Search Results (557)

The removal of nickel from industrial wastewater necessitates efficient sorbent materials. This study investigates nanostructured potassium- and sodium-substituted aluminosilicate-based nanocomposites for this application. Materials were synthesized and characterized using SEM-EDS, XPS, XRD, FTIR, low temperature N₂ adsorption–desorption and Ni²⁺ adsorption experiments. SEM and XRD confirmed an X-ray amorphous structure attributable to fine crystallite size. The sodium-substituted material Na₂Al₂Si₂O₈ exhibited the lowest specific surface area (48.3 m²/g) among the tested composites. However, it demonstrated the highest Ni(II) sorption capacity (64.6 mg/g, 1.1 mmol/g) and the most favorable sorption kinetics, as indicated by a Morris-Weber coefficient of 0.067 ± 0.008 mmol/(g·min¹/²). Potassium-substituted analogs with higher Si/Al ratios showed increased surface area but reduced capacity. Analysis by XPS and SEM-EDS established that Ni(II) uptake occurs through a complex mechanism, involving ion exchange, surface complexation, and chemisorption resulting in the formation of new nickel-containing composite surface phases. The results indicate that optimal sorption performance for Ni(II) is achieved with sodium-based aluminosilicates at a low Si/Al ratio (Si/Al = 1). The functional characteristics of Na₂Al₂Si₂O₈ compare favorably with other silicate-based sorbents, suggesting its potential utility for wastewater treatment. Further investigation is needed to elucidate the precise local coordination environment of the adsorbed nickel. Full article

Activated carbon F-400 was modified by using different oxidation agents: nitric acid, sulfuric acid, and ozone. The influence of the type of carbon surface groups on adsorption effectiveness towards selected aromatic compounds was analyzed. The commercial carbon F-400 was deashed and modified, and the obtained materials were characterized by using different techniques to determine their textural, thermal, morphological, and surface properties: low-temperature adsorption/desorption isotherms of nitrogen, scanning electron microscopy (SEM), Boehm titration, and Fourier transform infrared spectroscopy (FTIR). The adsorption properties towards four aromatic compounds, i.e., toluene, 4-nitrotoluene, nitrobenzene, and 4-nitrobenzoic acid, were evaluated based on isotherm measurements. Adsorption equilibrium data were analyzed by applying the generalized Langmuir isotherm. The influence of carbon surface groups and adsorbate functional groups in interaction mechanisms was discussed. It was found there was a strong effect of oxidation on adsorption efficiency. The adsorption capacity of modified activated carbon F-400 strongly depends on the type of oxidant used, e.g., in the case of toluene, the use of ozone as an oxidant gives a sorption capacity of 5.51 mmol/g, and of nitric acid—4.20 mmol/g. Full article

The efficiency of the sorption–biological method for treatment of oil-polluted coastal substrates (soil and sand) of the Barents Sea under low temperature (10 °C) using the active hydrocarbon-oxidizing bacterial strain Rhodococcus erythropolis HO-KS22 was assessed in the laboratory. The highest rate of hydrocarbon degradation was in sand polluted with a low-density oil emulsion and in soil polluted with a medium-density oil emulsion. Sorption–biological treatment increased the rate of hydrocarbon degradation in sand by 3–4 times during the first month and enhanced the overall efficiency by 20% over a three-month period. The use of sorbents (granular activated carbon, thermally activated vermiculite and peat) both in sand and soil prevents secondary pollution of coastal ecosystems, since it significantly reduces the hydrocarbons’ desorption and their leaching by water. Rhodococcus erythropolis HO-KS22, in combination with sorbents, can be applied during the biological remediation of coastal sandy substrates following the initial removal of emergency oil spills. However, for biological treatment of oil-polluted soils of the Barents Sea coast, further selection of active strains of hydrocarbon-oxidizing bacteria resistant to low pH values and temperatures typical for this region is necessary. The use of microbiological preparations without taking into account the soil and climatic factors of the region may be ineffective, which will increase the cost of remediation of the territory without significantly improving its condition. Full article

This study examined the effects of 2, 4 and 8% digestate-derived compost (DCP) on the retention/release of the fungicide penconazole (PEN), the herbicide S-metolachlor (S-MET) and the endocrine disruptor bisphenol A (BPA) in two agricultural soils sampled in Valenzano (SOV) and Trani (SOT), in Sothern Italy. DCP alone showed a conspicuous adsorption of the three xenobiotics, followed by their slow and scarce release. Sorption isotherm data of the compounds on unamended and DCP-amended soils were well described by the Freundlich model. Compared to unamended soil, the addition of the highest dose (8%) DCP to SOV increased the distribution coefficient, Kd, values of PEN, S-MET and BPA by 281%, 192% and 176%, respectively, while for SOT, the increases were 972%, 786% and 563%, respectively. Desorption of PEN and S-MET from all treatments was slow and partial (hysteresis), and only slightly reduced or unaffected by the addition of DCP, whereas BPA was almost entirely undesorbed in all treatments. Highly significant correlations between the adsorption coefficients of the three compounds in all soil treatments and the corresponding organic C contents confirm the prominent role of native and anthropogenic OM in the adsorption of contaminants and, consequently, in the control of their transfer into natural waters and/or entry in crop plants. Full article

CH₄ is a powerful greenhouse gas that is thought to be one of the main causes of global warming. The catalytic conversion of methane in the presence of oxygen into hydrogen-rich syngas, known as the partial oxidation of methane (POM), is highly appealing for environmental and synthetic concerns. In search of a cheap catalytic system, the Ni-supported MgO-based (5Ni/MgO) catalyst and the promotional supplement of 1–3 wt.% Sr over 5Ni/MgO are investigated for the POM reaction. Catalysts are characterized by N₂ sorption isotherm analysis, X-ray diffraction spectroscopy, Raman spectroscopy, temperature-programmed desorption techniques, and thermogravimetry. Increasing the loading of strontium over Ni/MgO induced a strong interaction of NiO with the support, pronouncedly. In the presence of oxygen during the POM, the moderate-level interaction of NiO with the support grows markedly. Overall, at a 600 °C reaction temperature, the 5Ni2Sr/MgO catalyst shows 72% CH₄ conversion (~67% H₂ yield) at 14,400 mL/h/g_cat GHSV and ~86% CH₄ conversion (84% H₂ yield) at 3600 mL/h/g_cat GHSV. Achieving a higher activity towards the POM over cheap Ni, Sr, and MgO-based catalysts might draw the attention of environmentalists and industrialists as a low-cost and high-yield system. Full article

Atmospheric water harvesting, as an emerging water collection technology, is expected to mitigate water resource crises. Adsorption-based atmospheric water harvesting technology offers distinct advantages, including geographical independence and reduced reliance on ambient humidity levels. Herein, a thermoresponsive gel (PNIPAM/TO-CNF) integrated with lithium chloride was constructed to achieve accelerated moisture sorption and rapid desorption capabilities. In the designated PNIPAM/TO-CNF/LiCl gel, PNIPAM provided a temperature-responsive hydrophilic–hydrophobic transition network; the hydrophilicity and structural strength were enhanced by TO-CNF, the moisture absorption capacity was dramatically elevated by hygroscopic salt LiCl, and pore-forming agent polyethylene glycol created a favorable porous structure. This synergistic design endows the gel with an optimized hydrophilic network, temperature-responsive behavior, and a porous architecture conducive to water vapor transportation, thereby achieving rapid moisture absorption and desorption. Under 60% relative humidity, the gel exhibited a water vapor adsorption capacity of 144% within 1 h, reaching its maximum absorption capacity of 178% after 140 min. The gel exhibited an even more superior desorption performance: when heated to 70 °C, its moisture content rapidly decreased to 16% of its initial weight within 1 h, corresponding to the desorption of 91% of the total absorbed water. A simplified pore-forming methodology that enables the integration of temperature-responsive properties with efficient moisture transfer channels was reported in this paper, providing a viable design pathway for achieving accelerated adsorption–desorption cycles in atmospheric water harvesting. Full article

Molecularly imprinted polymers (MIPs) for silver sorption were synthesized using diethylene glycol dimethacrylate (DEGDMA) and divinylbenzene (DVB) as crosslinking agents. Synthesis was carried out using a ratio template: monomer: monomer: cross-linker = 1:2:2:8. The yield of obtained imprinting structures was 63.2% and 67.8% for MIP(DEGDMA) and MIP(DVB), respectively. The MIPs were analyzed by FTIR analysis, which showed the presence of characteristic peaks indicating the presence of monomers and crosslinkers in the MIP structure. According to the results of SEM analysis, the average cavity size for MIP(DEGDMA) is 0.81 ± 0.20 μm and for MIP(DVB) is 0.68 ± 0.23 μm in diameter. MIP(DEGDMA)’s sorption degree is 66.08%, and its sorption capacity is 3.31 g/g; MIP(DVB)’s sorption degree is 78.35%, and its sorption capacity is 3.92 g/g. The desorption degree is 69.85% for MIP(DEGDMA) and 69.52% for MIP(DVB). For analysis of sorption kinetics, the Radushkevich and Elovich kinetic models were applied. Full article

In sorption cooling systems, an important stage of the thermodynamic cycle is the separation of the refrigerant fluid from the absorbent mixture. This process is called “regeneration” or “desorption,” and it is similar to thermal desalination, where water is separated from an aqueous saline solution. However, since sorption systems utilize high salt concentration solutions, conventional desalination techniques such as reverse osmosis are not suitable. In this regard, membrane devices can enhance heat and mass transfer processes in compact sizes. In the present paper, a membrane device with an air gap membrane distillation configuration was evaluated, operating with the H₂O/LiBr + LiCl solution (with a mass ratio of 2:1, LiBr:LiCl), to assess the produced distilled water flux. Among the operating parameters analyzed (solution temperature, cooling water temperature, salt concentration, and membrane pore size), solution temperature had the highest impact on the distilled water flux, while the membrane pore size had the lowest impact. The maximum distilled water flux was 7.63 kg/h·m² with a solution temperature of 95.3 °C, a cooling water temperature of 25.1 °C, a salt concentration of 44.99% w/w, and a membrane pore size of 0.45 μm. On the other hand, the minimum distilled water flux was 0.28 kg/h·m² with a solution temperature of 80.3 °C, a cooling water temperature of 40.1 °C, a salt concentration of 50.05% w/w, and with a membrane pore size of 0.22 μm. Full article

TiVCr-based alloys are well-explored body-centered cubic (BCC) materials for hydrogen storage applications that can potentially store higher amounts of hydrogen at moderate temperatures. The challenge remains in optimizing the alloy-hydrogen stability, and several transition elements have been found to support the reduction in the hydride stability. In this study, Ni and Nb transition elements were incorporated into the TiVCr alloy system to thoroughly understand their influence on the (de)hydrogenation kinetics and thermodynamic properties. Three different compositions, (TiVCr)₉₅Ni₅, (TiVCr)₉₀ Ni₁₀, and (TiVCr)₉₅Ni₅Nb₅, were prepared via arc melting. The as-prepared samples showed the formation of a dual-phase BCC solid solution and secondary phase precipitates. The samples were characterized using hydrogen sorption studies. Among the studied compositions, (TiVCr)₉₀Ni₁₀ exhibited the highest hydrogen absorption capacity of 3 wt%, whereas both (TiVCr)₉₅Ni₅ and (TiVCr)₉₀Ni₅Nb₅ absorbed up to 2.5 wt% hydrogen. The kinetics of (de)hydrogenation were modeled using the JMAK and 3D Jander diffusion models. The kinetics results showed that the presence of Ni improved hydrogen adsorption at the interface level, whereas Nb substitution enhanced diffusion and hydrogen release at room temperature. Thus, the addition of Ni and Nb to Ti-V-Cr-based high-entropy alloys significantly improved the hydrogen absorption and desorption properties at room temperature for gas-phase hydrogen storage. Full article

The development of high-performance adsorbent materials is crucial for any sorption-based energy conversion process. In such a context, composite sorbent materials, although promising in terms of performance and stability, are often challenging to shape into complex geometries. Additive manufacturing, also known as 3D printing, has emerged as a powerful technique for fabricating intricate structures with tailored properties. In this paper, an innovative three-dimensional structure, constituted by zeolite as filler and sulfonated polyether ether ketone as matrix, was obtained using additive manufacturing technology, which is mainly suitable for sorption-based energy conversion processes. The lattice structure was tailored in order to optimize the synthesis procedure and material stability. The complex three-dimensional lattice structure was obtained without a metal or plastic reinforcement support. The composite structure was evaluated to assess its structural integrity using morphological analysis. Furthermore, the adsorption/desorption capacity was evaluated using water-vapor adsorption isobars at 11 mbar at equilibrium in the temperature range 30–120 °C, confirming good adsorption/desorption capacity. Full article

This study reported covalent organic frameworks (COFs) and their hybrid composites with two-dimensional materials, graphene oxide (GO), graphitic carbon nitride (g-C₃N₄), and boron nitride (BN), to examine their structural, textural, and gas adsorption properties. Material characterization confirmed the crystallinity of COF-1 and the preservation of framework integrity after integrating the 2D nanomaterials. FT-IR spectra exhibited pronounced vibrational fingerprints of imine linkages and validated the functional groups from the COF and the integrated nanomaterials. TEM images revealed the integration of the two components, porous, layered structures with indications of interfacial interactions between COF and 2D nanosheets. Nitrogen adsorption–desorption isotherms revealed the microporous characteristics of the COFs, with hysteresis loops evident, indicating the development of supplementary mesopores at the interface between COF-1 and the 2D materials. The BET surface area of pristine COF-1 was maximal at 437 m²/g, accompanied by significant micropore and Langmuir surface areas of 348 and 1290 m²/g, respectively, offering enhanced average pore widths and hierarchical porous strcuture. CO₂ adsorption tests were investigated showing maximum adsorption capacitiy of 1.47 mmol/g, for COF-1, closely followed by COF@BN at 1.40 mmol/g, underscoring the preserved sorption capabilities of these materials. These findings demonstrate the promise of designed COF-based hybrids for gas capture, separation, and environmental remediation applications. Full article

This study presents the results of an investigation of carbonate-containing sorbents for CO₂ capture with natural support materials—kaolin and calcium carbonate—at various loadings of the active phase of Na₂CO₃. The effects of the support type on the distribution of the active component, phase composition, and pore structure of the sorbents were studied. It was found that a Na₂CO₃ loading of 25 wt.% provides the best balance between sorption capacity and technological feasibility. The thermal stability and regeneration capacity of the sorbents were evaluated under high-temperature conditions, revealing high thermal stability of the Na₂CO₃/CaCO₃ system up to 1000 °C, along with its durability over multiple adsorption–desorption cycles. Kinetic studies on the Na₂CO₃/CaCO₃ sorbent using the shrinking core model demonstrated that the overall CO₂ chemisorption process is controlled by surface chemical reaction at temperatures below 50 °C. The obtained results demonstrate the high potential of CaCO₃-based sorbents for practical applications in low-temperature CO₂ capture technologies. A promising direction for the use of such sorbents within CCUS is the development of integrated systems, where CO₂ capture is combined with its conversion into valuable products (e.g., methane, methanol, formic acid) through catalytic processes. Full article

Sugarcane bagasse-derived biochars, produced at 350 °C (B350) and 600 °C (B600), were evaluated for their capacity to modify the sorption behavior of the herbicide sulfentrazone (SFZ) in Red–Yellow Latosol (RYL) and to serve as carriers for its controlled release. Batch sorption experiments indicated that SFZ exhibits low affinity for soil and undergoes sorption–desorption hysteresis. Adding B350 biochar (up to 0.30%) did not significantly affect the herbicide sorption, whereas B600 enhanced its retention. Sequential desorption assays were conducted by incorporating SFZ either directly into the soil or into the biochars, which were subsequently blended into the soil (at 0.15% w/w). The SFZ desorbed more rapidly from the soil than from the biochars, suggesting that the pyrogenic material has potential for modulating herbicide release. Phytotoxicity assessments using Sorghum bicolor confirmed that only SFZ incorporated into B350 (at 0.15% w/w) retained herbicidal efficacy comparable to its direct application in soil. These findings underscore the potential of B350 biochar as a controlled-release carrier for SFZ without compromising its weed control effectiveness. Full article

This study evaluated the effect of post-printing polymerization time on residual monomer elution and water sorption in a 3D-printed resin composite. Eighty samples were fabricated and assigned to four groups based on post-curing duration: 0, 20, 40, and 60 min. Each group was subdivided according to two storage conditions (distilled water and 75% ethanol–water solution), and evaluated at 1 and 7 days. High-performance liquid chromatography (HPLC) quantified eluted monomers. Additionally, 40 specimens underwent a 4-month sorption/desorption cycle for water sorption and solubility assessment. Data were statistically analyzed using kernel regression (monomer data) and Welch ANOVA (water sorption and solubility) at a significance level of p < 0.05. BisEMA was the only monomer detected, with significantly higher elution recorded in ethanol-based storage. Increasing post-curing time notably reduced both monomer release and water sorption/solubility (p < 0.001); however, the optimal results were observed at 40 min post-curing. These findings suggest that extending post-curing beyond an optimal threshold does not further improve composite properties, underscoring the importance of identifying precise curing parameters in order to enhance durability and material performance. Full article

This work presents the recent development of a fiber-coupled multipass near-infrared (NIR) gas sensor used to monitor water vapor desorption of small material coupons. The gas sensor design employs a White cell topology to maximize the optical path length over a compact, hand-size footprint. Water vapor concentrations are quantified over a large dynamic range by simultaneously applying wavelength modulation and tunable diode laser absorption spectroscopy techniques. A custom headspace optimized for material desorption experiments is assembled using commercially available vacuum chamber components. We provide in situ measurements of water vapor desorption from two geometries of the industrially important silicone elastomer Sylgard-184 as a case study for sensor viability. To corroborate the results, the gas sensor data are compared to numerical simulations based on a triple-mode diffusion–sorption model, consisting of Henry, Langmuir, and Pooling modes. Full article