Order Cl Research Articles

Competing C and N as Reactive Centers for Microsolvated Ambident Nucleophiles CN-(H2O)n=0-3: A Theoretical Study of E2/SN2 Reactions with CH3CH2X (X = Cl, Br, I).

As an ambident nucleophile, CN- has both C and N atoms that can act as the reactive center to facilitate substitution reactions. We investigate in detail the potential energy profiles of CN-(H2O)0-3 with CH3CH2X (X = Cl, Br, I) to explore the influence of solvent molecules on competition between the different nucleophilic atoms C and N involving the SN2 and E2 pathways. The energy barrier sequence for the transition states follows C@inv-SN2 < N@inv-SN2 < C@anti-E2 < N@anti-E2. When two different atoms act as nucleophilic atoms, the SN2 reaction is always preferred over the E2 reaction, and this preference increases with microsolvation. For the ambident nucleophiles CN-(H2O)0-3, C as the reactive center always has stronger nucleophilicity and basicity than N acting as the reactive center. Regarding the leaving group, the height of the energy barrier is positively correlated with the acidity of the CH3CH2X substrate for the E2 pathway and with X-heterolysis for the SN2 pathway. Furthermore, we found that in the gas phase, the energy barrier for different leaving group systems decreases gradually in the order Cl > Br > I, while in the SMD solution, the energy barrier and product energy increase slightly in the system from X = Cl to Br; this change may be due to the significantly weakened transition-state interaction for the X = Br system. Our activation strain, quantitative molecular orbital, and charge analyses reveal the physical mechanisms underlying the various computed trends. In addition, we also demonstrate the two points recently proposed by Vermeeren, P. . Chem. Eur. J. 2020, 26, 15538-15548.

Groundwater geochemistry and hydro-geochemical processes in coastal area South Phan Thiet, Binh Thuan Province, Vietnam

As one of the largest dragon fruit areas and many tourism projects, the southern coastal area of Phan Thiet (including three communes: Tien Thanh, Thuan Quy, and Tan Thanh) has been a bright spot in the economy of Binh Thuan. Economic development puts pressure on water resources, especially groundwater resources, the main supply for irrigation and domestic water in the region. In this research, 19 groundwater samples from the Holocene and Pleistocene aquifers were collected in February 2023 and analyzed for the concentration of Ca2+, Mg2+, Na+, K+, NH4 +, NO3 −, PO4 3-, Cl−, HCO3 –, and SO4 2-, thereby evaluating groundwater geochemistry, hydro-geochemical processes, and the suitability for irrigation purposes. The rank of cations in the aquifers of the region is Na+ > Ca2+ ∼ Mg2+, and Ca2+ ∼ Mg2+ > Na+ respectively. The concentrations of major anions in the study area are in order Cl− > HCO3 − > SO4 2- respectively. The predominant processes in the aquifer involve the interplay between rock and water as well as anthropogenic activity. The saturation indices of dolomite, gypsum, and halite are under-saturated in all collecting sample sites. According to the quality evaluation for irrigation, 14 of the 19 samples with % sodium levels less than 60 are suitable, while the others should be treated before use. The study area also indicated nitrate pollution (4/19 groundwater samples exceeding 15 mgN L−1 of the Nitrate limited for groundwater, National technical regulation on underground water quality). It is recommended that local authorities have strategies to supply water for different purposes, control pollution sources, and treat water waste to protect these aquifers.

Reducing Ice Adhesion to Polyelectrolyte Surfaces by Counterion-Mediated Nonfrozen Hydration Water.

Hydrophilic anti-icing coatings can be energy-effective passive solutions for combating ice accretion and reducing ice adhesion. However, their underlying mechanisms of action remain inferential and are ill-defined from a molecular perspective. Here, we systematically investigate the influence of the counterion identity on the shear ice adhesion strength to cationic polymer coatings having quaternary alkyl ammonium moieties as chargeable groups. Temperature-dependent molecular information on the hydrated polymer films is obtained using total internal reflection (TIR) Raman spectroscopy, complemented with differential scanning calorimetry (DSC) and ellipsometry. Ice adhesion measurements show a pronounced counterion-specific behavior with a sharp increase in adhesion at temperatures that depend on the anion identity, following the order Cl- < F- < SCN- < Br- < I-. Linked to the freezing of hydration water, the specific ordering results from differences in ion pairing and the amount of water present within the polymer film. Moreover, similar effects can be promoted by varying the cross-linking density in the coating while keeping the anion identity fixed. These findings shed new light on low ice adhesion mechanisms and may inspire novel approaches for improved anti-icing coatings.

Effect of Halides on MPS Orientation and Cu Deposition Rates at Cu Surfaces

Surface enhanced Raman spectroscopy (SERS), electrochemical measurements, and contact angles were used to evaluate the effect of halides on Cu electrodeposition rates in the presence of 3-mercapto-1-propanesulfonate (MPS). The Cu(II) reduction rate was shown to decrease in the order Cl− > Br− > I−. In-situ SERS and contact angle measurements showed that adsorbed MPS will exhibit decreased gauche to trans (g:t) ratio and decreased hydrophobicity in the same order as the Cu(II) reduction rate. The amount of MPS in the gauche form, due to the hydrophobicity of the halide decorated surface, is a key factor in the Cu(II) reduction rate in acid sulfate baths containing the accelerator.

Terminal-substituted benzoxazole based Schiff-base Mesogens and their Cu(II) complexes: Synthesis and structural characterization

Three homologous series of 3‑hydroxy-4-(((-4-benzoxazol-2-yl)phenyl)imino)methyl)phenyl-4-alkoxybenzoate (with ester linkage) and 5-(alkoxy)-2-(((4-(5-benzoxazol-2-yl)phenyl)imino)methylphenol (without ester linkage) Schiff based derivatives, bearing different substituents at 5 position i.e., 5-methylbenzoxazole, benzoxazole and 5-chlorobenzoxazole units at the end of the molecule and their Copper complexes were synthesised. The molecular structure of all the compounds were elucidated by different spectroscopic techniques such as FT-IR, 1H & 13C NMR and mass spectrometry together with elemental analysis. Their phase transition behaviour was investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction. The structure-property relationships, compounds bearing a variety of polar substituents and changing the spacer from ester linked to without ester-linked has been studied. Substituents with stronger electron-withdrawing properties gave a wider mesomorphic temperature domain, in the order Cl > CH3>H.

Nucleobase-Functionalized 7-Deazaisoguanine and 7-Deazapurin-2,6-diamine Nucleosides: Halogenation, Cross-Coupling, and Cycloaddition.

The functionalization in position-7 of 7-deazaisoguanine and 7-deazapurin-2,6-diamine ribo- and 2'-deoxyribonucleosides by halogen atoms (chloro, bromo, iodo), and clickable alkynyl and vinyl side chains for copper-catalyzed and copper-free cycloadditions is described. Problems arising during the synthesis of the 7-iodinated isoguanine ribo- and 2'-deoxyribonucleosides were solved by the action of acetone. The impact of side chains and halogen atoms on the pKa values and hydrophobicity of nucleosides was investigated. Halogenated substituents increase the lipophilic character of nucleosides in the order Cl < Br < I and decrease the pK values of protonation. Photophysical properties (fluorescence, solvatochromism, and quantum yields) of azide-alkyne click adducts bearing pyrene as sensor groups were determined. Pyrene fluorescence was solvent-dependent and changed according to the linker lengths. Excimer emission was observed in dioxane for the long linker adduct. Bioorthogonal inverse-electron-demanding Diels-Alder cycloadditions (iEDDA) were conducted on the electron-rich vinyl groups of 7-deazaisoguanine and 7-deazapurin-2,6-diamine nucleosides as dienophiles and 3,6-dipyridyl-1,2,4,5-tetrazine as diene. The initially formed complex reaction mixture of isomers could be easily oxidized with iodine in tetrahydrofuran (THF)/pyridine leading to single aromatic tetrazine adducts within a short time and in excellent yields.

Assessment of groundwater suitability for sustainable irrigation: A comprehensive study using indexical, statistical, and machine learning approaches

Groundwater quality for irrigation purposes varies across regions, countries, and specific locations, primarily due to factors such as groundwater extraction and utilization methods, the intensity of rainfall, and the subsequent recharge of aquifers. The present study aimed to evaluate seasonal groundwater suitability for irrigation purposes using indexical approaches, statistical computing, graphical plotting, and machine learning algorithms. Groundwater samples were collected from intensively cultivated areas before and after the monsoon season and were analysed for different physicochemical parameters. The results revealed that the cation concentration of groundwater during pre-monsoon season followed the order of Na+ (59.9 %) > Ca2+(21.9%) > Mg2+ (17.1 %) > K+ (1.2%), whereas, anion chemistry followed the order of Cl−(50.9%) > HCO3− (43.6%) > SO42− (4.0 %) > CO32− (1.4%). A significant increase in the concentrations of major cations (Ca2+ and Na+) and anions (Cl− and HCO3−) was observed during the post-monsoon season. Various irrigation suitability indices expressed that 98.9, 73.5, 99.5, 56.12, and 97.9 % of groundwater samples were found suitable for irrigation based on electrical conductivity (EC), residual sodium carbonate (RSC), sodium adsorption ratio (SAR), percentage sodium (Na%) and water quality index (WQI), respectively. The factor and cluster analyses revealed that salinity, natural processes, and anthropogenic factors are the key determining factors affecting the correlations among water quality parameters. In the purview of predicting groundwater quality, multiple linear regression (MLR) and artificial neural network (ANN) models excelled, with ANN consistently outperforming MLR. Thus, it can be concluded that seasonal shifts in groundwater quality for irrigation are influenced by monsoon dynamics, demonstrating notable changes in cation and anion chemistry, with ANN models displaying superior predictive capabilities of irrigation suitability.

Halogen (Cl, Br, I) regulation Cu-BTC for NH3-SCR: NO and Hg0 removal and mechanism analysis

Emissions of NOx and Hg0 in the atmosphere are primarily derived from coal-fired power plant flue gases. The control of these pollutants has emerged as a focal point of research in recent years. In this study, we synthesized a novel halogen-modified Cu-BTC catalyst designed for the synergistic removal of NO and Hg0. The results showed that: Cu-BTC catalyst maintained its original physicochemical properties even after being modified with different halogens (Cl, Br, I), and C-X (Cl, Br, I) bonds indicated the successful incorporation of halogens into the Cu-BTC. Furthermore, the catalytic performance was investigated through NH3-SCR method. Research indicated that halogens amplified the catalytic reduction of NO and the catalytic oxidation ability of Hg⁰. Furthermore, the effect of post-modification proved to be superior to pre-modification, following the order of Cl＞Br＞I. Under the conditions of 200 °C and 30000 h−1, the Cu-BTC-Cl catalyst exhibited the highest removal efficiency for both NO and Hg⁰, reaching 84.895 % and 76.841 %. While NO had a minor impact, NH₃ enhanced the removal of NO but inhibited the removal of Hg⁰. O2 significantly promoted pollutants removal, and the catalyst also showed strong resistance to both sulfur and water. The modified catalyst exhibited covalent C–Cl species, which effectively captured Hg0. Cu2+ participated in the removal of NO and Hg0, with partial transformation into Cu+.

Water quality index, ecotoxicology and human health risk modelling of surface and groundwater along illegal crude oil refining sites in a developing economy

Water quality index, ecotoxicology and human health risk models were applied to surface and groundwater samples along illegal crude oil refining sites in Rivers State, Nigeria. Eight (8) surface water and four (4) groundwater sampling points were identified along illegal refining sites. Thirty-six (36) samples in triplicates were collected monthly from each of the twelve (12) sampling points over a three (3) month period. Water samples were collected and analyzed using standard methods as prescribed by the American Public Health Association. The mean pH for surface and groundwater ranged from 5.61 ± 0.15 to 7.34 ± 0.10 and 5.80 ± 0.10 to 6.39 ± 0.13, respectively. Turbidity, TDS, and BOD data for surface water samples exceeded the WHO guideline values. The ionic dominance pattern of anions for both surface and groundwater water samples were the same and in the order Cl− > SO42− > NO3− > PO42−. Mean heavy metal concentration was in the order Pb > Ni > Fe > Cd > Mn > Cu for surface water and Pb > Cd > Fe > Mn > Ni > Cu for groundwater. Cd and Pb concentrations in both sources were generally high, with Cd exceeding the WHO guideline value (GV). The CCME water quality index model ranked 62.5% of surface water as marginal, 12.5% as good, 12.5% as poor, and 12.5% as fair. The impact of heavy metals on public health was in the order Pb > Cd > Ni > Fe > Mn, with 83% of samples seriously affected by Pb pollution. The potential ecological risk index ranged from 1.61 × 103 to 2.64 × 103 for surface water and 8.10 × 102 to 2.21 × 103 for groundwater. Heavy metal contamination was very high, and the ecological risk effect was extremely high. The health risk through oral ingestion was in the order of adults > infants > children. Two principal components, PC1 and PC2, explained 50.51% and 16.00% of the variations in surface water quality, respectively. For groundwater quality data, three principal components explained the observed variations in water quality data, of which 51.39% is attributed to PC1, 26.29% to PC2, and 16.58% to PC3.

Treatment of textile dye wastewater by peroxymonosulfate activation using facilely prepared Fe3O4@TiO2 heterogeneous photocatalyst

AbstractIn this study, Fe3O4@TiO2 was synthesized by a facile precipitation–impregnation method and applied as a magnetic photocatalyst for degrading synthetic and actual textile dyeing wastewater in the presence of peroxymonosulfate (PMS). In Rhodamine B (RhB) degradation, the removal efficiency reached 99.86% (for RhB) and 93.67% (for color) under optimal operating conditions of 80 mg L–1 RhB, 0.5 g L–1 PMS, 0.5 g L–1 Fe3O4@TiO2, at pH 6, and after 30 min of UVA irradiation. The influence levels of anions on the RhB removal and decolorization were in the order of Cl− &lt; SO42− &lt; CO32− &lt; PO43−. In addition, the Fe3O4@TiO2 composite exhibited good applicability for treating other dyes (e.g., 99.6% of tartrazine and 60.3% of methylene blue after 30 min) in water and actual textile dyeing wastewater with high color (70.3% after 5 min) and COD removal (71.4% after 120 min). The radical scavenging tests indicated the role of reactive oxygen species in the order of O2•− ∼ 1O2 &gt; h+ &gt; SO4•− &gt; HO• for RhB degradation but O2•− &gt; h+ &gt; 1O2 &gt; SO4•− &gt; HO• for decolorization. These results suggest the potential application of PMS activation using Fe3O4@TiO2 in the photocatalytic treatment of textile and dyeing wastewater with the dominant role of O2•−.

Systematic separation of carboxylic acids from H8[PMo7V5O40]-catalyzed lignite oxidation products via deep eutectic solvent

To separate the valuable carboxylic acids (CAs) from the complicated oxidized products (OPs) of H8[PMo7V5O40]-catalyzed lignite, systematic processes including distillation, ether extraction, acetone dissolution and separation by deep eutectic solvent (DES) were first constructed and sequentially performed. First, formic acid and acetic acid are separated in vacuum at 56 °C with the separation efficiency of 95% and 82%, respectively. Subsequently, sequential treatments of OPs by ether extraction and acetone/water dissolution are implemented to reduce the low-polarity compounds contents and fully dissolve CAs from concentrated residue. Separation results indicate that choline chloride (ChCl) shows a better separation performance compared to acetylcholine chloride and gives optimal separation efficiencies of 78.19% and 94.45% for benzenepentacarboxylic acid (BPA) and mellitic acid (MLA) within 2 h at ambient temperature, respectively. The hydrogen-bonded binding energies (BEs) formed in DES are calculated based on density functional theory, and results show that total BEs of MLA and ChCl is as high as −31.09 kcal/mol, and the next is −26.79 kcal/mol for BPA, leading to their quick and high separation efficiencies within 2 h. As a result, only MLA and BPA show the high correlation with pseudo-second-order kinetic model, and the rate constant of MLA is as high as 0.3367 g/(mg·h), which is far more than that of BPA. Additionally, the effect of hydrogen bonds on the separation of CAs follows the order of Cl∙∙∙H-O > O-H∙∙∙O-C > O-H∙∙∙O = C. Overall, this attractive strategy provides ideas for efficient separation of CAs, which will pave the way for utilization of lignite.

A comparative study of structural and spectroscopic properties of three structurally similar mechanically bending organic single crystals – 2-Amino-3-nitro-5-halo (halo = Cl, Br, or I) pyridine

In recent years, scientists have been very interested in single crystals of monoaromatic compounds with mechanical softness, but they are hard to find. The present work reports a comparative study of structural, spectroscopic, and quantum chemical investigations of three structurally similar mechanically bending monoaromatic compounds, namely, 2-amino-3-nitro-5-chloro pyridine (I), 2-amino-3-nitro-5-bromo pyridine (II), and 2-amino-3-nitro-5-iodo pyridine (III). The mechanical responses of the three organic crystals studied here are very intriguing due to the similarity of their chemical structures, which only differ in the presence of halogen atoms (Cl, Br, and I) at the fifth position of the pyridine ring and are explained through examining intermolecular interaction energies from energy frameworks analysis, slip layer topology, and Hirshfeld surface analysis. The crystals of all the three feature one dimensional ribbons comprising alternating NaminoH⋯Onitro and NaminoH⋯Npyridine hydrogen bonds that form R22(12) and R22(8) dimeric rings, respectively. In (III), weak I⋯I interactions link the adjacent ribbons forming a two dimensional sheet. Layer-like structures are observed in all three crystals, with no significant interactions between the adjacent architectures (ribbons or sheets). Energy framework calculations are used for estimating the bending ability of the three compounds, with the three following the order Cl ≪ Br < I. The iterative electrostatic scheme coupled with the supermolecule approach (SM) at the DFT/CAM-B3LYP/aug-cc-pVTZ level is used to calculate the third-order nonlinear susceptibility (χ3) values in a simulated crystalline environment for the static case as well as two typical electric field frequency values, (λ = 1064 nm) and (λ = 532 nm). In addition, estimates of the topological studies (localized orbital locator and electron localization function) and reactivity characteristics (global reactivity parameters, molecular electrostatic potential, and Fukui function) are made for the compounds under investigation. Docking studies done using AutoDock software with a protein target (PDB ID: 6CM4) revealed that three compounds could be used to treat Alzheimer's disease.

Contamination and health risk assessment of groundwater along the Red Sea coast, Northwest Saudi Arabia

Coastal groundwater is the major source of freshwater in coastal areas, due to shortage of the water resource in coastal zones. Groundwater samples were collected from 48 sites along the Saudi Red Sea coast between Rabigh and Yanbu to document the hydrogeochemical characteristics, water quality, and the health risks of nitrate, fluoride, nickel, copper, and zinc on adults and children. Groundwater chemistry indicated neutral to slightly alkaline nature, and the total dissolved salts (TDS) concentrations mainly increase towards the coastal plain. Major cations, major anions, and heavy metals (HMs) were in the order of Cl− > Na+ > SO42− > Ca2+ > HCO3− > NO3− > Mg2+ > K+, F− > Zn > Cu > Ni. Na-Cl, mixed Ca-Mg-Cl and Na-K-HCO3, CaCl, and Mg-HCO3 were the principal hydrochemical water types. Results of heavy metal pollution index (HPI), and water quality index (WQI) showed moderate to heavy pollution and unsuitable groundwater for human consumption mostly in the western side along the coastal plain, which might be influenced by the groundwater salinization. Principal component analysis (PCA) generated four components, which indicated the various sources of contamination. Hazard index (HI) of nitrate and fluoride were above the safety limit of 1, suggesting increase non-cancer health risk issues in both children and adults.

Halogen Bond to Experimentally Significant N-Heterocyclic Carbenes (I, IMe2, IiPr2, ItBu2, IPh2, IMes2, IDipp2, IAd2; I = Imidazol-2-ylidene).

The subjects of the article are halogen bonds between either XCN or XCCH (X = Cl, Br, I) and the carbene carbon atom in imidazol-2-ylidene (I) or its derivatives (IR2) with experimentally significant and systematically increased R substituents at both nitrogen atoms: methyl = Me, iso-propyl = iPr, tert-butyl = tBu, phenyl = Ph, mesityl = Mes, 2,6-diisopropylphenyl = Dipp, 1-adamantyl = Ad. It is shown that the halogen bond strength increases in the order Cl < Br < I and the XCN molecule forms stronger complexes than XCCH. Of all the carbenes considered, IMes2 forms the strongest and also the shortest halogen bonds with an apogee for complex IMes2⋯ICN for which D0 = 18.71 kcal/mol and dC⋯I = 2.541 Å. In many cases, IDipp2 forms as strong halogen bonds as IMes2. Quite the opposite, although characterized by the greatest nucleophilicity, ItBu2 forms the weakest complexes (and the longest halogen bonds) if X ≠ Cl. While this finding can easily be attributed to the steric hindrance exerted by the highly branched tert-butyl groups, it appears that the presence of the four C-H⋯X hydrogen bonds may also be of importance here. Similar situation occurs in the case of complexes with IAd2.

The prospects of cation transfer to chalcogen nucleophiles

In this study, we used computational quantum chemistry to investigate the cation affinity for a range of nucleophiles to gauge the possibility of using organochalcogens as catalysts for cation transfer (reference data and geometries are provided in the repository https://github.com/armanderch/ca176 ). In general, the calculated gas-phase cation affinities decrease in the order Cl+&gt; Br+&gt; I+&gt; carbon-centered cation, the anionic nucleophiles have significantly larger cation affinities than the neutral ones, sulfides have larger cation affinities than selenides, and solvation lowers the cation affinities and especially for anionic nucleophiles. These observations are consistent with general chemical intuitions. The energies for the resulting condensed-phase cation transfer reactions show that transferring a carbon-centered cation from a neutral source (e.g., Me2CO3) to a chalcogen nucleophile (e.g., Me2S) is thermochemically viable. However, they are associated with large kinetic barriers. Overall, we find that SeMeC6H5may be a suitable catalyst for transferring a carbon-centered cation from an active source such as MeCO3R or MeSO4R. In this study, we also find that double-hybrid DFT methods, e.g., DSD-PBEP86 to be reasonable for the study of these cation transfer processes.

Interactions Evaluation between the Jouamaa Hakama Groundwater and Ouljat Echatt River in the North of Morocco, Using Hydrochemical Modeling, Multivariate Statistics and GIS

The processed discharges from Tangier Automotive City’s (TAC) Chrafate Wastewater Treatment Plant (WWTP) contaminate the Jouamaa Hakama groundwater and the Ouljat Echatt river. We aimed to study the unknown interactions between surface water (SW) and groundwater (GW). A total of nine Jouamaa Hakama GW samples and eleven Ouljat Echatt SW samples were taken and analyzed in 2021 and 2022 to determine 16 physical and chemical parameters (pH, temperature (T), electrical conductivity (EC), dissolved oxygen (DO), total hardness (TH), turbidity (TURB), and total dissolved solids (TDS), cations: Na+, K+, Mg2+ and Ca2+, anions: Cl−, CO32−, HCO3−, NO3−, and SO42−). For exploitation of the data, we used a methodology based on hydrochemical modeling (HM), principal component analysis (PCA), Water Quality Index (WQI), Irrigation Water Quality Index (IWQI), inverse distance weighted interpolation (IDW) using Geographic Information Systems (GIS), and regression analysis (RA). We studied the interaction of the surface water of the river (contaminated by discharges from the WWTP) with the shallow groundwater on a strip of 100 m on either side of the river to understand the transverse and longitudinal dispersion of this pollution The investigations indicated that the major ions found in GW and SW were characterized in a different order in the anion list order Cl− &gt; CO32− &gt; NO3− &gt; HCO3− &gt; SO42− and Cl− &gt; SO42− &gt; CO32− &gt; NO3− &gt; HCO3−, respectively, while the concentrations of cations showed the same order for both: Na+ &gt; Ca2+ &gt; Mg2+ &gt; K+. As a result, GW showed in the Piper diagram the type of sodium chloride to magnesium carbonate, while SW belongs to the sodium chloride to magnesium sulfate type. The WQI showed that the river waters are all unsuitable for use (WQI &gt; 100), while the GW is of poor quality (WQI &gt; 76). Moreover, the results of the GW–SW interaction along the river revealed a significant relationship (R2 = 0.85), which means that strong circulation and the infiltration of contaminated SW into shallow GW occur in this area. The approaches followed have been proven effective in evaluating water quality for human and animal uses. These results can help decision-makers in the region take suitable management measures to mitigate this environmental problem.

Ions Transport in Seasonal Frozen Farmland Soil and Its Effect on Soil Salinization Chemical Properties

The salinization of farmland soil is exacerbated during the freeze–thaw (FT) process, endangering agricultural production. The change of soil salt ions results in the formation and development of soil salinization. The objectives of this study were to investigate the migration characteristics of salt ions during the FT process, identify the effects of inconsistencies in ions transport on the development of soil salinization chemical properties. A six-month field observation was conducted from November 2020 to April 2021 in the Hetao Irrigation District, China, a typical seasonally frozen soil area affected by salinization. Soil salt ions, soil moisture content (SMC), soil temperature, and pH were measured. Soil salt content (SSC), sodium adsorption ratio (SAR) were calculated. The ions accumulated in the frozen soil layer during the freezing period in the order of Cl− &gt; Mg2+ &gt; Ca2+ &gt; Na+ &gt; SO42−, and accumulated in the topsoil during the thawing period in the order of Cl− &gt; Na+ &gt; Mg2+ &gt; Ca2+ &gt; SO42−, while the change in HCO3− was mostly the opposite. The FT process changed the main salt anions from sulfate to chloride. After the FT process, the topsoil was endangered by high salinization, excess Cl− toxicity, and a potential alkalization threat. This study has great guiding significance for the management and control of soil salinization before spring sowing in saline areas.

Visible light-driven photocatalytic degradation of Microcystin-LR by Bi2WO6/Reduced graphene oxide heterojunctions: Mechanistic insight, DFT calculation and degradation pathways

Developing heterostructure photocatalysts for removing Microcystin-LR (MC-LR) under visible light was of positive significance to control the risk of Microcystins and ensure the safety of water quality. Herein, the Bi2WO6/Reduced graphene oxide (RGO) nanocomposites were prepared via a simple one-spot hydrothermal method for the first time to degrade MC-LR. The optimized Bi2WO6/RGO (Bi2WO6/RGO3%) achieved a removal efficiency of 82.3% toward MC-LR, with 1.9-fold higher efficiencies than Bi2WO6, and it showed superior reusability and high stability after 5 cycles. The degradation efficiency of MC-LR demonstrated a negative trend with the initial concentration of MC-LR, fulvic acid, and initial algal density increased, while MC-LR removal rate for the presence of anions was in the order of Cl− > CO3−2 > NO3− > H2PO4−. The degradation efficiency of MC-LR could reach up to 82.3% within 180 min in the neutral condition. The active species detection experiments and EPR measurements demonstrated that the holes (h+), hydroxide radicals (∙OH), and superoxide radicals (∙O2−) participated in the degradation of MC-LR. The DFT calculations showed that 0.56 of electron transferred from Bi2WO6 to RGO, indicating RGO introduction could prevent the recombination of photoelectrons and holes and was beneficial for MC-LR degradation. Finally, the possible intermediate products and degradation pathways were also proposed by the LC-MS/MS analysis.

Water quality index and GIS-based technique for assessment of groundwater quality in Wanaparthy watershed, Telangana, India

A comprehensive study of 58 groundwater samples was collected in the Wanaparthy catchment area (1600 km2), Telangana, India to assess hydrochemistry, quality, water types, and potability using hydrogeochemical characterization, WQI, and GIS techniques. The main concentrations of Na+, K+, Ca2+, Mg2+, Cl−, F−, NO3 −, and SO4 2− ions in groundwater were analysed using ion chromatography (IC). Physicochemical values of potential hydrogen (pH), total dissolved solids (TDS), and electrical conductivity (EC) were determined using portable Hanna meters, while total hardness (TH), alkalinity, and bicarbonates were estimated by titrimetric methods. The obtained results clarify the main anions and cations, which are found in the order Cl− &gt; HCO3 − &gt; SO4 2− &gt; NO3 − &gt; F− and Na+ &gt; Ca+2 &gt; Mg+2 &gt; K+. Among the various ions measured were fluoride (18.97%), chloride (3.44%), nitrate (8.62%), Sulphate (5.17%), sodium (34.48%), and calcium (1.72 %) found above the acceptable limit values of the authority. Indian Standards (BIS) for drinking purposes. According to Piper's trilinear diagram, two dominant hydrochemical facies were identified, Na-Cl-SO4 and Ca-Na-HCO3 types. The Gibbs diagram conferred the dominance of samples in the area, namely the rock-water reaction and the dominance of evaporation. The WQI shows that 67.79% of the samples refer to excellent to good types of water that are suitable for drinking. The drainage diagram calculated that the concentration of the measured parameters exceeds the lower area, which may be caused by the chemical reaction of the rock-water interaction (infiltration and recharge). Since groundwater is the main source of drinking water in the study area, a proper management plan must be put in place before its quality deteriorates.

Electrolyte contribution to the multifunctional response of cellulose carbon nanotube fibers

Flexible wearable multifunctional devices such as cellulose loaded with electroactive components are in the focus of modern research for electrochemical energy storage, sensors and actuators. In this report, the multifunctional response of cellulose with 50 wt% MWCNT formed into Cell-CNT composite fibers is demonstrated. The effect of (aqueous) electrolyte choice on the electro-mechanical response of Cell-CNT was studied. Aqueous electrolytes such as tetramethylammonium chloride (TMACl), sodium perchlorate (NaClO4), and 1-ethyl-2,3-dimethylimidazolium trifluoromethanesulfonate (EDMITF) were considered, with the resulting stress and strain decreasing in the order Cl− > ClO4− > TF−, matching the order of the size of the ions. Upon negative charging, the cations of the electrolytes showed electromechanical response in the order: TMA+ > EDMI+ > Na+, where the solvation strength of the cations had stronger influence than their size without solvation shell. The highest specific capacitance was shown by TMACl in the range of 74 mF cm−2 upon positive charging, with also the best retention of capacitance of 86% in long-term measurements. Chronopotentiometric measurements of Cell-CNT fibers where conducted to evaluate if the composites can also act as sensors for different electrolytes. The Cell-CNT fibers were characterized with scanning electron microscopy, energy dispersive X-ray, FTIR and Raman spectroscopy.