Basic Anion Research Articles

Preconcentration of Zinc, Cadmium, and Mercury(II) Ions on a Polymeric Modified Adsorbent Based on a Highly Basic ARA-8p Anionite and a Rhodanine Derivative

We studied the conditions for the adsorption of zinc, cadmium, and mercury(II) ions on a modified adsorbent based on an ARA-8p highly basic anion exchange resin and a Rhodanine derivative, 5-(4-carboxyphenyl-azo)rhodanine (ARA-8p-p-KBAR), in a batch mode. The values of pH, phase contact time, and adsorbate concentration at which the maximum recovery of zinc, cadmium, and mercury(II) ions was achieved were determined. The adsorption capacity of the adsorbent for the adsorbed ions was determined from the obtained adsorption isotherms. The calculated value of the free energy shows that adsorption proceeds with the formation of an ionic bond. Eluents were selected to ensure the quantitative desorption of zinc, cadmium, and mercury(II) ions. The interfering effect of macrocomponents and trace elements of water was studied; zinc, cadmium, and mercury(II) ions were quantitatively adsorbed by this adsorbent from a solution of a complex composition. A procedure was developed for the adsorption–atomic-absorption determination of zinc, cadmium, and mercury(II) ions in various water samples.

Efficient adsorption of alginate oligosaccharides by ion exchange resin based on molecular simulation and experiments

Alginate oligosaccharides (AOS) with low polymerization have gained considerable attention due to their unique physiological activities. However, the lack of understanding regarding the mechanism of action for resin selection and optimization of separation processes has impeded their precise chromatographic separation and large-scale production. Here, the adsorption–desorption characteristics of AOS on the resins with varying solid phase composition, including backbones, functional groups, crosslinking degrees, and counterions resin structures, were analyzed using simulations and experiments. The simulation results revealed that the structural differences of AOS are characterized by their electrostatic potential and lowest unoccupied molecular orbital energy level. Based on molecular simulations, we predicted that the basic anion resin with a styrene backbone would be suitable for AOS separation. Subsequently, we constructed SM-7Cl resin based on the simulation results and performed static adsorption experiments to verify the prediction. SM-7Cl resin demonstrated noteworthy adsorption–desorption performance for AOS, with an adsorption capacity of 471.2 mg/g and a desorption rate of 89.45%. The fitting adsorption isotherm was consistent with the Freundlich model, indicating that the adsorption proceeded spontaneously. The equilibrium times for AOS adsorption on the gel-type resin and the macroporous resin, which both followed a pseudo-second-order kinetic model, were 30 min and 60 min, respectively. This study provides optimized chromatographic media and separation processing that can be implemented for the amplification of chromatographic separation in AOS production.

New Halide-Based Sodium-Ion Conductors Na3Y2Cl9 Inversely Designed by Building Block Construction.

Due to the excellent ionic conductivity and compatibility with high-voltage cathodes, halide-based superionic conductors as promising electrolytes have received widespread attention. A series of halide-based conductors, including Na3YCl6, are investigated aiming to find new solid electrolytes for sodium-ion batteries. However, Na3YCl6 with high ionic conductivity is meta-stable in thermostability while the stable phase exhibits poor ionic transport properties. In this work, we find that the coplanar formed anionic group (Y2Cl9)3- is the result of a combination of the structural features of the fast ion phase and stable phase of Na3YCl6 by systematic analysis of crystal structures. Aiming to find fast sodium-ion conductors, the three-step structure construction method using functional (Y2Cl9)3- groups as building blocks is proposed, and three new crystal structures in the composition of Na3Y2Cl9 with the space group of P63, Cc, and R32 are obtained. Na+ transport properties, thermostability, and electrochemical window of these structures with various symmetries are investigated by first-principles calculation methods. The results show that the principle to inverse design crystal structures of halides by basic blocks, e.g., anion groups and mobile cations, is proven to be effective and successful. For P63-Na3Y2Cl9 with outstanding transport properties, the simulation results indicate that its superionic behavior is attributed to the coherent diffusion connecting two directions. The synchronization of the migration pathways along the ab plane and the migration pathways along the c direction promotes the Na ion conductivity in Na3Y2Cl9. Our research will promote the understanding of the transport mechanism in halide-based electrolytes, and the structure construction method based on functional basic building blocks and special stacking modes will accelerate the inverse design of inorganic crystal structures.

Use of ionic liquids for extraction separation and concentration of iodide ions in brine samples.

Iodine in natural salt waters such as iodine-rich underground brine generally exists as iodide ions, and to extract iodide ions, it is necessary to oxidize them to nonpolar iodine molecules. In this study, we report that iodide ions in natural brine containing high concentrations of chloride ions can be quantitatively extracted without oxidation by extraction using ionic liquids. Extraction with the ionic liquids trihexyltetradecylphosphonium chloride and trioctyl ammonium chloride was found to be able to enrich trace amounts of iodide in brine samples up to 40- and 100-fold, respectively. The selectivity coefficients for I- over Cl- determined in this study clearly show that the ionic liquids have much higher I-/Cl- selectivity than typical strongly basic anion exchangers. Extraction with trihexyltetradecylphosphonium chloride was applicable as a preconcentration method for iodine determination by XRF analysis. Iodide ions extracted with trioctyl ammonium chloride were quantitatively stripped with an aqueous alkaline solution. These results indicate that ionic liquid extraction is useful for the separation and concentration of iodide from brines.

Green and Cost-Effective Separation of Cadmium from Base Metals in Chloride Medium with Halide-Loaded Anion Exchanger

A novel strategy for the separation of cadmium from base metals in chloride medium by anion exchange based on the formation of cadmium halo-complexes is presented in this article. Instead of using excess Br− or I− in the feed solution, the anion exchange resin or fibre was first preloaded with Br− or I− for Cd2+ adsorption from Cl− solution. Thus, the consumption of iodide or bromide was minimized while promising high adsorption stability of Cd2+. The adsorption thermodynamics and kinetics of Cd2+ were studied. The adsorption thermodynamics results were processed with Langmuir and Freundlich models and adsorption kinetics results were treated with Pseudo first order model, Pseudo second order model and intraparticle diffusion model. The adsorption mechanism was studied with the aid of FTIR and elemental analysis. Three strategies were applied for the stripping of Cd2+, including the use of water for disequilibrating its halo-complex formation, the formation of positively charged species with ammonia, and the formation of positively charged chelate with multidentate ligand ethylenediamine. On the bases of these results, separation performance was investigated with strongly basic anion exchange resin and fibre, and it was shown that Cd2+ can be efficiently separated from base metals in a wide range of acidity, and that pure Cd2+ solution can be obtained, thus providing a robust, environmentally friendly, and economic technology for its separation.

Assessment of the ecological state of water bodies of the drainless area of the Ob-Irtysh River basin

Aim. Assess the current state of water bodies, compare with retrospective study data, update the bank of hydrological, hydrochemical and hydrobiological information.Material and Methods. Three groups of indicators were used: hydrological, hydrochemical and hydrobiological. Hydrological measurements were carried out to determine the flow of water in the rivers and their sections not covered by the Roshydromet observation system. Hydrochemical analysis of samples was carried out by ion chromatography and spectrophotometry and included the determination of basic cations and anions, organic substances and biogens. The assessment of water quality by hydrobiological indicators was carried out using the structural characteristics of phyto- and zooplankton.Results. According to environmental and sanitary indicators, the water quality of only three rivers - Solonovka, Cheremshanka and Burla (downstream) - belongs to class 4 (polluted waters). Most of the rivers have the 2nd class of water quality (clean).Conclusions. A trend towards an increase in the level of mineralization and metamorphization of the chemical composition of natural waters in the inland region of the Ob-Irtysh interfluve was revealed. The pollution of water bodies with organic substances and biogens was noted.

Active Pd intermediates of the Suzuki-Miyaura reaction with low reactive aryl chlorides under “ligand-free” conditions

Despite extensive studies regarding Pd intermediates reacting in the transmetalation step of the Suzuki–Miyaura reaction (SMR), direct evidence obtained under real turnover conditions supporting the widely accepted assumptions regarding the activity of Pd hydroxo complexes is lacking. Herein, results concerning the major reactivity of Pd-OH- and/or Pd-OR-containing complexes (RO− is the base anion) in the transmetalation step with arylboronic acid under “ligand-free” turnover conditions are presented. By contrast, aryl chloride activation was mainly realized through halide-containing Pd complexes. Data regarding the catalytic involvement of particular Pd species were obtained under real catalytic conditions by measuring differential selectivity of the competing reactions. In the reaction with demanding aryl chlorides catalyzed by “ligand-free” catalytic systems that is optimal from the viewpoints of environment, cost, and availability, the composition of active Pd complexes in the transmetalation step was similar to that for the reaction using more reactive aryl bromides and iodides.

Probing the Role of the Bridging Nitrogen in the Signaling Mechanism of an Anthracene–Boronic Acid Sugar Sensor and a Different Version of the PET-Based Mechanism

The N-quaternized derivative 5 of the James-Shinkai anthracene-boronic acid fluorescence sugar sensor 1 was prepared to probe the role of the bridging nitrogen in the signaling mechanism of 1. Both 5 and 1 contain positively charged bridging groups NMe+ or NH+, respectively, but 5 lacks the ability to form the intramolecular ammonium-boronate doubly ionic hydrogen bond present in 1. Receptors 1 and 5 display opposite fluorescence vs pH profiles with a small turn-on effect of the sugar binding to the zwitterion of 5 in contrast to a large effect observed with 1. It is concluded that the ammonium-boronate hydrogen bond is essential for the signaling mechanism of 1. Its possible function is enabling the PET quenching effect by shifting the NH+ proton toward boronate anion inside the hydrogen bond, the degree of which is modulated by the ester formation with diols affecting the basicity of boronate anion. This mechanism agrees with observed signaling selectivity of 1 toward a series of di- and polyols of variable structures as well as with the behavior of 1 in buffered D2O and methanol solvents at controlled pH and provides an addition to the established "loose bolt" mechanism signaling mode essential for receptors with nonpolar fluorophores.

Adsorptive Removal of Direct Azo Dyes from Textile Wastewaters Using Weakly Basic Anion Exchange Resin

Direct dyes are still widely used for coloring a variety of materials due to their ease of use and the wide range of colors available at a moderate cost of production. In the aquatic environment, some direct dyes, especially the azo type and their biotransformation products, are toxic, carcinogenic and mutagenic. Hence the need for their careful removal from industrial effluents. It was proposed adsorptive retention of C.I. Direct Red 23 (DR23), C.I. Direct Orange 26 (DO26) and C.I. Direct Black 22 (DB22) from effluents using anion exchange resin of tertiary amine functionalities Amberlyst A21 (A21). Applying the Langmuir isotherm model, the monolayer capacities were calculated as 285.6 mg/g for DO26 and 271.1 mg/g for DO23. The Freundlich isotherm model seems to be the better one for the description of DB22 uptake by A21, and the isotherm constant was found to be 0.609 mg1-1/n L1/n/g. The kinetic parameters revealed that the pseudo-second-order model could be used for the description of experimental data rather than the pseudo-first-order model or intraparticle diffusion model. The dye adsorption decreased in the presence of anionic and non-ionic surfactants, while their uptake was enhanced in the presence of Na2SO4 and Na2CO3. Regeneration of the A21 resin was difficult; a slight increase in its efficiency was observed using 1M HCl, 1 M NaOH and 1 M NaCl solutions in 50% v/v methanol.

Multi-channel anion sensing behaviour of a Ru(II)-bipyridine complex based on benzothiazolyl pyrazole ligand: Experimental and implication of machine learning tools for data prediction

Multi-channel anion sensing characteristics of a Ru(II) complex of the form [(bpy)2Ru (Hpzbzth)](ClO4)2 (1) {bpy = 2,2′-bipyridine and Hpzbzth = 3,5-bis(benzthiazol-2-yl)pyrazole} has been carried out in this work and analyzed through multiple machine learning tools. The complex possesses one pyrazole NH proton in its outer sphere which upon interaction with specific anions yields considerable change in its photo-redox behaviours. The anion sensing aspect of the complex is systematically investigated in acetonitrile through absorption, steady state and time-resolved emission spectroscopy as well as by square-wave (SWV) voltammetry. In absence of anions, the complex displays emission and represents the “on-state”, while complete quenching of emission takes place in presence of basic anions and designates the “off-state” of the system. The initial state of the complex could also be restored upon addition of acid and the process is reversible. Essentially, the complex acts as anion- and acid-induced molecular switches. The absorption, emission and electrochemical outputs of the complex in presence of anions and acid are employed to mimic different types of Boolean and Fuzzy logic (FL) functions. Additionally, we implemented herein different deep learning tools such as artificial neural networks (ANNs) and adaptive neuro-fuzzy inference system (ANFIS) to envisage the full anion sensing aspects of the complex. The outcomes of the three models are compared and also tallied with the experimental results.

Anionic Effects on Li-Ion Activity and Li-Ion Intercalation Reaction Kinetics in Highly Concentrated Li Salt/Propylene Carbonate Solutions

Certain highly concentrated electrolytes (HCEs) enhance the charge-transfer reaction rate at the electrode/electrolyte interface in Li-ion batteries. The solvation structure of Li+ in HCEs significantly affects the electrochemical interfacial reaction kinetics. However, the effects of different anions on these kinetics have not yet been fully understood. Therefore, in this study, we investigated the effects of anionic species on the liquid structure and electrochemical reactions of HCEs composed of various Li salts and propylene carbonate (PC). Raman spectra revealed that both PC and anions were coordinated to Li+ ions in HCEs and that the concentration of uncoordinated (free) PC changed depending on the anionic species. Consequently, the activity of Li+ in the electrolyte changed depending on the anionic species. The use of Li salts with weakly Lewis basic anions increased the activity of Li+ and decreased the concentration of free PC in HCEs. The activity of Li+ in the electrolyte significantly affected the Li+ intercalation/deintercalation reaction rate of the LiCoO2 thin-film electrode. Electrochemical impedance spectroscopy revealed that the interfacial reaction rate of LiCoO2 was enhanced in the HCEs with anions having weaker Lewis basicity owing to the higher Li+ ion activity.

Tuning Ionic Liquid-Based Catalysts for CO2 Conversion into Quinazoline-2,4(1H,3H)-diones.

Carbon capture and storage (CCS) and carbon capture and utilization (CCU) are two kinds of strategies to reduce the CO2 concentration in the atmosphere, which is emitted from the burning of fossil fuels and leads to the greenhouse effect. With the unique properties of ionic liquids (ILs), such as low vapor pressures, tunable structures, high solubilities, and high thermal and chemical stabilities, they could be used as solvents and catalysts for CO2 capture and conversion into value-added chemicals. In this critical review, we mainly focus our attention on the tuning IL-based catalysts for CO2 conversion into quinazoline-2,4(1H,3H)-diones from o-aminobenzonitriles during this decade (2012~2022). Due to the importance of basicity and nucleophilicity of catalysts, kinds of ILs with basic anions such as [OH], carboxylates, aprotic heterocyclic anions, etc., for conversion CO2 and o-aminobenzonitriles into quinazoline-2,4(1H,3H)-diones via different catalytic mechanisms, including amino preferential activation, CO2 preferential activation, and simultaneous amino and CO2 activation, are investigated systematically. Finally, future directions and prospects for CO2 conversion by IL-based catalysts are outlined. This review is benefit for academic researchers to obtain an overall understanding of the synthesis of quinazoline-2,4(1H,3H)-diones from CO2 and o-aminobenzonitriles by IL-based catalysts. This work will also open a door to develop novel IL-based catalysts for the conversion of other acid gases such as SO2 and H2S.

Determination of the Ni(II) Ions Sorption Mechanism on Dowex PSR2 and Dowex PSR3 Ion Exchangers Based on Spectroscopic Studies.

This paper estimates the suitability of the strongly basic anion exchangers, Dowex PSR2 and Dowex PSR3, as sorbents of nickel ions in aqueous solutions. These actions are aimed at searching for new solutions due to the growing discharge of nickel into wastewaters, primarily due to its addition to steel. The nickel sorption experiments were conducted under static conditions and resulted in the optimization of pH, phase contact time, initial solution concentration, and temperature. The next step was to calculate the kinetic, isothermal, and thermodynamic parameters. Moreover, the ion exchangers were characterized by means of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and CHN elemental analysis. It was found that the sorption process was most effective at pH 6 after 240 min and at the temperature of 293 K. The values of the thermodynamic parameters revealed that the adsorption was exothermic and spontaneous. The physicochemical analyses combined with the experimental research enabled determination of the sorption mechanism of Ni(II) ions.

Iron(III) Complexation with Barbituric and 2-Thiobarbituric Acids in Aqueous Solution

Complexation in systems containing iron(III) chloride and barbituric (H2BA) or 2-thiobarbituric (H2TBA) acid has been studied by spectrophotometry and pH-metry in the pH range of 1.3–3.3 (I = 0.1 (NaCl), t = 20°C). The presence of 1 : 1 complexes with mono- and deprotonated forms of the ligand has been established, and their stability constants (in log units) have been determined: 1[FeHBA]2+ (3.49 ± 0.15), [FeHTBA]2+ (2.69 ± 0.07), [FeBA]+ (12.22 ± 0.13), and [FeTBA]+ (11.05 ± 0.08). It has been shown that the higher thermodynamic stability of barbiturate complexes compared to 2-thiobarbiturate ones is due to the greater basicity of the barbiturate anion. Based on the stability constants obtained, it has been proposed to use orthophosphate, fluoride, and ethylenediaminetetraacetate ions to eliminate the interfering effect of iron(III) in the determination of malondialdehyde by the thiobarbiturate method. Orthophosphoric acid is the most convenient for practical applications, as it makes it possible to mask iron(III) and to create a strongly acidic medium necessary for the formation of a colored malondialdehyde–H2TBA adduct.

Pilot-Scale Field Demonstration of Environmental Nanotechnology for Groundwater Defluoridation

Fluoride contamination in groundwater is a global issue. Nanoscale oxides of Zr(IV), Al(III), and Ti(IV) can form the inner-sphere complex with fluoride through ligand exchange, offering a new chance for efficient groundwater purification. However, pilot-scale field demonstration of nanotechnology in groundwater defluoridation is very rare. Herein, we conducted a 150-day field defluoridation study using the nanocomposite HZO@D201, which was prepared by encapsulating nano-hydrated zirconium oxide (HZO) inside the strongly basic anion exchanger D201. The HZO@D201 beads were packed in five-stage series columns (40 L for each column), and the groundwater was pumped through the columns sequentially. The effective treatment amount for the single column ([F–] < 1.0 mg/L) exceeded ∼3000 bed volume (BV). The exhausted HZO@D201 was fully refreshed through ex situ treatment with NaOH–NaCl solution for repeated use without significant loss in defluoridation reactivity. Owing to the specific interaction with HZO, the fluoride concentration could be steadily reduced below 1.0 mg/L throughout the 150-day field demonstration, while the common anions coexisting in groundwater (K+, Na+, Ca2+, Mg2+, SO42–, Cl–, etc.) remained almost unchanged. The operational cost for deep defluoridation was estimated as 0.574 RMB per ton of groundwater, much less than that of the widely studied reverse osmosis. TEM, XPS, and Fourier transform infrared (FTIR) analysis indicated that negligible change occurred in the structure and chemical composition of HZO@D201 after the long-term field assay. This study may inspire more attempts at the pilot scale and engineering demonstration of nano-enabled water treatment techniques.

Molecular Pincers Using a Combination of N-H and C-H Donors for Anion Binding.

A naphthalene imide (1) and a naphthalene (2) bearing two pyrrole units have been synthesized, respectively, as anion receptors. It was revealed by 1H NMR spectral studies carried out in CD3CN that receptors 1 and 2 bind various anions via hydrogen bonds using both C-H and N-H donors. Compared with receptor 2, receptor 1 shows higher affinity for the test anions because of the enhanced acidity of its pyrrole NH and naphthalene CH hydrogens by the electron-withdrawing imide substituent. Molecular mechanics computations demonstrate that the receptors contact the halide anions via only one of the two respective available N-H and C-H donors whereas they use all four donors for binding of the oxyanions such as dihydrogen phosphate and hydrogen pyrophosphate. Receptor 1, a push-pull conjugated system, displays a strong fluorescence centered at 625 nm, while receptor 2 exhibits an emission with a maximum peak at 408 nm. In contrast, upon exposure of receptors 1 and 2 to the anions in question, their fluorescence was noticeably quenched particularly with relatively basic anions including F-, H2PO4-, HP2O73-, and HCO3-.

ЛЕЙКОЦИТЫ И ТРОМБОЦИТЫ ПЕРИФЕРИЧЕСКОЙ КРОВИ ТЮЛЬКИ ЧЕРНОМОРСКО-КАСПИЙСКОЙ (CLUPEONELLA CULTRIVENTRIS, NORDMANN 1840) ИВАНЬКОВСКОГО И УГЛИЧСКОГО ВОДОХРАНИЛИЩ

For the first time, the hematological parameters of tyulka (Clupeonella cultriventris, Nordmann, 1840) in the reservoirs of the Upper Volga were studied. The composition of leukocytes and thrombocytes, morphometric characteristics of cells were studied by routine methods of light microscopy. It was shown that blood of tyulka has a lymphocytic character, but an increase in the number of granulocytes and their size was found against the background of a decrease in the number of lymphocytes in tyulka a in the lower section of the Ivankovo ‒ the upper section of the Uglich reservoirs, which may indicate the presence of anthropogenic pressure. The proportion of thrombocytes was approximately three times higher than the proportion of leukocytes, which indicates a high blood clotting of the tyulka. Correlations between the characteristics of leukocytes and platelets and the content of basic cations and anions in water were studied.

Modified Ion Exchange Resin Method for Extraction of Micronutrient Cations from Soils

ABSTRACT Different chemical extractants and ion exchange resins are used to assess the bioavailability of soil nutrients for crop plants. The major problems associated with the use of IER in soil testing are their reusability and the difficulties encountered in their separation from the soil being extracted. We addressed these difficulties by encapsulating a weakly acidic cation exchange resin and weakly basic anion exchange resin in separate dialysis membrane pouches and suspending them together in a cellulose extraction thimble during extraction. The suitability of this method has been evaluated for diverse types of soils widely varying in physicochemical properties. The standardization of protocol revealed that the ideal conditions for extraction of micronutrients were: 20:40 soil water ratio and 4 h extraction at 25°C in a shaker incubator at 120 rpm. This simple modified ion exchange resin method can be used multiple times for routine soil tests in laboratories for extraction of cationic micronutrients. The soil extracts can be analyzed for cationic micronutrients. The coefficients of determination (R2) between resin extractable- and diethylene triamine pentaacetic acid extractable- nutrients were 0.31, 0.59, 0.67, and 0.88 for Zn, Cu, Fe, and Mn, respectively.

New Chelate Resins Prepared with Direct Red 23 for Cd2+, Ni2+, Cu2+ and Pb2+ Removal.

In this paper, two chelate resins prepared by a simple procedure were used for the removal of Cd2+, Ni2+, Cu2+, and Pb2+ (M2+) from aqueous solutions. Amberlite IRA 402 strongly basic anion exchange resin in Cl- form (IRA 402 (Cl-) together with Amberlite XAD7HP acrylic ester co-polymer (XAD7HP) were functionalized with chelating agent Direct red 23 (DR 23). The chelate resins (IRA 402-DR 23 and XAD7HP-DR 23) were obtained in batch mode. The influence of interaction time, pH and the initial concentration of DR 23 solution was investigated using UV-Vis spectrometry. The time necessary to reach equilibrium was 90 min for both resins. A negligible effect of adsorption capacity (Qe) was obtained when the DR 23 solution was adjusted at a pH of 2 and 7.9. The Qe of the XAD7HP resin (27 mg DR 23/g) is greater than for IRA 402 (Cl-) (21 mg DR 23/g). The efficiency of chelating resins was checked via M2+ removal determined by the atomic adsorption spectrometry method (AAS). The M2+ removal by the IRA 402-DR 23 and XAD7HP-DR 23 showed that the latter is more efficient for this propose. As a consequence, for divalent ions, the chelated resins followed the selectivity sequence: Cd2+ &gt; Cu2+ &gt; Ni2+ &gt; Pb2+. Additionally, Cd2+, Cu2+ and Ni2+ removal was fitted very well with the Freundlich model in terms of height correlation coefficient (R2), while Pb2+ was best fitted with Langmuir model for IRA 402-DR 23, the Cu2+ removal is described by the Langmuir model, and Cd2+, Ni2+ and Pb2+ removal was found to be in concordance with the Freundlich model for XAD7HP-DR 23. The M2+ elution from the chelate resins was carried out using 2 M HCl. The greater M2+ recovery from chelating resins mass confirmed their sustainability. The chelate resins used before and after M2+ removal by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis were evaluated.

Development of Nanoscale Hydrated Titanium Oxides Support Anion Exchange Resin for Efficient Phosphate Removal from Water

In this work, a macroporous strongly basic anion exchange resin D201 was used as the matrix and loaded with nano hydrated titanium oxide (HTO) to fabricate a novel resin-based nano hydrated titanium oxide adsorbent (HTO-D201), which was characterized by scanning electron microscope-energy dispersion spectroscopy (SEM-EDS), transmission electron microscope (TEM), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. Adsorption isotherm, pH influence competitive adsorption and column adsorption experiments were conducted to investigation the adsorption behavior of HTO-D201 to phosphorus in water. The adsorption effect of adsorbent HTO-D201 on phosphorus in water, and the corresponding adsorption mechanism, are discussed. It was observed that HTO-D201 exhibited spontaneous adsorption behavior with Langmuir fitting maximum adsorption capacity of 34.08 mg∙g−1 under a pH of 6.8 and a temperature of 298 K. Adsorption isotherms confirmed that enhancing temperature could promote the adsorption process. SO42−, NO3− and Cl− were used as competing ions in competitive adsorption, which confirmed better anti-interference ability of HTO-D201 compared with that of unmodified D201. The column adsorption experiment implied that HTO-D201 possessed a stable structure and good dynamic adsorption performance, with effective processing capacity of 420BV, which could be regenerated and recycled. The adsorption mechanism of HTO-D201 to phosphorus in water is discussed, which was ascribed to a quaternary amine group on the resin and a hydroxyl group on the HTO. This work shows that HTO-D201 is a promising adsorbent that a possesses excellent phosphorus-removing capacity from wastewater and the potential for practical application.