Ultra-rapid detoxification of Sb(III) using a flow-through electro-fenton system.

Environmental pollution caused by antimony (Sb) has attracted worldwide attention recently. Here, we employed a flow-through electro-Fenton system for the rapid and efficient detoxification of highly toxic Sb(III). A FeOCl modified carbon nanotube (CNT) filter served as functional cathode, where FeOCl as nanocatalyst promoted the generation of HO by facilitating effective Fe3+/Fe2+ cycling. Upon application of a proper potential, an ultra-rapid conversion of Sb(III) to less toxic Sb(V) can be achieved in situ just by a single-pass filtration (>99% within 2 s). Compared with the conventional batch reactor, the proposed system demonstrated ultra-rapid Sb(III) detoxification kinetics due to the convection-enhanced mass transport. The proposed flow-through E-Fenton system works effectively across a wide pH range (e.g., 3-9). EPR technique and radical quenching experiments indicate that HO and HO2 were the dominant radical species responsible for Sb(III) detoxification. At -0.4 V vs. Ag/AgCl, a >96.4% Sb(III) conversion efficiency still can be achieved when challenged with 500 µg L-1 Sb(III)-spiked tap water. The as-produced Sb(V) can be removed effectively by another Sb(V)-specific CNT filter functionalized with nanoscale iron oxides. The outcome of this research provides a promising strategy by integrating state-of-the-art electro-Fenton, membrane separation, carboncatalysis and nanotechnology for detoxification of Sb(III) and other similar heavy metal ions in polluted water.

Simultaneous oxidation and removal of Sb(III) from water by using synthesized CTAB/MnFe2O4/MnO2 composite.

Low levels of antimony (Sb) can be effectively removed from water by adsorption onto various materials, and searching for low-cost and high-efficiency new adsorbents has been a hot topic in recent years. In the present study, the performance of cetyltrimethylammonium bromide (CTAB) modified MnFe2O4/MnO2 composites (CTAB/MnFe2O4/MnO2) as an adsorbent for Sb(III) removal from aqueous solution was investigated. Kinetic study revealed that adsorption of Sb(III) by CTAB/MnFe2O4/MnO2 was fast in the first 430 min and the equilibrium was achieved within 1440 min. The adsorption kinetic data were well fitted with pseudo-second-order model. The maximum adsorption capacity of the synthesized adsorbent for Sb(III) at pH 7 calculated from Langmuir adsorption isotherms in batch experiments was 321.03 mg g-1. During the adsorption process, Sb(III) can be simultaneously oxidized to Sb(V) and the average oxidation percentage reached 95.43% within 1440 min. The adsorption capacity did not significantly vary with pH. Common metal cations (Ca2+ and Mg2+) slightly enhanced Sb(III) adsorption at pH 7. In comparison, the effect of anions (Cl-, NO3-, and PO43-) on Sb(III) adsorption was not obvious. The results suggest that CTAB/MnFe2O4/MnO2 is a potential cost-effective adsorbent for Sb(III) removal in water treatment.

Leaching behavior of Sb and Br from E-waste flame retardant plastics.

The improper disposal of E-waste flame retardant plastics laden with antimony (Sb) and bromine (Br) has brought enormous environmental hazards, however, rare information on the effective removal of Sb and Br is available. In this study, through building an alkaline sulfide system under hydrothermal conditions, Sb and Br were simultaneously extracted from flame retardant plastic with high efficiency of 85.60% and 90.13%, respectively. Sulfur ion through mass transfer reacted with encapsulated Sb2O3 to form safe and non-toxic SbS33-. Alkaline solution trapped the Br through substitution or neutralization reaction to inhibit the formation of brominated organic compounds. The results showed that the optimum temperature, residence time, Na2S and NaOH concentration for hydrothermal removal of Sb and Br were 220 °C, 2 h, 50 g/L and 20 g/L. The results also revealed that both Na2S and NaOH played an interrelated role in the process of Sb removal. However, NaOH was the only factor controlling the process of debromination. Moreover, the FTIR structure of plastic after alkaline sulfide hydrothermal treatment remained unchanged, which implies that the treated plastic can be reused, and is an added advantage of this technology. The TG-DTG analysis proved the effectiveness of alkaline sulfide hydrothermal treatment in removing Sb and Br.

Antimony mobility from E-waste plastic in simulated municipal solid waste landfills.

The fate of antimony (Sb) leached from electronic and electrical equipment plastic when disposed of in a municipal solid waste (MSW) landfill was assessed using simulated anaerobic landfill lysimeters and three different batch leaching tests: toxicity characteristic leaching procedure (TCLP), EPA method 1313, and MSW leachate extractions. Plastic from cathode ray tube televisions sets was noted to have the highest Sb concentrations, and was thus the focus of the study. Sb leachability from EPA 1313 stat and TCLP were similar at approximately 0.1% by weight at the same pH (4.93), while MSW landfill leachates extracted less Sb at approximately 0.02% by weight. Solution pH was not the controlling factor, and other conditions resulting from the landfill leachate resulted in lower concentrations of leached Sb. In simulated landfill experiments, Sb leached at approximately 0.01% by weight after a liquid-to-solid ratio of 3. Sb behaves differently in the landfill environment than arsenic leaching from a similar study, most likely from the reducing conditions brought on by the decomposing waste.

Hyperbranched polyamide-functionalized sodium alginate microsphere as a novel adsorbent for the removal of antimony(III) in wastewater.

In order to enhance the removal of Sb(III) in wastewater, hyperbranched polyamide-functionalized sodium alginate (HA@SA) microsphere was prepared by grafting of hyperbranched polyamide (HA) on the surface of sodium alginate (SA) microsphere. Adsorption properties of Sb(III) were investigated via static and dynamic adsorption tests. The cycling reusability of HA@SA microspheres was explored through adsorption-desorption tests. The changes of HA@SA microspheres before and after adsorption were characterized by FT-IR, SEM-EDS, and XPS. Results showed that the maximum Sb(III) adsorption capacity of HA@SA microspheres reached up to 195.7 mg/g, improved by 1.16 times in comparison with SA microspheres. The Sb(III) adsorption processes of HA@SA microspheres were depicted by pseudo-second-order kinetics and the Langmuir isotherm models with accuracy. It covered a homogeneous single-layer adsorption controlled by chemisorption along with exotherm spontaneously. After recycling for 8 times, the adsorption capacity of HA@SA microspheres still retained higher than 90% of the original value.

Innovative and practical deep eutectic solvent based vortex assisted microextraction procedure for separation and preconcentration of low levels of arsenic and antimony from sample matrix prior to analysis by hydride generation-atomic absorption spectrometry.

Considering the negative impacts on human health and the environment, determinations of arsenic (As) and antimony (Sb), is of unquestionable importance. The present study describes the development of innovative and practical deep eutectic solvent (DES) based vortex assisted microextraction (DES-VAME) method for preconcentration of As and Sb from environmental waters, honey and rice prior to analysis by hydride generation-atomic absorption spectrometry (HG-AAS). The use of As(III) and Sb(III) in presence of dithizone at pH 10.5 by means of donor-acceptor mechanism were decided as analytes. Total As and Sb were determined after reduction process. The analytical properties obtained following optimization were as follows. Limit of detection (LOD), precision (as RSD%), recoveries and enhancement factor for As and Sb were calculated as 7.5 ng L-1/15.6 ng L-1, 2.1% /2.7%, 93.5%/96.2% and 104/85, respectively. Following validation with certified reference material, the method was successfully applied to the analysis of real samples.

Enhanced removal of antimony by acid birnessite with doped iron ions: Companied by the structural transformation.

In the environment, antimony as a priority control pollutant is mainly associated with Fe- or Mn- related minerals. In this work, acid birnessite (AB) doped with iron was synthesized as the artificial mineral to study the adsorption and oxidation of antimony. As compared to the pristine birnessite, Fe-doping birnessites show a markedly enhanced removal efficiency for both Sb(III) and Sb(V), where 10% Fe exhibited an excellent adsorption capacity of 759 mg/g Sb(III). The removal of Sb(III) clearly underwent a novel kinetic process of adsorption-desorption- (re-adsorption). By monitoring the kinetics with XRD, XPS, and IR, it is demonstrated that the three-stage kinetics were attributed to the strong interaction between Sb(III) and birnessite, including Sb(III) oxidation, followed by destruction of birnessite and then phase transformation into vernadite. Furthermore, the increase of iron content doped into birnessite enhanced the rate of its phase transition, which led to an increased adsorption of the oxidized antimony on the surface of vernadite by substituting iron and manganese associated with hydroxyl group. This work suggested that the strong interactions between heavy metal ions and mineral particles, more than adsorption, are critical to the transformation, mobility and biotoxicity of antimony in nature.

Study on Speciation of As, Cr, and Sb in Bottled Flavored Drinking Water Samples Using Advanced Analytical Techniques IEC/SEC-HPLC/ICP-DRC-MS and ESI-MS/MS.

The main aim of the research was to develop a complementary analytical approach consisting of bespoke speciation analysis and non-targeted speciation analysis of As, Sb, and Cr in flavored bottled drinking water samples using HPLC/ICP-DRC-MS and ESI-MS/MS. The scope of two previously developed analytical procedures, (1) multielemental speciation procedure for AsIII, AsV, CrVI, SbIII, and SbV analysis and (2) arsenic speciation procedure for AsB, AsIII, DMA, MMA, and AsV quantification, was extended to the analysis of a new sample type in terms of bespoke speciation analysis. As for the non-targeted speciation, analysis size exclusion chromatography was used with ICP-MS and a complementary technique, ESI-MS/MS, was used for the organic species of As, Sb, and Cr screening. Full validation of procedures 1 and 2 was conducted. Procedure 1 and 2 were characterized with precision values in the range from 2.5% to 5.5% and from 3.6% to 7.2%, respectively. Obtained recoveries ranged from 97% to 106% and from 99% to 106% for procedures 1 and 2, respectively. Expanded uncertainties calculated for procedures 1 and 2 ranged from 6.1% to 9.4% and from 7.4% to 9.9%, respectively. The applicability of the proposed procedures was tested on bottled drinking water samples. Results for the real samples in procedure 1 were in the range from 0.286 ± 0.027 [µg L-1] to 0.414 ± 0.039 [µg L-1] for AsIII, from 0.900 ± 0.083 [µg L-1] to 3.26 ± 0.30 [µg L-1] for AsV, and from 0.201 ± 0.012 [µg L-1] to 0.524 ± 0.032 [µg L-1] for SbV. CrVI and SbIII were not detected in any sample. As for procedure 2, results were in the range from 0.0541 ± 0.0053 [µg L-1] to 0.554 ± 0.054 [µg L-1] for AsB. Results for AsIII and AsV obtained with procedure 2 were in good accordance with results obtained with procedure 1. DMA and MMA were not detected in any sample.

Numerical simulation and exploration of electrocoagulation process for arsenic and antimony removal: Electric field, flow field, and mass transfer studies.

In order to intuitively and clearly evaluate the potential and current distribution, the fluid flow and mixing, as well as mass transfer involved in electrocoagulation process for As and Sb removal, numerical simulation of electric field, flow field and mass transfer were constructed by Comsol Multiphysics and verified by experiments. Results displayed that the primary current and potential distribution were improved by changing electrode distance or adding insulator in a batch reactor. When configuration 2 and 2 cm electrode distance were applied, a more uniform primary current distribution and higher electrode current efficiency were obtained. In a continuous flow reactor, the increase of flow rate resulted in the left shift of the peak in residence time distribution curve, gradual decrease of the tailing area, reduction of the stagnation zone, and more uniform mixing of the fluid. However, higher than 0.043 L/min was unfavorable to the formation of flocs and its effective combination with pollutants. According to the simulation of mass transfer, at the initial stage, the rate of electrolysis/hydrolysis was greater than that of mass transfer. Fe2+, OH-, and Fe(OH)2 were primarily concentrated on the anode, cathode, and between the two electrodes, respectively. Under the action of electromigration, diffusion and convection, the concentration distribution of Fe(OH)2 increased at the direction of streamline. The concentration of Fe2+ and OH- achieved the minimum value at the outlet. However, Fe(OH)+ concentration and distribution were hardly affected by the treatment time, and once generated, immediately proceed to the next hydrolysis reaction.

Fraction and mobility of antimony and arsenic in three polluted soils: A comparison of single extraction and sequential extraction.

Co-contamination of arsenic (As) usually occurs with antimony (Sb) in Sb mine ores. However, the mobility and bio-availability of Sb and As in different types of mine impacted soils have received relatively little attention. This study aimed to investigate the fraction, mobility and removal of Sb and As in three types of polluted soils using environmentally friendly and cost-effective extractants. In the present study, lightly polluted (L), moderately polluted (M), and 3) highly polluted (H) soils were collected from the Xikuangshan (XKS) mine area in Hunan, China. Toxicity risk assessment, fraction and extraction of Sb and As were performed to evaluate Sb and As mobility and availability. According to the speciation fractions, the percent of residual Sb was larger than As in all studied soils, which suggested that As is far more mobile than Sb. Sb and As extractabilities from selected polluted soils were compared and ranked as: citric acid > tartaric acid > EDTA > HCl > Na2HPO4 > CaCl2. Citric acid showed the highest extractabilities for both Sb and As (up to 24% for total Sb and 41% for total As respectively). Moreover, obvious alteration of Sb and As fractionations in three types of soils were observed after chemical extractions. The mobility of Sb and As increased after extraction by citric acid and tartaric acid, suggesting that these organic acids can make soil trace metals more bio-available and that, Sb/As polluted soils can be remediated via phytoextraction.

Separation of six compounds including two n-butyrophenone isomers and two stibene isomers from Rheum tanguticum Maxim by recycling high speed counter-current chromatography and preparative high-performance liquid chromatography.

Six compounds including two n-butyrophenone isomers and two stibene isomers were obtained from Rheum tanguticum Maxim. Two n-butyrophenone isomers with a separation factor of 1.14 were successfully separated by recycling high-speed counter-current chromatography after ten cycles. Two stibene isomers were successfully separated by preparative high-performance liquid chromatography. High-performance liquid chromatography analysis showed that the purities of the compounds were all over 98%. These compounds were identified as lindleyin, isolindleyin, resveratrol-4'-O-(2″-O-galloyl)-glucopyranoside, resveratrol-4'-O-(6''-O-galloyl)-glucopyranoside, emodin 1-O-ß-d-glucoside, and 3,5-dihydroxy-4'-methoxystilbene-3-O-ß-d-glucopyranoside. The results indicated that recycling high-speed counter-current chromatography and preparative high-performance liquid chromatography could be effective combination for the preparation of bioactive compounds from Rheum tanguticum Maxim.

Antimony contamination, consequences and removal techniques: A review.

A significant amount of antimony (Sb) enters into the environment every year because of the wide use of Sb compounds in industry and agriculture. The exposure to Sb, either direct consumption of Sb or indirectly, may be fatal to the human health because both antimony and antimonide are toxic. Firstly, the introduction of Sb chemistry, distribution and health threats are presented in this review, which is essential to the removal techniques. Then, we provide the recent and common techniques to remove Sb, including adsorption, coagulation/flocculation, membrane separation, electrochemical methods, ion exchange and extraction. Removal techniques concentrate on the advantages, drawbacks, economical efficiency and the recent achievements of each technique. We also take an overall consideration of experimental conditions, comparison criteria, and economic aspects.

Antimonate uptake by calcined and uncalcined layered double hydroxides: effect of cationic composition and M2+/M3+ molar ratio.

This study gives a contribution to assess the efficacy of some LDHs (layered double hydroxides) in Sb(V) uptake and understand the mechanisms involved in the removal process. Uncalcined nitrate Mg/Al LDHs and the mixed Mg-Al oxides derived from calcined carbonate Mg/Al LDHs mainly remove Sb(OH)6- from aqueous solution through the formation of a brandholzite-like phase (a non-LDH compound with general formula Mg[Sb(OH)6]2·6H2O), although with a different efficiency (< 50 and 90-100% of Sb(V) removed, respectively). The formation of a brandholzite-like compound highlights the fundamental role of Mg in the removal process. The Sb(OH)6- removal capacity of uncalcined nitrate Mg/Al LDHs increases from 22 to 46% as the Mg/Al molar ratio decreases from 4 to 2 thanks to the increasing excess of positive charge of brucite-like sheets and the expanding interlayer thickness due to the different spatial orientations of nitrate groups (flat for Mg/Al = 4, perpendicular for Mg/Al = 2). The presence of Fe3+ in the trivalent cationic site of carbonate LDHs (Mg/(Al + Fe) = 3/(0.5 + 0.5)) improves the Sb(OH)6- removal capacity of their calcined products. When Mg is replaced by Zn in the divalent cationic site of carbonate LDHs and the sorption experiments are performed using the mixed Zn-Al oxides derived from calcination, Sb(OH)6- is mainly removed from the solution through the reconstruction of an antimonate LDH structure (i.e., a zincalstibite-like compound with general formula Zn2Al(OH)6[Sb(OH)6]). The removal efficiency of calcined carbonate Zn/Al LDHs is high and comparable to that of calcined carbonate Mg/Al LDHs; however, the mechanisms involved in the removal process are substantially different: entrance of Sb(OH)6- in the interlayer in the first case, adsorption of Sb(OH)6- onto the surface and formation of a new phase (a brandholzite-like compound) in the second case. In both cases, the removal processes are described with the pseudo-second-order kinetic model; the theoretical maximum adsorption capacity determined with the Langmuir isotherm results to be 4.54 and 4.37 mmol g-1 for calcined carbonate Mg/AlFe and Zn/Al LDHs, respectively.

Removal of Antimonite (Sb(III)) and Antimonate (Sb(V)) from Aqueous Solution Using Carbon Nanofibers That Are Decorated with Zirconium Oxide (ZrO2).

Zirconium oxide (ZrO2)-carbon nanofibers (ZCN) were fabricated and batch experiments were used to determine antimonite (Sb(III)) and antimonate (Sb(V)) adsorption isotherms and kinetics. ZCN have a maximum Sb(III) and Sb(V) adsorption capacity of 70.83 and 57.17 mg/g, respectively. The adsorption process between ZCN and Sb was identified to be an exothermic and follows an ion-exchange reaction. The application of ZCN was demonstrated using tap water spiked with Sb (200 µg/L). We found that the concentration of Sb was well below the maximum contaminant level for drinking water with ZCN dosages of 2 g/L. X-ray photoelectron spectroscopy (XPS) revealed that an ionic bond of Zr-O was formed with Sb(III) and Sb(V). Based on the density functional theory (DFT) calculations, Sb(III) formed Sb-O and O-Zr bonds on the surface of the tetragonal ZrO2 (t-ZrO2) (111) plane and monoclinic ZrO2 planes (m-ZrO2) (111) plane when it adsorbs. Only an O-Zr bond was formed on the surface of t-ZrO2 (111) plane and m-ZrO2 (111) plane for Sb(V) adsorption. The adsorption energy (Ead) of Sb(III) and Sb(V) onto t-ZrO2 (111) plane were 1.13 and 6.07 eV, which were higher than that of m-ZrO2 (0.76 and 3.35 eV, respectively).

Simultaneous lead and antimony immobilization in shooting range soil by a combined application of hydroxyapatite and ferrihydrite.

This study investigated whether a combined application of hydroxyapatite and ferrihydrite could immobilize lead and antimony in shooting range soil in which the level of lead contamination is markedly higher than that of antimony. In addition, we evaluated the stability of lead and antimony immobilized by the combined application with varying soil pH. The levels of water-soluble lead and antimony for the combined application were lower than those of single applications of hydroxyapatite or ferrihydrite, indicating that the combined application could suppress the levels of water-soluble lead and antimony by 99.9% and 95.5%, respectively, as compared with the levels in shooting range soil without immobilization material. The amounts of residual lead and amorphous Fe/Al oxide-bound antimony fractions in sequential extraction increased with a decrease in the exchangeable and carbonate lead fractions as well as in non-specifically bound and specifically bound antimony fractions. The alteration of lead and antimony phases to chemically more stable ones as a result of the combined application would result in the suppression of their mobility. The stability of immobilized lead and antimony in the combined application was equal to that of lead with a single application of hydroxyapatite and that of antimony with a single application of ferrihydrite within neutral to alkaline pH conditions, respectively. Therefore, this study suggests that the combined application of hydroxyapatite and ferrihydrite can simultaneously immobilize lead and antimony in shooting range soil with neutral to alkaline pH.

Antimony(V) removal from water by hydrated ferric oxides supported by calcite sand and polymeric anion exchanger.

We fabricated and characterized two hybrid adsorbents originated from hydrated ferric oxides (HFOs) using a polymeric anion exchanger D201 and calcite as host. The resultant adsorbents (denoted as HFO-201 and IOCCS) were employed for Sb(V) removal from water. Increasing solution pH from 3 to 9 apparently weakened Sb(V) removal by both composites, while increasing temperature from 293 to 313 K only improved Sb(V) uptake by IOCCS. HFO-201 exhibited much higher capacity for Sb(V) than for IOCCS in the absence of other anions in solution. Increasing ionic strength from 0.01 to 0.1 mol/L NaNO3 would result in a significant drop of the capacity of HFO-201 in the studied pH ranges; however, negligible effect was observed for IOCCS under similar conditions. Similarly, the competing chloride and sulfate pose more negative effect on Sb(V) adsorption by HFO-201 than by IOCCS, and the presence of silicate greatly decreased their adsorption simultaneously, while calcium ions were found to promote the adsorption of both adsorbents. XPS analysis further demonstrated that preferable Sb(V) adsorption by both hybrids was attributed to the inner sphere complexation of Sb(V) and HFO, and Ca(II) induced adsorption enhancement possibly resulted from the formation of HFO-Ca-Sb complexes. Column adsorption runs proved that Sb(V) in the synthetic water could be effectively removed from 30 microg/L to below 5 microg/L (the drinking water standard regulated by China), and the effective treatable volume of IOCCS was around 6 times as that of HFO-201, implying that HFO coatings onto calcite might be a more effective approach than immobilization inside D201.

Analytical method for the determination of trace toxic elements in milk based on combining Fe3O4 nanoparticles accelerated UV fenton-like digestion and solid phase extraction.

A UV Fenton-like digestion method was developed first time for a complete digestion of milk samples by using 1.6 g L(-1) Fe3O4 magnetic nanoparticles, 0.2% (v/v) nitric acid, and 6% (w/w) H2O2. During the digestion, the liberated As-, Sb-, and Bi-containing species were preconcentrated onto the surface of Fe3O4 magnetic nanoparticles, which were conveniently separated with a hand-held magnet and subsequently dissolved in hydrochloric acid prior to hydride generation atomic fluorescence spectrometric detection. Owing to the integration of UV Fenton-like digestion, solid phase extraction, and magnetic separation into a single step, the developed method significantly simplifies sample preparation steps and reduces chemical consumption and hazardous waste. Limits of detection of 0.0015, 0.0022, and 0.0025 µg L(-1) were obtained for As, Sb, and Bi, respectively, using a 50 mL milk sample. The method was applied to the determination of these elements in a Certified Reference Material and milk samples.

Bioaccumulation of heavy metals by endemic Viola species from the soil in the vicinity of the As-Sb-Tl mine "allchar' Republic of Macedonia.

Allchar mine is an abandoned arsenic-antimony-thallium deposit located on the northwestern part of Kozuf Mt., Republic of Macedonia. Allchar is a unique deposit within the world, due to the variety of its mineral composition especially and in the high content of thallium. The aim of this work was to assess the level of contamination at this post-mining area as well as to determine the intensity of accumulation of various elements (Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Sr, Tl, V, and Zn) with focus on As, Sb and Tl, in two endemic Viola species from this locality (Viola allcharensis G. Beck, Viola arsenica G. Beck) and one Balkan endemic species (Viola macedonica Boiss. & Heldr.). Samples of different plant parts and soil were digested and then analysed by ICP-AES. It was found that the accumulation of As, Sb, and Tl in these endemic species is significantly high. In this study a systematic investigation of the As-Sb-Tl contamination of soils and their bioavailability was carried out using the extraction procedure in order to explore the mobility and potential bioavailability of the As, Sb, and Tl.

Evaluation of alternative rapid thin layer chromatography systems for quality control of technetium-99m radiopharmaceuticals.

Whatman 3MM™ and Tec-Control™ systems were evaluated as ITLC-SG alternatives for 99mTc-radiopharmaceuticals. They compare well in accuracy and reproducibility, and are faster and more convenient than ITLC-SG. Tec-Control™ radiochemical purity values for 99mTc-sestamibi were more conservative than ITLC-SG. Full solvent migration was not reproduced for 99mTc-tetrofosmin in Tec-Control™, and for this Whatman 3MM™ is preferred. Developing times were 10-15 min, 7-9 min and ~1min for ITLC-SG, Whatman 3MM™ and Tec-Control™, respectively. Overall, Tec-Control™ strips are preferred due to speed and ease of use.

Efficient removal of trace antimony(III) through adsorption by hematite modified magnetic nanoparticles.

Hematite coated magnetic nanoparticle (MNP@hematite) was fabricated through heterogeneous nucleation technique and used to remove trace Sb(III) from water. Powder X-ray diffraction, transmission electron microscopy (TEM), and alternating gradient magnetometry were utilized to characterize the prepared adsorbent. TEM image showed that MNP@hematite particles were spherical with size of 10-30nm. With saturation magnetization of 27.0emu/g, MNP@hematite particles could be easily separated from water with a simple magnetic process in short time (5min). At initial concentration of 110µg/L, Sb(III) was rapidly decreased to below 5µg/L by MNP@hematite in 10min. Sb(III) adsorption capacity of MNP@hematite was 36.7mg/g, which was almost twice that of commercial Fe3O4 nanoparticles. The removal of trace Sb(III) was not obviously affected by solution pH (over a wide range from 3 to 11), ionic strength (up to 100mM), coexisting anions (chloride, nitrate, sulfate, carbonate, silicate, and phosphate, up to 10mM) and natural organic matters (humic acid and alginate, up to 8mg/L as TOC). Moreover, MNP@hematite particles were able to remove Sb(III) and As(III) simultaneously. Trace Sb(III) could also be effectively removed from real tap water by MNP@hematite. The magnetic adsorbent could be recycled and used repeatedly.