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1.
Yan Yang Ruixue Zhang Shiwan Chen Jian Zhu Pan Wu Jiayan Huang Shihua Qi 《RSC advances》2022,12(13):7720
Oxidation of As(iii) to As(v) is an effective way to improve the performance of most arsenic removal technologies. In this study, a new alternative biosorbent, TiO2-loaded biochar prepared by waste Chinese traditional medicine dregs (TBC) was applied in remediation for As(iii) from aqueous solution. Compared with unmodified biochar, the specific surface areas and total pore volumes of TBC increased while the average aperture decreased due to the loading of nano-TiO2. The X-ray diffraction (XRD) of TBC confirmed that the precipitated titanium oxide was primarily anatase. pH did not have a significant effect on the adsorption capacity at 10 mg L−1 As(iii) in suspension with a pH ranging from 2 to 10. Adsorption kinetics data were best fitted by the pseudo-second-order model (R2 > 0.999). The Sips maximum adsorption capacity was 58.456 mg g−1 at 25 °C, which is comparable with other adsorbents reported in previous literature. The Gibbs free energy (ΔG) of As(iii) adsorption was negative, indicating the spontaneous nature of adsorption. The results of free radical scavenging and N2 purging experiments indicated that O2 acted as an electron accepter and O2˙− dominated the oxidation of As(iii). The oxidation of As(iii) obviously affected the adsorption capacity for As(iii) by TBC. X-ray photoelectron spectroscopy (XPS) studies showed that As(iii) and As(v) existed on the surface of TBC, suggesting that the oxidation of As(iii) occurred. TBC played multiple roles for As(iii), including direct adsorption and photocatalytic oxidation adsorption. Regeneration and stability experiments showed that TBC was an environment-friendly and efficient adsorbent for As(iii) removal.TiO2-loaded biochar prepared by waste Chinese traditional medicine dregs (TBC) was applied in remediation for As(iii) from aqueous solution. 相似文献
2.
Quancheng Yang Yunxiang Dai Zijian Huang Jing Zhang Ming Zeng Changsheng Shi 《RSC advances》2019,9(51):29689
Novel Bi2WO6/bentonite (denoted as BWO/BENT) composites were prepared via a typical hydrothermal process and employed for the photocatalytic oxidation of arsenic(iii) (As(iii)). The properties of the prepared samples were characterized through X-ray diffraction, transmission and scanning electron microscopy, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. Effects of the BENT ratio on the As(iii) removal were explored under simulated sunlight, and the best photocatalytic effect was observed for the composite with BWO : BENT = 7 : 3 w/w. Compared with the pure BWO, the BWO/BENT composites exhibited an improved photocatalytic ability in the removal of As(iii), which was mainly ascribed to the enlarged specific surface area and the suppressed electron–hole recombination by the incorporated BENT. Furthermore, photo-generated holes (h+) and superoxide radicals ·O2− were confirmed to be the major contributors to the oxidation of As(iii), and an associated mechanism of photocatalytic oxidation of As(iii) over BWO/BENT composites was proposed.Novel Bi2WO6/bentonite (denoted as BWO/BENT) composites were prepared via a typical hydrothermal process and employed for the photocatalytic oxidation of arsenic(iii) (As(iii)). 相似文献
3.
Bifunctional heterogeneous catalytic processes for highly efficient removal of arsenic (As(iii)) are receiving increased attention. However, the agglomerated nature and stability of nanoparticles are major concerns. Herein, we report a new process regarding the anchoring of CuFe2O4 nanoparticles on a substrate material, a kind of Fe–Ni foam, to form porous CuFe2O4 foam (CuFe2O4-foam) by in situ synthesis. The prepared material was then applied to activate peroxymonosulfate (PMS) for fast and efficient removal of As(iii) from water. The results of removal experiments show that the complete removal of arsenic (<10 μg L−1) from 1 mg L−1 As(iii) aqueous solution can be achieved within shorter time (<10 min) using this adsorbent coupled with PMS. The maximum adsorption capability of As(iii) and As(v) on the prepared adsorbent is observed to be about 105.78 mg g−1 and 120.32 mg g−1, respectively. CuFe2O4-foam/PMS couple could work effectively in a wide pH range (3.0–9.0) and temperature range (10–60 °C), which is more beneficial to its application in actual water treatment engineering. The exhausted adsorbents can be refreshed for cyclic runs (at least 7 cycles) with insignificant capacity loss using alkaline solution as a regeneration strategy, suggesting this process has good stability. Investigation of the mechanism reveals that the route to the removal of As(iii) is synchronous oxidation and sequestration in the arsenic removal process. The large As(iii) removal capability and stability of CuFe2O4-foam/PMS show its potential as a promising candidate in real As(iii)-contaminated groundwater treatment.Bifunctional heterogeneous catalytic processes for highly efficient removal of arsenic (As(iii)) are receiving increased attention. 相似文献
4.
Nicole A. DiBlasi Agost G. Tasi Michael Trumm Andreas Schnurr Xavier Gaona David Fellhauer Kathy Dardenne Jrg Rothe Donald T. Reed Amy E. Hixon Marcus Altmaier 《RSC advances》2022,12(15):9478
The impact of calcium on the solubility, redox behavior, and speciation of the An(iii)–EDTA (An = Pu or Cm) system under reducing, anoxic conditions was investigated through batch solubility experiments, X-ray absorption spectroscopy (XAS), density functional theory (DFT), and time-resolved laser fluorescence spectroscopy (TRLFS). Batch solubility experiments were conducted from undersaturation using Pu(OH)3(am) as the solid phase in contact with 0.1 M NaCl–NaOH–HCl–EDTA–CaCl2 solutions at [EDTA] = 1 mM, pHm = 7.5–9.5, and [CaCl2] ≤20 mM. Additional samples targeted brine systems represented by 3.5 M CaCl2 and WIPP simulated brine. Solubility data in the absence of calcium were well-described by Pu(iii)–EDTA thermodynamic models, thus supporting the stabilization of Pu(iii)–EDTA complexes in solution. Cm(iii)–EDTA TRLFS data suggested the stepwise hydrolysis of An(iii)-EDTA complexes with increasing pH, and current Pu(iii)-EDTA solubility models were reassessed to evaluate the possibility of including Pu(iii)–OH–EDTA complexes and to calculate preliminary formation constants. Solubility data in the presence of calcium exhibited nearly constant log m(Pu)tot, as limited by total ligand concentration, with increasing [CaCl2]tot, which supports the formation of calcium-stabilized Pu(iii)–EDTA complexes in solution. XAS spectra without calcium showed partial oxidation of Pu(iii) to Pu(iv) in the aqueous phase, while calcium-containing experiments exhibited only Pu(iii), suggesting that Ca–Pu(iii)–EDTA complexes may stabilize Pu(iii) over short timeframes (t ≤45 days). DFT calculations on the Ca–Pu(iii)–EDTA system and TRLFS studies on the analogous Ca–Cm(iii)–EDTA system show that calcium likely stabilizes An(iii)–EDTA complexes but can also potentially stabilize An(iii)–OH–EDTA species in solution. This hints towards the possible existence of four major complex types within Ca–An(iii)–EDTA systems: An(iii)–EDTA, An(iii)–OH–EDTA, Ca–An(iii)–EDTA, and Ca–An(iii)–OH–EDTA. While the exact stoichiometry and degree of ligand protonation within these complexes remain undefined, their formation must be accounted for to properly assess the fate and transport of plutonium under conditions relevant to nuclear waste disposal.Combined advanced spectroscopy and solubility studies provide evidence for the formation of novel calcium-containing and hydrolyzed (Cm,Pu)(iii)–EDTA complex(es). 相似文献
5.
Kazumasa Oshima Hiromichi Kondo Eriko Konishi Tsuyoshi Yamamoto Yoshifumi Tsuge Takayuki Watanabe Masahiro Kishida 《RSC advances》2022,12(26):16843
To remove arsenite (As(iii)) from wastewater effectively, the catalytic oxidation of As(iii) to arsenate (As(v)) and As(v) precipitation with iron ions (Fe(iii)) was investigated. The Pt/SiO2 catalyst functioned as a reaction site for As(iii) with oxygen in the atmosphere. The combination of the Pt/SiO2 catalyst and Fe(iii) precipitant improved the removal of As(iii) in the precipitate; Pt/SiO2 worked as both an As(iii) oxidation site and precipitation site with Fe(iii) precipitant.A Pt/SiO2 catalyst promoted an oxidative reaction of arsenite to arsenate with air, and it also functioned as a nucleation site of its precipitate with iron precipitant, achieving high removal efficiency from water. 相似文献
6.
Xiaolin Zhang Fei Niu Donghui Liu Shimin Yang Youming Yang Zhifang Tong 《RSC advances》2019,9(55):32085
Y mainly exists in ionic rare-earth resources. During rare-earth carbonate precipitation, rare-earth ion loss in the precipitated rare-earth mother liquor often occurs due to CO32− coordination and Y(iii) hydration. Microscopic information on the coordination and hydration of CO32− and H2O to Y(iii) has not yet been elucidated. Therefore, in this study, the macroscopic dissolution of Y(iii) in different aqueous solutions of Na2CO3 was studied. The radial distribution function and coordination number of Y(iii) by CO32− and H2O were systematically analyzed using molecular dynamics (MD) simulations to obtain the complex ion form of Y(iii) in carbonate solutions. Density functional theory (DFT) was used to geometrically optimize and calculate the UV spectrum of Y(iii) complex ions. This spectrum was then analyzed and compared with experimentally determined ultraviolet-visible spectra to verify the reliability of the MD simulation results. Results showed that Y(iii) in aqueous solution exists in the form of [Y·3H2O]3+ and that CO32− is present in the bidentate coordination form. In 0–0.8 mol L−1 CO32− solutions, Y(iii) was mainly present as the 5-coordinated complex [YCO3·3H2O]+. When the concentration of CO32− was increased to 1.2 mol L−1, [YCO3·3H2O]+ was converted into a 6-coordinated complex [Y(CO3)2·2H2O]−. Further increases in CO32− concentration promoted Y(iii) dissolution in solution in the form of complex ions. These findings can be used to explain the problem of incomplete precipitation of rare earths in carbonate solutions.Based on MD results, DFT was used to geometrically optimize and calculate the UV spectrum of Y(iii) complex ions. Data validation was further performed using UV-vis experiments to reveal Y(iii) coordination and hydration properties. 相似文献
7.
In order to effectively destroy the structure of the passive oxidation film that covers zero-valent iron (ZVI), an Fe(iii)-reducing strain, namely Morganella sp., was isolated from anaerobic activated sludge and coated on ZVI, which was distributed in porous ceramsite made of iron dust, kaolin and straw, with a ratio of 7 : 3 : 1. Batch experiments showed that under the optimized conditions, the maximum removal amount of Cr(vi) by ZVI increased from 7.33 mg g−1 to 26.87 mg g−1 in the presence of the Fe(iii)-reducing bacterium. The column experiment was performed with the addition of the agar globules to supply nutrients to the strain. Compared with ZVI, the column penetration time and maximum capture amount of RB-ZVI increased to 17 h and 112.5 mg g−1, respectively, on the 15th day. Furthermore, the service life of RB-ZVI was prolonged in the existence of the strain. Based on X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy analyses, the key mechanisms for the removal of Cr(vi) by ZVI coated with Fe(iii)-reducing bacterium were determined to be adsorption, reduction, coprecipitation and biomineralization.To effectively destroy the structure of the passive oxidation film covering zero-valent iron (ZVI), an Fe(iii)-reducing strain, Morganella sp., was isolated from anaerobic activated sludge and coated on the ZVI. 相似文献
8.
Md. Mahbubul Alam Md. A. Rashed Md. Musfiqur Rahman Mohammed
M. Rahman Yuki Nagao Mohammad A. Hasnat 《RSC advances》2018,8(15):8071
Pd nanoparticles were electrochemically immobilized on a Pt surface in the presence of sodium dodecyl sulfate (SDS) molecules to study the electrokinetics of arsenite oxidation reactions and the corresponding sensing activities. The X-ray photoelectron spectroscopy (XPS) analysis showed that on the Pt surface, Pd atoms exist as adatoms and the contents of Pd(0) and Pd(ii) were 75.72 and 24.28 at%, respectively, and the particle sizes were in the range of 61–145 nm. The experimental results revealed that the catalytic efficiency as well as the charge transfer resistance (at the redox potential of the Fe(ii)/Fe(iii) couple) increased in the order of Pt < Pt–Pd < Pt–Pdsds. A Pt–Pdsds electrode exhibited an open circuit potential (OCP) of 0.65 V in acidic conditions; however, when 50.0 mM NaAsO2 was present, the OCP value shifted to 0.42 V. It has been projected that the As(iii) oxidation proceeds using a sequential pathway: As(iii) → As(iv) → As(v). After optimization of the square wave voltammetric data, the limits of detection of As(iii) were obtained as 1.3 μg L−1 and 0.2 μg L−1 when the surface modification of the Pt surface was executed with Pd particles in the absence and presence of the SDS surfactant, respectively. Finally, real samples were analyzed with excellent recovery performance.Amplification of true surface area can be improved when Pd particles are deposited on a substrate in the presence of sodium dodecyl sulfate (SDS) surfactant. In acidic medium, As(iii) undergoes a two-step oxidation process. 相似文献
9.
Bhuneshwari Sahu Ramsingh Kurrey Manas Kanti Deb Kamlesh Shrivas Indrapal Karbhal Beeta Rani Khalkho 《RSC advances》2021,11(34):20769
We report a simple and cost-effective paper-based and colorimetric dual-mode detection of As(iii) and Pb(ii) based on glucose-functionalized gold nanoparticles under optimized conditions. The paper-based detection of As(iii) and Pb(ii) is based on the change in the signal intensity of AuNPs/Glu fabricated on a paper substrate after the deposition of the analyte using a smartphone, followed by processing with the ImageJ software. The colorimetric method is based on the change in the color and the red shift of the localized surface plasmon resonance (LSPR) absorption band of AuNPs/Glu in the region of 200–800 nm. The red shift (Δλ) of the LSPR band observed was from 525 nm to 660 nm for As(iii) and from 525 nm to 670 nm for Pb(ii). The mechanism of dual-mode detection is due to the non-covalent interactions of As(iii) and Pb(ii) ions with glucose molecule present on the surface AuNPs, resulting in the aggregation of novel metal nanoparticles. The calibration curve gave a good linearity range of 20–500 μg L−1 and 20–1000 μg L−1 for the determination of As(iii) and Pb(ii) with the limit of detection of 5.6 μg L−1 and 7.7 μg L−1 for both metal ions, respectively. The possible effects of different metal ions and anions were also investigated but did not cause any significant interference. The employment of AuNPs/Glu is successfully demonstrated for the determination of As(iii) and Pb(ii) using paper-based and colorimetric sensors in environmental water samples.We report a simple and cost-effective paper-based and colorimetric dual-mode detection of As(iii) and Pb(ii) based on glucose-functionalized gold nanoparticles under optimized conditions. 相似文献
10.
Yu-Ying Wang Hai-Yang Ji Hao-Hao Lu Yu-Xue Liu Rui-Qin Yang Li-Li He Sheng-Mao Yang 《RSC advances》2018,8(6):3264
In this study, a jacobsite–biochar nanocomposite (MnFe2O4–BC) was fabricated and used to simultaneously remove Sb(iii) and Cd(ii) from water via adsorption. The MnFe2O4–BC nanocomposite was prepared via a co-precipitation method and analyzed using various techniques. The results confirm the successful decoration of the biochar surface with MnFe2O4 nanoparticles. The maximum Sb(iii) removal efficiency was found to be higher from bi-solute solutions containing Cd(ii) than from single-solute systems, suggesting that the presence of Cd(ii) enhances the removal of Sb(iii). The Langmuir isotherm model describes well Sb(iii) and Cd(ii) removal via adsorption onto the MnFe2O4–BC nanocomposite. The maximum adsorption capacities are 237.53 and 181.49 mg g−1 for Sb(iii) and Cd(ii), respectively, in a bi-solute system. Thus, the prepared MnFe2O4–BC nanocomposite is demonstrated to be a potential adsorbent for simultaneously removing Sb(iii) and Cd(ii) ions from aqueous solutions.In this study, a jacobsite–biochar nanocomposite (MnFe2O4–BC) was fabricated and used to simultaneously remove Sb(iii) and Cd(ii) from water via adsorption. 相似文献
11.
Eirik Mydske Thoresen Sigurd
ien-
degaard Gurpreet Kaur Mats Tilset Karl Petter Lillerud Mohamed Amedjkouh 《RSC advances》2020,10(15):9052
Four different ruthenium(ii) complexes were incorporated into the metal–organic framework (MOF) UiO-67 using three different synthetic strategies: premade linker synthesis, postsynthetic functionalization, and postsynthetic linker exchange. One of these complexes was of the type (N–N)3Ru2+, and three of the complexes were of the type (N–N)2(N–C)Ru+, where N–N is a bipyridine-type ligand and N–C is a cyclometalated phenylpyridine-type ligand. The resulting materials were characterized by PXRD, SC-XRD (the postsynthetic functionalization MOFs), N2 sorption, TGA-DSC, SEM, EDS, and UV-Vis spectroscopy, and were digested in base for subsequent 1H NMR analysis. The absorption profiles of the MOFs that were functionalized with cyclometalated Ru(ii) complexes extend significantly further into the visible region of the spectrum compared to the absorption profiles of the MOFs that were functionalized with the non-cyclometalated reference, (N–N)3Ru2+.The metal–organic framework (MOF) UiO-67 was functionalized by incorporating different cyclometalated ruthenium(ii) complexes using three different methods: premade linker synthesis, postsynthetic functionalization, and postsynthetic linker exchange. 相似文献
12.
Catherine Chen Charlotte Sommer Helge Thisgaard Vickie McKee Christine J. McKenzie 《RSC advances》2022,12(10):5772
The antimony(iii) complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA) has been prepared and its exceptionally low stability observed. The Sb(iii) ion in Na[Sb(DOTA)]·4H2O shows an approximately square antiprismatic coordination geometry that is close to superimposable to the Bi(iii) geometry in [Bi(DOTA)]− in two phases containing this anion, Na[Bi(DOTA)]·4H2O, [H3O][Bi(DOTA)]·H2O for which structures are also described. Interestingly, DOTA itself in [(H6DOTA)]Cl2·4H2O·DMSO shows the same orientation of the N4O4 metal binding cavity reflecting the limited flexibility of DOTA in an octadentate coordination mode. In 8-coordinate complexes it can however accommodate M(iii) ions with rion spanning a relatively wide range from 87 pm (Sc(iii)) to 117 pm (Bi(iii)). The larger Bi3+ ion appears to be the best metal–ligand size match since [Bi(DOTA)]− is associated with greater complex stability. In the solution state, [Sb(DOTA)]− is extremely susceptible to transmetallation by trivalent ions (Sc(iii), Y(iii), Bi(iii)) and, significantly, even by biologically important divalent metal ions (Mg(ii), Ca(ii), Zn(ii)). In all cases just one equivalent is enough to displace most of the Sb(iii). [Sb(DOTA)]− is resistant to hydrolysis; however, since biologically more abundant metal ions easily substitute the antimony, DOTA complexes will not be suitable for deployment for the delivery of the, so far unexploited, theranostic isotope pair 119Sb and 117Sb.The antimony(iii) complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA) has been prepared and its exceptionally low stability observed. 相似文献
13.
S. A. Abou El-Enein A. M. Ali Y. K. Abdel-Monem M. H. Senna Metwally Madkour 《RSC advances》2019,9(72):42010
A series of metal complexes were prepared from separate reactions of lanthanide nitrate salts (La(iii), Ce(iii), Sm(iii), Gd(iii) and Ho(iii)) with 4-methylbenzoylhydrazide. The structures of the complexes were confirmed by analytical studies, spectral measurements and thermal studies. Complexes were formed with different stoichiometries of 1 : 2 and 1 : 3 (M : L). The ligand chelates by the nitrogen and oxygen atoms of the amino and carbonyl groups of the hydrazide moiety in the neutral keto form. The coordination compounds were converted to metal oxide nanoparticles (MONPs) through solid state thermal decomposition as monocular source precursors. The obtained MONPs were investigated via XRD, TEM and UV-Vis spectra. As a representative, CeO2 was utilized as a nanophotocatalyst to examine the photocatalytic activity of the MONPs for methylene blue (MB) photodegradation. CeO2 showed high removal of MB dye by 90.1% after UV illumination for 220 min. The reported method provides a generalized and systematic method for the preparation of many metal oxide nanoparticles with manageable and reproducible features.A series of metal complexes were prepared from separate reactions of lanthanide nitrate salts (La(iii), Ce(iii), Sm(iii), Gd(iii) and Ho(iii)) with 4-methylbenzoylhydrazide. 相似文献
14.
15.
Yanbiao Liu Jinyu Yao Fuqiang Liu Chensi Shen Fang Li Bo Yang Manhong Huang Wolfgang Sand 《RSC advances》2019,9(32):18196
Herein, nanoscale iron (oxyhydr)oxide-coated carbon nanotube (CNT) filters were rationally designed for rapid and effective removal of Sb(iii) from water. These iron (oxyhydr)oxide particles (<5 nm) were uniformly coated onto the CNT sidewalls. The as-fabricated hybrid filter demonstrated improved sorption kinetics and capacity compared with the conventional batch system. At a flow rate of 6 mL min−1, a Sb(iii) pseudo-first-order adsorption rate constant of 0.051 and a removal efficiency of >99% was obtained when operated in the recirculation mode. The improved Sb(iii) sorption performance can be ascribed to the synergistic effects of convection-enhanced mass transport, limited pore size, and more exposed active sorption sites of the filters. The presence of 1–10 mmol L−1 of carbonate, sulfate, and chloride inhibits Sb(iii) removal negligibly. Exhausted hybrid filters can be effectively regenerated by an electrical field-assisted chemical washing method. STEM characterization confirmed that Sb was mainly sequestered by iron (oxyhydr)oxides. XPS, AFS and XAFS results suggest that a certain amount of Sb(iii) was converted to Sb(v) during filtration. DFT calculations further indicate that the bonding energy for Sb(iii) onto the iron (oxyhydr)oxides was 2.27–2.30 eV, and the adsorbed Sb(iii) tends to be oxidized.Herein, nanoscale iron (oxyhydr)oxide-coated carbon nanotube (CNT) filters were rationally designed for rapid and effective removal of Sb(iii) from water. 相似文献
16.
In this study, a granular red mud supported zero-valent iron (ZVI@GRM) was successfully prepared and was used to remove Pb(ii) and Cr(vi) from aqueous solution. Zero-valent iron (ZVI) was synthesized by direct reduction of iron oxide in red mud by maize straw as a reductant at 900 °C in an anoxic atmosphere. The technical characterization (SEM, EDS, XRD, FTIR and BET) revealed that ZVI@GRM was loaded with zero-valent iron and contained different size pores. The factors of adsorption experiments include initial concentration, contact time, pH and temperature. The Pb(ii) and Cr(vi) removal by ZVI@GRM well fitted the pseudo-second-order kinetics model and the removal of heavy metals was an endothermic process. Essentially, Pb(ii) was transformed to precipitate forms (Pb0, Pb (OH)2, or 2PbCO3·Pb (OH)2) and Cr(vi) was converted to Cr (OH)3 or Cr3+/Fe3+ hydroxides. The maximum removal capacity for Pb(ii) and Cr(vi) by ZVI@GRM was 149.42 and 37.14 mg g−1. ZVI@GRM was a low-cost material and had outstanding performance and great potential in wastewater treatment.In this study, a granular red mud supported zero-valent iron (ZVI@GRM) was successfully prepared and was used to remove Pb(ii) and Cr(vi) from aqueous solution. 相似文献
17.
In this work, an outstanding nanolayered tin phosphate with 15.0 Å interlayer spacing, Sn (HPO4)2·3H2O (SnP–H+), has been synthesized by conventional hydrothermal method and first used in the adsorptive removal of Cr(iii) from aqueous solution. A number of factors such as contact time, initial concentration of Cr(iii), temperature, pH, and ionic strength on adsorption were investigated by batch tests. Moreover, the isothermal adsorption characteristics and kinetic model of Cr(iii) onto SnP–H+ were studied. The results showed that the adsorption of Cr(iii) by SnP–H+ was in accordance with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. The adsorption capacity of Cr(iii) onto SnP–H+ at temperature 40.0 °C and pH 3.0 could reach 81.1 mg g−1. And the distribution coefficient Kd was 23.0 g L−1. Overall, experiments certified that SnP–H+ was an excellent adsorbent that can effectively remove Cr(iii) from aqueous solution.In this work, an outstanding nanolayered tin phosphate with 15.0 Å interlayer spacing, Sn (HPO4)2·3H2O (SnP–H+), has been synthesized by conventional hydrothermal method and first used in the adsorptive removal of Cr(iii) from aqueous solution. 相似文献
18.
Stylianos Spathariotis Nand Peeters Karl S. Ryder Andrew P. Abbott Koen Binnemans Sofia Riao 《RSC advances》2020,10(55):33161
Deep eutectic solvents (DESs) were used as alternatives to the aqueous phase in solvent extraction of iron(iii), zinc(ii) and lead(ii). The selective extraction of iron(iii) and zinc(ii) was studied from a feed of ethaline (1 : 2 molar ratio of choline chloride : ethylene glycol) and lactiline (1 : 2 molar ratio of choline chloride : lactic acid), with the former DES being more selective. A commercial mixture of trialkylphosphine oxides (Cyanex 923, C923) diluted in an aliphatic diluent selectively extracted iron(iii) from a feed containing also zinc(ii) and lead(ii). The subsequent separation of zinc(ii) from lead(ii) was carried out using the basic extractant Aliquat 336 (A336). The equilibration time and the extractant concentration were optimized for both systems. Iron(iii) and zinc(ii) were stripped using 1.2 mol L−1 oxalic acid and 0.5 mol L−1 aqueous ammonia, respectively. An efficient solvometallurgical flowsheet is proposed for the separation and recovery of iron(iii), lead(ii) and zinc(ii) from ethaline using commercial extractants. Moreover, the process was upscaled in a countercurrent mixer-settler set-up resulting in successful separation and purification.Deep eutectic solvents (DESs) were used as alternatives to the aqueous phase in solvent extraction of iron(iii), zinc(ii) and lead(ii). 相似文献
19.
Tat'yana G. Khonina Elena Yu. Nikitina Alexander Yu. Germov Boris Yu. Goloborodsky Konstantin N. Mikhalev Ekaterina A. Bogdanova Denis S. Tishin Alexander M. Demin Victor P. Krasnov Oleg N. Chupakhin Valery N. Charushin 《RSC advances》2022,12(7):4042
Iron(ii) and iron(iii) salts of strong acids form iron glycerolates on heating at 180 °C with glycerol in the presence of an equivalent amount of alkali. Individual iron(iii) glycerolate was obtained for the first time. When Fe3O4 magnetic nanoparticles were heated with glycerol, an iron(iii) glycerolate shell was formed on their surface.Individual iron(iii) glycerolate was obtained and characterized; a method for the preparation of an iron(iii) glycerolate shell on the surface of Fe3O4 MNPs was proposed.Currently, glycerolates of various metals (Ti, Co, Fe, Zn, etc.) are used as catalytic systems1,2 or as precursors to obtain nanoparticles, including iron oxide magnetic nanoparticles (MNPs),3 and nanostructure materials for technical and biomedical applications.4–8Glycerolates of biogenic elements (Si, Zn, B and Ti) are of particular interest because of their biological activity. They are used as biocompatible precursors in the sol–gel synthesis of pharmacologically active hydrogels with reparative, regenerative, antioxidant, immunotropic and antimicrobial effects.8–10 In this regard, glycerolate of the biogenic iron element can be considered as an innovative biocompatible precursor in the sol–gel synthesis of composite bioactive hydrogels possessing a haemostatic effect characteristic of various iron compounds.11A promising trend in biomedicine is the core–shell modification of Fe3O4 MNPs for MRI diagnostics or magnetic hyperthermia of tumors.12–14 So, the development of an iron glycerolate shell on the surface of Fe3O4 MNPs15 and studying an opportunity of using modified nanoparticles in magnetic hyperthermia is of particular interest. In addition, the antibacterial activity of Fe3O4 MNPs with glycerol adsorbed on the surface was also demonstrated.16,17In the literature, individual iron(ii) and iron(iii) glycerolates have not so far been described. At the same time, the synthesis of individual forms is extremely important for biomedical purposes in order to determine bioavailability parameters. The available literature data concern only mixed iron(ii,iii) glycerolate that is usually formed as a result of the interaction of di- or trivalent iron oxides, hydroxides or salts (mainly oxalates) with glycerol at elevated temperatures (up to 245 °C).15,18–20 It is worth noting that all attempts to synthesize iron glycerolates from chlorides and sulfates of ferrous or ferric irons proved to be unsuccessful.20 At the same time, iron glycerolate was obtained from iron(iii) nitrate in boiling glycerol under reflux (280 °C);3 however, contents of iron(iii) and iron(ii) were not determined in that product.Regardless of the iron valence state in the starting compound, Fe(ii) and Fe(iii) are present in the resulting glycerolate in all cases. It should be noted that the possible pathways of the redox process for obtaining mixed iron(ii,iii) glycerolate are not discussed in the literature. The quantitative Fe(ii)/Fe(iii) ratio is usually determined by the Mössbauer spectroscopy21 or the colorimetric method.19 The composition of iron(ii,iii) glycerolate is mainly described by the following formulas: Fe2C6H11O6 (powder diffraction file JCPDSD-ICDD PDF 2, card [23-1731])18 and Fe3+2Fe2+3(C3H5O3)4.19–21 It was not possible to obtain single crystals of iron glycerolate and calculate the unit cell parameters.4,18We have found that the reactions of iron(ii) or iron(iii) chlorides and sulfates with glycerol proved to proceed only in the presence of an equivalent amount of alkali to give glycerolates of various chemical compositions. Thus, for the first time, individual iron(iii) glycerolate FeC3H5O3 (1) was obtained in 91% yield on heating iron(iii) chloride hexahydrate FeCl3·6H2O with sodium hydroxide in an excess of glycerol C3H8O3 at 180 °C for 18 h (Scheme 1) (see ESI†).Open in a separate windowScheme 1Synthesis of iron(iii) glycerolate 1.The resulting product 1 is a light green powder insoluble in water and organic solvents, thus indicating a probable polymeric structure. It should be noted that the reaction temperature (180 °C) and duration (18 h) appear to be optimal taking into account a high yield of the product and its purity.Heating iron(ii) sulfate heptahydrate FeSO4·7H2O in glycerol in the presence of an equivalent amount of NaOH under the same conditions (180 °C, 18 h) resulted in mixed iron(ii,iii) glycerolate Fe3+2Fe5+3(C3H5O3)7 (2) in 83% yield (see ESI†). The resulting product is a dark green powder that is poorly soluble in water and organic solvents.Iron glycerolates 1 and 2 were formed as colored powders; they are storage stable with no change in structure and no noticeable change in color; they do not melt to decomposition temperature. Dilute acids or hot water caused decomposition with the production of glycerol and iron (hydroxy)oxides or salts, as it was noted earlier.18 Plausible pathways for the formation of iron glycerolate 1, as well as iron glycerolate 2 (Scheme 2) and the features of the process are discussed below.Open in a separate windowScheme 2Formation of iron(ii,iii) glycerolate 2.Magnetic materials based on Fe3O4 nanoparticles with a biologically compatible coating are of great interest for biology and medicine.12–14 Previously, we were the first to demonstrate the possibility of forming a shell of iron glycerolate on the surface of Fe3O4 MNPs by a simple and reproducible method, namely, by interacting Fe3O4 MNPs with glycerol at 220 °C for 40 h.15 In this work, we optimized the synthetic procedure and chose the optimum conditions (180 °C, 18 h) (see ESI†). The composition of the resulting shell was found to correspond to iron glycerolate 1.To determine the Fe(ii)/Fe(iii) ratio in the obtained products, we used the Mössbauer spectroscopy. Fig. 1 shows the Mössbauer spectra of iron glycerolates 1 (a and c) and 2 (b). The samples were prepared by deposition of the powder onto aluminum foil with a diameter of 22 mm (see ESI†).Open in a separate windowFig. 1 57Fe Mössbauer spectra at 295 K of (a) iron(iii) glycerolate 1, (b) iron(ii,iii) glycerolate 2, and (c) iron(iii) glycerolate 1 from Fe3O4 MNPs. The doublets of Fe3+ and Fe2+ ions are marked in red and blue, respectively. The black line represents the sum of these lines. Sodium nitroprusside C5FeN6Na2O was taken as reference.The Mössbauer spectrum of iron glycerolate 1 (Fig. 1a) contains only one doublet (red line) with quadrupole splitting value of 0.48 mm s−1 (iii) positions,21 at the same time there are no signals typical for Fe(ii). The Mössbauer spectrum of iron glycerolate 2 (Fig. 1b) contains two doublets (red and blue lines) with quadrupole splitting Qs values of 0.46 and 2.29 mm s−1 (iii) and Fe(ii) positions, respectively.21 In this case, the content of Fe(ii) was 38%; Fe(iii), 62%.Fitting parameters of 57Fe Mössbauer spectra (Fig. 1) for iron glycerolates
Open in a separate windowThe Mössbauer spectrum of a sample obtained from Fe3O4 MNPs (Fig. 1c) also contains a doublet (red line) with Qs = 0.51 mm s−1 (iii). Any signals typical for Fe(ii) are absent, which confirms the presence of a shell of iron glycerolate 1. It should be noted that the signals of Fe(ii) contained in the core of the Fe3O4 MNPs were not recorded under these conditions of spectrum registration.The results of the quantitative determination of Fe(ii) and Fe(iii) by the Mössbauer spectroscopy in the studied products, as well as the data of their elemental analyses (Iron glycerolate Composition (%) Experimental Calculated C H Fe C H Fe FeC3H5O3 (1) 24.75 3.44 38.40 24.86 3.48 38.54 Fe2C6H11O6a 24.70 3.25 41.00 24.78 3.81 38.40 Fe3+2Fe2+3(C3H5O3)4b 22.47 3.31 43.69 22.68 3.17 43.94 Fe3+2Fe5+3(C3H5O3)7 (2) 23.12 3.20 41.89 23.66 3.48 41.22
Sample | Starting material | Spectral lines | Isomer shift, δiso (mm s−1) | Q S (mm s−1) | Relative content (%) | Line width (mm s−1) |
---|---|---|---|---|---|---|
Iron(iii) glycerolate 1 (a) | FeCl3·6H2O | Fe3+ | 0.66 | 0.48 | 100 | 0.31 |
Iron(iii) glycerolate 1 (c) | Fe3O4 MNPs | Fe3+ | 0.66 | 0.51 | 100 | 0.33 |
Iron(ii,iii) glycerolate 2 (b) | FeSO4·7H2O | Fe3+ | 0.66 | 0.46 | 62 | 0.24 |
Fe2+ | 1.33 | 2.29 | 38 | 0.30 |