Oxide Sorbents Research Articles

#42 Maternal exposure to venlafaxine during the first trimester: 10-years experience of the Florence Teratology Information Service

New carbon-doped ferric zinc oxide sorbents were fabricated to capture the environment carcinogen tobacco specific nitrosamines (TSNA) efficiently in solution, following new adsorption model of electrostatic attraction instead of traditional geometric constraints. The influence of ferric content on the structure-property of the sorbents was systemically studied with XRD, N2 adsorption-desorption and SEM methods combined with the adsorption of TSNA in different solutions. New sorbent captured 99% of 4-methylnitrosamino-1-3-pyridyl-1-butanone (NNK) in simulated surface water and 40% of TSNA in the tobacco extract solution, more than activated carbon or zeolites. Ferric ZnO sorbent took about 15 min to reach the adsorption equilibrium in the NNK or Pb(Ⅱ) solution, faster than NaZSM-5 zeolite. Moreover, the adsorbed NNK on ferric ZnO sorbent decomposed at mild conditions for the first time, providing a new way to control environment pollution.

Improved CO2 Sorption Performance of Calcium Oxide (CaO) Sorbent with Nickel Oxide Additive

Currently, carbon capture and storage (CCS) technology appeared to be the most viable method to reduce carbon dioxide (CO2) emission from its existing sources. This paper reports the improved performance of calcium oxide (CaO)-based sorbents with the addition of nickel oxide (NiO) as an additive (denoted as CaO:NiO) in CO2 sorption process (CaO carbonation reaction). Pure CaO was used as benchmarked sorbent in this study. The samples were synthesized using the sol-gel method and CaO:NiO were evaluated for their performance in CaO carbonation at different sorption temperatures, from its CO2 sorption capacity, CO2 sorption rate, and kinetic performance. CaO:NiO has demonstrated an excellent CO2 sorption capacity of 0.79 mmol CO2/mmol CaO, meanwhile pure CaO exhibited lower CO2 sorption capacity of 0.61 mmol CO2/mmol CaO at 600 °C. During the chemical reaction controlled stage, the CO2 sorption rate of CaO:NiO was 0.78 mmol CO2/mmol CaO.min at 600 °C compared to pure CaO with sorption rate of 0.18 mmol CO2/mmol CaO.min. This study indicates that the addition of nickel oxide has successfully improved the CO2 sorption rate and capacity of CaO for CaO:NiO. Based on the kinetic study, it has been observed that the diffusion controlled stage has a greater resistance towards the CO2 sorption process (carbonation reaction) compared to rapid chemical reaction controlled stage. Experimental carbonation data for CaO:NiO fitted very well to the shrinking core model (SCM) with high correlation coefficient (R2 >0.936). The specific rate constants of rapid chemical reaction and diffusion-limited stages are directly proportional to the carbonation temperature. The activation energy required for CaO:NiO sorbent during the chemical reaction control stage was 31.81 kJ/mol.

Using porous iron composite (PIC) material to immobilize rhenium as an analogue for technetium

Technetium (99Tc), a uranium-235 (235U) and plutonium-239 (239Pu) fission product, is a primary risk driver in low level radioactive liquid waste at U.S. Department of Energy sites. Previous studies have shown success in using Zero Valent Iron (ZVI) to chemically reduce and immobilize redox sensitive groundwater contaminants. Batch and column experiments were performed to assess the ability of a novel porous iron composite material (PIC) to immobilize Tc(VII) in comparison with two commercial Fe oxide sorbents and reagent grade ZVI in the presence and absence of NO3−, a competing oxidized species that is often found in high concentrations in liquid nuclear waste. Perrhenate (ReO4−) was used as a non-radioactive chemical analogue for pertechnetate (TcO4−) under both oxic and anoxic test conditions. The PIC powder was the most effective at immobilizing Re(VII) under all batch test conditions. The presence of nitrate (NO3−) slowed the removal of ReO4− from solution, presumably through chemical reduction and precipitation. Even so, the PIC and ZVI were effective at removing both Re(VII) and NO3− completely from solution. Nitrate was reduced to NH3 with very little nitrite (NO2−) buildup during equilibration. Significant Re immobilization was observed in the column tests containing PIC sorbent, even though inlet solutions were in equilibrium with O2. The presence of NO3− hastened Re breakthrough, while NO3− reduction to NH3 was observed. The results suggest that PIC and ZVI would be the most effective at the removal of TcO4− from contaminated groundwater sites.

Adsorption properties of manganese oxides prepared in aqueous-ethanol medium toward Sr(II) ions

In this study, nanostructured manganese oxides were synthesized using sol–gel method by reduction of KMnO4 with ethyl alcohol. Firstly, the effect of K+, Na+, Ca2+, and Mg2+ ions as templates on their structure and adsorption properties was studied. According to X-ray diffraction analysis, all samples were identified as amorphous phases. Fourier-transform infrared spectroscopy confirmed that prepared sorption materials had a band around 760 cm−1, characteristic for the tunnel-type manganese oxides. The BET surface area of the obtained samples was 188–293 m2 g−1, the sorption volume of 0.431–1.136 m3 g−1, and the average pore size of 6–20 nm. The maximum Sr2+ sorption capacity of 120 mg g−1 was observed for the non-templated manganese oxide sorbents synthesized at 25 °C during 5 h. The calculated isotherm parameters and corresponding correlation coefficients revealed that the Sr2+ uptake process followed the Freundlich and Redlich-Peterson models for metal ion-templated manganese oxides. The increase in temperature and time of synthesis, as well as the application of K+, Na+, Ca2+, and Mg2+ ions as templates led to the decrease of sorption capacity down to 40–60 mg g−1 and 60–80 mg g−1, respectively. The highest sorption efficiency of metal ion-templated manganese oxides in Na+, K+, and Ca2+-form was shown for 90Sr, its Kd being (3.8–5.1) × 103 cm3 g−1. For Na+ ion-templated sample, as typical, the Kd values were 2.0 × 10−1–8.6 × 104 cm3 g−1 in the pH range of 0.5–12.0 and 3.5 × 102–6.2 × 101 cm3 g−1 for Ca2+ ion concentration varied from 10 to 80 mM, respectively.

Polyvinyl alcohol-stabilized granular Fe–Mn binary oxide as an effective adsorbent for simultaneous removal of arsenate and arsenite

ABSTRACT A novel granular Fe–Mn (GFM) binary oxide sorbent, with a diameter of approximate 2.0 mm and a length of 2.0–3.0 mm, was successfully prepared using extrusion granulation method in this study. The GFM sorbent is highly porous with a BET-specific surface area of 210.3 m2/g. It shows high effectiveness in simultaneously adsorbing As(V) and As(III). The maximal sorption capacities for As(V) and As(III) are 33.2 and 50.7 mg/g at pH 7.0 ± 0.1, respectively, which are superior to most of granular sorbents reported in the literature. The present Ca2+, Mg2+, humic acids and fulvic acids do not have obvious influence on the arsenic sorption. But, coexisting anions affect negatively arsenic sorption in the following order: H2PO4 − > SiO3 2− > HCO3 − > SO4 2−. NaOH solution is an effective eluent for regeneration of the arsenic-loaded GFM. The GFM packed in the fixed-bed column can treat approximately 3400 and 6500 bed volumes of simulated groundwater containing 233 μg/L As(V) and As(III), respectively, before the arsenic concentration in the effluent reached a drinking water limit of 10 μg/L. The features of high effectiveness, selectivity and reusability make the GFM a potential alternative to remove simultaneously As(V) and As(III) from groundwater.

Fabrication of Magnetic Nano-Fe3O4chitosan/Graphene Oxide sorbents by New Method and Application in Solid Phase Extraction for Preconcentration of Mo (II)

Fabrication of Magnetic Nano-Fe3O4chitosan/Graphene Oxide sorbents by New Method and Application in Solid Phase Extraction for Preconcentration of Mo (II)

Selective magnetic nanographene oxide solid‐phase extraction with high‐performance liquid chromatography and fluorescence detection for the determination of zearalenone in corn samples

A magnetic nanographene oxide sorbent as a selective sorbent for the magnetic solid-phase extraction combined with high-performance liquid chromatography and fluorescence detection was developed and proved to be a robust method for zearalenone determination in corn samples. Optimum extraction of zearalenone (20mg magnetic nanographene oxide sorbent, extraction for 15min, desorption time of 15min using 1mL of 0.5% formic acid in methanol) resulted in low limits of detection (05mg/L) and quantitation (0.13mg/L) and good linearity range of 0.13-1.25mg/L with the correlation coefficient of 0.9957. Acceptable recoveries (79.3-80.6%) with relative standard deviations below 4% and satisfactory intra- and interday precisions (2-7.4%) were achieved. Additionally, the proposed method has been proved to be good in several aspects: easily prepared sorbent with high affinity to zearalenone, convenient and fast procedure, and high extraction efficiency.

Stabilization of Brownmillerite-Type SrCoO2.5 by a Cost-Effective Quenching Method for Oxygen-Scavenging Applications

Brownmillerite (BM)-type oxide sorbents have gained attention recently for producing oxygen-enriched streams. Herein, a cost-effective method of quenching with the use of an Al foil pad is adapted ...

Simulation and optimization of pressure swing adsorption process for high-temperature air separation by perovskite sorbents

This work presents an experimental and simulation study on a low-cost and efficient high-temperature air separation technique using perovskite oxide sorbents by pressure swing adsorption (PSA). The sorbent material, La0.1Sr0.9Co0.9Fe0.1O3-δ (LSCF1991), have a large oxygen adsorption capacity, a relatively high adsorption and desorption rate, and an infinitely large oxygen selectivity over nitrogen or other non-oxygen species due its unique oxygen storage property. The oxygen nonstoichiometry of LSCF1991 at different temperatures and oxygen partial pressures was measured by thermogravimetric analysis (TGA). The adsorption dynamic behavior of the LSCF1991 pellets was investigated by fixed-bed breakthrough experiments. A numerical process simulation model of the PSA process for the high-temperature air separation using LSCF1991 was developed in Matlab. The model was validated by comparing the simulation results with the experimental results from fixed-bed experiments. A parametric study was performed to design and optimize the operating parameters of the PSA process by investigating their effects on the oxygen purity, recovery and productivity. Under the optimum conditions, oxygen purity of 98.21%, recovery of 74.05% and productivity of 1.22 mmol/s/kg were achieved. The obtained values are much higher than the reported values form previous studies. Additionally, the energy assessment results showed that the energy consumption of the new process is lower than both the cryogenic distillation method and the conventional PSA process.

Re-use of waste red mud: Production of a functional iron oxide adsorbent for removal of phosphorous

An iron oxide sorbent derived from red mud waste (termed red mud akaganeite (RMA)) was investigated for the treatment of waters containing excess phosphorus (P) based nutrients such as phosphate. The hypothesis was that this innovative sorbent could outperform commercial granular ferric hydroxide (GFH). Sorbent performance was tested by a combination of sorption kinetics and equilibrium studies. Key factors evaluated included influence of phosphorous concentration, solution pH, and presence of competing anions. The kinetics of phosphorous sorption on both RMA and GFH were best described by the pseudo first order model, albeit the RMA material showed a higher rate of sorption. The equilibrium capacity as modelled by the Langmuir equation was 12.9 mg P/g for RMA, which was over 140% greater than that of GFH. X-ray photoelectron spectroscopy suggested that surface hydroxyl species were part of the mechanism for phosphorus uptake. The efficiency of phosphorous uptake by RMA was relatively unaffected by solution pH. In contrast with GFH, a significant loss in performance above pH 8 was found. It was postulated that point of zero charge on the sorbent and ability to release protons and chloride into the water may explain the pH data. Nitrate, sulfate, and chloride had minimal effect on phosphorus uptake by RMA or GFH, but both materials were impacted by the presence of carbonate species. Infrared spectroscopy indicated the presence of carbonate on the sorbent surface. Treatment of stormwater revealed that RMA was potentially suitable as a sorbent for phosphorus from real water samples.

Metal oxide nanoparticle-modified graphene oxide for removal of elemental mercury

ABSTRACTMercury is an extremely toxic element that is primarily released by anthropogenic activities and natural sources. Controlling Hg emissions, especially from coal combustion flue gas, is of practical importance in protecting the environment and preventing human health risks. In the present work, three metal oxides (MnO2, CuO, and ZnO) were loaded on graphene oxide (GO) sorbents (designated as MnO2-GO, CuO-GO, and ZnO-GO). All three adsorbents were successfully synthesized and were well characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicated that the metal oxide nanoparticles (NPs) successfully decorated the GO. The elemental Hg adsorption capabilities of the three sorbents were subsequently evaluated using an in-house built setup for cold vapour atomic fluorescence spectrophotometry (CVAFS) with argon as the carrier gas for mercury detection. The testing temperature ranged from 50°C to 200°C at intervals of 50°C. MnO2-GO showed an excel lent Hg0 adsorption capacity via chemisorption from 50 to 150°C and a mercury removal efficiency as high as 85% at 200°C, indicating that the MnO2-NP-modified GO is applicable for enhancing gas-phase elemental mercury removal. However, neither CuO-GO nor ZnO-GO performed well. This work provides useful insights into the development of novel sorbent materials for the elemental mercury removal from flue gases.

Efficient oxidation and sorption of arsenite using a novel titanium(IV)-manganese(IV) binary oxide sorbent

Owing to the high toxicity and mobility, the removal of arsenite (As(III)) is significantly more difficult than arsenate (As(V)), thus representing a major challenge in arsenite-contaminated water treatment. For efficient elimination of As(III), we successfully fabricated a novel Ti-Mn binary oxide via a simultaneous oxidation and coprecipitation process. The amorphous oxide was aggregated from nanosized particles with a high specific surface area of 349.5 m2/g. It could effectively oxidize As(III) to As(V) and had a high As(III) sorption capacity of 107.0 mg/g. As(III) sorption occurred rapidly and equilibrium was achieved within 24 h. The kinetic data was well fitted by the pseudo-second-order equation, indicating a chemical sorption process. The material was almost independent upon the presence of competitive ions. The As(III) removal by the sorbent is a combined process coupled oxidation with sorption, where the MnO2 content is mainly responsible for oxidizing As(III) to As(V) and the formed As(V) is then adsorbed onto the surface of amorphous TiO2 content, through replacing the surface hydroxyl group or the adsorbed As(III) and forming inner-sphere surface complexes. Furthermore, the arsenic-containing oxide could be effectively regenerated and reused. The bi-functional sorbent could be used as a potentially attractive sorbent for As(III) removal in drinking water treatment and environmental remediation.

Oxidative weathering decreases bioaccessibility of toxic metal(loid)s in PM10 emissions from sulfide mine tailings.

Environmental contamination from legacy mine waste deposits is a persistent problem due to the long history of hard‐rock mining. Sulfide ore deposits can contain elevated levels of toxic metal(loid)s that, when mobilized by weathering upon O2 and H2O infusion, can result in groundwater contamination. Dry climate and lack of vegetative cover result in near‐surface pedogenic processes that produce fine‐particulate secondary minerals that can be translocated as geodusts leading to ingestion or inhalation exposure in nearby communities. In this study, in vitro bioassays were combined with synchrotron‐based X‐ray spectroscopy and diffraction to determine the potential risk for toxic element release from dust (PM10) samples into biofluid simulants. PM10 were isolated from across the oxidative reaction front in the top meter of tailings subjected to 50 years of weathering under semiarid climate and introduced to synthetic gastric and alveolar fluids. Aqueous concentrations were measured as a function of reaction time to determine release kinetics. X‐ray diffraction and absorption spectroscopy analyses were performed to assess associated changes in mineralogy and elemental speciation. In vitro bioaccessibility of arsenic and lead was highest in less‐weathered tailings samples (80–110 cm) and lowest in samples from the suboxic transition zone (40–52 cm). Conversely, zinc release to biofluids was greatest in the highly weathered near‐surface tailings. Results indicate that bioaccessibility of As and Pb was controlled by (i) the solubility of Fe2+‐bearing solids, (ii) the prevalence of soluble SO4 2−, and (iii) the presence of poorly crystalline Fe(III) oxide sorbents, whereas Zn bioaccessibility was controlled by the pH‐dependent solubility of the stable solid phase.

From the Decomposition of Chemical Warfare Agents to the Decontamination of Cytostatics

The ability of pilot samples of destructive metal oxide sorbents to decompose a sulfur mustard-type chemical warfare agent into nontoxic products in a nonaqueous solvent was compared with that of the commercial product FAST-ACT. Additionally, samples of the destructive metal oxide sorbents were used to decompose nitrogen mustards, which are used as chemotherapeutic agents, in water, and the results were compared with those of FAST-ACT. All the prepared pilot samples exhibited stoichiometric activities, i.e., the degradation rate expressed by the rate constant, k [s–1, min–1], and the decomposition efficiencies, which are expressed by the degree of conversion d [%], higher than those of the comparative commercial product FAST-ACT. Scaling up the sulfur mustard decomposition from the laboratory conditions (reaction volume, 4 L) to quarter-operating (pilot) reaction conditions (reaction volume, 100 L) had a positive effect on the reaction and final product.

Natural Calcium‐Based Residues for Carbon Dioxide Capture in a Bubbling Fluidized‐Bed Reactor

AbstractUsed clamshells (Paphia undulata), as a precursor of calcium oxide (CaO) sorbents, were employed for carbon dioxide (CO2) adsorption in a bubbling fluidized‐bed reactor. To find the optimal calcination conditions, a 2k experimental design was used to vary the ground clamshell particle size, heating rate, and calcination time at 950 °C under a nitrogen atmosphere. The heating rate was the most significant factor affecting the CO2 adsorption capacity of the obtained CaO sorbent. The maximum CO2 adsorption capacity of the CaO obtained under these study conditions was higher than that of commercial CaO.

Effective Removal of Hexavalent Chromium from Aqueous Solutions Using Ionic Liquid Modified Graphene Oxide Sorbent

Effective Removal of Hexavalent Chromium from Aqueous Solutions Using Ionic Liquid Modified Graphene Oxide Sorbent

Highly porous copper oxide sorbent for H2S capture at ambient temperature

A series of novel highly porous Cu-based sorbents with three-dimensionally ordered macropores structure (3DOM) were synthesized and studied for hydrogen sulfide (H2S) removal in dynamic conditions at ambient temperature. The fresh, sulfide and regenerated materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption studies, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structures (XANES) spectra. The results show that because of the highly dispersed CuO nanoparticles and large surface area, especially the well-developed macropores, sorbent 3DOM-SC-43 with 3DOM structure presented a considerably high breakthrough H2S removal capacity from gas streams full of moisture (wet feed) at ambient temperature, almost 6 times than the sample without 3DOM structure, suggesting that 3DOM structure greatly enhanced the H2S removal ability. The presence of moisture was found to be crucial to keep a high activity for H2S removal, but the existing H2S concentration before breakthrough was higher. Modification of sorbent by ammonia vapor deposition method can not only achieve high H2S removal capacity but also maintain low existing H2S concentration before breakthrough without the help of moisture. Thermogravimetry coupled with mass spectroscopy (TG-MS) was used to investigate the regeneration of sorbent, showing the regeneration temperature had to be greater than 600°C considering the decomposition of CuSO4 which is easily formed in air. However, the regenerated CuO/3DOM sorbents did not perform well compared with the fresh CuO/3DOM, but they were still superior to the fresh sorbent without the 3DOM structure.

Pelletization of Iron Oxide Based Sorbents for Hydrogen Sulfide Removal

Biogas derived from anaerobic digestion of biological wastes has been extensively used for heating purposes and/or electricity generation. Presence of hydrogen sulfide (H2S) in biogas affects engine performance adversely, thus reducing H2S content is a valuable part in practical application before utilizing biogas. Adsorptive separation is very appealing due to being an economical and effective method including the use of iron oxide based adsorbents. Pelletization of iron oxide adsorbents has never been reported among the adsorbents described to date. Therefore, H2S capture in two iron oxides (ferric oxide (Fe2O3) and magnetite (Fe3O4)) was experimentally investigated to determine technical feasibility of shaping pellets based on active iron oxide sorbent in removing H2S from a simulated gas stream (0.35 vol.% H2S balanced in N2). Many factors affecting the behavior of gas adsorption such as gas in-flow rate, adsorption temperature, binder loadings and textural characteristics were considered. The pellet strengths were also undertaken using a bulk crushing strength analyzer. The results indicated that higher temperature favors the diffusion of H2S molecules from the surface into the bulk of iron oxides. The H2S-sorption capacity of Fe3O4 sorbent was higher than that of Fe2O3 sorbent corresponding with the different pore volume and surface area in each adsorbent. With the same active Fe3O4, the extruded pellet produced with starch binder showed the excellent H2S uptake and crushing resistance. The higher gas in-flow rate had positive impact to contacting efficiency and mass transfer of solid and gas phase. The adsorbed H2S gas can be readily desorbed from the pellets with the desorption temperature below 60°C and the H2S-sorption capacity was consistent over repeated cycles. The pellets can be reused several times for consecutive adsorption/desorption cycles, without loss of performance in a large-scale reactor and therefore represent serious candidates for use in commercial absorbers.

Effects of Microwave Irradiation on the Structure of Zinc Oxide Sorbents for High Temperature Coal Gas Desulfurization

To investigate the effects of microwave irradiation on the structure properties of ZnO sorbents, fractal dimensions and desulfurization kinetics of sorbents prepared by microwave and conventional heating respectively have been studied in the present paper. The performances for desulfurization were tested in a fixed-bed reactor, and the sorbents were characterized by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Fractal dimensions were calculated based on the Frenkel-Halsey-Hill theory, and desulfurization kinetics of sorbents was acquired by the equivalent grain model. The analysis date revealed that the fractal dimensions and sulfur capacity of sorbents prepared by microwave heating are 2.744 and 10.77%, while those of the sorbents prepared by conventional heating are 2.719 and 8.633%. Desulfurization kinetics studies presented that the apparent chemical reaction activation energy and the diffusion activation energy of sorbents heated by the microwave method are 6...

Super high sensitive plate acoustic wave humidity sensor based on graphene oxide film

The changes of density and elastic modules due to water vapor adsorption are measured for graphene oxide film at room temperature. Dominant mechanism for acoustic wave humidity sensing by the film is shown to be related with variation of its electric conductivity. Basing on the data, super high sensitive humidity sensor employing high-order Lamb wave with large coupling constant, standard lithium niobate plate, and graphene oxide sorbent film is developed. The minimal detectable level of the sensor is as low 0.03% RH, response times are 60/120s, and reproducibility is ±2.5%. The sensor is completely selective towards H2, CO, CH4, NO, O2.