Removal Of Anions Research Articles

Ferrate(VI) Synthesis Using Fe(OH)<sub>3</sub> from Waste Iron Electrolysis and Its Application for the Removal of Metal Ions and Anions in Water

Ferrate(VI) salt is an effective oxidant and coagulant for water treatment and removal of metal ions. This study demonstrates a new approach to processing metal ions and anions in water by Fe(VI) through Fe(III) obtained from the electrolysis of waste iron transformer. The electrolysis was successfully carried out in the Na2SO4 electrolyte using waste iron and zinc plates as anode and cathode, respectively. Fe(III) electrolysis results through the characterization of FTIR and XRD indicate compliance with Fe(OH)3 standards. Synthesis of ferrate was carried out by adding Fe(III) from electrolysis with NaOCl in alkaline conditions. The formed ferrate solution shows a purple color with a typical maximum wavelength of 505 nm. Furthermore, the ferrate obtained is used to remove metal ions (Fe(III), Cu(II), Zn(II), Mg(II), Pb(II)) and anions (sulfate, nitrate, and carbonate) in water with pH variations. Ferrate treatment filtrate was analyzed using AAS for metal ions, while sulfate, nitrate, and carbonate anions used UV-Vis spectrophotometry, turbidimetry, and titration methods. The results showed that ferrate effectively eliminates metal ions and anions in water with optimum pH 6. The mechanism of heavy metal removal by ferrate(VI) can be explained by ionic bonding and adsorption.

Optimal Operational Profiles in an Electrodialysis Unit for Ion Recovery

Electrodialysis is an efficient process for the cleaning of industrial water effluent streams from toxic ionic substances with the simultaneous recovery of valuable ions for reuse. Energy consumption and waste recovery are the two key goals of the process. A dynamic optimisation program aims to determine the optimal operating conditions in terms of applied voltage and effluent flow rate in a batch operating scheme. A model is developed that accounts for the ion transfer through the ion selective membranes and the dynamics of the system. A combination of three objective functions targeting the minimisation of the overall batch process time, the minimisation of the electrical energy consumption required for the ion transfer, and the maximisation of the overall degree of separation is investigated. The manipulated variables applied voltage and feed stream flow rate are considered as piecewise constant during each time interval, spanning the duration of the entire batch. The dynamic optimisation problem is solved through standard non-linear programming techniques which calculate the optimal batch duration and condition profiles for the system. A multi-objective analysis is presented for various combinations of weight values for the joint objective function through the development of the Pareto optimal front. The current approach has been implemented in the removal and recovery of sulfuric anions from an aqueous solution and resulted in the achievement of a high degree of separation in a shorter period at a much lower energy consumption.

Fe(II)-activated peroxymonosulfate coupled with nanofiltration removes natural organic matter and sulfamethoxazole in natural surface water: Performance and mechanisms

Ferrous-activated peroxymonosulfate (PMS) is regarded as a promising technology to treat organic pollutants. However, the excessive sulfate anions generated in the oxidation process need to be considered with respect to their potential harm to the environment and human health. The removal of organic compounds and sulfate anions by Fe(II)/PMS oxidation coupled with nanofiltration (NF) was studied in this research. The mechanism of Fe(II)/PMS coupled with NF in natural organic matter (NOM) and sulfamethoxazole (SMX) removal were systematically investigated by comparison with single Fe(II)/PMS and NF treatments. The results demonstrated that the hybrid system showed better performance than the single treatments for both pollutants. High-performance size exclusion chromatography (HPSEC) analysis indicated that macromolecular organic matter in Songhua River water was broken down and converted into small fragments with a size of approximately hundreds of Da by Fe(II)/PMS oxidation. Zeta potential analysis showed that the zeta potential of the effluent decreased under the effect of Fe(III) and that some small organic molecules generated in the process of oxidation were negatively charged. The SMX removal experiment showed that Fe(II)/PMS oxidation played a leading role in SMX removal in the hybrid system. Moreover, a radical quenching experiment was conducted to explore the effects of SO4·− and HO· on SMX degradation. Fe(II)/PMS treatment effectively alleviated membrane fouling and improved the flux behaviour, with a stable sulfate anion rejection rate of approximately 90% achieved by NF in the long term. These results suggested that Fe(II)/PMS coupled with NF could control membrane fouling, intercept sulfate anions and improve effluent quality, which provides a new strategy for water treatment.

Synthesis of Allyl Pentaerythritol Crosslinker based Polymer Hydrogels and Determination of the Crosslink Density

In this study, we report the synthesis and characterization of polymer hydrogels. The polymer gels have been prepared from acrylic acid (AA) monomer using allyl pentaerythritol as the crosslinker in the presence of potassium persulfate initiator. The synthesized polymer gels have been characterized by Fourier-transform infrared (FT-IR) spectroscopy. The swelling capacity and crosslink density of the synthesized polymer gels have been determined and it was found that some of the polymer samples behave like super-absorbent polymers. These polymeric-gels can be utilized in various applications viz. as a catalyst for dye removal, for anion removal from water and for heavy metal removal etc.

Single-Step Topochemical Synthesis of NiFe Layered Double Hydroxides for Superior Anion Removal from Aquatic Systems.

Layered double hydroxides (LDHs) have attracted significant attention as adsorbents for the removal of anions from wastewater. However, it is challenging to develop a simple, economical, and environmentally friendly method for fabricating efficient LDH adsorbents. In this paper, we present an alternative approach for preparing a superb NiFe LDH adsorbent via a single-step topochemical synthesis method based on density functional theory (DFT) calculation. The NiFe LDH adsorbent [Ni0.75Fe0.25(OH)2]·(CO3)0.125·0.25H2O was obtained via the topotactic transformation of an oxide precursor (NaNi0.75Fe0.25O2), which was prepared by utilizing the high-temperature flux method, in ultrapure water. When the oxide precursor was soaked in ultrapure water, the host layer valence state changed from Ni3+ and Fe3+ to Ni2+ and Fe3+, and carbonate (CO32-) ions were simultaneously intercalated in the interlayer. Thereafter, the CO32- ions were deintercalated by Cl- ions to increase the adsorption capacity. The adsorbent exhibited high crystallinity, cation state, and porosity, and unique particle shape. In addition, it showed superior adsorption capacities of approximately 194.92, 176.15, and 146.28 mg g-1 toward phosphate, fluoride, and nitrate ions, respectively. The adsorption capacity toward all the anions reached over 70% within 10 min. The adsorption behavior was investigated by performing from adsorption kinetics, isotherm, and thermodynamics studies. The results showed that the anions were endothermically and spontaneously chemisorbed through an ion exchange process onto the adsorbent in a monolayer. In addition, the as-prepared NiFe LDH adsorbent showed high stability after multicycle testing.

Effect of Fe oxidation state (+2 versus +3) in precursor on the structure of Fe oxides/carbonates-based composites examined by XPS, FTIR and EXAFS

Here we investigate the influence of Fe oxidation state (either Fe(II) or Fe(III) sulfates) in precursor of the same chemical composition on the atomic scale structure, surface speciation and adsorptive anion removal of the purely inorganic composites produced under the urea supported hydrothermal synthesis. In case of utilization of Fe3+ precursor, the materials chemistry was solely dominated by the formation of highly crystalline Fe(III) oxides, however the particle surfaces were covered with small quantities of FeCO3 (not detectable by EXAFS/XANES/FTIR) precipitated after the autoclave was turned off. Within the reactive medium with Fe2+ precursor, due to high pressure in autoclave which facilitated reducing conditions and sedimentation of Fe divalent, two main processes took place one of which was the formation of Fe hydrous oxides; the second reaction resulted in generation of FeCO3, which become a predominant phase in volume averaged composition. Notably, despite the prevalence of Fe(II) carbonates in bulk structure, the narrow upper layers (XPS detectable) was enriched with Fe(III) oxides. At the chosen autoclave temperature of 150 °C, both samples had low hydration of physisorbed water, which confirmed our recent hypothesis about correlation between Fe (or another metal formed oxides) local structure in outer shells fitted with several (many) oxygen atoms and the material hydration with physisorbed water. None of the two composites demonstrated strong adsorptive removal of seven anions (F−, Br−, BrO3−, HAsO42−, H3AsO3, HPO42−, SeO42−), which verified another idea about the interdependence of distinguished (EXAFS simulated) outer shells of metals (here, Fe) fitted with two paths simultaneously ({Fe–Fe}+{Fe–O}) one peak and the anion exchange potential. Overall, the Fe(III)-precursor product was more crystalline, less heterogeneous (fewer phases), showed worse anion uptake than the other sample. The material prepared from Fe(II) precursor is considered to be a promising precursor for further phase transformations via thermal or hydrothermal treatments (due to generous presence of FeCO3).

A systematic study for the removal of anionic dyes by sepiolites modified with a homologous series of trimethylammonium-surfactants from single and binary component solutions

ABSTRACT Trimethylammonium surfactants have been extensively used for modification of sepiolite to improve its sorption ability for anionic dye removal. Here, a detailed systematic sorption study is presented to choose the best surfactant for modification having the highest removal efficiency for different types of anionic dyes belonging to anthraquinone (Lanaset-Green-B), azo (Lanaset-Red-2B) and complex (Lanaset-Red-G) subclasses. Adsorption kinetics and equilibria of the dyes onto the pristine and decyl-, dodecyl-, teradecyl- and hexadecyl-tetramethylammonium sepiolites were investigated in single and binary component systems. Multilayered arrangements have been proposed for surfactants on the sepiolite based on x-ray diffraction and diffuse-reflectance-Fourier-transform spectroscopy analyses. The arrangements and the size of the surfactants comparing to dyes play important role in the adsorption process. The proposed dye-surfactant interactions are consistent with all kinetics and equilibrium results. The tetradecylammonium modified sepiolite has the best capacity for all dyes (~0.32 mmol/g) at the first-stage of isotherms and is independent of the molecular structure of dyes. This correlated to the numbers of free head groups of surfactant oriented upward. The highest capacity is 0.50 mmol/g for Lanaset-Red-2B at the second stage of the isotherms on the dodecylammonium modified sepiolite which is attributed to dye–dye interactions.

One-Pot Synthesis of Some New s-Triazole Derivatives and Their Potential Application for Water Decontamination.

A rapid, efficient, and one-pot protocol has been developed for the synthesis of cyclized 2,6-dimethyl-5-substituted-thiazolo[3,2-b]-s-triazoles (3a–c) through the interaction of 5-methyl-1H-s-triazole-3-thiol (1) with aliphatic ketones (2a–d) in refluxing acetic acid in the presence of a catalytic amount of sulfuric acid (AcOH/H+) while with aromatic ketones (5a–d), a mixture of uncyclized 3-methyl-s-triazolylthioacetophenone derivatives (6a–d) and cyclized 6-aryl-2-methyl-thiazolo[3,2-b]-s-triazoles (7a–d) has been produced. With this catalytic system, inexpensive sulfuric acid was utilized as a catalyst, which prevented the production of poisonous and irritating halo carbonyl compounds. On the other hand, the interaction of s-triazole 1 with cyano compounds (9a,b) afforded the corresponding 6-amino-2-methyl-5-substituted-thiazolo[3,2-b]-s-triazoles (10a,b). Similarly, treatment of 4-amino-3-methyl-s-triazole-5-thiol (12) with aliphatic and aromatic ketones (2c and 5a–e) afforded directly 3-methyl-7H-s-triazolo[3,4-b]-1,3,4-thiadiazines (13a and 14a–e). Further, reaction of 12 with cyano compounds (9a,b) under the same reaction conditions yielded the corresponding 3-methyl-s-triazolo[3,4-b]-1,3,4-thiadiazole derivatives (15a,b). The reaction mechanism was studied, and the structures of all novel compounds were verified using spectroscopy and elemental analysis. Moreover, the potential application of the synthesized compounds toward heavy metal ions and inorganic anion removal from aqueous solution has been investigated. The removal effectiveness for metal ions reached up to 76.29%, while for inorganic anions it reached up to 100%, indicating that such synthesized compounds are promising adsorbents for water remediation.

CO2‐Mediated Non‐Destructive Cyanide Wastewater Treatment

AbstractThe facile removal of cyanide anions from cyanide‐containing water was achieved using CO2 in conjunction with aldehydes which can be recycled from the process. The conversion of the cyanide ion into an insoluble cyanohydrin in water allowed the removal of cyanide and could be used as a method for treating cyanide contaminated wastewater and for recovering cyanide or cyanohydrins for further applications.

Recent Advances in the Fabrication and Environmental Science Applications of Cellulose Nanofibril-Based Functional Materials.

Cellulose is one of the important biomass materials in nature and has shown wide applications in various fields from materials science, biomedicine, tissue engineering, wearable devices, energy, and environmental science, as well as many others. Due to their one-dimensional nanostructure, high specific surface area, excellent biodegradability, low cost, and high sustainability, cellulose nanofibrils/nanofibers (CNFs) have been widely used for environmental science applications in the last years. In this review, we summarize the advance in the design, synthesis, and water purification applications of CNF-based functional nanomaterials. To achieve this aim, we firstly introduce the synthesis and functionalization of CNFs, which are further extended for the formation of CNF hybrid materials by combining with other functional nanoscale building blocks, such as polymers, biomolecules, nanoparticles, carbon nanotubes, and two-dimensional (2D) materials. Then, the fabrication methods of CNF-based 2D membranes/films, three-dimensional (3D) hydrogels, and 3D aerogels are presented. Regarding the environmental science applications, CNF-based nanomaterials for the removal of metal ions, anions, organic dyes, oils, and bio-contents are demonstrated and discussed in detail. Finally, the challenges and outlooks in this promising research field are discussed. It is expected that this topical review will guide and inspire the design and fabrication of CNF-based novel nanomaterials with high sustainability for practical applications.

Removal of Nitrate Ions Using Thermally and Chemically Modified Bioadsorbents

Nitrate ions are one of the causes of surface water eutrophication. In the present research, the effective adsorption of nitrate ions (NO3) on bioadsorbents prepared from yam skins (Dioscorea alata) was evaluated. The yam skin was chemically modified with ammonium chloride (NH4Cl), and biochar was prepared from the thermally modified biomass. The results were compared with commercial coal (CC). The bioadsorbents were characterized by SEM-EDS analysis, which showed that the synthesized adsorbents have a heterogeneous surface with pores. The batch adsorption tests showed that the pH has the most significant effect on the NO3 adsorption capacity when using the modified yam skin (MYP), obtaining as best conditions pH 12 and a 0.5 mm particle size with an adsorption capacity of 25.75 mg/g; the best adsorption capacity when using the carbon synthesized from yam skin (CYP) and CC was obtained at pH 2, reaching values of 36 and 33.34 mg/g, respectively. The following performance in terms of adsorption capacity was found: CYP > CC > MYP, according to Langmuir’s model. The equilibrium isotherm of NO3 adsorption on MYP and CYP was adjusted by the Freundlich model, while the Langmuir model described adsorption on CC. The kinetics of all the systems studied showed a good fit to the pseudo-first-order, pseudo-second-order and Elovich models with R2 > 0.95, suggesting a mechanism of chemical adsorption by means of species exchange between the aqueous phase and the surface of the material, with the intervention of an intraparticle diffusion stage; based on these findings, the studied biomasses reached promising adsorption capacities in the removal of nitrate anions, showing that the carbon synthesized from yam skins and modified with ammonium chloride had a remarkable behavior in comparison with commercial carbon and NH4Cl-modified yam skins.

Removal of hexavalent chromium ions and Acid Red 18 by superparamagnetic CoFe2O4/polyaniline nanocomposites under external ultrasonic fields

In the present research, the adsorptive removal of dye and Cr(VI) ions from the aquatic solutions have been investigated using fabricated magnetic cobalt ferrite (CoFe 2 O 4 ) nanoparticles coated by polyaniline (CoFe 2 O 4 /PANI) via a hydrothermal and in-situ polymerization method. Magnetic composite of CoFe 2 O 4 /PANI was characterized by FE-SEM, EDS, XRD, VSM, FTIR, BET, BJH, and element mapping. The resulting composite was applied for the removal of hexavalent chromium (Cr(VI)) ions and Acid Red 18 (AR18) anionic azo dye individually from an aqueous solution under external ultrasonic fields. The removal efficiency of Cr(VI) ions and AR18 dye were studied as functions of the various parameters like time sonication, amount of adsorbent, initial concentration of Cr(VI) or AR18, and solution pH. The adsorption behavior and the equilibrium data were represented by the Langmuir isotherm model. The maximum monolayer adsorption capacity by as-prepared composite reached 103.11 mg g −1 and 172.41 mg g −1 for Cr(VI) ions and AR18 dye, respectively. The thermodynamic analysis demonstrated that these adsorption processes were spontaneous in nature and endothermic. The magnetically recyclable composite indicated suitable reusability during cyclic adsorption. The increase in ionic strength causes a decrease in the adsorption of Cr(VI) and AR18. This study may provide a promising magnetic composite for the efficient removal of inorganic and organic anions from the water environment. • Application of magnetic CoFe 2 O 4 /PANI for ultrasound assisted adsorption of Cr(VI) ions and AR18 dye. • Desirability function approach combined with CCD method was used to optimize the process variables. • CoFe 2 O 4 /PANI is superior to CoFe 2 O 4 for Cr(VI) ions and AR18 dye adsorption. • The maximum adsorption capacity for Cr(VI) ions and AR18 dye reached 103.11 mg g −1 and 172.41 mg g −1 , respectively. • Reusability tests indicated suitable regenerability of CoFe 2 O 4 /PANI.

Effect of magnesium on monohydrocalcite formation and unit-cell parameters

Abstract Monohydrocalcite (MHC) is hydrated calcium carbonate, which plays an active role in many geological processes, carbonate biomineralization, and can be used for fundamental science (as a paleoenvironmental indicator) and industry (for removal of hazardous anions). Despite a great number of works, the conditions preferable for MHC formation/stabilization and MHC crystal chemical patterns in relation to Mg and H2O are not clarified yet. In the course of current work, we conducted 38 syntheses to obtain information on MHC formation at different Mg/Ca ratios (0–12), pH (~9–12), and temperature (23 and 3 °C). Newly formed carbonate precipitates were studied by means of X-ray powder diffraction, optical, and scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman, and Fourier-transform infrared (FTIR) spectroscopies. The phase diagram for MHC, calcite, aragonite, and dypingite as a function of pH and Mg concentration in solution at T = 23 °C and Ca/CO3 = 0.5 was obtained. We demonstrated that MHC could be stable in dry conditions for up to two years and that the time of crystallization is important for the transformation of amorphous calcium carbonate to MHC. Our results on synthetic MHC stability show that the widespread idea that MHC is a short-lived intermediate phase is wrong. For the first time, on the basis of a regular changes in the unit-cell parameters the possibility of significant incorporation of magnesium in MHC has been demonstrated. According to FTIR data, it is shown to be accompanied by an increase in the water content, which leads to multidirectional change in a and c MHC parameters.

Experimental and theoretical study of a new CDI device for the treatment of desulfurization wastewater.

According to the characteristics of desulfurization wastewater, A new capacitive deionization (CDI) device was designed to study the desalination characteristics of desulfurization wastewater in this paper. The experiments investigated the desalination efficiency under different conditions which find that the best desalination efficiency is achieved at a voltage of 1.2V, pH=11 and 50°C. Besides, ion adsorption is more favorable under acidic and alkaline conditions. The anion and cation removal performance experiments showed that the order of cation removal is Mg2+>Na+>Ca2+>K+ and the order of anion removal is Cl->CO32->NO3->SO42->HCO3-. The mechanism of CDI was studied and analyzed by the isothermal adsorption model and COMSOL simulation software. It was found that the Freundlich model and Redlich-Peterson model have a good fit with the experimental results. The experiments show that the CDI device has excellent stability. CDI device was used to treat actual desulfurization wastewater. Furthermore, the study provides theoretical support for the industrial application of CDI for desulfurization wastewater treatment in the future. Graphical abstract.

Red mud-chitosan microspheres for removal of coexistent anions of environmental significance from water bodies

Aluminium industry waste red mud was combined with Chitosan so as to prepare novel composite in the form of beads. The Red mud–Chitosan beads (Rm-Ch) were studied for applicability in the removal of fluoride, chromate and phosphate ions from aqueous solution. The beads were characterized for surface morphology, elemental analysis, thermal stability and presence of functional groups. Thermodynamic, kinetics and isotherm studies carried for all the three anions revealed that the adsorption process is spontaneous, exothermic and follows pseudo second order kinetics in accordance with Langmuir adsorption isotherm. The adsorption capacities for these three ions were found to be 6.15 mg g-1, 30.88 mg g-1 and 23.54 mg g-1 respectively.

Supramolecular hydrogelation via host-guest anion recognition: Lamellar hydrogel materials for the release of cationic cargo

Supramolecular hydrogelation via host-guest anion recognition: Lamellar hydrogel materials for the release of cationic cargo

Synthesis of new anthracene-substituted calix[4]triazacrown-5 as highly sensitive fluorescent chemosensor and extractant against hazardous dichromate anion.

A new fluorogenic anthracene functionalized calix[4]triazacrown-5 (Ant-AzClx) was successfully synthesized using a simple Schiff's base reaction. The 1 H-NMR, 13 C-NMR, ESI-MS, and elemental analysis techniques were performed to characterize its structure. Excited at 370 nm, Ant-AzClx reveals excimer emission at 418 nm. Therefore, its anion binding properties were investigated against F- , HCO3 - , H2 PO4 - , NO3 - , Cr2 O7 2- , and SO4 2- ions. When hazardous dichromate anion was introduced into medium, the fluorescence intensity of Ant-AzClx was markedly quenched. The binding constant, stoichiometry, the detection limits and Stern-Volmer equation for the complex formed between Ant-AzClx and Cr2 O7 2- ion were determined. Furthermore, the 1 H-NMR technique was also performed to assess the mechanism of the complex (Ant-AzClx@Cr2 O7 2- ). Apart from its excellent fluorescent chemosensor properties for selective and sensitive recognition of Cr2 O7 2- ion, Ant-AzClx was used as an efficient extractant towards dichromate anion. The extraction results indicated that Ant-AzClx exhibited high extraction capability, leading to it being a promising extractant for the removal of dichromate anions from water.

Efficient Removal of Chromium(VI) Anionic Species and Dye Anions from Water Using MOF-808 Materials Synthesized with the Assistance of Formic Acid.

This study presents a simple approach to prepare MOF-808, an ultra-stable Zr-MOF constructed from 6-connected zirconium clusters and 1,3,5-benzene tricarboxylic acid, with tailored particle sizes. Varying the amount of formic acid as a modulator in the range of 200–500 equivalents results in MOF-808 materials with a crystal size from 40 nm to approximately 1000 nm. Apart from the high specific surface area, a combination of a fraction of mesopore and plenty of acidic centers on the Zr-clusters induces a better interaction with the ionic pollutants such as K2Cr2O7 and anionic dyes. MOF-808 shows uptakes of up to 141.2, 642.0, and 731.0 mg/g for K2Cr2O7, sunset yellow, and quinoline yellow, respectively, in aqueous solutions at ambient conditions. The uptakes for the ionic dyes are significantly higher than those of other MOFs reported from the literature. Moreover, the adsorption capacity of MOF-808 remains stable after four cycles. Our results demonstrate that MOF-808 is a promising ideal platform for removing oxometallates and anionic dyes from water.

Electrochemical Driven Phase Segregation Enabled Dual-Ion Removal Battery Deionization Electrode.

Battery deionization (BDI) offers a powerful platform for integrating water treatment and energy conversion. Exploring novel BDI electrode materials with high energy storage capacity and high efficiency for both cations and anions removal is the key to advancing the BDI technique. Herein, we report the first BDI electrode material capable of simultaneously removing Cl- (58.4 mg g-1) and Na+ (8.7 mg g-1) in water with a reversible capacity of 160 mAh g-1. In situ powder X-ray diffraction (PXRD) unravels that the dual-ion removal capability is attributed to a novel reversible electrochemical driven phase segregation reaction mechanism between NaBi3O4Cl2 and the in situ formed metallic Bi. The unique dual-ion storage capability demonstrated with the NaBi3O4Cl2 electrode indicates that exploring electrochemical reversible phase segregation electrode material holds great promise for advancing the BDI electrode for future desalination techniques and aqueous rechargeable battery systems.

Polysaccharides isolated from Lycium barbarum L. by integrated tandem hybrid membrane technology exert antioxidant activities in mitochondria

Variations in the molecular weight (MW) of polysaccharides may lead to different pharmacological functions. Hierarchical alcohol precipitation is presently the most popular method of separating polysaccharides. However, as polysaccharide molecules in solution becomes dehydrated in ethanol, the conformation transforms and becomes assembled via intramolecular hydrogen bonding, which can complicate studies on the biological activities of polysaccharides. This work developed an integrated tandem hybrid membrane technology (ITHMT) to separate polysaccharides extracted from Lycium barbarum L. into fractions. The polysaccharide fractions LBP1, LBP2, LBP3, and LBP4 were separated using ITHMT. Preliminary structural analysis including homogeneity, molecular weight, monosaccharide composition, scanning electron microscopy and thermogravimetric analysis were investigated. Both LBP3 and LBP4 had symmetrical single peaks and were considered as one homogeneous polysaccharide. A lower MW cut-off for membrane elements was associated with increased polysaccharide homogeneity. LBP1∼LBP4 were found to be heteropolysaccharides and comprised rhamnose, galactose, glucose, mannose, and galacturonic acid with different molar ratios and MW. The MW of LBP1∼LBP4 were 225.6 kDa, 140.2 kDa, 65.0 kDa, and 38.3 kDa, respectively. Four polysaccharide fractions had unique morphologies, good thermal stabilities and different antioxidant effects. The LBP4 fraction exerted significant antioxidant effects against superoxide anion radicals and ferric-reducing antioxidant effect in vitro, as well as superoxide anion radicals in vivo, indicated L. barbarum polysaccharides with different molecular weight did had different antioxidant activity. All polysaccharides reduced the levels of superoxide anions in mitochondria but could not scavenge cytoplasmic H2O2, indicating that the antioxidant capacity of L. barbarum polysaccharides is achieved through the removal of superoxide anions from intracellular mitochondria.