Identification of Multiple Water–Iodide Species in Concentrated NaI Solutions Based on the Raman Bending Vibration of Water

Efficacy of a Graphene Oxide/Chitosan Sponge for Removal of Radioactive Iodine-131 from Aqueous Solutions

Iodine-131 is increasingly used for diagnostic and therapeutic applications. The excretion of radioactive iodine is primarily through the urine. The safe disposal of radioactive waste is an important component of overall hospital waste management. This study investigated the feasibility of using graphene oxide/chitosan (GO/CS) sponges as an adsorbent for the removal of iodine-131 from aqueous solutions. The adsorption efficiency was investigated using iodine-131 radioisotopes to confirm the results in conjunction with stable isotopes. The results revealed that the synthetic structure consists of randomly connected GO sheets without overlapping layers. The equilibrium adsorption data fitted well with the Langmuir model. The separation factor (R_L) value was in the range of 0-1, confirming the favorable uptake of the iodide on the GO/CS sponge. The maximum adsorption capacity of iodine-131 by GO/CS sponges was 0.263 MBq/mg. The highest removal efficiency was 92.6% at pH 7.2 ± 0.2. Due to its attractive characteristics, including its low cost, the ease of obtaining it, and its eco-friendly properties, the developed GO/CS sponge could be used as an alternative adsorbent for removing radioiodine from wastewater.

Quantitative vibrational spectroscopy on liquid mixtures: concentration units matter

Quantitative vibrational absorption spectroscopies rely on Beer's law relating spectroscopic intensities in a linear fashion to chemical concentrations. To address and clarify contrasting results in the literature about the difference between volume- and mass-based concentrations units used for quantitative spectroscopy on liquid solutions, we performed near-infrared, mid-infrared, and Raman spectroscopy measurements on four different binary solvent mixtures. Using classical least squares (CLS) and partial least squares (PLS) as multivariate analysis methods, we demonstrate that spectroscopic intensities are linearly related to volume-based concentration units rather than more widely used mass-based concentration units such as weight percent. The CLS results show that the difference in root mean square error of prediction (RMSEP) values between CLS models based on mass and volume fractions correlates strongly with the density difference between the two solvents in each binary mixture. This is explained by the fact that density differences are the source of non-linearity between mass and volume fractions in such mixtures. We also show that PLS calibration handles the non-linearity in mass-based models by the inclusion of additional latent variables that describe residual spectroscopic variation beyond the first latent variable (e.g., due to small peak shifts), as observed in the experimental data of all binary solvent mixtures. Using simulation studies, we have quantified the relative errors (up to 10-15%) that are made in PLS modeling when using mass fractions instead of volume fractions. Overall, our results provide conclusive evidence that concentration units based on volume should be preferred for optimal spectroscopic calibration results in academic and industrial practice.

Structural elucidation and osteogenic activity of a novel heteropolysaccharide from Alhagi pseudalhagi

Alhagi pseudalhagi, commonly known as camel thorn, is used as an indigenous medicinal plant in China. The present study was designed to elucidate the structure of a novel polysaccharide, APP90-2, isolated from Alhagi pseudalhagi and evaluate its osteogenic activity. A homogeneous polysaccharide (APP90-2) was obtained from A. pseudalhagi via DEAE-52 and Sephacryl S-100 columns, with a molecular weight of 5.9 kDa. Monosaccharide, GC-MS, and NMR analyses showed that APP90-2 consisted of α-l-Rhap-(1→, →3)-α-l-Araf-(1→, →5)-α-l-Araf-(1→, →4)-β-d-Xylp-(1→, α-d-Glcp-(1→, →3,5)-α-l-Araf-(1→, →4)-β-d-GlcAp-(1→, →4)-3-OAc-α-d-Glcp-(1→, →3)-α-d-Galp-(1→, →3)-β-d-GalAp-(1→, →4)-α-d-Galp-(1→, →6)-α-d-Manp-(1→, →4,6)-β-d-Galp-(1→, and →3,6)-β-d-Glcp-(1→ with relative molar ratios of 4.1:1.8:6.1:6.7:1.7:1.0:1.5:2.7:2.4:1.1:2.3:2.6:1.4:2.0. Morphological analyses revealed that APP90-2 interacted with Congo-red and had an obvious honeycomb structure. Additionally, APP90-2 significantly promoted proliferation, differentiation, and mineralization of MC3T3-E1 cells, indicating that APP90-2 exhibited pronounced osteogenic activity. Therefore, our findings suggest that A. pseudalhagi may be used as an alternative medicine or health supplement for the prevention and treatment of osteoporosis.

Surface Enhanced Raman Spectroscopy Detection of Sodium Thiocyanate in Milk Based on the Aggregation of Ag Nanoparticles

A method is developed for detecting the concentration of sodium thiocyanate (NaSCN) in milk based on surface-enhanced Raman scattering (SERS) technology. A trichloroacetic acid solution can be used to enhance the SERS signal because of its function in promoting the aggregation of Ag nanoparticles (Ag NPs). Meanwhile, the protein in milk would be precipitated as trichloroacetic acid added and the interference from protein could be reduced during the detection. In this work, the enhancement factor (EF) is 7. 56 × 10⁵ for sodium thiocyanate in water and the limit of detection (LOD) is 0.002 mg/L. Meanwhile, this method can be used to detect the concentration of sodium thiocyanate in milk. Results show that SERS intensity increased as the concentration of sodium thiocyanate increase from 10 to 100 mg/L. The linear correlation coefficient is R² = 0.998 and the detection limit is 0.04 mg/L. It is observed that the concentration of sodium thiocyanate does not exceed the standard in the three kinds of milk. The confirmed credibility of SERS detection is compared with conventional methods.

An initial estimation method using cosine similarity for multivariate curve resolution: application to NMR spectra of chemical mixtures

Mixture spectra is decomposed into pure spectra without prior knowledge, and the MCR calculation refines the spectra and provides the concentrations.

Surprising Hofmeister Effects on the Bending Vibration of Water

The Hofmeister series, which originally described the specific ion effects on the solubility of macromolecules in aqueous solutions, has been a long-standing unsolved and exceptionally challenging mystery in chemistry. The complexity of specific ion effects has prevented a unified theory from emerging. Accumulating research has suggested that the interactions among ions, water and various solutes play roles. However, among these interactions, the binding between ions and solutes is receiving most of the attention, whereas the effects of ions on the hydrogen-bond structure in liquid water have been deemed to be negligible. In this study, attenuated-total-reflectance Fourier transform infrared spectroscopy is used to study the infrared spectra of salt solutions. The results show that the red- and blue-shifts of the water bending band are in excellent agreement with the characteristic Hofmeister series, which suggests that the ions' effects on water structure might be the key role in the Hofmeister phenomenon.