect cell viability or the expression of NLRP3 inflammasome components in macrophages derived from THP-1 cells. However, the DSW significantly inhibited IL-1β secretion and caspase-1 activation in response to NLRP3 activators such as nigericin, ATP, or monosodium urate (MSU) crystals. Mechanically, it was discovered that the presence of 5 mM magnesium ions (Mg2+), equivalent to the Mg2+ concentration found in the DSW with a water hardness of 500 mg/L, inhibits NLRP3 inflammasome activation. This indicates that Mg2+ contributes to the mechanism by which DSW mitigates NLRP3 inflammasome activation. Moreover, DSW administration effectively lessens MSU-triggered peritonitis in mice, a commonly used model for examining the impacts of NLRP3 inflammasome activation. These results show that DSW enriched with Mg2+ could potentially be beneficial in modulating NLRP3 inflammasome-associated diseases.

Biochar with root pore channels loaded copper cobalt bimetallic metal organic framework for effective peroxomonosulfate activation to degrade organic pollutants

Biochar (BC) with root pore channel structure was used as the carrier, and bimetallic organic framework (CuCo-MOF) as the main active site. The CuCo-MOF was successfully dispersed in the internal channels of BC by in situ reaction, forming a composite catalyst (BC/CuCo-MOF(10%)) with unique reaction channels. The degradation efficiency of ciprofloxacin (20mg/L) in only 25min was 96.4%, and its catalytic performance was superior to that of the single BC and CuCo-MOF. On the one hand, abundant CuCo-MOF reaction sites were distributed in the relatively closed porous reaction channel of BC, which accelerated the mass transfer process (short mass transfer distance) during the CIP degradation process and improved the CIP degradation performance. On the other hand, highly conductive BC facilitates electron transfer between Cu2+/Cu+ species and HSO5-, accelerating the redox cycle of Cu2+/Cu+, thereby improving catalytic activity. Besides, the composite catalyst was still able to achieve a degradation efficiency of 87.6% for CIP after five cyclic degradation experiments. The concentrations of Cu and Co ions in the reaction solution were only 0.04 and 0.03mg/L. Therefore, the composites have excellent catalytic activity and stability. Both non-radical 1O2 and radicals (SO4·- and ·OH) were involved in the reaction, and the non-radical 1O2 pathway played a dominant role in the CIP degradation process.

Predicting the Electrophoretic Mobility of Charged Particles in an Aqueous Medium.

Electrophoresis of charged particles has important applications in biochemical separation processes. The mobility of these particles depends on the surrounding electric double layer (EDL), which is impacted by solvent restructuring because of hydration interactions. Nevertheless, most theoretical estimates ignore such interactions during computation of the electrophoretic mobility. Here, we employ a complementary blend of mean-field analysis and molecular dynamics simulations performed for a peptide-G-quadruplex complex to assess how hydration interactions alter the mobility of a charged particle in an aqueous medium. These interactions are seen to stabilize the EDL, resulting in more significant localized counterion concentrations while strengthening the ensuing electrokinetic flow. The ordering of ions near the particle surface is obtained only upon including hydration interaction, revealing that the hydration water molecules act as a glue for forming a stable EDL, a key finding of this work. Conversely, the observed microstructure of ions near the charged surface as obtained from our theory establishes a bridge link between the micro and continuum model. The presence of larger counter ions enhances the drag on the particle, thus restricting its mobility. The mobility also becomes dependent on size, which may be useful for isolating a wide array of biomolecules. The impact of hydration interactions intensifies with increases in particle size, surface charge density, and bulk ion concentration.

Room-temperature high-power laser emission of erbium-doped fluorite crystals at 2.8 µm

We report on a high-power continuous-wave (CW) laser at 2.8 µm employing erbium (Er)-doped fluorite crystals as gain materials. With an optimized Er3+ ion concentration, thin “slab” geometry of the sample matching with the tailored pump beam profile and compensated negative thermal lens using a pair of concave mirrors cavity configuration, a highest power of 14.5 W is achieved from a dual-end-pumped Er:CaF2 laser, which, to the best of our knowledge, presents the record power from the room-temperature Er-bulk lasers in the 3-µm spectral range. In addition, 8.05 W output power is obtained from the Er:SrF2 laser with an RMS power stability of 0.35%. This work indicates that Er-doped fluorite crystals with large-scale available fabrication are promising candidates for high-power laser emission at ∼3 µm.

Investigation of structural, elastic, thermal, magnetic, optical, and photocatalytic properties of nanosized Mg-Mn-Li ferrites

AbstractNanoferrites of (Mn1-xMgx)0.8Li0.1Fe2.1O4 (x: 0–1.0, step 0.2) were synthesized by the sol–gel autocombustion method. The structural properties of the samples were characterized by X-ray diffraction, particle size analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy. The X-ray diffraction patterns for the samples establish the nanoscale (38–54 nm) pure-phase spinel cubic structure (Fd-$$\bar{3}$$ 3 ̅ m). Also, the particle size analysis results demonstrate the narrow distribution of their particle sizes, which range from 10 to 33 nm. The impact of Mg2+ ion concentration on the thermal, elastic, magnetic, and optical properties of these samples was studied. The saturation magnetization decreases from 56.9 to 31.1 emu/g, and the coercivity increases from 65.8 to 106.8G with the addition of Mg2+ ions, showing thin S-shaped hysteresis loops revealing the samples’ soft magnetic behavior. Thermal results indicate that these samples are interesting candidates for thermoelectric applications due to their noticeably lower thermal conductivity, which ranges from 0.3572 to 0.5881 W/mK. The optical band gap values determined by using ultraviolet-visible diffuse reflectance spectroscopy range from 5.11 to 5.25 eV, where quantum confinement for crystallite size triggers a larger band gap. As the concentration of Mg2+ ions increases, their ability to degrade methyl green dye under ultraviolet radiation for 100 min rises from 13.6 to 61.1% with the addition of H2O2, an indication of their photocatalytic activity. Moreover, the optimum ferrite sample, Mn0.4Mg0.4Li0.1Fe2.1O4, maintained its photocatalytic efficiency for at least six reaction cycles. Graphical Abstract

Box-Behnken Design for Mitigation of Cadmium Bivalent Ions from Aqueous Medium.

Statistical analysis is essential for minimizing the time, cost, and number of experiments needed to get the maximum output. In this work, the removal of cadmium bivalent (Cd (II)) ions was optimized using Box-Behnken design methodology. The effects of pH, concentration, time, and temperature were investigated for the removal of cadmium. Maximum removal (85.70%) was achieved at pH of 5.34, initial Cd(II) ions concentration 46.61,contact time 166.09 (min), and at 59.40 oC temperature on Punica Granatum carpellary membrane powder (PGCMP) and 88.61% removal was achieved on its modified forms (MPGCMP) at pH of 5.79, initial Cd(II) ions concentration 65.70,contact time 178.96, and at 59.91 oC temperature. The model was validated by analyzing variance (ANOVA). The practical data was well fitted to the quadratic model. PGCMP and MPGCMP were found to be naturally occurring, environmentally friendly adsorbents for the mitigation of Cd (II) ions as well as other toxic heavy metals from drinkable or wastewater.

Pilot Study on the Production of Negative Oxygen Ions Based on Lower Voltage Ionization Method and Application in Air Purification

In the current highly industrialized living environment, air quality has become an increasing public health concern. Natural environments like forests have excellent air quality due to high concentrations of negative oxygen ions originating from low-voltage ionization, without harmful ozone. Traditional negative oxygen ion generators require high voltage for corona discharge to produce ions. However, high voltage can increase electron collisions and excitations, leading to more dissociation and recombination of oxygen molecules and consequently higher ozone production. To address the challenge of generating negative oxygen ions without accompanying ozone production, this study designed and constructed a low-voltage negative oxygen ion generator based on nanometer-tip carbon fiber electrodes. The advantage of this device lies in the high curvature radius of carbon fibers, which provides high local electric field strength. This allows for efficient production of negative oxygen ions at low operating voltages without generating ozone. Experiments demonstrated that the device can efficiently generate negative oxygen ions at a working voltage as low as 2.16 kV, 28% lower than the lowest voltage reported in similar studies. The purification device manufactured in this study had a total decay constant for PM2.5 purification of 0.8967 min−1 within five minutes, compared to a natural decay constant of only 0.0438 min−1, resulting in a calculated Clean Air Delivery Rate (CADR) of 0.1535 m3/min. Within half an hour, concentrations of PM2.5, PM1, PM10, formaldehyde, and TVOC were reduced by 99.09%, 99.40%, 99.37%, 94.39%, and 99.35%, respectively, demonstrating good decay constants and CADR. These findings confirm its effectiveness in improving indoor air quality, highlighting its significant application value in air purification.

Hydrochemical Characteristics and Controlling Factors of the Mingyong River Water of the Meili Snow Mountains, China

The hydrochemical characteristics of rivers are affected by many natural factors, such as the nature of watershed bedrock, watershed environment, vegetation, and human activities. Examining the hydrochemistry of a river can provide insights into the baseline hydrological conditions, the geochemical environment, and the overall water quality of the river. In order to examine the hydrochemical characteristics and controlling factors of the water in the Mingyong River, a total of 154 water samples were gathered from the glacier meltwater, midstream, and downstream regions. Firstly, the findings revealed that the dominant cations are Ca2+ and Mg2+, while the dominant anions are HCO3− and SO42−. The mass concentration order of cations is Ca2+ > Mg2+ > Na+ > K+, and for anions, it is HCO3− > SO42− > NO3− > Cl−. The average concentration of TDS in the river water is 81.69 mg·L−1, with an average EC of 163.63 μs·cm−1 and an average pH of 8.99. Temporal variations in ion concentrations exhibit significant disparities between the glacier melting and accumulation periods. High ion concentration values are primarily observed during the glacier accumulation period, while values decrease during the glacier melting period due to increased precipitation. The river water in the study region is categorized as (HCO3− + SO42−)-(Ca2+ + Mg2+) type. Secondly, the Pearson correlation analysis indicates clear relationships between different parameters, indicating that the major ions were mostly influenced by materials from the Earth’s crust. The primary principal source of solutes in the water of the Mingyong River is rock weathering. The cations and anions present in the river water are derived from the breakdown of carbonate rocks and the dissolving of substances from silicate rocks. However, the influence of carbonate rocks is more significant compared to that of silicate rocks. Finally, the Mingyong River water is suitable for agricultural irrigation with minimal land salinization damage, making it appropriate for agricultural purposes but not suitable for people and animals to drink from directly.

Nitrogen–silicon Co-doped carbon dots synthesized based on lemon peel for copper (II) detection via a dynamic quenching mechanism

As a metal, copper plays an important role in biological systems. However, excessive intake can lead to toxicity and disease. Therefore, there is a need to establish accurate and sensitive methods to detect and monitor copper levels in food and the environment. Herein, nitrogen-silicon co-doped carbon dots (N,Si-CDs) were synthesized using lemon peel as the biomass precursor by one-step hydrothermal synthesis with the addition of citric acid solution and 3-aminopropyl triethoxysilane (APTES). The prepared N,Si-CDs showed excellent photobleaching resistance, brilliant fluorescence performance and good selectivity. The experiments showed that the fluorescence of N,Si-CDs decreased after the interaction of N,Si-CDs with copper ions. Further studies showed that the decrease in fluorescence intensity of the fluorescent probe due to Cu2+ was dynamic quenching. In addition, the fluorescence intensity of N,Si-CDs showed a good linear relationship with the concentration of copper ions. The linear range was 0.5 μM–250 μM, the R2 was 0.995, and the limit of detection was 0.43 μM. Finally, the method has been successfully applied to the detection of copper ions in the water environment and food, and the recoveries of 99.4%–102.1 % were obtained, which indicated that the method had a promising future.