Thorium In Water Research Articles

Self-flocculating Chlorella vulgaris: A high-efficiency purification mechanism of radioactive Th4+ in an aquatic environment

This study aimed to investigate the purification of radioactive thorium (Th4+) by Chlorella vulgaris in aquatic environments. Single-factor experiments and response surface optimization tests identified optimal purification conditions. The purification and metabolic response mechanisms of Chlorella to Th4+ were elucidated using physiological and biochemical analyses, three-dimensional excitation-emission matrix (3D-EEM) analysis, and metabolomic profiling. Increases in the Th4+ concentration caused Chlorella to self-flocculate, significantly improving the Th4+ purification efficiency. Under optimal conditions, the Th4+ purification efficiency for Th4+ in wastewater by Chlorella stabilized between 94.3 % and 98.2 %. Morphological analysis revealed that the purified Th4+ existed mainly in a stable residual state. Chlorella efficiently purified wastewater during treatment by regulating environmental pH, performing redox reactions, and utilizing extracellular polymeric substances (EPS) to interact with Th4+. Metabolomic analysis indicated that Chlorella adapted to the Th4+-contaminated environment and enhanced its purification function by adjusting the synthesis of metabolites, such as carbohydrates, nucleotides, and amino acids. Chlorella demonstrated a remarkable self-flocculation phenomenon and a high-efficiency purification capability for Th4+, offering new possibilities for environmental remediation. Its purification mechanism involves environmental regulation, redox reactions, and complex metabolic adjustments. The results presented here provide theoretical support for environmental remediation using Chlorella.

A review of thermodynamic data for lanthanum, iron, and thorium applied to rare earth extraction

A consolidated and revised database for thermodynamic simulation of lanthanum (representing the rare earth elements), iron, and thorium in water, sulfate, and phosphate systems was built. Thermodynamic parameters (∆Gf°, ∆Hf°, and Sf°) collected from the original sources were compared with those reported in thermochemical software databases. The inconsistencies found in the latter were mainly ascribed to typographical errors, incorrect unit conversions, and errors generated by combining data from different sources. The Eh-pH diagrams illustrate the significant effects of data discrepancies on the stability regions of aqueous and solid species. The results obtained with the revised database helped the identification of operating windows for the selective precipitation of common impurities (e.g., Fe and Th) in rare earth extraction. In the presence of sulfate, the complex LaSO4+(aq) is the only stable species up to pH = 8 and then La(OH)3(s) is formed. In phosphate solutions, lanthanum salts precipitate at lower pH. The precipitation pH varies with the nature and crystal features of the different lanthanum phosphate phases. Under oxidizing conditions, wide operational windows favor the selective precipitation of Fe2O3(s) or FePO4.2H2O(s) at pH 1–5. Thorium hydroxide is formed at pH 4. The inclusion of phosphate complexes in the simulation expands the thorium solubility region from pH 4 to 6.5 (approximately), depending on phosphate concentration.

Measuring of radioactive contamination by Gamma-ray Spectroscopy for many water projects in Baghdad City

The study aims to provide the effective monitoring of radioactive contents in refining water stations. Attempts were made to measure the radionuclide’s concentrations level which indicates to radioactive contamination in the samples of raw water taken from the Tigris River and samples of river sediments. The radionuclides contents have been obtained using the gamma-ray spectroscopy technique. Analysis system (HPGe) has been applied to measure the radioactivity concentration of Uranium, Radium, and Thorium in water and sediment samples. For solid samples (sediments), results have shown that the activity for238U the range was from (52±5.31Bq/kg)In S4 to(120±8)in S3, for 232Th the range was from(26±2.4Bq/kg)in S1to (48±3.1Bq/kg) in S3, for 40K, the range was from (247±17Bq/kg) in s4 to (453±18Bq/kg) in S3, for 137Cs the range was from(1.28±0.1Bq/kg) in S3 to (7.8±0.67) in S2. For liquid samples (water), the activity for 238U was from (10±1 Bq/l) in Kh1to(38±4.2Bq/l) in D1, for 232Th was from (1±0.35Bq/l) in kD1 to (1.8±0.60Bq/l) in D1, for 40K was from (10±0.3 Bq/l), in ka1to(48±5.7Bq/l) in KD1. In the final step (drinking water) showed only 40K isotope appeared at range(18±0.03 - 55±0.06Bq/l).

Determination of uranium and thorium in water for human consumption in the county of Angra dos Reis

Studies indicate that the presence of uranium and thorium radionuclides in the environment are of great importance in monitoring radiation levels. Humans can have a direct or indirect exposure. The radiological impact for the members of the population living in Angra dos Reis - RJ was evaluated using environmental monitoring data of uranium and thorium in the waters for human consumption of the county of Angra dos Reis. Monitoring data showed concentrations much lower than the guidelines based on the maximum permitted value of uranium in waters for consumption established by CONAMA. Thorium is the most significant radionuclide. The public that lives in the county of Angra dos Reis is not exposed to the radiation that would result in a radiological impact.

A rapid dispersive liquid-liquid microextraction based on hydrophobic deep eutectic solvent for selective and sensitive preconcentration of thorium in water and rock samples: A multivariate study

Thorium [Th(IV)] and its compounds are highly toxic and cause severe damage to bone and kidney through long term exposures. Conventional methods of Th(IV) detection are complicated and costly. In this study, we developed a new dispersive liquid-liquid microextraction (DLLME) based on hydrophobic deep eutectic solvent (HDES) for preconcentration of Th(IV) in water and rock samples prior to UV–Vis. spectrophotometric detection. The microextraction procedure was carried out by applying thorin as a chelating agent, cethyltrimethyl ammonium bromide (CTAB) as an ion pairing agent and a DES consisted of 1-hexyl-3-methylimidazolium and salicylic acid components as an extraction solvent. Central composite design (CCD) was applied to obtain the best condition of the microextraction procedure. The developed method is a green, facile, fast, selective and sensitive that could detect Th(IV) in the concentration range of 10–600 ng mL−1 with a limit of detection (LOD) and preconcentration factor of 2.1 ng mL−1 and 59, respectively. The relative standard deviation of five replicate measurements of Th(IV) at 100 ng mL−1 was 1.7%. Finally, the proposed method was successfully applied to the analysis of Th(IV) in water and rock samples, and desirable results were obtained.

Determination for levels of uranium and thorium in water along Oum Er-Rabia river using alpha track detectors

Different river water samples have been collected and analyzed from different locations along Oum Er-Rbia River in Morocco. The uranium and thorium concentrations were investigated in the studied river and dam water samples. Mean activity concentrations of uranium and thorium in water were found to be between 12 and 37 Bq.m−3 and 2–10 Bq.m−3, respectively. The pH measured at all river water simples was slightly alkaline and ranged from 7.5 to 8.75. The electrical conductivity ranged from 2790 to 794 μS cm−1. It was found that uranium and thorium concentrations were correlated with some chemical parameters in Oum Er-Rabia River water. Uranium and thorium measurements in this river are important for monitoring environmental radioactivity and to know the geochemical behaviour of these radionuclides in the surficial water bearing environments.

Selective determination of thorium in water using dual-wavelength β-correction spectrophotometry and the reagent 4-(2-pyridylazo)-resorcinol

A simple, fast, low cost, and precise direct β-correction spectrophotometric method was developed for thorium determination in water. The method is based on the reaction of Th(IV) with 4-(2-pyridylazo)-resorcinol (PAR) in aqueous solution of pH 5–6 and measuring the absorbance of the resulting red-colored complex at λmax 497 nm. The effective molar absorptivity of the Th(IV)-PAR complex was 2.52 × 104 L mol−1 cm−1. Beer’s law and Ringbom plots were obeyed in the concentration range 0.04–2.0 and 0.07–1.2 μg mL−1 of thorium ions using β-correction spectrophotometry, respectively. The limits of detection and quantification of Th(IV) were 0.02 and 0.066 μg mL−1, respectively. The developed method was applied for the analysis of thorium in certified reference material (IAEA-soil-7), tap-, underground- and Red-sea water samples. The validation of the method was also tested by comparison with data obtained by ICP-MS. The method is convenient, less sensitive to common interfering species and less laborious than most of published methods. The statistical treatment of data in terms of Student t-tests and variance ratio f-tests has revealed no significance differences. The structure of the Th(IV)-PAR complex was determined with the aid of spectroscopic measurements (UV–Visible and Fourier Transform Infrared Spectroscopy).

Floatation-spectrophotometric Determination of Thorium, Using Complex Formation with Eriochrome Cyanine R.

A novel and sensitive floatation-spectrophotometric method is presented for determination of trace amounts of thorium in water samples. The method is based on the ion-associated formation between thorium, Eriochrome cyanine R and Brij-35 at pH = 4 media. The complex was floated in the interface of the aqueous phase and n-hexane by vigorous shaking. After removing the aqueous phase the floated particles were dissolved in methanol and the absorbance was measured at 607 nm. The influence of different important parameters such as Eriochrome cyanine R and surfactants concentration, pH, volume of n-hexane, standing time and interfering ions were evaluated. Under optimized conditions the calibration graph was linear in the range of 6–230 ng mL−1 of thorium with a correlation coefficient of 0.9985. The limit of detections (LOD), based on signal to noise ratio (S/N) of 3 was 1.7 ng mL−1. The relative standard deviations for determination of 150 and 30 ng ml−1 of thorium were 3.26 and 4.41%, respectively (n = 10). The method showed a good linearity, recoveries, as well as some advantages such as sensitivity, simplicity, affordability and a high feasibility. The method was successfully applied to determine thorium in different water and urine samples.

Determination of thorium isotopes in mineral and environmental water and soil samples by α-spectrometry and the fate of thorium in water

A method has been developed for determination of thorium isotopes in water and soil samples by α-spectrometry. After fusion with Na 2CO 3 and Na 2O 2 at 600 °C, soil samples were leached with HNO 3 and HCl. Thorium in water sample or in soil leaching solution was coprecipitated together with iron (III) as hydroxides and/or carbonates at pH 9 with ammonia solution, separated from uranium and other α-emitters by a Microthene-TOPO (tri-octyl-phosphine oxide) chromatographic column, electrodeposited on a stainless steel disk, and measured by α-spectrometry. The method was checked with two certified reference materials supplied by the IAEA, and reliable results were obtained. The detection limits of the method for water (soil) samples are 0.44 μBq l −1 (0.070 Bq kg −1) for 232Th, 0.80 μBq l −1 (0.13 Bq kg −1) for 230Th and 1.0 μBq l −1 (0.16 Bq kg −1) for 228Th, respectively, if 100 l of water (0.50 g) for each sample are analysed. A variety of water or soil samples were analysed using this procedure and giving average thorium yields of 75.5±14.2% for water and 93.4±4.5% for soil. The obtained concentrations of thorium isotopes in water samples are in the range of 0.0007–0.0326 mBq l −1 for 232Th, ⩽0.0008–0.0258 mBq l −1 for 230Th and 0.0014–1.32 mBq l −1 for 228Th. The 230Th/ 232Th and 228Th/ 232Th ratios are in the range of ⩽0.57–3.9 and 1.06–717, respectively. The disequilibrium between 232Th and 228Th activity in water is observed and the fate of thorium isotopes in water was studied. The exposure impact due to intake of thorium in the analysed drinking water was evaluated, showing a negligible amount of dose contribution. The concentrations of 232Th, 230Th and 228Th in the analysed soil samples are in the range of 30.2–48.6, 32.5–60.5 and 31.0–53.0 Bq kg −1, respectively. The obtained mean ratio is 1.04±0.05 for 228Th/ 232Th and 1.20±0.41 for 230Th/ 232Th.

Hydrolysis and Colloid Formation of Thorium in Water and Consequences for its Migration Behaviour – Comparison with Uranium

Article Hydrolysis and Colloid Formation of Thorium in Water and Consequences for its Migration Behaviour – Comparison with Uranium was published on January 1, 1992 in the journal Radiochimica Acta (volume 56, issue 1).

The preconcentration with synergist-impregnated Polyurethane foams and spectrophotometric determination of trace thorium in natural waters

This paper reports the use of synergist-impregnated Polyurethane foams for preconcentrating trace thorium from natrual waters. The polyether type Polyurethane foams were employed, which were loaded with bis (2-ethylhexyl) phosphoric acid/tributyl phosphate/carbon tetrachloride (2:5:93, V/V/V) mixture. The surplus reagent was removed by filter paper. The loaded foams prepared in this way were dipped into the water sample and stirred for 20 minutes. The optimum conditions for preconcentration are: samples should be adjusted to about pH 1 and temperature kept within 30°-45°C.The distribution and phase ratios were calculated to be 4.26 x104 and 2.01x104 respectively, assuming that the mixture and water were totally immiscible with each other. The actural values were all slightly greater than the calculated ones. After removing the foam from the sample, the former was washed with water and subjected to wet oxidation with concentrated nitric and perchloric acids. The residue was taken up with dilute hydrochloric acid. The amount of thorium in the water sample was spectrophotometrically determined with Arsenazo III at 665 nm. The method is simple, rapid, accurate and inexpensive.

The localisation of point sources of radioactivity in absorbing media.

The accurate localisation of a point source of radioactivity in an absorbing medium is frequently desirable and the theory has been developed by Mayneord (1950). The applicability of his formula to the localisation of small (“point”) sources of thorium in water has been tested by measuring the γ radiation from opposite sides of the container. The positions calculated by means of his formula were in disagreement with the known positions of the source and a modified formula has been developed. Experimental evidence has been obtained to show that the approximation involved in the theory is sufficiently good to justify its use.

Determination of Microgram Quantities of Thorium in Water

Determination of Microgram Quantities of Thorium in Water