Determination of Trace Antimony (III) in Water Samples with Single Drop Microextraction Using BPHA-[C4mim][PF6] System Followed by Graphite Furnace Atomic Absorption Spectrometry

Ultrasound-assisted dispersive solidified floating organic drop microextraction based on a novel thiazolyl azo deep eutectic solvent for antimony determination in water and food samples

A new thiazolyl azo-derivative was prepared to be a hydrogen bonding acceptor (HBA) on the tertiary deep eutectic solvents (TDESs). Seven various TDES were created by combining [Methyl phenyl thiazolyl azo]-3-methyl-4-methoxy-2-naphthol (MPTAMN), menthol, and 1-dodecanol at varying molar ratios. An easy, quick, inexpensive, sensitive, and selective analytical technique was created for the extraction and identification of antimony in food and water samples using hydride generation atomic absorption spectroscopy (HGAAS) and ultrasound-assisted dispersive solidified floating organic drop microextraction (US-SFOD-DLPME-TDES). The utilized chelating reagent, 4,4-dimethyl-2,6-dioxo-N-phenylcyclohexanecarbothioamide (DMTA), was synthesized and characterized. Analytical factors were optimized, including pH, TDES kinds and molar ratios, ligand DMTA quantity, ultrasonic time, solvent volume, and interference impact. This approach recovered antimony from the collected samples at rates ranging from 98.2 to 100.3 %. The validation figures for LOD, LOQ, calibration curve linearity, enhancement, and preconcentration factors were determined to be 0.006 μg L-1, 0.02 μg L-1, 0.02-850 μg L-1, 180, and 150, respectively. A factorial design was used to determine the significance of various variables and their impact on antimony extraction using different statistical tools ANOVA, 3D surface plots, Pareto charts and diagnostic plots. The certified standard material (CSM) was utilized to validate and ensure the accuracy of the methodology. The current US-SFOD-DLPME-TDES technique performed well on actual samples.

Community ecological study on the reduction of soil antimony bioavailability by SRB-based remediation technologies

Sulfate-reducing bacteria (SRB) were effective in stabilizing Sb. However, the influence of electron donors and acceptors during SRB remediation, as well as the ecological principles involved, remained unclear. In this study, Desulfovibrio desulfuricans ATCC 7757 was utilized to stabilize soil Sb within microcosm. Humic acid (HA) or sodium sulfate (Na2SO4) were employed to enhance SRB capacity. The SRB+HA treatment exhibited the highest Sb stabilization rate, achieving 58.40%. Bacterial community analysis revealed that SRB altered soil bacterial diversity, community composition, and assembly processes, with homogeneous selection as the predominant assembly processes. When HA and Na2SO4 significantly modified the stimulated microbial community succession trajectories, shaped the taxonomic composition and interactions of the bacterial community, they showed converse effect in shaping bacterial community which were both helpful for promoting dissimilatory sulfate reduction. Na2SO4 facilitated SRB-mediated anaerobic reduction and promoted interactions between SRB and bacteria involved in nitrogen and sulfur cycling. The HA stimulated electron generation and storage, and enhanced the interactions between SRB and bacteria possessing heavy metal tolerance or carbohydrate degradation capabilities.

Ultrasound assisted dispersive solid phase microextraction using polystyrene-polyoleic acid graft copolymer for determination of Sb(III) in various bottled beverages by HGAAS

A new polyoleic acid-polystyrene (PoleS) block/graft copolymer was synthesized and applied as adsorbent for ultrasound assisted dispersive solid phase microextraction (UA-DSPME) of Sb(III) in different bottled beverages and analysis using hydride generation atomic absorption spectrometry (HGAAS). Adsorption capacity of the PoleS was 150 mg g^-1. Several sample preparation parameters such as sorbent amount, solvent type, pH, sample volume and shaking time were optimized (based on central composite design (CCD) approach) and evaluated in respect to the recovery of Sb(III). The method revealed a high tolerance limit of matrix ions presence. Under optimized conditions, linearity range, the limit of detection, the limit of quantitation, extraction recovery, enhancement factor, preconcentration factor were 5-800 ng L^-1, 1.5 ng L^-1, 5.0 ng L^-1, 96%, 82, 90, respectively. Accuracy of the UA-DSPME method was confirmed based on different certified reference materials and standard addition method. Factorial design was utilized to estimate the influences of variables of recovery of Sb(III).

Antimony reduction by a non-conventional sulfate reducer with simultaneous bioenergy production in microbial fuel cells

Environmental toxicity of antimony (Sb) is significantly increased through the widespread industrial application. The extended release of Sb above the regulatory level became a risk to humans habituated in the ecosystem. Conventional methods to remediate Sb demand high energy or resource input, which further leads to secondary pollution. The bio-electrochemical system offers a promising bioremediation strategy to remove or reduce toxic heavy metals. Thus, this research explores the possibilities of simultaneous metal sulfide (MeS) precipitation and electricity production using a full biological Microbial fuel cell (MFC). A non-conventional sulfate-reducing bacteria (SRB) Citrobacter freundii SR10 was used for this investigation, where the MFC was operated for lactate utilization in the bio-anode and Sb reduction at the bio-cathode. This study observed 81% of coulombic efficiency (bio-anode) and 97% of sulfate reduction with 99.3% Sb (V) reduction (bio-cathode), and it was concluded that the MeS precipitation entirely depends on sulfide concentration via SR10 sulfate reduction. The MFC-SR10 offers a maximum power density of 1652.9 ± 32.1 mW/m^3, and their performance was depicted using cyclic voltammetry and electrochemical impedance spectroscopy. The Sb reduction was evaluated through fluorescence spectroscopy, and the Sb (V) MeS precipitation was confirmed as stibnite (Sb₂S₃) by Raman spectroscopy and X-ray photoelectron spectroscopy. Furthermore, the matured anodic and cathodic biofilm formation was confirmed by Scanning electron microscopy with Energy-dispersive X-ray spectroscopy. Thus the MFC with SRB bio-cathode can be used as an alternative to simultaneously remove sulfate and Sb from the wastewater with electricity production.

Ultra-sensitive Sb speciation analysis in water samples by magnetic ionic liquid dispersive liquid-liquid microextraction and multivariate optimization

Efficient separation and preconcentration of inorganic Sb species in different water samples were performed in this work by a novel dispersive liquid-liquid microextraction (DLLME) method based on the application of a magnetic ionic liquid (MIL) and electrothermal atomic absorption spectroscopy (ETAAS) detection. The Sb(iii) species was selectively extracted by complexation with ammonium diethyldithiophosphate (DDTP) and 45 μL of the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate ([P6,6,6,14]FeCl4) as extractant. Subsequently, a magnetic rod was applied for phase separation, introducing it directly into the sample solution, and the MIL phase was then diluted in chloroform. Afterwards, 15 μL of this solution was injected into the graphite furnace of ETAAS for Sb determination. A multivariate study was performed to obtain the optimal extraction conditions. Selective reduction of Sb(v) to Sb(iii) with 1% (w/v) KI before preconcentration was applied for total inorganic Sb determination and Sb(v) concentration was calculated by subtraction. The analytical performance of the method included extraction efficiencies of 98.0% for Sb(iii) and 92.6% for Sb(v), LOD of 0.02 μg L-1 for Sb(iii) and relative standard deviations of 3.1% for Sb(iii) and 3.5% for Sb(v) (at 6 μg L-1 Sb(iii) and Sb(v), n = 10). The calibration linear range was 0.08-20 μg L-1. The results showed that the proposed methodology was highly sensitive and selective for Sb speciation analysis in tap, dam, mineral, wetland, underground, rain and river water samples.