Iron(III) oxidized nucleophilic coupling of catechol with o-tolidine/p-toluidine followed by 1,10-phenanthroline as new and sensitivity improved spectrophotometric methods for iron present in chemicals, pharmaceutical, edible green leaves, nuts and lake water samples

Characteristic study of biological CaCO3-supported nanoscale zero-valent iron: stability and migration performance

nZVI has attracted much attention in the remediation of contaminated soil and groundwater, but the application is limited due to its aggregation, poor stability, and weak migration performance. The biological CaCO3 was used as the carrier material to support nZVI and solved the nZVI agglomeration, which had the advantages of biological carbon fixation and green environmental protection. Meanwhile, the distribution of nZVI was characterised by SEM-EDS and TEM carefully. Subsequently, the dispersion stability of bare nZVI and CaCO3@nZVI composite was studied by the settlement experiment and Zeta potential. Sand column and elution experiments were conducted to study the migration performance of different materials in porous media, and the adhesion coefficient and maximum migration distances of different materials in sand columns were explored. SEM-EDS and TEM results showed that nZVI could be uniformly distributed on the surface of biological CaCO3. Compared with bare nZVI, CaCO3@nZVI composite suspension had better stability and higher absolute value of Zeta potential. The migration performance of nZVI was poor, while CaCO3@nZVI composite could penetrate the sand column and have good migration performance. What's more, the elution rates of bare nZVI and CaCO3@nZVI composite in quartz sand columns were 5.8% and 51.6%, and the maximum migration distances were 0.193 and 0.885 m, respectively. In summary, this paper studies the stability and migration performance of bare nZVI and CaCO3@nZVI composite, providing the experimental and theoretical support for the application of CaCO3@nZVI composite, which is conducive to promoting the development of green remediation functional materials.

Effects of salinity on iron-organic carbon binding in the rhizosphere of Kandelia obovata: Insights from root exudate analysis

Iron (Fe) oxides in wetland soils are crucial for stabilizing soil organic carbon (SOC) by forming stable Fe-OC complexes, thus protecting SOC from microbial breakdown and aiding its preservation. This study delves into the response of Fe (hydr-)oxides to salt stress, a relatively unexplored area, by examining Kandelia obovata, a key mangrove species. Through controlled climate chamber experiments, we investigated how salt stress affects the interactions between Fe (hydr-)oxides and SOC in root exudates (REs) and rhizosphere soils. Our results demonstrate that salinity at 30 ppt significantly increases the release of sugars, amino acids, inorganic nutrients (NH4+, NO3-), and phosphorus in K. obovata's REs, while reducing crystalline and amorphous Fe (hydr-)oxides and increasing complexed Fe (hydr-)oxide levels, thereby reducing their crystallinity in rhizosphere soils. Importantly, at elevated salinity (30 ppt), the Fe-OC bond in the rhizosphere shows greater stability, indicating enhanced resilience to salt stress compared to bulk soil. Salt stress also raises the carbon to nitrogen (C/N) ratio in REs. Testing artificial REs (AREs) with different C/N ratios showed that Fe (hydr-)oxide content decreases at C/N ratios of 10 and 30 compared to the control, whereas Fe-OC content increases with higher C/N ratios. Introduction of AREs with a C/N ratio of 20 significantly affected rhizosphere crystalline Fe (hydr-)oxide and Fe-OC content, highlighting AREs' impact on the binding of Fe (hydr-) oxides and OC. The presence of soil microorganisms was critical for the binding of Fe (hydr-) oxides and OC, as sterilized soil exhibited significantly lower levels of Fe (hydr-) oxides and Fe-OC compared to unsterilized soil. This research reveals that under salt stress, mangrove plants play a crucial role in stabilizing rhizosphere SOC by influencing Fe (hydr-) oxide crystallinity and promoting the formation of stable Fe-OC complexes, highlighting the complex interactions between plant REs, salt stress, and soil minerals.

Unveiling the impact of flooding and salinity on iron oxides-mediated binding of organic carbon in the rhizosphere of Scirpus mariqueter

The abundant Fe (hydr-) oxides present in wetland sediments can form stable iron (Fe)-organic carbon (OC) complexes (Fe-OC), which are key mechanisms contributing to the stability of sedimentary OC stocks in coastal wetland ecosystems. However, the effects of increased flooding and salinity stress, resulting from global change, on the Fe-OC complexes in sediments remain unclear. In this study, we conducted controlled experiments in a climate chamber to quantify the impacts of flooding and salinity on the different forms of Fe (hydr-) oxides binding to OC in the rhizosphere sediments of S. mariqueter as well as the influence on Fe redox cycling bacteria in the rhizosphere. The results of this study demonstrated that prolonged flooding and high salinity treatments significantly reduced the content of organo-metal complexes (FePP) in the rhizosphere. Under high salinity conditions, the content of FePP-OC increased significantly, while flooding led to a decrease in FePP-OC content, inhibiting co-precipitation processes. The association of amorphous Fe (hydr-) oxides (FeHH) with OC showed no significant differences under different flooding and salinity treatments. Prolonged flooding significantly increased the relative abundance of Fe-reducing bacteria (FeRB) Deferrisoma and Geothermobacter and decreased polyphenol oxidase in the rhizosphere, while the relative abundance of Fe-oxidizing bacteria (FeOB) Paracoccus and Pseudomonas decreased with increasing salinity and duration of flooding. Overall, short-term water and salinity stress promoted the binding of FeDH to OC in the rhizosphere of S. mariqueter, leading to a reduction in the OC content held by FePP. However, there were no significant differences observed in the OC stocks or the total Fe-OC content in the rhizosphere sediments. The findings suggest a degree of consistency in the Fe-OC of the "plant-soil" complex system within tidal flat wetlands, showing resilience to abrupt shifts in flooding and salinity over short periods.

Assessment of a novel aminated magnetic adsorbent with excellent adsorption capacity for dyes and drugs

Dyes and drugs with high toxicity and low biodegradability pose risk to human health and ecological security, and should be purified efficiently from effluents before discharge. Traditional adsorbents are limited by the insufficient active adsorption sites and low stability. In this study, a novel aminated magnetic adsorbent (MCTs) was fabricated via two cross-linking steps using chitosan and triethylenetetramine to fill the gaps between current adsorbent and performance requirements. The morphological and physicochemical characteristics of the as-prepared MCTs were determined and identified with the aid of several characterization techniques. The adsorption performance of dyes and drugs was also investigated and represented by their adsorption capacities. In particular, the adsorption capacities of Congo Red, Chicago Sky Blue, Reactive Brilliant Red, and Ibuprofen were 583.11, 465.01, 403.12, and 291.71 mg/g, respectively. They also remained at around 80% after four reuse cycles. MCTs were adsorbed via a monolayer spontaneous chemical reaction, and hydrogen bonding and electrostatic interaction were the dominant adsorption mechanisms. These results demonstrated that the preparation of MCTs via two cross-linking steps enhanced the adsorbents' adsorption capacity, reusability, and stability. They provided a new perspective for the preparation of high-efficient adsorbents and the purification of dye- and drug-polluted wastewater.

Bent 1,10-Phenanthroline Ligands within Octahedral Complexes Constructed around a TiO4N2 Core

The synthesis of monomeric octahedral complexes constructed around a TiO₄N₂ core bearing neocuproine derivatives is detailed. These architectures follow the [Ti(1)₂(N-N)] general formulas, where 1 is the 6,6'-diphenyl-2,2'-biphenolato ligand and N-N is a 1,10-phenanthroline derivative. Single-crystal analysis revealed that the neocuproine-based ligands within these architectures adopt a nonplanar geometry. The distortion of these aromatic diimine systems has been quantified through measurement of a torsion angle (α) and a dihedral angle (β) defined by two planes within the aromatic diimine molecule (π₁ and π₂), permitting one to evaluate the twisting and bending of a coordinated nitrogen ligand, respectively. Next, the scope of this investigation was extended to the synthesis of a dimeric architecture, [Ti₂(1)₄(3)], where 3 is the 5,5'-bis(neocuproine) ligand. Again, a strong distortion of the neocuproine fragments was characterized in the crystalline state for such a complex. The UV-visible properties of these complexes were interpreted with the help of time-dependent density functional theory calculations. The solution behavior as well as good hydrolytic stability of these species has been established.

Ex Vivo and in Vivo Study of Sucrosomial® Iron Intestinal Absorption and Bioavailability

The present study aimed to demonstrate that Sideral^® RM (SRM, Sucrosomial^® Raw Material Iron) is transported across the excised intestine via a biological mechanism, and to investigate the effect that this transport route may produce on oral iron absorption, which is expected to reduce the gastrointestinal (GI) side effects caused by the bioavailability of non-absorbed iron. Excised rat intestine was exposed to fluorescein isothiocyanate (FITC)-labeled SRM in Ussing chambers followed by confocal laser scanning microscopy to look for the presence of fluorescein-tagged vesicles of the FITC-labeled SRM. To identify FITC-labeled SRM internalizing cells, an immunofluorescence analysis for macrophages and M cells was performed using specific antibodies. Microscopy analysis revealed the presence of fluorescein positive particulate structures in tissues treated with FITC-labeled SRM. These structures do not disintegrate during transit, and concentrate in macrophage cells. Iron bioavailability was assessed by determining the time-course of Fe³⁺ plasma levels. As references, iron contents in liver, spleen, and bone marrow were determined in healthy rats treated by gavage with SRM or ferric pyrophosphate salt (FP). SRM significantly increased both area under the curve (AUC) and clearance maxima (C_max) compared to FP, thus increasing iron bioavailability (AUC_rel = 1.8). This led to increased iron availability in the bone marrow at 5 h after single dose gavage.

Sucrosomial® iron absorption studied by in vitro and ex-vivo models

This paper presents a comparative evaluation of different oral ferric iron formulations for ability to retain Fe³⁺ in simulated gastric fluid (SGF), be internalized by cells lining intestinal epithelium, and cross it to reach the bloodstream. In all formulations iron was ferric pyrophosphate, the excipients were different types and fractions of lecithin plus sucrose esters of fatty acids matrix (Sideral® RM; PRT1; PRT2) or lecithin without sucrester (SUN). Dissolution kinetics of formulations in SGF was studied by USP method. The ability of the formulations to promote iron intestinal absorption was evaluated by the Caco-2 cell model, measuring cellular ferritin content, and by the excised rat intestine model, yielding apparent permeability parameters (P_app). All formulations limited iron release in SGF to ≤10%. Sideral® RM was by far the most absorbed by Caco-2, as ferritin content was in the order: Sideral® RM≫PRT2>PRT1>SUN>control. The Fe³⁺ crossing the intestinal barrier was in part reduced to Fe²⁺ by epithelial enzymes, in part it was carried by formulation rearrangement into nano-structures able to protect it from reduction and apt for internalization by epithelium cells. P_app parameters were in the order: Sideral® RM≫PRT1>PRT2>SUN=control. Relevance of transepithelial Fe²⁺carrier, DMT-1, to Fe³⁺ transport was ruled out using a DMT-1 inhibitor. In conclusion, Sideral® RM retains iron in SGF, and is the most suitable for Fe³⁺ internalization by Caco-2 cells, Fe³⁺ protection from enzymatic reduction and promotion of Fe³⁺ absorption across intestinal epithelium, non-mediated by DMT-1.

Spectrophotometric determination of gold(III) in forensic and pharmaceutical samples and results complemented with ICP AES and EDXRF analysis

Spectrophotometric method with three systems were developed here for the determination of gold(III) using o-dianisidine, aniline sulphate and catechol. Gold(III),in the system 1 it oxidizes o-dianisidine, in the system 2 it oxidizes catechol followed by its coupling with o-dianisidine, in the system 3 it oxidizes catechol followed by its coupling with aniline sulphate forming dye products with respective λ_max 446nm, 540nm, and 505nm. All the three systems were optimized and analytical parameters were calculated. The molar absorptivity values were 9.27×10⁴, 1.97×10⁴ and 1.62×10⁴ respectively for the systems 1, 2 and 3 with the corresponding Sandell sensitivity values (μgcm^-2), 0.0021, 0.0096 and 0.011. The optimized systems were used for the determination of gold present in some forensic jewellery and pharmaceutical samples and the results obtained were compared with the results of all samples determined by Inductively Coupled Plasma - Atomic Emission Spectrometric method and a few of them were also complemented by Energy Dispersive X-Ray Fluorescent spectral analysis.

Hydrothermal synthesis of nitrogen-doped carbon quantum dots from microcrystalline cellulose for the detection of Fe3+ ions in an acidic environment

Nitrogen-doped carbon quantum dots prepared with microcrystalline cellulose display excellent sensitivity to Fe³⁺via dynamic quenching in an acidic environment.

New spectrophotometric methods for the determinations of hydrogen sulfide present in the samples of lake water, industrial effluents, tender coconut, sugarcane juice and egg

The new methods are working on the principle that iron(III) is reduced to iron(II) by hydrogen sulfide, catechol and p-toluidine the system 1/hydrogen sulfide the system 2, in acidic medium followed by the reduced iron forming complex with 1,10-phenanthroline with λ(max) 510 nm. The other two methods are based on redox reactions between electrolytically generated manganese(III) sulfate taken in excess and hydrogen sulfide followed by the unreacted oxidant oxidizing diphenylamine λ(max) 570 the system 3/barium diphenylamine sulphonate λ(max) 540 nm, the system 4. The increase/decrease in the color intensity of the dye products of the systems 1 and 2 or 3 and 4 are proportional to the concentration of hydrogen sulfide with its quantification range 0.035-1.40 μg ml(-1)/0.14-1.40 μg ml(-1).