Search

In this study, various solvents were evaluated for their efficacy in extracting biofuel components, such as acetone (ACT), n-butanol (nBuOH), ethanol (EtOH), and isobutanol (IBA) from aqueous solution at 37.5 °C and atmospheric pressure using liquid-liquid extraction (LLE). The extraction performance of solvents was evaluated by their solute distribution coefficients and selectivity. The experimental results are compared with theoretical prediction using ASPEN plus and the model shows an excellent fit. Among the solvents examined, 2,6-dimethyl-4-heptanol (DMHT) and 2-ethyl-1-hexanol (2E1H) are more effective solvents for the extraction of IBA and nBuOH from aqueous solution. [ABSTRACT FROM AUTHOR]

The Hg fractions in three sediment cores of the eutrophic estuary in northern Taiwan were determined by the Bloom sequential extraction method, which chemically divided the sedimentary Hg into five fractions: water-soluble (F1); human stomach acid (F2); organo-chelated (F3); elemental Hg (F4), and residual (F5). The pH, redox potential, and dissolved total Hg in sediment pore waters, grain size, and total organic carbon (TOC) in sediment cores were analyzed, and the results were interpreted. The three sediment cores were in an anoxic environment. The total Hg concentrations in the sediment cores ranged between 110 and 369 ng/g, and most values exceeded the guideline value (ERL, 150 ng/g) of the EPA, U.S.A. However, the total Hg concentrations were mainly dominated by the non-labile Hg fraction (the elemental and the residual fraction), accounting for an average of 60% of the total Hg pool. The organo-chelated fraction accounted for an average of 29% of the total Hg pool. The amounts of the labile fraction (F1 + F2) of Hg in sediment cores of the middle and lower estuary were generally <2% of the total Hg pool. However, the F2 fraction in the sediment core of the upper estuary exceeded 10% of the total Hg pool. This result implied that Hg still poses a potential risk to the benthic organisms in the DRE based on the risk assessment code method. The profile variations between the labile and non-labile Hg fractions exhibited a negatively well-linear correlation, suggesting the transformation of the labile and moderately labile Hg fraction into the non-labile Hg fraction in sediment cores during the sediment burial processes. In addition, the TOC content seemed to play an important role in controlling the sediment Hg fractions in sediment cores. [ABSTRACT FROM AUTHOR]

The heavy metals in the effluents of industries threatens the human health. In this research, aqueous two-phase systems based on two deep eutectic solvents, choline chloride/urea and betaine/urea, along with dipotassium hydrogen phosphate, were used as environmentally friendly systems to extract hexavalent chromium. Binodal curves and tie lines were obtained for two systems. The effect of temperature, pH, metal concentration and salt composition was investigated on the extraction efficiency of chromium. Increasing the temperature, the concentration of metal and the amount of salt increased the extraction efficiency. The system consisting of choline chloride/urea had better extraction than other and showed extraction efficiency of 86.82 ± 1.99 at pH = 10 and temperature of 25 ºC and metal concentration of 80 mg/l. the system based on betaine/urea showed extraction efficiency of 89.51 ± 1.69 at pH = 8.9 and temperature of 25 °C and metal concentration of 80 mg/l. Considering the same cost of two systems, the system including betaine/urea was evaluated as a better system for the separation of chromium. These systems were also used to separate lead, cobalt, nickel and cadmium that showed their high tendency to the low phase. [ABSTRACT FROM AUTHOR]

Direct lithium extraction from unconventional resources requires the development of effective adsorbents. Crown ether-containing materials have been reported as promising structures in terms of lithium selectivity, but data on adsorption in real, highly saline brines are scarce. Crown ether-grafted graphene oxides were synthesized using 2-hydroxymethyl-12-crown-4, hydroxy-dibenzo-14-crown-4 and epichlorohydrin as a source of anchoring groups. The obtained carbonaceous materials were used to prepare chitosan–polyvinyl alcohol composites. The prepared materials (and intermediate products) were characterized using FTIR, XRD, Raman spectroscopy and SEM-EDS methods. Adsorption tests were performed in a pure diluted LiCl solution ([Li] = 200 mg/kg) as well as in a real, highly saline oilfield brine ([Li] ≈ 220 mg/kg), and the distribution coefficients (Kd) were determined. The obtained results show that Kd in pure LiCl solution was in the range of 0.9–75.6, while in brine it was in the range of 0.2–2.3. The study indicates that the high affinity for lithium in pure LiCl solution is mostly associated with the non-selective interaction of lithium ions with the graphene oxide matrix (COOH groups). It was also shown that the application of dibenzo-14-crown-4 moiety to graphene oxide modification groups increases the affinity of the composite material for lithium ions compared to an analogous material containing 12-crown-4-ether groups. [ABSTRACT FROM AUTHOR]

The possibility of using new anion-exchange resins AM-4VP, AM_pu, AMP-p, AM-p, and AM-2B produced by Smoly Group of Enterprises for plutonium recovery from nitric acid process solutions was examined. The physicochemical characteristics of the resins, the thorium distribution coefficients as functions of the nitric acid concentration, and the static exchange capacities of the resins were determined. The plutonium recovery from process solutions was studied in column experiments. The physicochemical properties and sorption ability of the anion-exchange resins were compared to those of the previously used VP-1Ap resin. AM-4VP resin shows promise for plutonium recovery from nitric acid process solutions. [ABSTRACT FROM AUTHOR]

The study aims to assess the marine environmental hazards resulting from some industrial activities areas being found at the Suez Bay. The survey was done to select five industrial locations along the studied areas where different water and sediment samples were collected during September 2020. The study methods showed that different concentrations were measured in the collected water and sediment samples, such as; Al, Fe, Mn, Hg, Cd, Cr, Co, Mo, V, Pb, Ni, Cu, Zn, where the digested samples were measured by using Inductively Coupled Argon Plasma spectroscopy (ICAP 6500 Duo), while the natural radioactivity concentrations of the selected radio-nuclides such as 238U, 226Ra, 232Th, 40K, were measured in both water and sediments samples by using Hyper germanium detector, as the radiological risk assessment of different samples was detected by using ERICA modeling software. The study results showed that the concentrations of the measured trace elements in the selected five industrial sites were slightly higher than the standard limits, while the measured radioactivity concentrations of the selected radio-nuclides in both water and sediment samples were below the standard limits. The results showed that the calculated distribution coefficient of the selected trace elements was (Kd Metal Pollution Index < 3), which indicated that the measured trace elements were more dissolved in the aqueous than the sediment medium. The study used the mean probable effect Level (m-PEL-Q) for estimating the metal concentration hazards in the sediment samples at the selected sites, where these values were ranged from 0.04 to 0.1, indicating that the combined concentration effects for these metals were caused 9% toxic probability. The study showed that both the calculated quotient risk (QR) and dose rate values of the marine organisms which were being calculated by the ERICA model were below the recommended limits. [ABSTRACT FROM AUTHOR]

The selection of appropriate transport parameters of radionuclides is of utmost importance in the safety assessment of radioactive waste disposal sites. Both batch and column methods are widely performed to determine the transport parameters of radionuclides through soil layers. In this paper, the distribution coefficients Kd of Co ions in sandy mixtures containing soil samples taken from Anarak near-surface repository (Iran) were determined by batch and 3 different column methods namely, breakthrough curve, thin-section, and gamma spectroscopy methods. The distribution coefficients Kd of the mixture was obtained as 160 L kg−1 for the batch method, 23 L kg−1, 19 L kg−1, and 18 L kg−1 for the breakthrough curve, the thin-section, and the gamma spectroscopy methods, respectively. These results emphasize proper selection of transport data for using in the safety assessment programs.

Human activities, such as plant cultivation, enhance the activity concentrations (ACs) of radionuclides in the topsoil and have the potential to affect humans and the environment. The soil with a high radiation background not only acts as a source of continuous radiation exposure to humans but also as a medium of migration for the transfer of radionuclides to food crops. Some spectrometers can measure the AC of radionuclides in the soil, but long‐term variation of AC is difficult to investigate. Therefore, developing methods for predicting the AC of radionuclides in agricultural soil is an interesting topic that many studies have focused on. In this work, a simple method was introduced to estimate long‐term changes of some radioisotopes in the top layer of soil (0–20 cm). The estimation considered four major processes: fertilization, irrigation, vertical leaching, and plant uptake. The leaching rates (Rl) of radionuclides were predicted by their ACs in the soil water and the infiltration rate of water in the soil. The method was applied to the soils of five study fields in southern Vietnam, and the Rl values of 226Ra were between 7.4 Bq·m−2·y−1 and 60 Bq·m−2·y−1, while the rates of 210Po were between 22.1 and 111 Bq·m−2·y−1. For long‐term assessment, it was found that 226Ra increases in sweat potato soil and tomato soil with annual rates (ΔC) of 0.99 Bq·kg−1·y−1 and 0.69 Bq·kg−1·y−1, respectively. The AC of 210Po was predicted to increase in some soils. The corresponding ΔC values for 210Po were 0.028 Bq·kg−1·y−1 in rice, 0.617 Bq·kg−1·y−1 sweet potato, and 0.099 Bq·kg−1·y−1 in tomato soils. The results imply that interventions are necessary to reduce the radioactivity accumulation in fields with high ΔC values. The effective methods can be changing the fertilizer types and the irrigation systems. [ABSTRACT FROM AUTHOR]

Sorption of Sr(II) and/or Rb(I) onto synthesised silico antimonate (SiSb) nanocomposite was investigated in this work, using batch equilibrium and column techniques. SiSb was fabricated by precipitation technique and characterised by various analytical tools. The adsorption of Sr(II) and/or Rb(I) includes the influence of shaking time, distribution coefficient, kinetics, capacity, and column separation. The data prove that SiSb has a quick equilibrium time (40 min), the distribution coefficients (Kd) as a function of pH have maximum separation factors $$(\alpha _{Rb}^{Sr})$$ (α R b S r) equal to 162.1 at pH 6, reaction kinetics follow a pseudo-second-order model, sorption capacity for Sr(II) and Rb(I) is 48.5 and 13.8 mg/g, respectively. Column data reveal that Sr(II) can be loaded and separated from Sr(II)-Rb(I) as a simulation model for Sr(II) recovery from its Sr(II)-Rb(I) system using different concentrations of HNO3 as eluent. [ABSTRACT FROM AUTHOR]

A granular manganese oxide-based sorbent was synthesized. One volume of the sorbent decontaminates 125–145 volumes of hardness water from strontium radionuclides to background values of radioactivity. The synthesis includes interaction of MnSO4 with KMnO4 in aqueous medium at [Mn2+]/[MnO4−] = 1.8, followed by the precipitation, aging the precipitate at pH = 11, and calcining it at 160 °C. Characteristics of the sorbent obtained were as follows: the distribution coefficient of the tracer 85Sr radionuclide in 0.01 mol dm−3 CaCl2 solution of 1.6 × 104 cm3 g−1, the batch capacity by Ca2+ of 1.10 mol g−1, and the Sr/Ca pair separation coefficient of 65. [ABSTRACT FROM AUTHOR]

Environmental pollution by toxic heavy metals is increasing at an alarming rate which demands the development of an appropriate analytical method to investigate and quantify the target analytes. In response to this call, polyaniline Titanium (IV) tungstomolybdate (PANI/TWM) nanocomposite was synthesized by incorporating polyaniline into Titanium (IV) tungstomolybdate using sol–gel method. The material was then characterized using X-ray diffraction (XRD), UV-Vis, Fourier transform infrared (FTIR), Thermogravimetric analysis (TGA-DTA), and Scanning electron microscope (SEM-EDX). It was amorphous with appreciable thermal stability as it retained 65.2% of its ion exchange capacity (IEC) up to 600 OC. It acts as a bifunctional strong acid cation exchanger with an IEC of 1.58 meq/g for Na+ ions. Moreover, the high distribution coefficients (Kd) of 1572 and 928 mL/g for Pb(II) and Co(II), respectively, indicate its potential to treat these ions in an aqueous matrix selectively. Real sample treatment with the prepared material was undertaken for binary separation of selected metal ions in column mode and practically appreciable efficiency (90.3 to 96.8%) was achieved. Therefore, the synthesized material can be considered as a promising cation exchanger to treat an environmental matrix containing toxic heavy metals. [ABSTRACT FROM AUTHOR]

The demand of 4-hydroxybenzoic acid (4-HBA) has increased due to their promising properties in the various industries such as pharmaceutical, cosmetic, and plastic sectors. Mostly 0.005 to 0.035 mol/liter of 4-HBA was observed in the waste stream or fermentation broth. Hence, this work presents a schematic study of 4-HBA separation from the aqueous phase by physical extraction method using conventional and natural solvents (CANS). The harmless and eco-friendly green solvents such as alsi (flaxseed) oil, castor oil, and conventional solvents such as diethyl carbonate, diethyl succinate, and xylene are employed in the extraction experiments. Several parameters, such as the KDHBA, %EHBA, PHBA, and the DHBA, were examined. The parameters were examined to evaluate the equilibrium for this physical extraction experiment. The obtained results showed the following trend of KDHBA and %EHBA, respectively, diethyl carbonate (0.951, 48.75%) > alsi oil (0.565, 36.12%) > diethyl succinate (0.504, 33.51%) > castor oil (0.457, 31.35%). > xylene (0.283, 22.06%). [ABSTRACT FROM AUTHOR]

Introduction Soil contamination due to heavy metals is a global environmental issue. One vital aspect for understanding the impact of a contaminant in porous media is to describe their transport behavior using appropriate models. The governing equations for solute transport in soil consist of the convection–dispersion equation (CDE) and the mobile–immobile model (MIM). Mathematical models are usually used to evaluate solute transport in porous media. The first model used to express the transport of solutes and pollutants in porous media is CDE it provides acceptable and satisfactory results in homogeneous soils in laboratory tests. Hydrus-1D is a modeling environment for simulating water, heat, and solute movement in one-dimensional variably saturated media. Sensitivity analyses and model identification are standard approaches in modeling applications to investigate the relative importance of model components that control the system’s behavior. The sensitivity analysis is applied to identify the parameters that influence the model performance most. The sensitivity analysis is defined as the rate of variation in the model outputs due to changes in the input parameters. This study is a fundamental practice for analyzing the behavior of a model under different conditions of an application. The sensitivity analysis could be a practical and powerful tool for investigating the role and importance of model components, such as parameters and forcing data on the model responses. Materials and Methods The loamy soil samples were collected in both disturbed and undisturbed forms from a farm in the Qaramalek area with appropriate humidity located in western Tabriz, Iran, at 38º 5' 59.89' north and 45º 12' 38.57' east. To determine and present breakthrough curves, concentration values are required throughout the laboratory columns at different times. To simulate the CDE model, Hydrus software was used. Solute transport parameters such as diffusion coefficient (D), distribution coefficient (Kd), and dispersion coefficient (β) were estimated using soil hydraulic parameters and data related to the metal concentration of cadmium, nickel, and zinc by an inverse modeling method. A sensitivity analysis was carried out for the identification of the most influential factors on the model output. This method examines the impact of input data on a given model and its actual conditions. In line with this purpose, in each run, one input data was changed to a value equal to Positive and negative five to 15%, and the other input data was kept constant. To identify the effect of the input parameters of a given model on its output, the sensitivity analysis for the Hydrus model was utilized. The parameters of hydrodynamic dispersion coefficient (D), distribution coefficient (Kd), and spreading parameter (β) were changed between five to 15 %. Sensitivity analysis was carried out on cadmium, nickel, and zinc metals with densities equal to 50, 100, and 150 mg l-1 in two disturbed and undisturbed soils. Results and Discussion Examining the breakthrough curves of cadmium in disturbed and undisturbed soils shows that the fitted curves using the Hydrus model and the measured curve almost coincide with each other, which is more obvious in disturbed soils. It should be noted that the model fits better in the disturbed soil than in the undisturbed soil. This may be due to the disruption of the structure the increase in the contact surface of the particles in the disturbed soil and the presence of heterogeneity in the undisturbed soil column. The simulation results show the transport of heavy metals (Zn, Ni, Cd) and Hydrus output have the highest and the lowest sensitivity to dispersion coefficient β and diffusion coefficient (D), respectively. In general, the impact of input parameters can be reported as follows: spreading parameter (β) > distribution coefficient (Kd) > dispersion coefficient (D). Therefore, it can be observed that D has a negligible effect on the model results; and consequently, measurement errors can be ignored. Conclusion Sensitivity analysis is used to analyze model behavior under different conditions. This analysis is used to investigate the relative importance of model components that control the system’s behavior. In this research, the transfer of hydraulic parameters of heavy metals Cd, Ni, and Zn in disturbed and undisturbed loam soil columns with initial concentrations of 50, 100, and 150 mg l-1 was performed under the simulation of the Hydrus-1D model. The comparison of the simulated BTCs of the Hydrus-1D model and the measured data indicates a high agreement between the simulation curves and the measured data. Solute transport parameters such as hydrodynamic dispersion coefficient (D), distribution coefficient (Kd), and spreading parameter (β) were estimated using soil hydraulic parameters and data related to Cd, Ni, and Zn metal concentration by inverse modeling method. Based on the results of sensitivity analysis, the spreading parameter (β) and hydrodynamic dispersion coefficient (D) had the highest and lowest sensitivity, respectively. In other words, due to the significant effect of β changes on the output values of the model, this parameter should be measured more accurately and on the other hand, the measurement errors of parameter D can be ignored. The degree of sensitivity of the parameters was independent of the initial concentration of the elements. [ABSTRACT FROM AUTHOR]

In this study, the chemical distribution of triclocarban (TCC), in natural aqueous systems, between water and sediment, with different chemical compositions of the aqueous phase and different percentages of organic carbon (OC%) in the sediments is presented. The influences of the temperature, of the composition of the aqueous matrices of natural waters and (OC%) in the sediment over the solubility of triclocarban, and its distribution coefficient Kd values were studied. log KD at 25 °C varied between 1.94 and 3.27 for a sediment with 5.50% OC and between 3.95 and 5.93% for a sediment with 6.75% OC, in the studied aqueous systems, with different concentrations of OC in the sediment. [ABSTRACT FROM AUTHOR]

Long-term application of organic and inorganic fertilizers increases the possibility of contamination of greenhouse soils with heavy metals. This study investigated heavy metals (Cd, Co, Cu, and Zn) adsorption-desorption under mono and competitive systems in 10 soils from agricultural and greenhouse soils in western Iran. In most of the studied soils, the values of the Freundlich distribution coefficient (Kf) of Cu were higher than other heavy metals, indicating that Cu is maintained by the soils stronger than Cd, Co, and Zn. Based on the average Kf, the selectivity sequence of heavy metals in agricultural and greenhouse soils was ordered as Cu > Zn > Cd > Co in both mono and competitive systems. In general, greenhouse soils had lower Kf for heavy metals compared with agricultural soils, indicating the vulnerability of greenhouse soils to heavy metals leaching. In desorption experiments, the percentage of heavy metal desorption increased as the concentration of added heavy metals increased in both systems (except Cu in the mono-heavy metal system). The findings revealed that continuous vegetable production and the application of organic and inorganic fertilizers in these greenhouse soils may cause changes in soil properties and heavy metal mobility, posing hazards to human health and groundwater quality. [ABSTRACT FROM AUTHOR]

This study focuses on numerically optimizing key process parameters related to the liquid–liquid extraction batch process (LLEBP) technique for carrying out batch runs to remove methyl red effectively (MR) from dye effluent. LLEBP, a suitable industrial process for treating dye effluents, depends on the number of reaction parameters such as feed concentration, extraction time, and dye ratio (solution/solvent). The current research utilized a central composite design (CCD) of experiments along with numerical optimization techniques to optimize process parameters over a range of dye concentrations: (20–100) ppm, extraction time range 10–30 min, and dye ratio 1–3 mL/mL (solution/solvent). The batch runs performed at room temperature and a constant pH of 3, according to the experimental design criteria, suggest that maximum dye removal efficiency and distribution coefficient value could be achieved within the feed concentration range of (20–30) ppm, 20–30 min of extraction time, and 1–3 mL/mL of dye ratio (solution/solvent). Solvent capacity increases significantly within the (60–100) ppm feed concentration range. Numerical optimization with desirability function criteria identified optimal conditions: 20 ppm dye concentration, 30 min extraction time, and 3 mL/mL dye ratio ensuring maximum LLEBP yield. The current investigation achieved a 4% higher dye removal (%) of 85.682 compared to the previous study. The distribution coefficient and solvent capacity attained were 5.287 and 4.504 mg/L, respectively. The research enhances understanding of the optimization process for LLEBP in MR dye removal from textile effluent, surpassing previous findings within the same input range. The manuscript aims to maximize process optimization using CCD, promoting sustainable industry progress in line with UN sustainable development goals. [ABSTRACT FROM AUTHOR]

To obtain site-specific values of the Derived Concentration Guideline Levels (DCGLs) for decommissioning of KRR-1&2, the soil density and distribution coefficient values for Cs-137, a major contaminant radionuclide, were determined. The soil density was evaluated according to the test method established by the Korean Agency for Technology and Standards of the Ministry of Trade, Industry, and Energy (KATS). The distribution coefficient was evaluated using a batch test. The validity of using the evaluated soil density and distribution coefficient as site-specific values was assessed through radiation dose assessment reflecting these values. Average soil density value obtained was 1.738 g/cm3, which was within the typical range of normal soil density, 1.0–1.8 g/cm3. The average distribution coefficient value was 7,754 mL/g. Applying the maximum, average, and minimum values of the evaluated soil density and distribution coefficient showed similar radiation dose results, thus suggesting that it is reasonable to use the average values of each parameter as site-specific values. Findings of this study can help determine DCGLs that reflect the characteristics of the research reactor site.

This study is interested in the sorption of Fe(III) and/or La(III) from liquid solutions by modified Melia Azedarach zinc oxide (MAZO) sorbent. MAZO was fabricated by impregnation of ZnO on the external surface of thermally treated Melia Azedarach fruits. The prepared sorbent was characterised by different analytical tools; FT-IR, XRD, TGA&DTA, EDX, SEM, and TEM. Sorption data showed equilibrium time (60 min). The distribution coefficients as a function of pH have a separation factor $${\alpha ^{La}}_{Fe}$$ α La Fe (77) at pH 2.4. Capacity has the values 66.8 & 37.42 mgg−1 for Fe(III) & La(III) respectively. Finally, column data reveal that Fe(III) and/or La(III) can be loaded and separated from the crude phosphoric acid and synthetic waste using different concentrations of HNO3 as eluent. The investigation evidenced that MAZO is suitable for the recovery of Fe(III) and/or La(III) from liquid waste. [ABSTRACT FROM AUTHOR]

The distribution coefficient (Kd) of radionuclides is a crucial parameter in assessing the safety of high-level radioactive waste (HLW) geological repository. It is determined in the laboratory through batch and column experiments. However, differences in obtained Kd values from distinct experiments have not been thoroughly assessed and compared. This study evaluated strontium (Sr) sorption on different granite materials using static batch and dynamic experiments (column and core-flooding experiments). The results from batch sorption experiments showed higher Sr sorption on granite under acidic and strongly alkaline conditions, low solid–liquid ratios, and low ionic strength. In column experiments, a two-site sorption model was used to simulate Sr transport in crushed granite and mixed pure minerals. The sorption of Sr on crushed granite exhibited a higher affinity than that of mixed pure minerals. The dual-porosity transport model was employed to investigate Sr transport behavior in fractured granite in the core-flooding experiment. Kd obtained from batch sorption experiments are four to twenty times higher than those from column experiments, and two to three orders of magnitude higher than that from a core-flooding experiment. The results of this study provide valuable insights into safety assessment for the HLW geological repository. [ABSTRACT FROM AUTHOR]

The physicochemical characteristics, optical uniformity and photorefractive properties of a series of four LiNbO3:Er:Zn single crystals have been studied. Single crystals have been obtained by the Czochralski method. The erbium content in the crystals was ~0.5 mol % and the zinc content in the crystals was ~4.02, 4.41, 4.65, 4.66 mol %. The dopant distribution in the LiNbO3:Er:Zn melt—crystal system has been studied, and the optimal concentration ranges of erbium and zinc in the initial melt have been determined. The ranges provide crystals with high chemical, optical uniformity and resistance to optical damage for applications in optoelectronics and laser technology. [ABSTRACT FROM AUTHOR]

In this work the distribution coefficients (D) of polonium between 0.1 mol dm−3 TOPO/toluene; TOPO/cyclohexane; TBP/toluene and TBP/cyclohexane and aqueous solutions of inorganic acids (HCl, HNO3, H2SO4 and H3PO4) were determinated. The molarities of inorganic acids were between 0.5 and 12.0 mol dm−3. The activity of extracted Po-209 was measured by means of liquid scintillation counting. The best result was obtained for TOPO/toluene and 2 mol dm−3 H2SO4 system (D = 62 ± 9). The most stable conditions of extraction were found for TOPO/toluene-HCl system. [ABSTRACT FROM AUTHOR]

BACKGROUND: Vanillic acid, an aromatic carboxylic acid and a derivative of vanillin, is used as an additive in consumer goods for its aroma. Previously, most vanillic acid was produced through a petrochemical route, but as a consequence of stringent environmental policies, it is now produced by the biotransformation of ferulic acid. Vanillic acid is also found in the wastewater streams of paper‐pulp industries and olive‐oil mills. So, recovering vanillic acid from fermentation broth, either during bioproduction or from a wastewater stream, while minimizing toxicity, is a difficult task. In order to reduce the toxicity substantially, bio‐based solvents such as sunflower, mustard and rice bran oils were employed as diluents along with tri‐n‐butyl phosphate (TBP) as extractant in order to recover vanillic acid by reactive extraction. RESULTS: The extraction performance was elucidated using terms such as distribution ratio, extraction efficiency, loading ratio and equilibrium complexation constant for different extractant–diluent combinations. The highest extraction efficiency and distribution ratio for the different solvents were in the following order: TBP + sunflower‐oil (72.02%–92.47%; 2.57–12.29) > TBP + rice bran‐oil (65.56%–90.55%; 1.90–9.58) > TBP + mustard‐oil(64.03%–89.87%; 1.78–8.87). The theoretical number of stages was determined as 4 to achieve a targeted extraction efficiency of 90%; these predictions were borne out experimentally. CONCLUSION: In this study, vanillic acid was recovered from the aqueous phase using tri‐n‐butyl phosphate in sustainable, environmentally friendly, bio‐based solvents such as rice bran oil, sunflower oil and mustard oil. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Effective remediation of radioactive IO3− is highly desirable for fuel reprocessing, medical waste disposal, and nuclear accidents. However, the nature of high solubility, strong mobility, and extremely hard to bind with minerals for IO3− makes this task an enormous challenge. Herein, a metal-organic framework material [Ce(IV)-MOF-808] with available Ce(IV) sites was used to efficiently remove IO3−. Ce(IV)-MOF-808 exhibits superior selectivity and one of the highest adsorption capacities (623 mg·g−1) for IO3− removal. Moreover, Ce(IV)-MOF-808 shows great adsorption performance for IO3− at low concentrations, and the distribution coefficient (Kd) value was calculated to be 2.60 × 106 mL·g−1. The exceptional IO3− uptake performance is attributed to the high affinity between Ce(IV) cluster and the oxyanion based on the comprehensive analysis of zeta potential and X-ray photoelectron spectroscopy (XPS) results, in which IO3− can easily replace the weakly coordinated ligand and form a strong coordination structure of Ce-O-I-O2. More importantly, Ce(IV)-MOF-808 exhibits excellent uptake performance for IO3− from both the simulated Beishan groundwater system and Hanford groundwater system in the dynamic column separation test, indicating the highly promising practical application of Ce(IV)-MOF-808 in IO3− remediation from actual radioactive wastes.

The valuable chemical 4-hydroxybenzoic acid (4-HBA), the phenolic compound of carboxylic acid possesses promise as an antioxidant, antifungal, anticancer, antidiabetic, and cardioprotective properties. 4-HBA has promising uses in the pharmaceutical, cosmetic, and plastic sectors, making it worthwhile to recover. Using renewable solvent like Karanja oil and traditional solvents like n-Butanol, and Di-chlorobenzene, the experimental tests were carried out to separate 4-hydroxybenzoic acid from solute mixed aqueous solution. Parameters including the distribution coefficient KD, the percentage extraction efficiency %E, the partition coefficient P, and the dimerization constant D were discovered and associated with several solvent physicochemical features while evaluating the equilibrium for this physical extraction experiment. The following parametric values were obtained for KD and %E: n-Butanol (1.704, 63.02%)> Karanja oil (0.810, 44.75%) > Di-chlorobenzene (0.555, 35.69%).

The aim of this study was to extract vanillic acid from an aqueous solution through reactive extraction. Vanillic acid is utilized in the food and beverage industry as a flavoring agent. Tri-n-butyl phosphate (TBP) served as the reactive extractant, while natural oils like sesame oil and groundnut oil acted as diluents. The recovery of vanillic acid from fermentation broth or wastewater poses challenges due to toxicity concerns. However, employing natural solvents in the extraction process can significantly reduce toxicity. Various parameters, such as extraction efficiency, loading ratio, distribution coefficient, and equilibrium complexation constant, were determined to evaluate the extent of extraction achieved. Groundnut oil emerged as more effective than sesame oil as a diluent, exhibiting a maximum distribution coefficient of 13.31 and an extraction efficiency of 93.01 % at 5.27 mmol L–1 of acid concentration and 40 % v/v of TBP. Additionally, the number of theoretical stages required for the reactive extraction system was calculated, resulting in five stages for groundnut oil and four stages for sesame oil.

Abstract The microalgae Haematococcus pluvialis are the main source of the natural antioxidant astaxanthin. However, the effective extraction of astaxanthin from these microalgae remains a significant challenge due to the rigid, non-hydrolyzable cell walls. Energy savings and high-efficiency cell disruption are essential steps in the recovery of the antioxidant astaxanthin from the cysts of H. pluvialis. In the present study, H. pluvialis microalgae were first cultured in Bold's Basal medium under certain conditions to reach the maximum biomass concentration, and then light shock was applied for astaxanthin accumulation. The cells were initially green and oval, with two flagella. As the induction time increases, the motile cells lose their flagellum and become red cysts with thick cell walls. Pre-treatment of aqueous two-phase systems based on deep eutectic solvents was used to decompose the cell wall. These systems included dipotassium hydrogen phosphate salt, water, and two types of deep eutectic solvents (choline chloride–urea and choline chloride–glucose). The results of pre-treatment of Haematococcus cells by the studied systems showed that intact, healthy cysts were significantly ruptured, disrupted, and facilitated the release of cytoplasmic components, thus facilitating the subsequent separation of astaxanthin by liquid–liquid extraction. The system containing the deep eutectic solvent of choline chloride–urea was the most effective system for cell wall degradation, which resulted in the highest ability to extract astaxanthin. More than 99% of astaxanthin was extracted from Haematococcus under mild conditions (35% deep eutectic solvent, 30% dipotassium hydrogen phosphate at 50 °C, pH = 7.5, followed by liquid–liquid extraction at 25 °C). The present study shows that the pre-treatment of two-phase systems based on deep eutectic solvent and, thus, liquid–liquid extraction is an efficient and environmentally friendly process to improve astaxanthin from the microalgae H. pluvialis.

Water shortages and population surges pose notable challenges to food security. North China is an important grain base of the country, with limited available water resources. Therefore, it is necessary to research the patterns of photosynthate accumulation, distribution, and transfer in summer maize under water stress. On the basis of existing methods, in this study, we considered the impact of water stress with two methods, namely the distribution coefficient method and the distribution index method. The results showed that the water correction coefficient indices of the stem–leaf ratio spike–stem ratio, and root–shoot ratio were 0.2705, 0.3530, and −0.2097, respectively, which revealed that water stress caused a decrease in the stem–leaf ratio and spike–stem ratio and an increase in the root–shoot ratio. Water stress caused a reduction in the stem distribution index and leaf distribution index and a slight increase in the spike distribution index. The filling stage was the critical period for water stress to affect the distribution coefficient of each organ, while the jointing stage was the critical period for water stress to affect the leaf distribution index. During the middle growth period, water stress exerted the greatest impact on the distribution parameters. Water stress imposed a greater influence on the distribution coefficient than on the distribution index. The two methods effectively simulated the accumulation and distribution process of photosynthates under water stress conditions, and the R2, average absolute percentage and root mean square error values were 0.9358–0.9997, 4.15–22.71%, and 2.6–24.37%, respectively. The change trend of the photosynthate transfer rate calculated by the distribution coefficient method under water stress conditions was more consistent with that of the actual values. The distribution coefficient method generally performed better than the distribution index method. This study avoids the problem of solely relying on experimental data to determine crop growth dynamics and provides a way to describe crop photosynthate accumulation continuously and quantitatively. [ABSTRACT FROM AUTHOR]

A study was made of the ability of crown ethers in heavy polar organic diluents (chloroform; 1,2‑dichloroethane; bis(2-chloroethyl) ether; 1,1,7-trihydrododecafluoroheptyl alcohol) to extract cesium and strontium from nitrate solutions. It was shown that the use of bis(2-chloroethyl) ether as a polar diluent in the extraction with dibenzo-21-crown-7 and 4,4'(5')di-tert-butyldibenzo-18-crown-6 leads to sufficiently high distribution coefficients DCs of cesium from solutions with a nitric acid concentration of 1–5 mol/dm3. When extracting strontium with dicyclohexyl-18-crown-6, the highest distribution coefficients DSr were achieved using chlorine-substituted hydrocarbons and bis(2-chloroethyl) ether with a maximum extraction of 1–3 mol/dm3 HNO3, depending on the diluent used. Extraction systems based on selective crown ethers in a mixture of solvents were proposed for the co-extraction of cesium and strontium from nitric acid solutions of complex chemical compositions. [ABSTRACT FROM AUTHOR]

The equilibrium concentrations in membrane contactors are investigated in closed system for the extraction of copper from sulfate medium with di-Schiff base in toluene. The equilibrium distribution curves, is carried out from the mass action law, allows the determination of the reaction equilibrium constant. The calculation of the distribution coefficient in the membrane contactor is carried out from global mass balances and extraction isotherms. The experimental distribution coefficient is compared with the calculated value. The influence of parameters as the aqueous and organic phase flowrates and the distribution coefficient on the sensitivity of the system has been checked with experimental data. [ABSTRACT FROM AUTHOR]

The microalgae Haematococcus pluvialis are the main source of the natural antioxidant astaxanthin. However, the effective extraction of astaxanthin from these microalgae remains a significant challenge due to the rigid, non-hydrolyzable cell walls. Energy savings and high-efficiency cell disruption are essential steps in the recovery of the antioxidant astaxanthin from the cysts of H. pluvialis. In the present study, H. pluvialis microalgae were first cultured in Bold's Basal medium under certain conditions to reach the maximum biomass concentration, and then light shock was applied for astaxanthin accumulation. The cells were initially green and oval, with two flagella. As the induction time increases, the motile cells lose their flagellum and become red cysts with thick cell walls. Pre-treatment of aqueous two-phase systems based on deep eutectic solvents was used to decompose the cell wall. These systems included dipotassium hydrogen phosphate salt, water, and two types of deep eutectic solvents (choline chloride–urea and choline chloride–glucose). The results of pre-treatment of Haematococcus cells by the studied systems showed that intact, healthy cysts were significantly ruptured, disrupted, and facilitated the release of cytoplasmic components, thus facilitating the subsequent separation of astaxanthin by liquid–liquid extraction. The system containing the deep eutectic solvent of choline chloride–urea was the most effective system for cell wall degradation, which resulted in the highest ability to extract astaxanthin. More than 99% of astaxanthin was extracted from Haematococcus under mild conditions (35% deep eutectic solvent, 30% dipotassium hydrogen phosphate at 50 °C, pH = 7.5, followed by liquid–liquid extraction at 25 °C). The present study shows that the pre-treatment of two-phase systems based on deep eutectic solvent and, thus, liquid–liquid extraction is an efficient and environmentally friendly process to improve astaxanthin from the microalgae H. pluvialis. [ABSTRACT FROM AUTHOR]

In this work, the physical characterization of LiGdxY1−xF4 (x = 0.05, 0.3, 0.7, and 1.0) and LiGdF4:Eu3+ microparticles was performed. The distribution coefficient of LiGdxY1−xF4 (x = 0.05) was determined for the first time (0.84). Based on kinetic characterization data, the LiGdF4 sample was chosen for further Eu3+ doping (0.1 and 1.0 at.%). For the LiGdF4:Eu3+ sample, Eu3+ emission was clearly observed under the excitation of Gd3+. This fact indicates an effective energy transfer from Gd3+ to Eu3+. The temperature-dependent spectral characterization of the LiGdF4:Eu3+ (1.0%) sample revealed that in the 30–250 K temperature range, a broad emission peak is evidenced. Its intensity sharply increases with the temperature decrease. We made a suggestion that this phenomenon is related to the irradiation-induced defects. The integrated luminescence intensity ratio of this broad peak and the Eu3+ emission were taken as temperature-dependent parameters. The sensitivity values are very competitive, and the first maximum occurs at 174 K (3.18%/K). The kinetic characteristics of both Gd3+ and Eu3+ did not demonstrate a notable temperature dependence. The LiGdF4:Eu3+ sample showed the possibility of being used as an optical temperature sensor, operating in the cryogenic temperature range. [ABSTRACT FROM AUTHOR]

In this work, the physical characterization of LiGdxY1−xF4 (x = 0.05, 0.3, 0.7, and 1.0) and LiGdF4:Eu3+ microparticles was performed. The distribution coefficient of LiGdxY1−xF4 (x = 0.05) was determined for the first time (0.84). Based on kinetic characterization data, the LiGdF4 sample was chosen for further Eu3+ doping (0.1 and 1.0 at.%). For the LiGdF4:Eu3+ sample, Eu3+ emission was clearly observed under the excitation of Gd3+. This fact indicates an effective energy transfer from Gd3+ to Eu3+. The temperature-dependent spectral characterization of the LiGdF4:Eu3+ (1.0%) sample revealed that in the 30–250 K temperature range, a broad emission peak is evidenced. Its intensity sharply increases with the temperature decrease. We made a suggestion that this phenomenon is related to the irradiation-induced defects. The integrated luminescence intensity ratio of this broad peak and the Eu3+ emission were taken as temperature-dependent parameters. The sensitivity values are very competitive, and the first maximum occurs at 174 K (3.18%/K). The kinetic characteristics of both Gd3+ and Eu3+ did not demonstrate a notable temperature dependence. The LiGdF4:Eu3+ sample showed the possibility of being used as an optical temperature sensor, operating in the cryogenic temperature range.

The heavy metal pollutant Cr (VI) has high toxicity and strong mobility, posing a great threat to groundwater safety. The current relevant soil standards often overlook groundwater safety. It is urgent to establish a Cr(VI) soil environmental reference value based on groundwater safety in order to provide support for the supervision of contaminated sites. In order to determine the calculation method of soil environmental reference value for groundwater protection that is in line with China’s characteristics, research and derivation of soil environmental reference value based on groundwater safety at home and abroad, and draw reference from foreign methods for formulating environmental reference value of pollutants based on groundwater safety. Taking Zhejiang clay loam, Jiangsu loamy sandy soil and Jilin loamy clay as research objects, the distribution coefficients of Cr(VI) in the three soils were obtained through indoor static adsorption tests. The soil parameters and aquifer-related parameters of the three soils were obtained through literature research, The soil screening level (SSL) method proposed by the United States Environmental Protection Agency in the Soil Screening Guidelines was adopted，based on groundwater quality standards (GBT14848—2017), a soil environmental reference value aiming at groundwater protection is obtained.The results show that the baseline values of Cr(VI) soil environment based on groundwater safety were 0.944 0.690, 0.514 mg/kg, respectively. The results are close to the reference values of foreign countries for the purpose of protecting groundwater safety. However, the differences of soil properties in each study area make the final base values different. Therefore, when improving the soil environmental quality system, local regulatory agencies should build a database of soil and aquifer parameters to help soil pollution control. The research results can provide scientific basis for deducing the environmental reference value of heavy metal soil based on groundwater safety in various regions of China.