Concentrations Of Ions In Water Research Articles

Synthesis and application of EDTA grafed metal-organic frameworks (MOFs) and graphene composite for the electrochemical detection of lead(II)

ABSTRACTThe rapid and sensitive detection of heavy metal ion concentrations in water holds significant importance for water resource quality control and protection. In this study, we developed a novel electrochemical sensor utilising a composite material consisting of ethylene diamine tetraacetic acid (EDTA) grafted metal-organic frameworks (MOFs NH2-UiO-66) and graphene to detect Pb2+ in water. The NH2-UiO-66 material exhibited a large specific surface area and porous structure, which was advantageous for the pre-enrichment of the heavy meatal ions. EDTA contained abundant – COOH groups, enabling it to chelate metal ions and increase the reaction sites of redox reactions. The introduction of graphene improved the conductivity of the composite, facilitating electron transfer and enhancing the sensitivity of the electrochemical sensor. Under optimal conditions, the linear range for Pb2+ detection was 0.1 μM–50 μM, and the limit of detection was achieved at 0.052 μM. Furthermore, simultaneous detection of Pb2+ and Cd2+ was successfully accomplished. The fabricated sensor also exhibited excellent selectivity, reproducibility and stability.

The hydrogeochemical characteristics and formation mechanism of high-fluoride mine water

Excessive fluoride ion (F−) concentrations in mine water affected by the geologic processes and coal mine activity prevent the reusage of it as domestic and production water resources. There are few researches on the accumulation mechanism of fluoride in mine water. In this study, 71 water samples and 39 rock samples were collected from 9 mines of the Inner Shaanxi-Mongolia Contiguous area for chemical analyses and laboratory experiments. Results indicate that the concentration of F− in mine water increased with the gradual increase of the coal mining depth. The average concentration of F− in no.3-1 coal mine water is higher than that in no.2-2 coal mine water. And concentrations of F− exceed the China national standard for drinking water quality (upper limit of 1 mg/L), which is closely related to fluoride in the no.3-1 coal roof groundwater and water-rock interaction in the goaf. The main hydrogeochemical processes include mineral dissolution (fluorapatite and hornblende), desorption of exchangeable F− from clay minerals (mica, illite, kaolinite and chlorite) and cation exchange between Ca2+ and Na+. Furthermore, long-term further water–rock interactions result in F− accumulation in mine water. Alkaline environments, decreased particle size of rock, and increased temperature all favor release of F− from clay mineral surface into mine water. Finally, conceptual model of high-fluoride mine water was first proposed, and the formation of high-fluoride mine water can be summed as two stages including water-rock interaction in groundwater and secondary water-rock interaction in goaf. This study helps to improve our understanding of genesis of high-fluoride mine water and our capability of predicting the future concentration, which may provide foundation for manage and utilization of mine water.

Study on the Interaction Mechanism between Residual Coal and Mine Water in Goaf of Coal Mine Underground Reservoir

In this paper, the coal pillar dam body of the underground reservoir in Daliuta coal mine, along with the residual coal and the mine water present in the goaf, were taken as research subjects, and a dynamic simulation experiment device was constructed to simulate the actual process of a coal mine underground reservoir (CMUR). The composition and structure of middling coal during the experiment were determined by X-ray diffraction analysis (XRD) and X-ray fluorescence spectrometry (XRF), while changes in ion content in the mine water were assessed through ion chromatography (IC) and inductively coupled plasma emission spectrometry (ICP-OES). Based on both the composition and structure of coal as well as variations in ion concentrations in water, the interaction mechanism between coal and mine water was explored. The results showed that the water–coal interaction primarily arose from the dissolution of minerals, such as rock salt and gypsum, within coal. Additionally, coal samples in mine water exhibited adsorption and precipitation of metal ions, along with cation exchange reaction. Na+ in mine water predominantly originated from the dissolution of rock salt (sodium chloride) in coal, while Ca2+ and SO42− were released through the dissolution of gypsum and other minerals in coal. In the process of the water–coal interaction, Ca2+ in the water body was adsorbed and immobilized by the coal sample, leading to the formation and deposition of CaCO3 on the surface of the coal, thereby increasing the calcite content. These processes collectively contributed to a decrease in the concentration of Ca2+ in the water body. Moreover, the cation exchange reaction occurred between Ca2+ and Mg2+ in mine water and Na+ in the coal sample. The presence of Ca2+ and Mg2+ resulted in their displacement of Na+ within the coal matrix, consequently elevating Na+ concentration in the mine water while reducing both the Ca2+ and Mg2+ concentrations. On this basis, combined with insights from the water–rock interaction, it can be inferred that the adsorption mechanisms involving rocks played a dominant role in the decrease of Ca2+ concentration during the water–rock interactions. Meanwhile, the dissolution processes of minerals both in the water–rock and water–coal interactions predominantly contributed to the increase of Na+ and Cl− concentrations.

Cu-Based Nanoneedle Array for Electrochemical Detection of Nitrate

The extensive usage of nitrogen-based fertilizers, food preservatives and explosive chemicals in various industries has led to the accumulation of nitrate in the ecosystems, especially in soil and water bodies. Several severe environmental and human health issues, including eutrophication, diseases related to N-nitroso compounds (such as Cancer, Parkinson and Gastritis) and blue-baby syndrome (methemoglobinemia), have arisen from the excessive nitrate concentration in the environment. Consequently, various government and regulatory agencies, such as the U.S. Environmental Protection Agency (EPA), have established the maximum nitrate ion concentration in drinkable water at 44 mg/L (0.71 mM). In this context, an accurate monitoring of the level of nitrate becomes important in environmental pollution control, food, clinical analysis, and other industries. While the spectroscopy techniques are of the most use due to its high precision and low limit of detection (LOD), these methods frequently require skilled workforces and specific instrumentations to operate. The electrochemical sensors benefit from recent developments of new nanomaterials to detect nitrate with a quick response, ability of continuously monitoring, small and simple instrumentation as well as easy to use. Several studies have utilized different strategies to fabricate Cu-based nanostructures (such as nanoparticles, nanoclusters, nanowires, and single-crystals) to achieve a low LOD. However, the sensitivity that has been achieved so far is still relatively low compared to the requirements for the real sampling applications.In this work, we utilized a one-step electrodeposition method to prepare Cu-based nano-array electrodes with high active surface sites, aiming for a fast and sensitive electrochemical detection of nitrate. The morphology of the array can be fine-tuned between nanoneedle and nanowire structures (Figure 1a and 1b). The x-ray diffraction (XRD) measurements indicate that the Cu-based nanoneedle array exhibited an abundant Cu(220) facet than the nanowire systems, which is usually associated with the active edge sites on copper (Figure 1c). The nanoneedle array was used for nitrate sensing via Cyclic Voltammetry methods which showed a sensitivity of 2.8 μA/μM*cm2, about 5-fold higher than the Cu foil control electrode (Figure 1d). The main reason of the sensitivity enhancement is that the nanoneedle structure resulted in a 30 times enrichment in the surface area compared to the Cu foil as shown in the electrochemical surface area (ECSA) measurement. Overall, our study provides a novel and convenient design of highly ordered Cu nanoneedle array structure for the sensitive electrochemical detection of nitrate. Figure 1

AN EVALUATION OF THE GANGA RIVER’S CARBON FLOW AND ITS IMPACT ON INDIA’S NUTRITIONAL AND CLIMATE CHANGE

<p>Changes in weather patterns and the global climate are a result of global warming, which has been linked to rising carbon dioxide concentrations. Understanding the mechanisms on earth that have an impact on atmospheric carbon concentrations and its cycling—collectively referred to as the "Carbon cycle"—is essential for estimating carbon budgets. Studies on carbon budgets have largely ignored the role of inland waterways in the carbon cycle, yet rivers play an active role by absorbing/releasing carbon into the atmosphere and transferring dissolved carbon into oceans. In tropical parts of the planet, it is anticipated that water bodies, like as rivers, would contribute to carbon emissions to a greater extent newline Although there are many studies on the impact of human activity on the Ganga River, there are very few that take an ecological viewpoint. In light of these facts, the following was designed as the study's hypothesis: newline The Ganga River has positive feedbacks as a result of human activity, which alters the environment at a level significantly greater than what has previously been projected.The current investigation was conducted in a significant tropical, non-perennial river of the Ganga. In order to calculate the carbon flow of the Ganga river newline, it is important to understand the interaction between geological processes and the concentration of different ions in groundwater and surface water.</p>

Fog and rain water chemistry in a tea plantation of northern Taiwan.

Tea plantations are expanding globally and many are in mountainous areas with frequent fog but few studies have examined fog chemistry in these areas. We examined chemical composition of fog and rain water at a tea plantation in northern Taiwan. Fog water was collected using a Kroneis passive cylindrical fog-water collector and rain water was collected using a 20-cm-diameter funnel. The most abundant ions were Cl- and Na+ in both fog and rain waters due to the proximity of the site to the coast. The order of abundance of other ions was NO3- > Mg2+ > SO42- > Ca2+ > NH4+ > K+ > H+ in fog water and SO42- > K+ > NO3- > NH4+ > Ca2+ > Mg2+ > H+ in rain water. The concentration enrichment ratio (fog to rain) ranged between 2.2 (K+) and 22 (Mg2+) lying between sites near major emission sources and sites in remote areas, possibly because the immediate surrounding landscape is covered with secondary forests although it is near large cities. Factor analysis highlights the influences of sea-salt aerosols on the variation of fog and rain water chemistry. Sea-salt corrections using Na+ as the sea salt tracer led to negative concentrations of Cl- and Mg2+ suggesting that assumptions involved in sea-salt corrections were not satisfied. Agriculture influence is identified as a unique factor for explaining variance of K+, NH4+, and dissolved organic nitrogen (DON) concentrations in fog water but not rain water. Ion concentrations in fog and rain water were generally higher in the weekly samples associated with air trajectories passing through the continental East Asia than those associated with oceanic trajectories pointing to the role of regional pollution sources in affecting local fog and rain water chemistry. Our study highlights greater effects of tea agriculture on fog than rain water chemistry.

Janus MXene-based photothermal membrane for efficient and durable water evaporation

The interfacial solar steam generation for seawater desalination has attracted attentions of many researchers because of its excellent photothermal performance and efficiency. However, relatively high cost, complex equipment, and poor salt resistance limit its further practicability. Therefore, a solar evaporator with low cost, easily prepared and certain salt resistance is desideration. For this purpose, MXene was chosen as a light absorber, and filterable deposited on filter paper easily to obtain MXene-based flexible Janus membranes. Due to the introduction of ethyl cellulose, the membrane has Janus characteristics of hydrophobic upper layer, hydrophilic lower layer. Besides, the elasticity, multiple folding skill means it can be used for a long time, efficient desalination of seawater. Under one solar intensity of light, the light absorption rate of the MXene flexible Janus membrane can reach 90.81 %, the average evaporation rate is 1.34 kg m−2 h−1 in nearly 120 h of evaporation experiments, the average evaporation efficiency ≈ 81.5 %, and the main ion concentration of fresh water obtained after the experiments was also far below the World Health Organization standard. In summary, it was demonstrated that the device is suitable for long-term and efficient solar seawater desalination.

Long-term evolution of groundwater hydrochemistry and its influencing factors based on self-organizing map (SOM)

The primary water source for agricultural irrigation in the People's Victory Canal irrigation area was the Yellow River water in the early stage, and the Yellow River water diversion volume decreased in the later stage. Hence, the groundwater became the primary water source for the irrigation area. It is significant for the rational utilization of groundwater resources to explore groundwater hydrochemistry's evolution characteristics and formation mechanism. Based on the hydrochemical data of groundwater and Yellow River in the irrigation area from 1987 to 2022. The spatiotemporal evolution of chemical components of groundwater and the main influencing factors were revealed using traditional hydrochemistry research methods, self-organizing map, and stable isotopes. The results show that the classification results of groundwater and Yellow River water samples by the self-organizing map show regional and phased characteristics. Regionally, the self-organizing map classifies groundwater into five clusters, and Cluster Ⅰ–III of groundwater are mainly distributed in the head, middle and northeast areas. Cluster Ⅳ and V of groundwater are mainly distributed in the northwest region. In terms of time, from 1987 to 2001, the Yellow River water diversion volume was higher, and the ion concentration of groundwater showed a decreasing trend. The ion concentration was close to the Yellow River water ion concentration except in the northwest area. Accordingly, the classification results of the self-organizing map change from Cluster Ⅰ of groundwater to Cluster Ⅱ of groundwater. After 2001, the amount of water diverted from the Yellow River decreased, and the concentration of each ion in the groundwater at the head of the canal and the central area showed an overall increasing trend from 2001 to 2022. The classification results of the self-organizing map change to Cluster Ⅰ of groundwater. Due to the change in runoff conditions and the influence of domestic sewage, the classification results of the self-organizing map in the funnel area in the middle of the irrigation district changed to Cluster III of groundwater after 2013.

Ultrasensitive and highly selective detection of nickel ion by two novel optical sensors.

Novel optical sensors for nickel determination by incorporation of 5-(2`-bromo-phenylazo)-6-hydroxypyrimidine-2,4-dione (I), 5-(2`,4`-dimethylphenylazo)-6-hydroxypyrimidine-2,4-dione (II), dibutylphthalate (DBP) and sodium tetra-phenylborate (Na-TPB) to the plasticized polyvinyl chloride matrices were prepared. The introduction of DBP in the membrane substantially increased the ability of both ionophores I and II to function as chromo ionophores. The advantages of the reported sensors include great stability, reproducibility, and relatively long lifespan, as well as excellent selectivity for Ni2+ ion detection across a wide range of alkali, alkaline earth, transition, and heavy metal ions.Under optimized membrane compositions and experimental parameters, the response of both sensors was linear throughout a concentration range of 3.5 × 10-8 to 8.1 × 10-5 and 2.0 × 10-8 to 5.1 × 10-5M for I and II, respectively. Sensor detection and quantification limits based on the definition that the concentration of the sample leads to a signal equal to the blank signal plus three and ten times its standard deviation were determined to be 1.15 × 10-8 and 3.45 × 10-8M when utilizing I, whereas they were 0.61 × 10-8 and 1.95 × 10-8M when utilizing II, respectively. The reaction time of optodes is defined as the period required achieving 95% of based sensors and found to be 8.0 and 5.0min using I and II, respectively. Ni2+ ion concentrations in water, food, and environmental samples were effectively determined using the proposed optical sensors. Representative diagram for preparation of the sensing Ni2+ sensor.

Triboelectric-electromagnetic hybrid generator assisted by a shape memory alloy wire for water quality monitoring and waste heat collecting

Thermal energy has garnered significant attention due to its widespread availability and environmentally friendly nature. Currently, the collection of thermal energy primarily depends on thermoelectric generators, which require significant temperature differences and high-performance materials, consequently imposing significant limitations on energy collection efficiency. Here, a shape-memory-alloy-wire driven hybrid generator (HG) composed of triboelectric nanogenerator and electromagnetic generator is developed, which could efficiently convert thermal energy into electric energy. Due to its remarkable output performance, achieving an output voltage of 8 V and an output current of 2.5 μA, the HG can be utilized for self-powered monitoring of water temperature, ion concentration, and sewage composition. This work provides a new strategy for collecting thermal energy and self-powered monitoring of water quality.

Folic acid-derived luminescent carbon dots: Effect of Ag inclusion and switch ON sensing of sulfide ions

One of the aesthetic concerns of the scientific community is to ensure all people have access to safe drinking water. Sulfide ion is considered as a public health risk-worthy constituent in water. The present work investigates the effect of localized surface plasmon resonance (LSPR) of silver nanoparticles (AgNP) on the photoluminescence response of folic acid-derived carbon nanodots (CD) and their application towards sulfide ion detection. Herein, CD are grown on the surface of AgNP, causing an absorption band centered at ∼ 400 nm due to LSPR. AgNP effectively quench the luminescence of CD through the static quenching mechanism. The Ag-CD system is designed as a simple and selective sensor for sulfide ions in water in a linear range of 0.8–1.5 µM with a Limit of Detection (LOD) of 50 nM and a Limit of Quantification (LOQ) of 170 nM. The ion selectivity for sensing was carried out in accordance with the Hard and Soft – Acids and Bases theory and its predictions. The practical applicability of the sensor was tested by determining the spiked sulfide ion concentrations in pond water and tap water, which produced an adequate outcome.

СКЛАД ЙОНІВ ЗАТОРНОЇ ВОДИ І ЇХ ВПЛИВ НА ЯКІСТЬ ПИВА

The water obtained by reverse osmosis was studied and the method of regulating the composition of its ions, necessary for the use of this water in the mashing process in order to obtain high-quality beer, was considered. The influence of mash water ions on beer quality indicators was studied. It was found that the concentrations of individual ions in water have the greatest effect on the organoleptic parameters of the finished drink and especially on the hop bitterness. It was studied that the increase in the ratio of cations Ca2+/Na+ and sulfates and chlorides SO42-/Cl- in mash water has a positive effect on the organoleptic and quality parameters of beer.

Quantitative Assessment of Intervertebral Disc Composition by MRI: Sensitivity to Diurnal Variation.

Whether diurnal variation exists in quantitative MRI indices such as the T1rho relaxation time (T1ρ) of the intervertebral disc (IVD) is yet to be explored. This prospective study aimed to evaluate the diurnal variation in T1ρ, apparent diffusion coefficient (ADC), and electrical conductivity (σ) of lumbar IVD and its relationship with other MRI or clinical indices. Lumbar spine MRI, including T1ρ imaging, diffusion-weighted imaging (DWI), and electric properties tomography (EPT), was conducted on 17 sedentary workers twice (morning and evening) on the same day. The T1ρ, ADC, and σ of IVD were compared between the time points. Their diurnal variation, if any, was tested for correlation with age, body mass index (BMI), IVD level, Pfirrmann grade, scan interval, and diurnal variation in IVD height index. The results showed a significant decrease in T1ρ and ADC and a significant increase in the σ of IVD in the evening. T1ρ variation had a weak correlation with age and scan interval, and ADC variation with scan interval. Diurnal variation exists for the T1ρ, ADC, and σ of lumbar IVD, which should be accounted for in image interpretation. This variation is thought to be due to diurnal variations in intradiscal water, proteoglycan, and sodium ion concentration.

Potential of Oil-free-Cake Dry Seed Kernels of Desert Date (Balanites aegyptiacus (L.) Delile) for simultaneous Removal of Pb (II), Cu (II) and Cd (II) ions from Battery Industry Effluent

This study was carried out to investigate the potential of oil-free-cake dry seed kernels of desert date (Balanites aegyptiacus (L.) Delile) for simultaneous removal of Pb (II), Cu (II) and Cd (II) ions from Battery Industry Effluent using standard methods in a batch sorption process.. The battery effluent was mimicked by dissolving known concentration of metal ions in distilled water. The optimum conditions for the simultaneous removal of Pb (II), Cu (II) and Cd (II) ions were: pH (6), contact time (105 min) and adsorbent dosage (6.5 g). The results obtained showed that the biosorbent was effective for the simultaneous removal of Pb (II), Cu (II) and Cd (II) ions with removal efficiencies of up to 87.7%, 78.6% and 61.6% respectively. The consistency of the model-predicted optimum conditions were confirmed by conducting experiments under those conditions. It was found that the experimental removal efficiencies under optimum conditions were very close (less than a 5% error) to the model-predicted value. The three parameter isotherm equations (Redlich-Peterson and Sips) provide better fitting than the two-parameter isotherm equations (Freundlich and Langmuir), which can be explained by the fact that these have three adjustable parameters. The best fitted was achieved with the Redlich–Peterson equation. The results of the sorption kinetic study showed that the data fitted well with the pseudo-second order model for Pb (II), Cu (II) and Cd (II) ions. In conclusion, desert date oil-free cake exhibits great potential as an efficient sorbent for removal of metal ions.

Research on Temporal Patterns of Water-Rock Interaction in the Coal Mine Underground Reservoir Based on the Dynamic Simulation Test.

The temporal pattern of water-rock interaction is significant in predicting the ion concentration of the effluent in coal mine underground reservoirs. This study used the roof-caved rock samples and main incoming water (mine water and fissure water) of the Daliuta coal underground reservoir as the research object and designed four groups of dynamic simulation experiments of the water-rock interaction. Based on the main ion concentrations in the water sample at different reaction times, Q-type hierarchical cluster analysis (HCA) was used to classify the stages of water-rock interaction. The types and intensities of water-rock interaction in each stage were identified by combining the ion ratio and principal component analysis (PCA). Q-type HCA shows that the dynamic simulation experimental water samples can be divided into three categories according to the reaction time, representing the early, middle, and late stages of the water-rock interaction process. The influence of water quality on the division of the water-rock interaction stage is greater than that of rock characteristics. The ion ratio and PCA show that the dissolution of pyrite minerals, cation exchange reaction, and mineral adsorption mainly occur in the early stage of water-rock interaction, in which the cation exchange reaction plays a leading role in the change of ions in water. In the middle stage, the cation exchange reaction and the dissolution of carbonate minerals, such as calcite and dolomite, mainly occur, in which mineral dissolution is the main. In the late stage, the water-rock interaction is relatively weak, and the change of ion concentration in water is not obvious. This study proves the temporal patterns of water-rock interaction between caved rock and mine water (or fissure water) and differences in the types and intensities of water-rock interaction in each stage. The results can provide a theoretical basis for the optimization of the operation cycle of coal mine underground reservoirs and the prediction of effluent ion concentration.

Preparation of Carbon/PVA/Chitosan Aerogel and Its Application to Direct Solar Steam Generator

Direct Solar Steam Generator（DSSG）is a technology that is currently attracting attention due to its advantages over conventional evaporative desalination technologies, such as the fact that it does not use fossil energy and has a photothermal conversion efficiency of almost 100%. The DSSG system is composed of steam generating membrane including photothermal and water transportation materials. Thus, the performance of DSSG system depends on the photothermal and water transportation materials, and heat management of system. Recently, carbon materials are considered as good photothermal materials under one sun irradiation（1 kW/m2）. Carbons synthesized by the solution plasma（SP）method show good feature such as porous structures, large surface area, and fast transportation of water. In this study, we synthesized photothermal carbon materials by SP method and prepared films composed of poly（vinyl alcohol）（PVA）and chitosan aerogel（CSA）with high affinity to water by freeze-drying, and composited carbon and PVA/CSA film（Cx/PVA/CSA: x＝0.1，0.5，1.0）．The morphologies and evaporation performance of the Cx/PVA/CSA were investigated. The evaporation rate and evaporation efficiency of C0.5/PVA/CSA were estimated to be 1.29 kg/m2･hand 86.1%, respectively. These values showed excellent evaporation performance within the range of C additions investigated. Finally, the desalination test of DSSG system using the C0.5/PVA/CSA was performed and the DSSG system showed desalination performance of more than 99.3% for Na＋, Ca2＋ and Mg2＋ ion concentrations in sea water obtained from Toyosu canal.

Decreasing of Mangan (II) in The Water Using Membrane of Moringa Seed Powder-TiO2 with Variation of Mass TiO2

Mn (II) is a metal ion commonly used in steel alloys, pigment industries, welding, fertilizers, pesticides, ceramics, and electronics. According to the Regulation of the Minister of Health No. 32 of 2017, the permissible content of Manganese in dug well water is 0.5 mg/L. The purpose of this study was to determine the concentration of Mn (II) ions in water before and after passing through a Moringa Seeds Powder (MSP)-TiO2 membrane 20:1; 20:3; 20:5; 20:7; 20:9 and measure the percentage decrease in the concentration of Mn (II) ions in water after through the MSP-TiO2 membrane. The object of this research is a 55 ppm Mn (II) ion artificial sample at a flow rate of 0.56 mL/minute for 90 minutes with 90-watt radiation UV. The concentration of Mn (II) ion was measured by visible spectrophotometric method, the morphology of MSP, TiO2, and MSP-TiO2 membranes was characterized by SEM-EDX, and its diffraction spectra by X-Ray diffraction. The results obtained that the initial Mn(II) was 55.06 ± 0.031 ppm, the concentration of Mn (II) ions with the MSP-TiO2 membrane of mass MSP-TiO2 were 20:1; 20:3; 20:5; 20:7; 20:9 respectively 36.47±0.00; 44.16±1.15; 44.31±1.04; 44.94±0.94; 42.27±2.61 ppm. The percentage of decrease concentration of Mn (II) ion are 34.19±0.44%; 21.37±0.43%; 20.94±0.85%; 19.24±0.86%; and 19.66±0.86%. The highest percentage decrease in Mn (II) ion concentration was 34.15±0.44% in the variation of mass MSP-TiO2 20:1. This study concludes that the MSP-TiO2 membrane has the potential to reduce the concentration of Mn (II) ions in water.

Overlooked effect of ordinary inorganic ions on polyaluminum-chloride coagulation treatment

Application of poly-aluminum chloride (PACl) coagulant is a popular mode of water treatment worldwide because of the high capacity of PACl to neutralize charge. The manufacture and use of PACls with various basicities in different regions around the world suggest that the characteristics of the raw water are important determinants of the efficacy of PACl application. However, attention has not been fully paid to the effects of water quality other than the substances to be removed. In this study, two typical PACls with different basicities were used to investigate why the performance of PACls depends on the characteristics of the raw water. We focused on the concentrations of inorganic ions in the raw water. Use of high-basicity PACl (HB-PACl) with a high content of polymeric-colloidal species (Alb+Alc) resulted in very slow floc formation and little turbidity removal in raw water with low concentrations of sulfate ions. The performance of the HB-PACl was inferior to that of normal-basicity PACl (NB-PACl), although the charge-neutralization capacity of the HB-PACl was higher. Rates of floc formation were strongly correlated with the rate of aluminum precipitation by hydrolysis reaction, which was identified as an indicator for evaluating the compatibility of raw water with PACl treatment. Among the common ions in natural water, the sulfate ion had the greatest ability to hydrolyze and precipitate PACl because of its divalency and tetrahedral structure. This conclusion followed from experimental results showing similar effects for selenate and chromate ions as for sulfate ions and somewhat smaller effects for thiosulfate ions. Bicarbonate ions and natural organic matter affected PACl hydrolysis-precipitation, but chloride ions, nitrate ions, and cations had little effect on PACl hydrolysis-precipitation. Interestingly, the abilities of sulfate ions to hydrolyze HB-PACl and NB-PACl were very similar, but bicarbonate ions were less effective in hydrolyzing HB-PACl than NB-PACl, and bicarbonate ions contributed little to the hydrolysis-precipitation of HB-PACl in raw water with normal alkalinity. Therefore, sufficient coagulation with HB-PACl therefore usually requires a certain concentration of sulfate ions in water to be treated. The implication is that which anions are most influential to the hydrolysis-precipitation of PACl, and thus to PACl's coagulation ability depends on the constituents of the PACl.

Efficient liquid-phase hydrogenation of bromate over nanosized Pd catalysts supported on TpBD-Me2 covalent organic framework

The formation of toxic and carcinogenic bromate, BrO3–, during the disinfection of fresh or seawater by ozonation poses a threat to the human health, and therefore the development of methodologies for its removal from water is of high importance. Heterocatalytic bromate hydrogenation has been widely employed to decrease the BrO3– ion concentration in water below the strict legal limit imposed. In this work, we evaluate for the first time the performance of a covalent organic framework (COF) for this reaction. TpBD-Me2 COF was synthesized on gram scale and used as both catalyst and support for Pd nanocatalysts with different Pd loadings for bromate hydrogenation reaction.TpBD-Me2 was found to present considerable catalytic activity for BrO3– reduction with 60% conversion after 180 min. The conversion increased with increasing Pd loading of the COF, with the sample with 5% Pd on COF reaching 93% conversion after 180 min. The catalytic activity was further improved by performing an in situ pre-reduction step before the reaction, resulting in complete conversion of BrO3– already after 60 min of reaction. These results show that COF materials are efficient catalysts for this application.

Вплив іонно-сольового складу води на якість пива

Minerals dissolved in water have an important effect on the overall chemistry of the brewing process. Ions from these minerals affect the pH of water, its hardness, alkalinity and mineral composition. These parameters are the most important factors in determining the suitability of water for brewing, in particular for the mashing process. For that reason, it is very important to study the ion-salt composition of mash water and its influence on the quality of beer. The method of regulating the ion-salt composition of water, which is necessary for its use in the mashing process in order to obtain high-quality beer is discussed in the article. Prepared water obtained by reverse osmosis is free from ions as much as possible, which enabled to prepare water with the necessary ion-salt composition for rubbing by adding appropriate salts. Using prepared water in the mashing process, beer samples were obtained, which were evaluated according to sensory and physicochemical indicators. The effect of ion-salt composition of mash water on beer quality indicators was studied. It was found that calcium and sodium cation complexes, as well as a mixture of sulfates and chlorides dissolved in the water used for the mashing process, have the most significant impact on beer quality. Concentrations of individual ions in such water do not show any pronounced dependence on beer quality indicators. It was studied that the increase in the ratio of cations Ca2+/Na+ and sulfates and chlorides SO4 2- /Cl in the mash water has a positive effect on the sensory and quality indicators of beer: the ratio of key ions affects hop bitterness to the greatest extent among the quality indicators of beer. In addition, the ratio of Ca2+/Na+ cations has a positive effect on the foam resistance of beer, and the ratio of sulfates and chlorides SO4 2- /Cl leads to an increase in the share of alcohol in the finished drink. According to the tasting evaluation of beer, samples with a higher ratio of key ions have a brighter taste and aroma.