Ammonium Oxalate Research Articles

Controlled fabrication of WO3 nanoplate films and its photoelectrochemical properties

WO3 nanoplate films on FTO glass have been prepared by hydrothermal method using ammonium oxalate and hydrochloric acid as the structure-directing agents. The experimental results showed the relative diffraction intensity of crystal plane (002) to (200), the uniformity, and the oxygen deficiencies of WO3 nanoplate films have changed considerably with the change of ammonium oxalate and hydrochloric acid concentration. Moreover, WO3 nanoplate film prepared by 0.2 g of ammonium oxalate and 6 ml of hydrochloric acid exhibited the highest photoelectrocatalytic activity for tetracycline degradation, which reached 72% in 80 min. Simultaneously, a high photocurrent density of 0.08 mA cm−2 at 0.4 V versus SCE in 0.5 M Na2SO4 electrolyte and the IPCE of 19.64% at 350 nm was obtained. The enhanced photoelectrochemical properties were ascribed to the uniform thickness, high density, and the increased oxygen deficiency content of WO3 nanoplate films, which further promoted the high light absorption and low recombination rate of electron-hole pairs at the interface.

Sulfation–Roasting–Leaching–Precipitation Processes for Selective Recovery of Erbium from Bottom Ash

Bottom ash (BA) is mainly composed of compounds of Al, Fe, Ca, and traces of rare earth elements (REEs). In this study, the selective recovery of erbium (Er) as REEs by means of sulfation–roasting–leaching–precipitation (SRLP) using BA was investigated. A pre-treatment process of sulfation and roasting of BA was developed to selectively recover REEs using ammonium oxalate leaching (AOL) followed by precipitation. Most of the oxides were converted to their respective sulfates during sulfation. By roasting, unstable sulfates (mostly iron) decomposed into oxides, while the REE sulfates remained stable. Roasting above 600 °C induces the formation of oxy-sulfates that are almost insoluble during AOL. Dissolved REEs precipitate after 7 days at room temperature. The effects of particle size, roasting temperature, leaching time, and AOL concentration were the important parameters studied. The optimal conditions of +100–500 μm particles roasted at 500 °C were found to leach 36.15% of total REEs in 2 h 30 min and 94.24% of the leached REEs were recovered by precipitation. A total of 97.21% of Fe and 94.13% of Al could be separated from Er.

The role of precipitant in the preparation of lithium-rich manganese-based cathode materials

Co-precipitation method employing two precipitants, oxalic acid and ammonium oxalate, has been used to synthesize Li1.2Ni0.13Co0.13Mn0.54O2. Various calcination temperatures are also compared to obtain the material with better properties. By optimizing the precipitant and calcination temperature, the material prepared by oxalic acid at 900 °C has good layered structure, small particle size (200–300 nm), and uniform distribution of particles. A high first discharge specific capacity of 298.4 mAh g−1 and a high first Coulombic efficiency of 77.2% at 0.1 C are obtained. After 50 cycles, the reversible discharge specific capacity is 272.2 mAh g−1 with a capacity retention of 91.2%.

Enhanced sonocatalytic performance of ZnTi nano-layered double hydroxide by substitution of Cu (II) cations.

In this research, a series of CuZnTi-LDHs with different Cu2+/Zn2+ molar ratio were synthesized by co-precipitation method with the purpose of improving the sonocatalytic performance of ZnTi-LDH. All the LDH samples were synthesized by a facile co-precipitation process. The as-prepared LDHs were characterized by Powder X-ray diffraction (XRD), Field emission-scanning electron microscopy (FESEM), Transition electron microscopy (TEM), Brunauer-Emmelt-Teller (BET) analysis, and UV-visible diffuse reflectance spectroscopy (DRS) analysis. The results showed that Cu2+ substitution can significantly enhance the sonocatalytic properties of ZnTi-LDH. The Methylene blue degradation percentage over ZnTi-LDH reached 30% in 90 min, whilst this percentage reaches 71% over CuZnTi-LDH (1:1). The role of the Cu2+ incorporation on the observed enhancement in sonocatalytic performance was revealed by investigating the effect of radical scavengers on degradation efficiency and DRS spectra of ZnTi-LDH and CuZnTi-LDH (1:1). Benzoquinone (BQ), ammonium oxalate and tert-Bu lead to 22.5%, 53.5% and 74.6% decrease in degradation percentage by CuZnTi-LDH (1:1). However, the degradation efficiency showed 16.6%, 3.3% and 63.3% reduction in the presence of BQ, ammonium oxalate and tert-Bu respectively, in dye degradation by ZnTi-LDH. DRS spectra demonstrated that the band gap of the LDH decreases by Cu2+ substitution. The effect of operational parameters on sonodegradation was investigated as well. The kinetics of sonodegradation reaction obeyed the first order reaction kinetics with R2 of 0.95.

Coligand syntheses, crystal structures, luminescence and photocatalytic properties of 2D and 3D Ni(II) coordination polymers based on terephthalic acid and flexible bis(benzimidazole) linkers

Two new Ni(II) coordination polymers (CPs) [Ni(TP)(L1)(H2O)]n (1) and [Ni(TP)(L2)]n (2), were synthesized via hydrothermal reaction (H2TP = terephthalic acid, L1 = 1,6-bis(2-methylbenzimidazol-1-yl)hexane, L2 = 1,6-bis(5,6-dimethylbenzimidazol-1-yl)hexane, and structurally characterized by X-ray single crystal diffraction analysis, elemental analyses, thermogravimetric analysis, X-ray powder diffraction and IR spectra. CP 1 exhibits a 2D hcb layer, which is further extended into 3D supramolecular architecture by classical O–H⋯O hydrogen-bonding interactions. CP 2 possesses a 3D 4-connected sra framework. Both CPs possess high thermal stability and promising photocatalytic activities for the degradation of methylene blue (MB) under UV irradiation. The photocatalytic mechanism was investigated by introducing benzoquinone (BQ), the ammonium oxalate (AO), and tert-butyl alcohol (TBA) as superoxide radical (·O2−), hole (h+), and hydroxyl radical (·OH) scavengers, respectively.

PEDOGENESIS ON COASTAL TABLELANDS AREA WITH LOW RANGE ALTIMETRY IN PARAÍBA STATE

ABSTRACT Small variations of relief may change drainage and runoff and hence promote the formation of sandy surface horizons and hardened subsurface horizons (fragipans and/or duripans) in Coastal Tablelands soils. This study aimed to investigate the pedogenesis on Coastal Tablelands area with low range altimetry in Paraíba state; secondly, we also sought to contribute to the improvement of the Brazilian Soil Classification System (BSCS). Four soil profiles ware described and collected to be submitted to routine physical and chemical analysis, determination of Fe, Al and Si extracted by sulfuric acid digestion, sodium citrate-bicarbonate-dithionite and acid ammonium oxalate, sodium pyrophosphate, and mineralogical analysis in the sand and clay fractions by X-ray diffractometry. Optical density of the oxalate extract (ODOE) was also determined; the results were statistically evaluated using the R software. Microrelief variations conditioning differentiated water flows, along with the sandy texture of the surface horizons (A and E) and the lower coarse sand/fine sand ratio in the subsurface horizon, seem to promote clay accumulation in depth in the Spodosols developed on Coastal Tablelands environments. For this soils, the argilluvic (argissólico) character at the subgroup level of the BSCS should be incorporated. In addition, Al amorphous mineral phases and/or poorly crystalline play an important role in the formation of strongly cemented horizons (duripans) of the Spodosols, as also reported by other authors. Finally, the ODOE showed to be an efficient indicator of soils under podzolization process, being possible its use as a taxonomic criterion for classification of Spodosols by the BSCS.

Scalable exfoliation and dispersion of few-layer hexagonal boron nitride nanosheets in NMP-salt solutions

Abstract Efficient and large-scale production of boron nitride (h-BN) nanosheets is very important for their applications. Here, we have developed a facile strategy for liquid-phase exfoliation of h-BN nanosheets in organic electrolyte solutions where N-methyl-pyrrolidinone (NMP) is used as an organic solvent, and sodium citrate, sodium tartrate, ammonium oxalate, potassium sodium tartrate or ethylenediaminetetraacetic acid disodium salt is used as a salt. It is found that the dispersion content of h-BN nanosheets has been greatly improved by using organic electrolyte solutions. For example, by addition of ethylenediaminetetraacetic acid disodium salt into NMP, the content of the exfoliated h-BN is 36 times that in neat NMP. Furthermore, approximately 85% of the h-BN nanosheets obtained in such a strategy is 1–4 layers. Mechanism study indicates that the strength of Lewis basicity of anion and size of cation of the salts play an important role in the exfoliation of h-BN by organic electrolyte solutions. The liquid exfoliation strategy reported here shows great promise for the mass production of high-quality few-layer h-BN nanosheets.

Study on catalytic performances and reaction mechanisms of graphene electroactive membrane in wastewater treatment

This study was conducted to access the catalytic performances and reaction mechanisms of Graphene Electroactive Membrane (GEM). The GEM was prepared by vacuum-pressing method, and characterized by FESEM and FTIR. Catalytic performances were measured in the index of decolorization ratio and mineralization rate. Active species were recognized by scavengers for investigating reaction mechanisms. The impacts of current intensity and water flux on catalytic performances were presented to illustrate the mechanisms of GEM electro-catalysis deeply. According to the results, the method of GEM preparation was reliable and Graphene was an appropriate material for Electroactive Membrane (EM). Compared with EM electro-catalysis and GEM with no electro-catalysis (GEM-NEC), the mineralization rate increased by 56.1% and 28.8% respectively, and the decolorization rate increased by 45.5% and 29.8% respectively. The decolorization rate of GEM electro-catalysis with 0.2 M Ammonium Oxalate (Scavenger of electron hole) decreased 32.7% more than GEM electro-catalysis with no scavenger. Thus, direct oxidation was the main mechanism of GEM electro-catalysis, which was very different from traditional electro-catalysis. When current intensity was less than 20 mA and water flux was higher than 3 mL/min, decolorization ratio increased dramatically. Thus, electro-catalytic process and adsorption-diffusion process played important roles in GEM electro-catalysis process. The GEM electro-catalysis was an effective and stable advanced wastewater treatment for removal of organic pollutants.

Formation of Micro- and Nanostructured TiO2 Films by Anodic Oxidation for Enhanced Photocatalytic Activities

This paper presents growth of micro- and nanostructured TiO2 layers on Ti6Al4 V by thermal and anodic spark oxidation for photocatalysis. Effects of anodization parameters on surface morphology and photocatalytic behavior were investigated. The photocatalysts divided into two groups consisting of four samples were prepared for growth of micro- and nanostructured TiO2 layer on Ti6Al4 V. The microstructured surfaces were obtained in 1 M H2SO4 electrolyte in 5 min at the anodization voltage in the range of 100–400 V, whilst the nanostructured TiO2 layers were prepared in 1% HF solution in the range of 10–40 V in equal time. Surface morphology, phase structure, band gap and surface roughness values of the micro- and nanostructured TiO2 photocatalysts were analyzed by scanning electron microscope, X-ray diffraction, UV–Vis diffuse reflectance spectroscopy and surface profilometer, respectively. Photocatalytic performances of TiO2 photocatalysts obtained with different anodization parameters were investigated via methylene blue aqueous solution. It was observed that the anodization voltage has a great effect on photocatalytic performances due to the formation of different crystallinity and morphology. Among the samples, the layer prepared at 100 V exhibited the best photocatalytic activity with 91.15% degradation efficiency and 95.5 × 10−4 min−1 kinetic rate constant. Moreover, the further investigation determining active species were carried out using ammonium oxalate, benzoquinone, and isopropyl alcohol. In this process, the photocatalytic mechanism revealed that the superoxide radicals $$(^{ \cdot } {\text{O}}_{ 2}^{ - } )$$ play a very important role during the photodegradation process. The TiO2 layer on Ti6Al4 V anodized at 100 V also showed high activity and stability, suggesting its potential for wastewater treatment.

EPR dosimetric potential of ammonium oxalate monohydrate in radiation technology

This study aims to examine the dosimetric properties of the ammonium oxalate monohydrate (COONH4)2H2O irradiated by 60Co gamma-rays. The EPR spectra of ammonium oxalate have the spectroscopic splitting g-factors of 2.0095 and 2.0047. Results indicate that the dose-response curves have a good linearity in the range between 10 and 1000Gy. Slight sub-linearity has been found in high dose region up to 25 kGy. The effects of temperature and humidity on the EPR signal amplitude of the irradiated samples were studied. Stability of the irradiation rods upon storage (signal fading) was also investigated. Energy dependence has been found within 38% at the range below 100 keV. The dosimeter displayed an increasing response by approximately 4% over the energy range 6–10 MeV. The overall uncertainty of this dosimetry system is 4.64% (σ2) in low dose range and 3.67% for the high dose range.

Pectic Polysaccharides have Relatively Potent Immunomodulatory Activity Compared to their Hydrolysates from Chickpea (Cicer arietinum L.) Husk

In the present study, the immunomodulatory effects of Pectic Polysaccharides (PPs) extracted sequentially using ammonium oxalate and ethylene-diamine-tetraacetic acid (PP-AO and PP-EDTA) and their oligosaccharides (PO-AO and PO-EDTA) from chickpea husk, characterized in our previous study, was investigated using the macrophage cell line, RAW 264.7 at different concentrations. Results showed that treatment with 12.5-100 μg/mL of PP-AO, PP-EDTA, PO-AO and PO-EDTA stimulated macrophage proliferation, nitric oxide production and phagocytosis. The proliferation rate was observed to be increased as the production of nitric oxide increased at time intervals of 48 h and 72 h, respectively. Furthermore, TNF-α, IL-4 and IFN-γ cytokine expression profiles were measured by ELISA 24 h following the treatment. Pectic Polysaccharides (PPs) and Pectic Oligosaccharides (POs), demonstrated an elevation in cytokine levels as compared to control. Pectic polysaccharide extracts (PP-AO and PP-EDTA) are relatively potent immunomodulatory complex by inducing iNOS expression as compared to their respective hydrolysates (PO-AO and PO-EDTA) may be due to a high degree of polymerization or high amount of uronic acid as well as acetyl groups. The presence of higher content of complex xylogalacturonan with relatively more galactan side chains of PP-AO compared to EDTA isolated PPs (data not shown) made them exhibit as a potent immunomodulatory. These results suggest that pectic polysaccharides from chickpea husk can improve immunity by enhancing immune function and could be explored as a potential immunomodulatory agent in functional foods.

Enhanced photodegradation of toxic organic pollutants using dual-oxygen-doped porous g-C3N4: Mechanism exploration from both experimental and DFT studies

Novel visible-light-driven dual-oxygen-doped porous g-C3N4 (OPCN) photocatalysts were synthesized by a facile thermal copolymerization of urea and ammonium oxalate. The introduced O atoms were preferable to synchronously substitute for two sp2-hybridized N atoms in the para-positions (i.e., N1′ and N4′ sites) of the melem unit by forming dual-O-doped g-C3N4. Together with porous structures, OPCN exhibited enlarged specific surface area, narrowed band gap and expanded visible light response. The photocatalytic activity of the optimal OPCN was approximately 9 times higher than that of pure g-C3N4 for bisphenol A (BPA) removal under visible light irradiation, and efficient removal rates for various chlorophenols, phenols and dyes were also observed. Combined with experiments and DFT calculations, this dual-O-doped structure resulted in effective charge transfer and separation of OPCN under visible light irradiation by forming e− and h+-related conjugated delocalized systems on the surface, which contributed to its interfacial contact with organic pollutants and adsorbed O2. As a result, the degradation of BPA was readily induced by photoinduced h+ and then thoroughly mineralized by O2−. On the other hand, more O2− radicals were generated, which could also oxidize BPA directly due to their strong oxidation power. The superior stability and reusability of OPCN catalysts were also revealed during photoreaction. This work provides a novel viewpoint to fabricate high-performance nonmetal photocatalysts for wastewater treatment.

Interactions on site between powdering porous limestone, natural salt mixtures and applied ammonium oxalate

The consolidation of powdering porous limestone with ammonium oxalate treatment is hereby being examined through its performance in the field. The literature to date reports this treatment’s potential use for consolidation and protection (from acid attack), while still retaining the water transport properties and supporting compatibility. This inspired a long-term research project which started in the laboratory and progressed to real buildings with a specific focus on the interactions in the stone taking place between the treatment and salt mixtures that may be present on site. This study focuses on the outcomes following a 24-h application of a 5% ammonium oxalate poultice on a historical soil-retaining wall located in a seventeenth century garden. In this case, besides calcium oxalate, the by-product formation of ammonium magnesium chloride was detected through X-Ray Diffraction (XRD). This is a first-time reported finding, which is important to consider within the environmental context of built heritage and ammonium oxalate treatment.

Malting process has minimal influence on the structure of arabinan-rich rhamnogalacturonan pectic polysaccharides from chickpea (Cicer arietinum L.) hull.

The objective of the study was to determine the changes brought about by malting/germination on the pectic polysaccharides (PP's), the major components of soluble fibres present in chickpea (Cicer arietinum L.) hull. Chickpea hull PP's were extracted sequentially using ammonium oxalate (AO) and ethylenediaminetetraacetic acid (EDTA), and a comparative study was conducted in native (unprocessed, N-PP) and after subjecting to 48h malting process (M-PP). Malting process did not show a significant change in the respective yields of AO and EDTA extracted pectic polysaccharides. The degree of esterification of N-PP-EDTA through Fourier transform infrared spectroscopy was found to be five times (~ 21%) more than N-PP-AO (~ 4%). AO isolated PP's have more complexed xylogalacturonan with relatively more galactan side chains compared to EDTA isolated PPs. Proton (1H) nuclear magnetic resonance result further suggested the occurrence of arabinan rich rhamnogalacturonan in chickpea hull and malting process showed no significant changes in structure.

Comparing Schwertmannite and Hydrobasaluminite Dissolution in Ammonium Oxalate (pH 3.0): Implications for Metal Speciation Studies by Sequential Extraction

The “poorly crystalline iron oxy-hydroxides” are one of the most reactive and environmentally important fractions in soils and sediments due to the association of many toxic elements associated with these minerals. The metal content of this fraction in sequential extraction procedures is usually evaluated by dissolution in ammonium oxalate ([NH4]2C2O4·H2O) at pH 3.0 and 25 °C. Such chemical treatment, however, may also dissolve other mineral phases of comparable reactivity, which can lead to wrong interpretations of mineral carriers for specific metals. In this study, we compare the dissolution kinetics of schwertmannite and hydrobasaluminite, two minerals of comparable crystallinity and reactivity that play a major role in the mobility of many trace metals in waters and sediments affected by acid mine drainage (AMD). We first synthesized these two minerals in the laboratory by partial neutralization of two different metal-rich mine waters, and then we applied the standard protocol of ammonium oxalate dissolution to different specimens; the solutions were periodically sampled at intervals of 2, 5, 10, 15, 30 and 60 min to compare (i) the kinetics of mineral dissolution, and (ii) the metals released during dissolution of these two minerals. The results indicate a very similar kinetics of mineral dissolution, though hydrobasaluminite exhibited a faster rate. Some toxic elements such as As, Cr or V were clearly bonded to schwertmannite, while many others such as Cu, Zn, Si, Co, Ni and Y were clearly linked to hydrobasaluminite. These results suggest that studies linking the mobility of many elements with the Fe cycle in AMD-affected soils and sediments could be inaccurate, since these elements could actually be associated with Al minerals of poor crystallinity. The step of ammonium oxalate dissolution in sequential extraction studies should be best described with a more general term such as “low-crystallinity oxy-hydroxides”.

Enhanced Photocatalytic Reduction of Cr(VI) by Combined Magnetic TiO2-Based NFs and Ammonium Oxalate Hole Scavengers

Heavy metal pollution of wastewater with coexisting organic contaminants has become a serious threat to human survival and development. In particular, hexavalent chromium, which is released into industrial wastewater, is both toxic and carcinogenic. TiO2 photocatalysts have attracted much attention due to their potential photodegradation and photoreduction abilities. Though TiO2 demonstrates high photocatalytic performance, it is a difficult material to recycle after the photocatalytic reaction. Considering the secondary pollution caused by the photocatalysts, in this study we prepared Ag/Fe3O4/TiO2 nanofibers (NFs) that could be magnetically separated using hydrothermal synthesis, which was considered a benign and effective resolution. For the photocatalytic test, the removal of Cr(VI) was carried out by Ag/Fe3O4/TiO2 nanofibers combined with ammonium oxalate (AO). AO acted as a hole scavenger to enhance the electron-hole separation ability, thereby dramatically enhancing the photoreduction efficiency of Cr(VI). The reaction rate constant for Ag/Fe3O4/TiO2 NFs in the binary system reached 0.260 min−1, 6.95 times of that of Ag/Fe3O4/TiO2 NFs in a single system (0.038 min−1). The optimized Ag/Fe3O4/TiO2 NFs exhibited high efficiency and maintained their photoreduction efficiency at 90% with a recyclability of 87% after five cycles. Hence, taking into account the high magnetic separation behavior, Ag/Fe3O4/TiO2 NFs with a high recycling capability are a potential photocatalyst for wastewater treatment.

Structural, rheological and antioxidant properties of pectins from Equisetum arvense L. and Equisetum sylvaticum L.

The pectins were isolated from sterile stems of E. arvense (EA, yield 5.9%) and E. sylvaticum (ES, yield 4.8%) (Equisetaceae) using ammonium oxalate extraction after preliminary treatment with dilute HCl (рH 4.0). The pectins possessed high molecular weight (Mw, 340–360 kDa), high GalA content (ca. 85%), low degrees of methyl-esterification (14–16%) and acetylation (3–8%). NMR analysis indicated extensive regions of partially methyl-etherified and 3-O-acetylated HG and minor regions of low branched RG in the fragment isolated after hydrolysis of pectin EA by pectinase. Pectin EA produced a higher viscosity solution, formed a stronger and more rigid ionotropic hydrogel than pectin ES. The pectins scavenged DPPH and hydroxyl radicals, but not the superoxide radical and hydrogen peroxide. Phenolic compounds (0.11 and 0.23%) associated with polysaccharide moieties were apparently responsible for the differences in the anti-DPPH scavenging activity of pectins EA and ES (63 and 49%). The findings suggested that pectin from E. arvense should be more perspective than pectin from E. sylvaticum on their use as components of wound healing remedies.

Weathering in a regolith on the Werenskioldbreen Glacier forefield (SW Spitsbergen). 2. Speciation of Fe, Mn, Pb, Cu and Zn in the chronosequence

The evolution of chemical speciation of Fe, Mn, Pb, Cu, and Zn was investigated in the chronosequence of young sediments, exposed by a currently retreating Arctic glacier on Spitsbergen. Werenskioldbreen is a 27 km 2 subpolar, land-terminated, polythermal glacier in recession, located near the SW coast of West Spitsbergen. Three samples of structureless till were collected at locations exposed for 5, 45 and 70 years. Four grain-size fractions were separated: > 63, 20–63, 2–20, and < 2 μm. Speciation of Fe, Mn, Pb, Cu, and Zn was determined using a 6-step sequential chemical extraction method: 1) 1 M sodium acetate, 2) 1 M hydroxylamine hydrochloride in acetic acid, 3) sodium dithionite in buffer, 4) acid ammonium oxalate, 5) boiling HCl, 6) residuum. The weathering in the proglacial area of the retreating glacier is very fast. The geochemical fates of the metals in question correlate with each other, reflecting a) the geochemical similarities between them, b) the similarities of their primary mineral sources, c) the significant role of incongruent dissolution. The weathering processes dominating the system are redox reactions and incongruent dissolution, followed by precipitation of secondary phases and partial sorption of aqueous species. As a result, the elements released from weathering minerals are only partially transported away from the system. The remaining part transforms by weathering from the coarse-grained fraction (dominated by fragments of primary minerals) into the fine-grained fraction (in the form of secondary, authigenic minerals or as species sorbed onto a mineral skeleton). This is very strongly pronounced within the chronosequence: the content of each of the metals studied correlates identically with the grain size, despite the differences in their chemical character and affinities. The microscope study presented herein indicates that the role of incongruent dissolution previously was underestimated. Also, the formation of coatings of secondary phases on primary mineral surfaces was observed. All these rapid weathering processes affect the mineral speciation of initial soils as well as the composition of mineral suspensions transported away by rivers to the nearby ocean.

Electrodeposition of Zn-Ni Coatings from Ammonium Oxalate Bath

Electrodeposition of Zn-Ni Coatings from Ammonium Oxalate Bath

Accurate Determination of Total Antimony Using ICP-MS and Optimization Its Extraction Efficiency From Reference and Soil Samples

Two independent digestion techniques (microwave acid digestion with HF and HCl, HNO3 and Na2O2 sintering, respectively) were applied to determine the total Sb concentration in a real soil sample and in reference materials: Icelandic Basalt (BIR-1), Cody Shale (SCo-1) and (Soil-7). ICP-MS was used to determine total antimony concentrations in the digested and the extracted solutions using external calibration and isotope dilution technique. The recoveries of Sb using HF in the acids digestion mixture in closed-vessels microwave digestion system were excellent and the concentrations are in very good agreement with certified or reported concentrations of reference materials. Using closed-vessels combined with microwave heating systems probably prevents the loss of volatile Sb compounds. The use of hydrogen fluoride with other strong acid can help dissociating insoluble antimony silicates. Different extraction reagents were tested for their ability to extract antimony using an ultrasonic bath namely: EDTA disodium salt, potassium hydroxide, citric acid monohydrate, pyridine-2,6-dicarboxylic acid, ammonium acetate, ammonium oxalate, ammonium thiocyanate, ammonium persulphate and di-ammonium hydrogen citrate. A 500 mmol L-1 solution of citric acid pH 1.08 proved to be the most efficient extractant. Optimization of the extraction conditions were investigated by studying the effect of pH, concentration, temperature, time of extraction, the ratio of sample mass to the volume of extractant and the number of consecutive extractions. As a result three consecutive extractions for a total time of 45 min at 80 ˚C was the most efficient condition for Sb extraction. Using these extraction conditions 61%, 3.7% RSD and 42%, 2.2% RSD (n=6) of the total antimony in the real soil and Soil-7 samples, respectively could be extracted.