Oxide Sorbents Research Articles

Application of Iron Oxide Sorbent Based on Cellular Ceramics for Purification of Biogas from Hydrogen Sulfide

Application of Iron Oxide Sorbent Based on Cellular Ceramics for Purification of Biogas from Hydrogen Sulfide

Mechanistic investigations into the removal of Hg0 over Pt-based sorbents by warm syngas cleanup

Commercial sorbents for Hg0 removal from syngas operate at low temperatures (<120 ºC), which impacts the thermal efficiency of integrated gasification and chemical production processes. For the first time, supported Pt-based sorbents with different supports, viz., Pt/SBA-15, Pt/S-40, Pt/ZrO2, Pt/CeO2, and Pt/TiO2 are synthesized for high-temperature (≥200 ºC) Hg0 removal. Pt/SBA-15 shows the highest cumulative Hg0 removal efficiency (>99%) at 270 ºC in N2, which is retained for much higher durations (>20h) compared to the best-reported Pd-based and metal oxide sorbents. Besides amalgam formation, Hg0 removal on Pt/ZrO2 and Pt/CeO2 occurs via oxidation at high temperatures (> 270 ºC), which explains the reduced negative effect of high temperature over these sorbents. In contrast to other supports, the removal efficiency over Pt/SBA-15 is above 99% even in the presence of H2, H2O, and CO2, and is attributed to the hydrophobic mesoporous silica support. DRIFTS studies indicate CO adsorption on the active Pt sites over all sorbents. Based on the inferences obtained, a kinetic model is developed and integrated into a reactor-scale model which effectively simulates the spatio-temporal features of Hg0 sorption over Pt/SBA-15.

Promotional effect of NaNO3/NaNO2 on CO2 adsorption performance of MgO sorbents

The magnesium oxide (MgO) sorbents doped with different NaNO3/NaNO2 molar ratios were prepared to improve their stability over multiple cycles. Regulating the NaNO3/NaNO2 molar ratio effectively improved the CO2 adsorption performance of the sorbent. The MgO sorbent with the NaNO3/NaNO2 molar ratio of 0.8 exhibited outstanding performance and stability. Characterization and density functional theory calculations confirmed the positive effects of the appropriate NaNO3 amount in improving the adsorption activity, whereas the suitable NaNO2 amount slowed the sintering step and improved stability. Notably, the molten salt remained stable during cycling and did not decompose even at high regeneration temperatures, guaranteeing the cyclic stability of the sorbent. Further characterization showed that the CO2 sorption drop in the first few cycles was ascribed to the decline in the active surface owing to the aggregation of MgO particles, incomplete regeneration of sorbents, and segregation of molten salt on the sorbent surface.

Fabrication of antimony oxide sorbent for sorption of some lanthanides from aqueous solutions

ABSTRACT The sorption of certain lanthanides from aqueous solutions is the focus of this work using antimony oxide (Sb2O5) sorbent. Sb2O5 sorbent was prepared using the precipitation technique, and it has been described using several analytical methods such as Fourier-transformed infrared (FT-IR), X-ray diffraction pattern (XRD), and scanning electron microscope (SEM). The sorption data were collected on Y(III), Ce(III), and Gd(III) including the effects of pH, shaking time, initial metal concentrations, and temperature. The results revealed that saturation capacity has values of (30.6, 27.5, and 24.1 mg/g) for Y(III), Ce(III), and Gd(III), respectively. The sorption of the studied cations is dependent on pH. The reaction kinetics obeyed the pseudo-2nd-order model, and thermodynamics was endothermic and spontaneous. Sorption isotherms are more relevant to a Langmuir isotherm, whose monolayer capacity values are 27.9, 23.2, and 19.8 mg/g for Y(III), Ce(III), and Gd(III), respectively. The real sample applications illustrate the superiority of antimony oxide sorbent in the removal of Y(III), Ce(III), and Gd(III) from high-grade monazite (HGM).

Alkali Extraction of Arsenic from Groundwater Treatment Sludge: An Essential Initial Step for Arsenic Recovery.

Arsenic (As)-bearing Fe(III) precipitate groundwater treatment sludge has traditionally been viewed by the water sector as a disposal issue rather than a resource opportunity, partly due to assumptions of the low value of As. However, As has now been classified as a Critical Raw Material (CRM) in many regions, providing new incentives to recover As and other useful components of the sludge, such as phosphate (P) and the reactive hydrous ferric oxide (HFO) sorbent. Here, we investigate alkali extraction to separate As from a variety of field and synthetic As-bearing HFO sludges, which is a critical first step to enable sludge upcycling. We found that As extraction was most effective using NaOH, with the As extraction efficiency increasing up to >99% with increasing NaOH concentrations (0.01, 0.1, and 1 M). Extraction with Na2CO3 and Ca(OH)2 was ineffective (<5%). Extraction time (hour, day, week) played a secondary role in As release but tended to be important at lower NaOH concentrations. Little difference in As extraction efficiency was observed for several key variables, including sludge aging time (50 days) and cosorbed oxyanions (e.g., Si, P). However, the presence of ∼10 mass% calcite decreased As release from field and synthetic sludges considerably (<70% As extracted). Concomitant with As release, alkali extraction promoted crystallization of poorly ordered HFO and decreased particle specific surface area, with structural modifications increasing with NaOH concentration and extraction time. Taken together, these results provide essential information to inform and optimize the design of resource recovery methods for As-bearing treatment sludge.

Pleated stainless steel net supported polystyrene/zinc oxide sorbent stir bar for inspection of residual fipronil and its degradation products in chicken eggs

Residual fipronil and its degradation products in chicken eggs are crucial issues in food safety. A stir bar sorptive extractor was developed by employing a pleated stainless steel (SS) net covered with hydrothermal synthesized zinc oxide (ZnO) nanostructure and dip-coated polystyrene (PS) from plastic foam waste. The combination of a PS/ZnO/SS stir bar extraction followed by gas chromatography detection with an electron capture detector yields a highly feasible process for the inspection of residual fipronils in chicken eggs with a linear range of 0.10–150 μg kg−1 and detection limit of 0.07–0.41 μg kg−1 with high recoveries (87.0 ± 2.4 to 95.2 ± 2.5%) and good precision (2.1–9.6% RSDs). The developed PS/ZnO/SS stir bar could be reused up to nine times. Its main advantages are simplicity of preparation, low-cost materials, and efficient utilization of PS waste.

Hydrogen Production from the Carbon Dioxide Sorption-Enhanced Steam Reforming of Biogas Over a Ni-Based Hybrid Material with a Calcium Oxide Sorbent

Hydrogen Production from the Carbon Dioxide Sorption-Enhanced Steam Reforming of Biogas Over a Ni-Based Hybrid Material with a Calcium Oxide Sorbent

Unlocking high-performance HCl adsorption at elevated temperatures: the synthesis and characterization of robust Ca–Mg–Al mixed oxides

The presence of HCl and SO2 gas imposes limitations on syngas utilization obtained from household waste in a wide range of applications. The hydrotalcite-like compounds (HTLs) have been proved that could remove HCl efficiency. However, the research on impact of synthesis conditions of HTLs and SO2 on HCl removal was limited. In this study, a range of Ca–Mg–Al mixed oxide sorbents was synthesized by calcining HTLs, with variations in crystallization temperature, solution pH, and the Ca/Mg molar ratio. These sorbents were examined for their effectiveness in removing HCl at medium–high temperatures under diverse conditions. The adsorption performance of selected sorbents for the removal of HCl, SO2, and HCl-SO2 mixed gas at temperature of 350 °C, 450 °C, and 550 °C, respectively, was evaluated using thermogravimetric analysis (TGA). It was observed that the HTL synthesis parameters significantly influenced the HCl adsorption capacity of Ca–Mg–Al mixed oxides. Notably, HTLs synthesized at 60 °C, a solution pH of 10–11, and a Ca/Mg ratio of 4 exhibited superior crystallinity and optimal adsorption characteristics. For individual HCl and SO2 removal, temperature had a minor effect on HCl adsorption but significantly impacted SO2 adsorption rates. At temperatures above 550 °C, SO2 removal efficiency substantially decreased. When exposed to a mixed gas, the Ca–Mg–Al mixed oxides could efficiently remove both HCl and SO2 at temperatures below 550 °C, with HCl dominating the adsorption process at higher temperatures. This dual-action capability is attributed to several mechanisms through which HTL sorbents interacted with HCl, including pore filling, ion exchange, and cation exchange. Initially, HCl absorbed onto specific sites created by water and CO2 removal due to the surface’s polarity. Subsequently, HCl reacted with CaCO3 and CaO formed during HTL decomposition.Graphical abstract

Synthesis of Manganese Oxide Sorbent for the Extraction of Lithium from Hydromineral Raw Materials.

The article presents the research results for the synthesis of inorganic sorbents based on manganese oxide compounds. It shows the results of the lithium sorption from brines with the use of synthesized sorbents. The effect of temperature, the molar ratio of Li/Mn, and the duration for obtaining a lithium-manganese precursor and its acid treatment was studied. The sorption characteristics of the synthesized sorbents were studied. The effect of the ratio of the sorbent mass to the brine volume and the duration of the process on the sorption of lithium from brine were studied. In this case, the sorbent recovery of lithium was ~86%. A kinetic model of the lithium sorption from brine on a synthesized sorbent was determined. The kinetics of the lithium sorption was described by a pseudo-second-order model, which implies limiting the speed of the process due to a chemical reaction.

Carbon dioxide minimization using sodium and potassium impregnated calcium oxide sorbent derived from waste eggshell

Carbon dioxide minimization using sodium and potassium impregnated calcium oxide sorbent derived from waste eggshell

Effect of Reaction Parameters on CO2 Absorption from Biogas Using CaO Sorbent Prepared from Waste Chicken Eggshell.

This study provides an efficient and straightforward approach to eliminate carbon dioxide (CO2) by absorption using a calcium oxide (CaO) sorbent derived from chicken eggshells. The sorbent concentration, stirring speed, and contact time were varied. The optimal condition for CO2 removal was a 10% calcium hydroxide (Ca(OH)2) suspension at 600 rpm with 20 min interaction. This optimum condition conferred the ever-highest absorption (98.71%) of CO2 through Ca(OH)2 suspensions from eggshell-derived CaO. X-ray diffraction was used to identify crystallographic phases and optimum conditions revealed calcium carbonate (CaCO3) formation with the highest intensity, Fourier transform infrared spectroscopy revealed peaks for the carbonate (CO32-) group, field emission scanning electron microscopy was used to investigate the morphological and structural properties of the sorbent before and after CO2 absorption, and thermogravimetric analysis was performed to understand the reaction mechanism. According to the kinetic analysis, the sorbent can be fully decomposed with a minimum activation energy (Ea) of 89.09 kJ/mol.

Metal oxide and nitrate-modified calcium gluconate-based sorbent with high stability for integrated carbon capture and utilization process

In this study, metal oxides (MgO, CeO2, and Al2O3) and metal nitrates (Mn(NO3)2, Al(NO3)3, Mg(NO3)2, and Fe(NO3)3) were used to modify calcium gluconate-based sorbents for the integrated CO2 capture and utilization (ICCU) process. We employed conventional thermogravimetric analysis (TGA) and microfluidized bed thermogravimetric analysis coupled with mass spectrometry (MFB-TGA-MS) to explore the cyclic CO2 capture behavior, physical and chemical properties, and morphology in detail. Our findings reveal that calcium gluconate modified with aluminum nitrate (CG-Al-N) exhibited superior CO2 capture capacity (9.81 mmol∙g−1 over 20 cycles), along with a high surface area (35.67 m2∙g−1) and pore volume (0.16 cm3∙g−1). In comparison, pure calcium gluconate displayed a capacity of 7.09 mmol∙g−1, a surface area of 27.66 m2∙g−1, and a pore volume of 0.06 cm3∙g−1, while commercial calcium oxide demonstrated 1.96 mmol∙g−1, 4.62 m2∙g−1, and 0.01 cm3∙g−1, respectively. Notably, after 100 cycles, CG-Al-N retained a CO2 capture capacity of 11.75 mmol∙g−1, achieving 66% of the capacity of the pure CaO sorbent. This observation strongly suggests that CG-Al-N has excellent anti-sintering properties. Furthermore, data was acquired under fluidized and isothermal conditions by utilizing MFB-TGA-MS. CG-Al-N consistently exhibited an average CO2 capture capacity (9.57 mmol∙g−1), CO yield (5.00 mmol∙g−1), and CO selectivity (∼100%) over 20 ICCU cycles, with the dominant route being the reverse water–gas shift (RWGS) reaction, highlighting the self-catalytic activity of gluconate-based sorbents. Morphological evolution also revealed finer pores and a skeleton structure of cycled CG-Al-N, which affirms the unobstructed gas entry and ensures a continuous gas–solid reaction.

Preparation and Use of Iron on Carbon Foam for Removal of Organic Dye from Water: Batch Studies.

The presence of dyes in effluents from textile industries has a detrimental effect on aquatic ecosystems as it hinders the process of photosynthesis by reducing the penetration of sunlight. The adsorption capacity of a carbon foam-based iron oxide sorbent obtained from natural sources for the removal of organic methylene blue (MB) dye from water was investigated. The adsorption capacities were examined by batch experiments, wherein the impacts of varying iron content, sorbent dosage, contact time, dye concentration, and characterization were assessed. The physical characteristics and surface morphology of the synthesized carbon foam were also investigated. The carbon precursor and iron oxide precursor were coalesced within a singular container and subjected to carbonization process. This resulted in the formation of a porous structure that is capable of effectively providing support to the iron oxide particles. The carbon foam produced is a self-assembled formation that possesses the characteristic shape and underlying network structure reminiscent of bread. As the number of nanoparticles went up, so did the number of active sites. At elevated temperatures, the interactions between the dye molecules were enhanced, resulting in a more efficient process of dye removal. The magnetite sample exhibited endothermic adsorption, and all other samples exhibited exothermic adsorption. The adsorption of MB onto iron supported by carbon foam did not exhibit intraparticle diffusion as the only rate-limiting step for all samples. The adsorption rate was governed by a multistep elementary reaction mechanism in which multiple processes occurred simultaneously. The experimental data in this study may be accurately modeled by the pseudo-second-order kinetic model (R2 > 0.96). Additionally, the Freundlich isotherm best describes the adsorption equilibrium, which is supported by the outstanding fit of data to the model (R2 > 0.999). The findings suggest that the utilization of a natural carbon foam as a support for an immobilized iron oxide sorbent demonstrates considerable effectiveness in the removal of methylene dye from industrial effluent.

Continuous production of O2-free enriched CO2 from ambient air using moisture swing sorbents

Herein, we report the production of O2-free CO2 from a CO2/O2/N2 mixture using moisture swing sorbents in two parallel reactors under isothermal conditions, wherein CO2/O2/N2 and H2O/N2 are alternately fed into the reactors. The CO2/O2/N2 mixture was fed into the reactor containing the water-pre-adsorbed metal oxide sorbent to capture CO2. After changing to an H2O/N2 gas mixture, moisture-promoted CO2 desorption took place. Sorbent-screening tests showed that Rb-loaded Al2O3 (Rb/Al2O3) was the most effective sorbent material for this process. Thus, Rb/Al2O3 sorbents with different Rb loadings were tested for continuous CO2 separation using two parallel reactors. Various structural analyses revealed that the highly dispersed Rb(I) species were responsible for CO2 capture/desorption. The formation and desorption of surface carbonates on Rb/Al2O3 under working conditions were then studied using in situ Fourier transform infrared spectroscopy (FTIR) with online gas composition analysis (operando FTIR). Finally, we demonstrate the continuous production of O2-free and ca. 5 times enriched CO2 from ambient air.

Favorably adjusting the oxygen species over Fe-Mn binary oxide sorbent by directional etching for arsenic oxidation and adsorption

In this study, raw and etched Fe-Mn binary oxide sorbents were prepared via the coprecipitation method to explore the catalytic oxidation and adsorption of As2O3. The oxidation and adsorption capacities for As2O3 were investigated at different temperatures, citric acid etching concentrations, and O2 concentrations. Compared with the raw sorbent, the sorbents etched with citric acid show excellent arsenic adsorption and oxidation capacities. As confirmed by scanning electron microscope (SEM) and Brunauer-Emmett-Teller (BET) studies, etching increased the number of oxygen vacancies and specific surface area. Oxygen temperature programming desorption (O2-TPD) characterization showed that the oxygen vacancy structure enhanced the instability and fluidity of the lattice oxygen, promoting arsenic adsorption and oxidation. Hydrogen temperature programmed reduction (H2-TPR) characterization indicated that citric acid etching facilitated the oxidation of the sorbent. In addition, density functional theory (DFT) calculations also confirmed that etching facilitated arsenic adsorption by altering the adsorption energies of the sorbents.

Unraveling the roles of microporous and micro-mesoporous structures of carbon supports on iron oxide properties and As (V) removal performance in contaminated water

This study investigates the impact of microporous (SP–C) and micro-mesoporous carbon (DP-C) supports on the dispersion and phase transformation of iron oxides and their arsenic (V) removal efficiency. The research demonstrates that carbon-supported iron oxide sorbents exhibit superior As(V) uptake capacity compared to unsupported Fe2O3, attributed to reduced iron oxide crystallite sizes and As(V) adsorption on carbon supports. Maximum As(V) uptake capacities of 23.8 mg/g and 18.9 mg/g were achieved for Fe/SP-C and Fe/DP-C at 30 wt% and 50 wt% iron loading, respectively. The study reveals a nonlinear relationship between As(V) sorption capacity and iron oxide crystallite size after excluding As(V) adsorption capacity on carbon supports, suggesting the iron oxide phase (Fe3O4) plays a role in determining adsorption capacity. Iron oxide-loaded DP-C sorbents exhibit faster adsorption rates at low As(V) concentrations (5 mg/L) than SP-C sorbents due to their bimodal pore structure. Adsorption behavior varies at higher As(V) concentrations (45 mg/L), with Fe/DP-C reaching maximum capacity more slowly due to limited available adsorptive sites. All adsorbents maintained near-complete As(V) removal efficiency over five cycles. The findings provide insights for designing more efficient adsorbents for As(V) removal from contaminated water sources.

Removal of Organic Sulfur Pollutants from Gasification Gases at Intermediate Temperature by Means of a Zinc–Nickel-Oxide Sorbent for Integration in Biofuel Production

Production of renewable fuels from gasification is based on catalytic processes. Deep desulfurization is required to avoid the poisoning of the catalysts. It means the removal of H2S but also of organic sulfur species. Conventional cleaning consists of a several-step complex approach comprising catalytic hydro-treating followed by H2S removal. In this work, a single-stage process using a zinc and nickel oxide sorbent has been investigated for the removal of organic sulfur species present in syngas. The process is called reactive adsorption and comes from the refinery industry. The challenge investigated by CIEMAT was to prove for the first time that the concept is also valid for syngas. We have studied the process at a lab scale. Thiophene and benzothiophene, two of the main syngas organic sulfur compounds, were selected as target species to remove. The experimental study comprised the analysis of the effect of temperature (250–450 °C), pressure (1–10 bar), space velocity (2000–3500 h−1), tar components (toluene), sulfur species (H2S), and syngas components (H2, CO, and full syngas CO/CO2/CH4/H2). Operating conditions for removal of thiophene and benzothiophene were determined. Increasing pressure and temperature had a positive effect, and full conversion was achieved at 450 °C, 10 bar and 3500 h−1, accompanied by simultaneous hydrogen sulfide capture by the sorbent in accordance with the reactive adsorption desulfurization (RADS) process. Space velocity and hydrogen content in the syngas had little effect on desulfurization. Thiophene conversions from 39% to 75% were obtained when feeding synthetic syngas mimicking different compositions, spanning from air to steam-oxygen-blown gasification. Toluene, as a model tar component present in syngas, did not strongly affect the removal of thiophene and benzothiophene. H2S inhibited their conversion, falling, respectively, to 2% and 69% at 350 °C and 30% and 80% at 400 °C under full syngas blends.

A monolith graphene oxide and mesoporous carbon composite sorbent in polyvinyl alcohol cryogel to extract and enrich fluoroquinolones in honey

A monolith graphene oxide and mesoporous carbon composite sorbent in polyvinyl alcohol cryogel to extract and enrich fluoroquinolones in honey

DEVELOPMENT OF SORPTION MATERIALS OF WIDE FUNCTIONAL PURPOSE IN THE V.I. VERNADSKII INSTITUTE OF GENERAL AND INORGANIC CHEMISTRY OF THE NAS OF UKRAINE

The review is devoted to the work, which were performed at the V.I. Vernadskii Institute of General and Inorganic Chemistry of the NAS of Ukraine according to the direction of the development of sorption naterials of wide functional purpose. All sorbents can be used in separation processes: due to their coarse dispersion and mechanical strength, they can be used as fillers for sorption columns.The direction of early works is the development of amorphous hydrophosphates and double hyd­rated oxides of multivalent metals, intended for the removal of toxic inorganic ions from water (arsenate-, chromate- and borate-anions, Cu2+, Pb2+, Cd2+cations etc.). Currently, attention is focused on the development of composite materials.The base of inorganic composites is hydrophosphate and oxide sorbents, and the modifiers are the advanced carbon materials, lithium-titanium and lithium-titanium-manganese spinels etc.Sorbents based on ion-exchange resins modified with inorganic ionites have also been developed.The combination of various components in composites makes it possible to obtain sorbents with improved properties (faster sorption, increased capacity and selectivity, sorption capacity in a wider pH range, easier regeneration) or multifunctional materials that sorb both inorganic and orga­nic compounds, for example, pesticides. Prospective field of research is the development of technologies that include not only the extraction of toxic and valuable components from liquids of natural, technological and biogenic origin, but also the regeneration of the sor­bent and processing of the concentrate to obtain commercial products.Thus, the integration of lithium sorption concentration into the process of reverse osmosis water desalination has been proposed. The processing of the solution formed during the regeneration of the sorbent includes the production of lithium carbonate and a complex fertilizer for acidic soils. Composites, the components of which are natural materials, are also in the focus of attention.Magnetic sorbents based on biopolymers, proposed for extraction of oil and oil products from water surfaces. Composites based on zeolites are used as containers for liquid fertilizers Another direction of research is the creation of composites - potential membrane modifiers for separation processes.

The elimination and extraction of organosulfur compounds from real water and soil samples using metal organic framework/graphene oxide as a novel and efficient nanocomposite

In the present work, an efficient metal organic framework/graphene oxide (MOF-801/GO) sorbent was fabricated and employed for the detection of organosulfur pesticides (OSPs) in real samples using gas chromatography-flame photometric detection (GC-FPD). The optimal extraction parameters for the suggested solid-phase extraction (SPE) include sorbent amount (60 mg), extraction solvent (acetonitrile) and extraction time (5 min). The linear dynamic ranges and detection limits for organosulfur pesticides (OSPs) samples under above extraction conditions were ranged from 0.5 to 300 μg L−1 and 0.1–1.1 μg L−1, respectively. Moreover, the proposed SPE/GC-FDP method was applied for the analysis of pesticides in different real environmental water and soil samples. The obtained recoveries of the analytes in were between 92.0 and 106.8% and relative standard deviation (RSD) values were lower than 9.2%. The application of the MOF-801/GO as a sorbent in dSPE of OSPs analytes showed to be reliable, fast and sensible methodology for pesticides monitoring in different environmental samples.