Sorption Time Research Articles

Effect of Soil-pH, temperature and moisture content on sorption dynamics of Metformin and Erythromycin.

The rising soil-groundwater quality issues due to pharmaceuticals and personal care products (PPCPs) have spurred significant concern. To understand the sorption characteristics of metformin (MTN) and erythromycin (ETM) in sandy and sandy loam soils with varying organic matter and particle composition, sorption kinetics (single and competitive), isotherms, and thermodynamics were studied. The effects of pH and soil moisture content (SMC) were also investigated at environmentally relevant concentrations. The equilibrium time of MTN and ETM sorption by the three soils in a competitive solute system was about 4 h, and the sorption process was in line with a pseudo-second-order model. The rate-determining step in the process involved both intraparticle diffusion and liquid film diffusion mechanisms for the two PPCPs. The highest pollutant uptake occurred in soils with higher organic matter, driven by enhanced H-bonding, electrostatic interactions, and π-π and n-π interactions facilitated by the organic matter. The equilibrium data in the three soils was well described by the Freundlich model and confirmed favourable adsorption (1/nf = 1.01 - 1.90). The sorption coefficient (Kd) on the three soils ranged from 2.1 to 332 L/kg for MTN and from 6.25 to 845 L/kg for ETM. The adsorption process was feasible at 293 K and 303 K (ΔG° = - 0.16 to -10.24 kJ/mol), physical and exothermic in nature (ΔH° = -75.21 to -10.30 kJ/mol) for both the contaminants. Observed alterations in Qe with pH confirmed the participation of electrostatic interactions. A low SMC favoured both MTN and ETM sorption onto the sandy soil. Overall, ETM exhibits higher expected sorption, whereas MTN has a greater tendency for migration in the soils and is thus liable to contaminate the groundwater. The study accentuates novel insights into the transport and fate of MTN and ETM in soil-groundwater systems at environmentally relevant concentrations.

Superhydrophobic/superoleophilic polyurethane /reduced graphene oxide/ sponge for efficient oil-water separation and photothermal remediation

Due to the rapid development of global industrialization, the frequent occurrence of organic matter leakage and oil leakage accidents has led to increasingly serious environmental pollution. Therefore, this paper has proposed a facile and affordable method for creating oil water separation materials, and successful creating a super hydrophobic/super oleophilic functional porous polyurethane sponge modified by reduced graphene oxide and polydopamine (PDA-rGO-PU). Dopamine undergoes a self-polymerization event that creates polydopamine, which is subsequently coated on a polyurethane framework to create a sponge structure with several active sites. The surface of the modified sponge structure was coated with graphene oxide by a simple drop-coating method, and graphene oxide coated on the surface of polydopamine was reduced to create the superhydrophobic/superoleophilic material. The PDA-rGO-PU demonstrated strong anti-adhesion properties and a high oil-water separation efficiency of 99.8 % while having high water contact angles of 155 ° ± 3 ° and oil contact angles (OCA) of 0 °. It has a strong ability to adsorb various oils and organic solvents, the excellent photothermal effect allows PDA-rGO-PU to raise temperature by 37.9 % in the presence of light. PDA-rGO-PU has good continuous oil sorption performance after installing the pump. When under simulated lighting conditions, the sorption time of modified sponge on crude oil was shortened by 2.3 times.

Experimental Study for the Sorption and Diffusion of Supercritical Carbon Dioxide into Polyetherimide.

Supercritical carbon dioxide (SCCO2) is a non-toxic and environmentally friendly fluid and has been used in polymerization reactions, processing, foaming, and plasticizing of polymers. Exploring the behavior and data of SCCO2 sorption and dissolution in polymers provides essential information for polymer applications. This study investigated the sorption and diffusion of SCCO2 into polyetherimide (PEI). The sorption and desorption processes of SCCO2 in PEI samples were measured in the temperature range from 40 to 60 °C, the pressure range from 20 to 40 MPa, and the sorption time from 0.25 to 52 h. This study used the ex situ gravimetric method under different operating conditions and applied the Fickian diffusion model to determine the mass diffusivity of SCCO2 during sorption and desorption processes into and out of PEI. The equilibrium mass gain fraction of SCCO2 into PEI was reported from 9.0 wt% (at 60 °C and 20 MPa) to 12.8 wt% (at 40 °C and 40 MPa). The sorption amount increased with the increasing SCCO2 pressure and decreased with the increasing SCCO2 temperature. This study showed the crossover phenomenon of equilibrium mass gain fraction isotherms with respect to SCCO2 density. Changes in the sorption mechanism in PEI were observed when the SCCO2 density was at approximately 840 kg/m3. This study qualitatively performed FTIR analysis during the SCCO2 desorption process. A CO2 antisymmetric stretching mode was observed near a wavenumber of 2340 cm-1. A comparison of loss modulus measurements of pure and SCCO2-treated PEI specimens showed the shifting of loss maxima. This result showed that the plasticization of PEI was achieved through the sorption process of SCCO2.

Uptake of uranium(VI) upon a novel developed nanocomposite of bimetallic Mg/Mn bentonite lupine peels

In this work, a new green nanocomposite material was synthesized, characterized, and implemented for the removal of Uranium(VI) from nuclear waste solution. The nanocomposite material consisted of bimetallic Mg/Mn-Tartaric intercalated with bentonite and functionalized with lupine peel biochar through a refluxing process with a mixed solution of water and formaldehyde (3:1). The synthesized nanocomposite and the pristine materials were characterized using FTIR, and XRD, and the thermal stability of all the components was investigated using TGA. Finally, the morphology of the synthesized materials was investigated using SEM images. The adsorption was studied through different parameters: different pH values, sorption time, different amounts of sorbent, and different uranium concentrations. In addition to the adsorption studies, the desorption studies and the elution process were also investigated. It was found that the maximum adsorption value at pH 4.0 and 60.0 min as about 113.90 mg·g−1, the kinetics fit with pseudo second-order, and the adsorption was fitted with the Langmuir model. Finally, the desorption study was established, and the effective eluting agent was Na2CO3, with an elution efficiency of about 97.4 %.

Synthesis of high-ordered mesoporous aluminosilica monoliths using triblock copolymer and application in the water purification

Mesoporous aluminosilica particulates (MASP) offer a high surface area and specific structural properties that make them effective for adsorbing specific contaminants from drinking water. The MASP’s surface characteristics were studied by SEM, TEM, Mapping-EDX, and BET analysis. Through the use of a batch adsorption approach, this work sought to examine the adsorption behavior of MASP sorbent towards Cd(II) ions at different pH values, time intervals, sorbent doses, and temperatures. MASP’s maximal capacity for Cd(II) ions uptake was 16.5 mg/g at pH 6.5, 25 °C, 0.1 g dose, and 5 h of sorption time. The pseudo-first-order model provided a good description of the uptake process. The best-fitting isotherm was found to be the Langmuir and Redlich–Peterson isotherm. The method came out to be exothermic and spontaneous by thermodynamic analysis. MASP demonstrates durability and reusability during over ten regeneration cycles.

Derivatization, solid-phase microextraction and gas chromatography for determination of dialdehydes—biomarkers of oxidative stress

Dialdehydes are often used as biomarkers, molecules of interest for diagnosis, medical studies, and scientific research. A well-known example is malondialdehyde, which is a biomarker of oxidative stress formed during lipid peroxidation. We used combination of derivatization with O-(1,2,3,4,5)-pentafluorobenzylhydroxylamine, headspace solid-phase microextraction and gas chromatography with flame ionization detector for the analysis of dialdehydes. This combination allows to ensure the stability of analytes by derivatization, to separate them from the matrix, to preconcentrate by solid-phase microextraction, and to perform determination of dialdehydes. All the parameters affecting sensitivity and selectivity (pH and time of derivatization, sorption time, temperature of sorption, salt addition) were studied specifically for malondialdehyde, glyoxal, and methylglyoxal. The addition of salting-out agent resulted in decrease in the signal; therefore, a possible matrix effect was tested using simulated body fluid as model solution with ion composition similar to blood plasma. Established conditions for this method for dialdehydes showed 84–102% recovery in the model solution and allowed to reach the limits of quantification 0.2–0.8 μmol/L, which is low enough for the analysis of real samples. This method has the potential to be automated and is environmentally friendly because it does not require organic solvents and single-used filters or cartridges.

Regularities in mercury cation sorption by a lignin-based sulfur-containing sorbent

The unfavorable environmental situation in the town of Usolye-Sibirskoye (Irkutsk Oblast, Russia) determines the relevance of investigating and applying a new lignin-based sulfur-containing sorbent for purification of groundwater from mercury compounds. The sorbent was synthesized on the basis of waste products of epichlorohydrin (1,2,3-trichloropropane), sulfur, and lignin. The IR spectrum of the sorbent under study showed the presence of an S–S bond in the region of 445–465 cm-1. Intensive absorption of Hg2+ ions in the regions of 2800–2950 cm-1 (valence vibrations of C–H bonds in CH and CH2 groups) and 1460 cm-1 (deformation vibrations in CH2 group) was observed. Absorption of Hg2+ ions by lignin fragments was accompanied by a change in the vibration band of S–S bonds, which splits into two bands of higher frequencies than the νS–S band in the original sorbent. The optimum sulfur content, which ensures the maximum sorption activity of the sorbent, was found to be 53.25%. The mercury sorption isotherms at 20 and 60 °C are described by parabolic dependencies with determination coefficients of 98.9 and 98.6 %, respectively. The kinetic curve at 20 °C and 40 °C is approximated by a hyperbola and a cubic polynomial with determination coefficients of 97.9 and 96.2 %, respectively. The reaction order (first order at 20 °C and second order at 40 °C) and the reaction rate constant (0.0876 min-1 at 20 °C and 0.00014 min-1 at 40 °C) were determined. At 20 °C, the sorption rate of Hg2+ was established to be significantly higher and the sorption time to be faster than those at 40 °C. Therefore, mercury sorption by the proposed sorbent should be carried out at 20 °C in order to reduce energy consumption.

Uptake of Cm (III) and Eu (III) by C–S–H phases under saline conditions in presence of EDTA: A batch sorption and TRLFS study

Eu (III) and Cm (III) uptake by calcium silicate hydrate phases (C–S–H) was investigated in presence of EDTA in NaCl and CaCl2 solutions. Different experimental parameters, i.e., ionic strength (0.1 m ≤ I'm ≤ 5.05 m), ligand concentration (10−5 m ≤ [EDTA] ≤ 10−2 m), calcium-to-silicon ratio (0.6 ≤ C/S ≤ 1.3) and sorption time (7 d ≤ t ≤ 365 d) were varied in the frame of batch sorption experiments and Time Resolved Laser Fluorescence spectroscopy (TRLFS) measurements. No effect of EDTA on the retention of Eu(III)/Cm(III) by C–S–H phases in NaCl or CaCl2 systems was observed at ligand concentrations ≤ 10−3 M. In NaCl solutions with [EDTA] = 10−2 M and C/S < 1.3, low retention (log Rd = 2–3, with Rd in L∙kg−1) of Eu(III) was detected after 7 d of sorption time, while strong retention (log Rd = 5–6) was observed after 50 d. This behaviour was explained by the initial stabilization of Eu(III)/Cm(III) in the aqueous phase due to the formation of two aqueous Eu(III)/Cm(III)-(OH)n-EDTA complexes, followed by the slow incorporation of Eu(III)/Cm(III) into the C–S–H structure. In CaCl2 solutions for all C/S ratios, as well as in NaCl solutions for C/S ∼ 1.3, the presence of [EDTA] = 10−2 M led to a significant decrease of the uptake (log Rd = 2–3) after 7 and 50 d of contact time. This effect was explained by the formation of stable aqueous Ca–Eu(III)/Cm(III)-EDTA complexes triggered by the presence of moderate to high Ca concentrations. No evident effect caused by increased ionic strength conditions could be confirmed in our sorption experiments.Results obtained in batch sorption experiments are underpinned by TRLFS data, with the observation of three main aqueous species, tentatively defined as Cm(OH)(EDTA)2-, Cm(OH)x (EDTA)-(x+1) and Ca–Cm(III)-EDTA, as well as a fourth species corresponding to Cm(III) incorporated in the CaO-layer of the C–S–H phases. In spite of the thermodynamic stability of the CaEDTA2− complex, which reduces the concentration of free EDTA, the formation of ternary Ca–Eu(III)/Cm(III)-EDTA complexes is expected to result in a significant impact of EDTA on the uptake of An (III)/Ln (III) by cement at high ligand concentrations. The assumption that Ca outcompetes actinides for the complexation with EDTA in cementitious systems may need to be revisited under these conditions.

Comprehensive analysis of water vapor sorption kinetics and mechanisms using biosorbent pellets from canola meal and oat hull

Agricultural residues, specifically canola meal (CM) and oat hull (OH), have been innovatively utilized to develop biosorbents for sorbing water vapor from the air. These biomaterials are comprised of hydrophilic functional groups that effectively perform air dehydration. Air, being non-polar, was used as a model gas in this study to simulate gas dehydration. In the current research, these materials were formed into pellets to produce high-quality biosorbents with controlled size, shape, and enhanced moisture uptake capacity. CM (309.48 mg/g) and OH (233.07 mg/g) pellets had higher or comparable water sorption capacities than commercialized adsorbents used for drying gases. The mixed-order kinetic model described the sorption process well and identified both mass transfer and sorption on active site steps (R 2 > 0.991 and χ 2 < 16.0). Regarding the OH pellet, sorption on active sites was the predominant kinetic mechanism at the beginning, followed by intraparticle diffusion until equilibrium. However, sorption on CM pellets was delayed at 4.2 min at the initial stage, owing to the external mass transfer resistance; then, intraparticle diffusion controlled the process until equilibrium. Adding sodium lignosulfonate (LSNa) lowered the initial sorption rate but enhanced the water uptake and strength of pellets. The addition of LSNa resulted in a 25% and 14% increase in the water uptake capacity of oat hull and canola meal pellets, respectively; conversely, it also caused an increase in the delay time for sorption on CM pellets at the beginning of the process, extending it to 9.50 min.

Utilization of Eggshell Waste Calcite as a Sorbent for Rare Earth Element Recovery.

The green energy transition requires rare earth elements (REE) for the permanent magnets used in electric cars and wind turbines. REE extraction and beneficiation are chemically intensive and highly damaging to the environment. We investigated the use of eggshell waste as a sustainable alternative sorbent for the capture and separation of REE from aqueous solutions. Hen eggshell calcite was placed in multi-REE (La, Nd, Dy) solutions at 25 to 205 °C for up to 3 months. A pervasive diffusion of the REE inside the eggshell calcite was observed along pathways formed by the intracrystalline organic matrix and calcite crystal boundaries. At 90 °C, kozoite (REECO3OH, orthorhombic) spherulites precipitate on the surface of the dissolving calcite. At 165 and 205 °C, an interface-coupled dissolution-precipitation mechanism is observed, resulting in the complete dissolution of the calcite shell and its pseudomorphic replacement by polycrystalline kozoite. At 205 °C, kozoite is slowly replaced by hydroxylbastnäsite (REECO3OH, hexagonal), the stable form of the rare earth hydroxycarbonate polymorphs. Our results demonstrate two potential applications of eggshell waste for the uptake of rare earth elements in solution: at low temperatures, as a mixed organic-inorganic adsorbent and absorbent, given sufficient sorption time; and at higher temperatures, as an efficient sacrificial template for the precipitation of rare earth hydroxycarbonates.

Application of kinetic models to study the sorption rate in the ‘ammonium ions–calcined sorbent’ system

This study examines sorption kinetics for the extraction of ammonium ions from an aqueous solution under static conditions using 5 g of sorbent. The sorbent was obtained by calcining ash and slag waste accumulated in the ash dump following hydraulic ash removal. The initial concentrations of ammonium ions in the model solutions were 5, 20, 50 and 100 mg/dm3. The volume of the model solution was 50 cm3. For each initial concentration, the kinetic curves of the ammonium ion sorption at the sorption duration of 10, 30, 60, 90, 120, 150 and 180 min were obtained. The kinetic curves were processed using the Lagergren (pseudo-first order), Ho and McKay (pseudo-second order), Morris-Weber (diffusion) and Elovich kinetic equations. It was demonstrated that all kinetic equations adequately describe the experimental data. The linear correlation of the equations was given. The Boyd equation was used to determine the limiting stage in the Morris–Weber model. It was established that the external diffusion mechanism is limiting for the sorption of ammonium ions by a calcined sorbent. The Lagergren model, with a coefficient of determination R2 of 0.9801–0.9949, best described the experimental data on sorption kinetics. Sorption rate curves as a function of the adsorption value and sorption time were given. The latter are described by exponential and polynomial dependence according to the Lagergren model, polynomial dependence according to the Ho and McKay model and exponential dependence according to the Morris–Weber and Elovich models. The sorption rate was the highest at the initial stage of sorption for all dependencies, which is consistent with previous studies on the sorption of pollutants from aqueous solutions using various sorbents.

Unlocking Agronutrient Resources: Sorption Strategies for sugar-energy industry waste

Vinasse and ash from sugarcane bagasse (SCB) are key byproducts in the sugar-energy industry. Vinasse is nutrient-rich but environmentally challenging, while sugarcane bagasse ash (SCBA) offers excellent adsorbent for treating effluents. This work aims to assess the effectiveness of SCBA in removing nitrogen (N) and potassium (K) nutrients from Vinasse. Simulated standard solutions of K2SO4 and (NH4)2HPO4 were used to mimic the nutrient concentrations in Vinasse and optimize experimental parameters such as adsorbent mass and contact time. Kinetic and isotherm models were also applied to elucidate the underlying adsorption mechanisms. Structural, morphological, and thermal analyses revealed the micro-mesoporous and heterogeneous nature of SCBA, primarily composed of SiO2 (quartz and cristobalite). The sorption assessment indicated the ideal conditions involved lower SCBA masses (2.5 g) and 6 h of contact time for the simulated standard solutions. The replicated conditions for Vinasse (at an adjusted sorption time of 24 h) demonstrated nutrient sorption and pH correction of the Vinasse, attributed to the alkaline nature of SCBA. Analysis of the sorption kinetic models for K+ and NH4+ revealed that SCBA interacts diffusively with the environment, not necessarily controlled by adsorption on active sites, indicating non-uniform characteristics. The sorption isotherms for K+ and NH4+ showed the non-linearized Freundlich model was the most suitable, indicating the adsorption sites with varying energy levels and a multilayer sorption process. In conclusion, we successfully demonstrated the sorption of nutrients from Vinasse by SCBA, enhancing the value of these residues and mitigating their environmental impact when used in agricultural applications.

The Use of Chitin for the Removal of Nitrates and Orthophosphates from Greenhouse Wastewater.

The study investigated the possibility of using chitin flakes as an unconventional sorbent for the removal of orthophosphates and nitrates from greenhouse wastewater (GW). The effluent parameters were as follows: 66.2 mg P-PO4/L, 566.0 mg N-NO3/L, 456.0 mg S-SO4/L, 13.7 mg Cl-/L, 721 mg Ca2+/L, 230 mg Mg2+/L, hardness 11.3 °dH, and pH 5.4. The scope of the research included determinations of the influence of pH on GW composition and the efficiency of nutrient sorption, the kinetics of nutrient sorption, the influence of the dose of chitin flakes on the effectiveness of nutrient binding and the maximum sorption capacity of the sorbent. The sorption of P-PO4 on the tested sorbent was most effective at pH 4, and the sorption of N-NO3 at pH 2. The equilibrium time of sorption of both nutrients from GW to chitin depended on the sorbent dose and ranged from 150 to 180 min. The sorbent dose of 40 g/L enabled removing 90% of orthophosphates and 5.7% of nitrates from the wastewater. The maximum sorption capacity of CH towards P-PO4 and N-NO3 contained in the GW was 3.20 mg/g and 3.04 mg/g, respectively. In turn, the sorption of calcium and magnesium ions on chitin flakes was completely ineffective.

Innovative Sol-gel functionalized polyurethane foam for sustainable water purification and analytical advances.

Nanomaterial combined polymeric membranes such as polyurethane foams (PUFs) have garnered enormous attention in the field of water purification due to their ease of management and surface modification, cost-effectiveness, and mechanical, chemical, and thermal properties. Thus, this study reports the use of novel Sol-gel impregnated polyurethane foams (Sol-gel/PUFs) as new dispersive solid phase microextractors (d- µ SPME) for the efficient separation and subsequent spectrophotometric detection of Eosin Y (EY) textile dye in an aqueous solution with a pH of 3-3.8. The Sol gel, PUFs, and Sol gel-impregnated PUFs were characterized using scanning electron microscopy (SEM), goniometry measurements, dynamic light scattering (DLS), energy dispersive spectroscopy (EDS), UV-Visible, and FTIR spectra. Batch experiment results displayed a remarkable removal percentage (96% ± 5.4%) of the EY from the aqueous solution, with the total sorption time not exceeding 60min. These data indicate rate-limited sorption via diffusion and/or surface complex ion associate formations after the rapid initial sorption steps. A pseudo-second order kinetic model thoroughly explained the sorption kinetics, providing a sorption capacity (qe) of 37.64mgg-1, a half-life time (t1/2) of 0.8 ± 0.01min, and intrinsic penetration control dye retention. The thermodynamic results revealed a negative value for ΔG⁰ (-78.07kJmol-1 at 293K), clearly signifying that the dye uptake was spontaneous, as well as a negative value for ΔH⁰ (-69.58kJmol-1) and a positive value for ΔS⁰ (147.65Jmol-1 K-1), making clear the exothermic nature of EY adsorption onto the sorbent, with a growth in randomness at the molecular level. A ternary retention mechanism is proposed, involving the "weak base anion exchanger" of {(-CH2-OH+ -CH2-) (Dye anion)-}Sol-gel/PUF and/or {(-NH2 + -COO-) (Dye anion)-}Sol-gel/PUF via solvent extraction and "surface adsorption" of the dye anion on/in the Sol-gel/PUFs membranes in addition to H-bonding, including surface complexation and electrostatic π-π interaction, between the dye and the silicon/zirconium oxide (Si-O-Zr) and siloxane (Si-O-Si) groups on the sorbent. Complete extraction and recovery (93.65 ± 0.2, -102.28 ± 2.01) of EY dye with NaOH (0.5M) as a proper eluting agent was achieved using a sorbent-packed mini column. In addition, the established extractor displayed excellent reusability and does not require organic solvents for EY enrichment in water samples, making it a talented nominee as a novel sorbent for EY sorption from wastewater. This study is of great consequence for expanding the applicatio1n of Sol-gel/PUFs in developing innovative spectrophotometric sensing strategies for dye determination. In view of this, it would also be remarkable to perform future studies to explore the analytical implications of this extractor regarding safety and environmental and public health issues associated to the pollutant.

Crude oil sorption capacity of modified and unmodified biowaste

Contamination of water by crude oil is ubiquitous particularly in developing countries. The governments of affected countries raise a lot of concern because of the associated economic and environmental impacts which are not in tandem with the United Nations Sustainable Development Goals (SDGs), 6, 8, 11, 13 &amp; 14. Remediation of crude oil-impacted water and soil become imperative. However, the exercise is expensive; hence the search for cheaper and local alternatives. In this study, unsegregated wood sawdust was collected from the various wood saw-dust dump sites within the main Timber shade in the vicinity of Udu Bridge, Udu LGA of Delta State, Nigeria. One half of the sample was chemically modified by acetylation using acetic anhydride while the other half wasn’t. They were characterized using Fourier Transformed Infra-Red Spectrophotometer (FTIR) and Scanning Electron Microscope coupled with Electron Dispersive X-ray (SEM/EDX) analyzer before employing them in the removal of the crude oil from the simulated crude oil spill- water media. The obtained results indicated that the modified sorbent (wood sawdust) sorbed more crude oil than the unmodified sorbent (wood sawdust). Experimental process control factors limited to time, sorbent dosage, particle size, was investigated using the modified sawdust. The modified sorbent gave maximum oil absorption capacity of 5.228 gg-1 for sorption time, 4.759 gg-1 for sorbent dosage and 5.838 gg-1 for particle size analyses. The study contributes to the knowledge of sorption studies using unsegregated wood sawdust for remediation of crude oil-contaminated media.

3D-printed extraction devices fabricated from silica particles suspended in acrylate resin

In recent years, there has been an increasing worldwide interest in the use of alternative sample preparation methods. Digital light processing (DLP) is a 3D printing technique based on using UV light to form photo-curable resin layer upon layer, which results in a printed shape. This study explores the application of this technique for the development of novel drug extraction devices in analytical chemistry. A composite material consisting of a photocurable resin and C18-modified silica particles was employed as a sorbent device, demonstrating its effectiveness in pharmaceutical analysis. Apart from estimating optimal printing parameters, microscopic examination of the material surface, and sorbent powder to resin ratio, the extraction procedure was also optimised. Optimisation included the type and amount of sample matrix additives, desorption solvent, sorption and desorption times, and proper number of sorbent devices needed in extraction protocol. To demonstrate this method's applicability for sample analysis, the solid-phase extraction followed by gas chromatography coupled with mass spectrometry (SPE-GC–MS) method was validated for its ability to quantify benzodiazepine-type drugs. This evaluation confirmed good linearity in the concentration range of 50–1000 ng/mL, with R2 values being 0.9932 and 0.9952 for medazepam and diazepam, respectively. Validation parameters proved that the presented method is precise (with values ranging in-between 2.98 %-7.40 %), and accurate (88.81 % to 110.80 %). A negative control was also performed to investigate possible sorption properties of the resin itself, proving that the addition of C18-modified silica particles significantly increases the extraction efficiency and repeatability.The cost-effectiveness of this approach makes it particularly advantageous for single-use scenarios, eliminating the need for time-consuming sorbent-cleaning procedures, common in traditional solid-phase extraction techniques. Future optimisation opportunities include refining sorbent size, shape, and geometry to achieve lower limits of quantification. As a result of these findings, 3D-printed extraction devices can serve as a viable alternative to commercially available SPE or solid-phase microextraction (SPME) protocols for studying new sample preparation approaches.

Lithium recovery from geothermal brines: An investigation into radioactive nuclide uptake on lithium‑manganese-oxide (LMO) granules

Due to the growing demand for lithium, the exploitation of non-conventional lithium sources such as Li-bearing geothermal brines is currently on the rise. These brines contain up to 200 mg L−1 of lithium along with a diverse range of other dissolved elements, including naturally occurring radionuclides. In this study, data from a radiochemical monitoring process performed during the pilot plant testing of direct lithium extraction (DLE) at a geothermal site in the Upper Rhine Graben (URG) are presented. The tests were conducted under thermodynamic p-T conditions of the geothermal plant (T = 60 °C, p = 18 bar). The results present an uptake of the long-lived radionuclides 226Ra (228Ra) and 210Pb by the granulated lithium‑manganese-oxides (LMO) sorbent employed. Elevated pH values enhance the sorption of nuclides formed in the Th-U decay series, due to the increased negative charge on the LMO surface. The radioactivity uptake on the sorbent was found to be time-dependent. Experiments with a 5-min contact time resulted in relatively low sorption capacities, while extending the sorption time to 30 min significantly increased the accumulation of Ra isotopes and 210Pb on the sorbent surface. During the regeneration phase, the radioactive load on the LMO sorbent could be reduced using 0.5 M HCl. The mass balance analysis of the investigated radionuclides demonstrates desorption percentages ranging from 16% to 100% per extraction cycle.

Selective and precise solid phase extraction based on a magnetic cellulose gold nanocomposite followed by ICP-OES analysis for monitoring of total sulfur content in liquid fuels.

This study describes the synthesis and characterization of a magnetic cellulose gold nanocomposite (MCNC@Au) for magnetic solid phase (m-SPE) extraction of total sulfur content in liquid fuel samples followed by analysis using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The nanocomposite was prepared using an in situ co-precipitation method and characterization results from FTIR, P-XRD, TEM and SEM-EDX techniques confirmed the formation of the targeted nanocomposite. To achieve good extraction efficiency, the 2-level half-fractional factorial design and central composite design were used to investigate the most influential parameters of the proposed m-SPE method. The multivariate optimization results showed that efficient extraction was obtained when 27.5 mg sorbent mass, 35 minutes sorption time, 200 μL eluent volume and 8 min elution time were used. The optimal parameters resulted in excellent accuracy (98.8%), precision (1.7%), LOD (0.039 mg L-1), LOQ (0.129 mg L-1), MDL (0.014 μg g-1) and MQL (0.047 μg g-1). The optimized and validated m-SPE method was applied in real fuel oil samples, revealing a total sulfur content range of 13.20 ± 0.05-15.70 ± 0.02 μg g-1 for crude oil, 7.32 ± 0.01-9.12 ± 0.03 for μg g-1, 8.41 ± 0.02-9.15 ± 0.06 μg g-1 for gasoline and 9.10 ± 0.02 and 9.70 ± 0.04 μg g-1 for kerosene samples, sugesting high concentration levels of sulfur in crude oils. However, the obtained sulfur content levels are within the accepted standards in fuel oils, except for those of crude oil and kerosene samples. Therefore, the proposed m-SPE method followed by ICP-OES analysis has proven to be an alternative procedure for rapid and selective quantification of total sulfur in fuel samples.

Исследование эффективности очистки воды от ионов аммония прокалённым сорбентом из золошлаковых отходов

Experimental studies of sorption on water treatment from ammonium ions by a calcined sorbent based on ash-and-slag waste from thermal power engineering have been carried out. The calcined sorbent was obtained by calcining samples of ash-and-slag from coal combustion at the Novocherkassk State District Power Plant at a temperature of 600 оC for 30 min. The sorption capacity of a sorbent with a dose of 2.0 g per 50 mL of a model solution, a stirrer speed of 200 rpm, pH 7, and sorption time from 10 to 180 minutes was studied. The influence of the initial concentration of model solutions with the content of ammonium ions 5, 20, 50 and 100 mg/L on the amount of adsorption and treatment efficiency was studied. The highest treatment efficiency of 60% was obtained for an initial concentration of ammonium ions in a solution of 20 mg/L. Processing of experimental data was carried out according to the models of pseudo-first, pseudo-second-order and intra-particle diffusion kinetics. The best description of the experimental data was obtained using the pseudo-first order model, which has the highest value of the coefficient of determination. The adsorption equilibrium in the system ammonium ions – calcined sorbent was studied for the initial concentration of ammonium ions in solution: 5, 20, 30, 50, 100, 200, 300 mg/L. Processing of experimental data on equilibrium was carried out on the basis of two-parameter adsorption isotherms: Langmuir, Freindlich and Temkin. The value of the coefficient of determination according to the Langmuir isotherm is the largest R2 = 0.9904. Dependences between the cleaning efficiency at adsorption equilibrium and the initial concentration of ammonium ions in solution for the system ammonium ions – calcined sorbent are obtained. With an increase in the initial concentration of ammonium ions in the solution, the treatment efficiency at low initial concentrations increases, and decreases with increasing concentration.

Physics informed neural networks reveal valid models for reactive diffusion of volatiles through paper

Predictive models for the transport of volatile organic compounds in paper need to consider the complex interplay of diffusion, adsorption, desorption, or chemical reactions. The relative importance of each of these processes is determined by the polarity of the volatile. Hence, it is challenging to pick a valid theoretical model that correctly predicts transport regardless of the polarity. Here, physics-informed neural networks (PINNs) assess which of five different models correctly describe transport of DMSO as polar and n-tetradecane as apolar model compound: (i) a pseudo first-order adsorption model for an irreversible sorption process, (ii) a first-order kinetics model allowing reversible sorption, (iii) a second-order model with a reversible process, and an effective diffusion model accounting for a constant (iv) and for a variable effective diffusivity (v). Each tested model is given as set of partial differential equations (PDE). Considering the model under testing and experimentally obtained spatially and temporally resolved concentration profiles through stacks of paper sheets, PINNs predict concentration of the volatiles and associated material constants such as sorption constants and effective diffusion coefficients by solving the inverse problem. Our PINNs revealed two models, pseudo first-order sorption and second-order reversible sorption, that correctly predict concentration profiles and polarity-driven differences in sorption times. While a PINN-based picking of valid transport models has important implications for the development of effective methods for controlling emission of volatiles from paper materials, PINNs represent a versatile mathematical tool to validate or refute the capability of PDE-based theoretical models to describe experimental data.