Subsequent Desorption Research Articles

Study on Room Temperature Oxidation Characteristics of Primary Active Sites in Low-Rank Coal from Western Mining Areas After Vacuum Desorption

ABSTRACT CO exceeding safety limits during room temperature oxidation (RTO) in low-rank coal mines, particularly in western regions, has garnered significant attention. This study systematically investigates the oxidation behavior of primary active sites in low-rank coal and their role in CO generation and safety limit exceedance. A vacuum desorption apparatus combining vacuum drying with cyclic oxidation technology was used to remove moisture and gases from coal samples under low-temperature, high-vacuum conditions, while accumulating oxidation gases. The oxidation process was studied comprehensively through RTO experiments across different coal types, cyclic desorption-oxidation tests on a single coal sample, and analyses using low-temperature nitrogen adsorption, XPS, and in-situ ESR. The results showed that CO and CO₂ concentrations continuously increased during RTO for all coal types. Samples subjected to vacuum desorption exhibited significantly higher oxidation activity, revealing the involvement of previously concealed active sites. As desorption cycles increased, oxidation capacity gradually weakened, with a marked decrease in the initial oxidation rate by Cycle 4, suggesting progressive depletion of exposed active sites. Changes in pore structure and functional groups indicate that pore characteristics and C-C/C-H structures influence oxidation reactions. In-situ free radical experiments revealed that when primary active sites remained intact, desorption significantly exposed concealed free radicals, particularly alkyl radicals. However, as active sites were depleted, subsequent desorption did not significantly increase free radical exposure, limiting further oxidation. CO was less affected by coal pore adsorption compared to CO₂, making it a more reliable indicator of oxidation intensity. This study provides insights into gas evolution during RTO of primary active sites in coal and offers theoretical guidance for addressing Coal spontaneous combustion and CO exceedance in low-rank coal mines.

Non-Fickian diffusion enhanced by temperature

In this paper we present a novel mathematical model to describe the permeation of a fluid through a polymeric matrix, loaded with drug molecules, followed by its subsequent desorption. Both phenomena are enhanced by temperature. We deduce energy estimates and stability estimates for the weak solution of the model, showing that this solution of the problem is stable in bounded time intervals. Numerical simulations illustrate how the coupling effects, of viscoelastic properties and thermal external assistance, can have a central role in the design of drug delivery devices.

Unveiling the Dual Role of Oxophilic Cr4+ in Cr-Cu2O Nanosheet Arrays for Enhanced Nitrate Electroreduction to Ammonia.

Cuprous oxide (Cu2O)-based catalysts present a promising activity for the electrochemical nitrate (NO3 -) reduction to ammonia (eNO3RA), but the electrochemical instability of Cu+ species may lead to an unsatisfactory durability, hindering the exploration of the structure-performance relationship. Herein, we propose an efficient strategy to stabilize Cu+ through the incorporation of Cr4+ into the Cu2O matrix to construct a Cr4+-O-Cu+ network structure. In situ and quasi-in situ characterizations reveal that the Cu+ species are well maintained via the strong Cr4+-O-Cu+ interaction that inhibits the leaching of lattice oxygen. Importantly, in situ generated Cr3+-O-Cu+ from Cr4+-O-Cu+ is identified as a dual-active site for eNO3RA, wherein the Cu+ sites are responsible for the activation of N-containing intermediates, while the assisting Cr3+ centers serve as the electron-proton mediators for rapid water dissociation. Theoretical investigations further demonstrated that the metastable state Cr3+-O-Cu+ favors the conversion from the endoergic hydrogenation of the key *ON intermediate to an exoergic reaction in an ONH pathway, and facilitates the subsequent NH3 desorption with a low energy barrier. The superior eNO3RA with a maximum 91.6 % Faradaic efficiency could also be coupled with anodic sulfion oxidation to achieve concurrent NH3 production and sulfur recovery with reduced energy input.

Unveiling the Dual Role of Oxophilic Cr4+ in Cr‐Cu2O Nanosheet Arrays for Enhanced Nitrate Electroreduction to Ammonia

Cuprous oxide (Cu2O)‐based catalysts present a promising activity for the electrochemical nitrate (NO3‐) reduction to ammonia (eNO3RA), but the electrochemical instability of Cu+ species may lead to an unsatisfactory durability, hindering the exploration of the structure‐performance relationship. Herein, we propose an efficient strategy to stabilize Cu+ through the incorporation of Cr4+ into the Cu2O matrix to construct a Cr4+‐O‐Cu+ network structure. In situ and quasi‐in situ characterizations reveal that the Cu+ species are well maintained via the strong Cr4+‐O‐Cu+ interaction that inhibits the leaching of lattice oxygen. Importantly, in situ generated Cr3+‐O‐Cu+ from Cr4+‐O‐Cu+ is identified as a dual‐active site for eNO3RA, wherein the Cu+ sites are responsible for the activation of N‐containing intermediates, while the assisting Cr3+ centers serve as the electron‐proton mediators for rapid water dissociation. Theoretical investigations further demonstrated that the metastable state Cr3+‐O‐Cu+ favors the conversion from the endoergic hydrogenation of the key *ON intermediate to an exoergic reaction in an ONH pathway, and facilitates the subsequent NH3 desorption with a low energy barrier. The superior eNO3RA with a maximum 91.6% Faradaic efficiency could also be coupled with anodic sulfion oxidation to achieve concurrent NH3 production and sulfur recovery with reduced energy input.

Diagnosis of Lung Cancer Through Exhaled Breath: A Comprehensive Study.

Exhaled breath analysis is an attractive lung cancer diagnostic tool. However, various factors that are not related to the disease status, comorbidities, and other diseases must be considered to obtain a reliable diagnostic model. Exhaled breath samples from 646 individuals including 273 patients with lung cancer (LC), 90 patients with cancer of other localizations (OC), 150 patients with noncancer lung diseases (NLD), and 133 healthy controls (HC) were analyzed using gas chromatography-mass spectrometry (GC-MS). The samples were collected in Tedlar bags. Volatile organic compounds (VOCs) were preconcentrated on Tenax TA sorbent tubes with subsequent two-stage thermal desorption followed by GC-MS analysis. The influence of age, gender, smoking status, time since last food consumption, and comorbidities on exhaled breath were evaluated. Also, the effect of histology, TNM, tumor localization, treatment status, and the presence of a tumor on VOC profile of patients with lung cancer were assessed. Intergroup statistics were estimated, diagnostic models were created using artificial neural networks (ANNs) and gradient boosted decision trees (GBDTs). Smoking status and food consumption affect exhaled breath VOC profile: benzene, ethylbenzene, toluene, 1,3-pentadiene 1,4-pentadiene acetonitrile, and some ratios are significantly different in exhaled breath of smokers and nonsmokers; the ratios 2,3-butandione/2-pentanone, 2,3-butandione/dimethylsulfide, and 2-butanone/2-pentanone are affected by time since last food consumption. Exhaled breath of LC is affected by the form of the disease and comorbidities. One-pentanol and 2-butanone were different in exhaled breath of patients with various tumor localization; 2-butanone was different in exhaled breath of patients before and during treatment. Diabetes as a comorbidity affects the pentanal level in exhaled breath; obesity affects the ratios of 2,3-butanedione/dimethylsulfide and 2-butanone/isoprene. Sensitivity and specificity of diagnostic models aimed to discriminate LC and HC, OC, and NLD were 78.7% and 51.0%, 62.2% and 53.4%, and 60.4% and 58.0%, respectively. HC and patients, regardless of the disease, can be classified with sensitivity of 76.6% and specificity of 68.2%. The models created to diagnose lung cancer can also classify OC and NLD as patients with lung cancer. Additionally, the influence of comorbidities and factors not related to the disease status must be considered before the creation of diagnostic models to avoid false results.

Ultrastable monolithic electrodes with single-atom platinum-oxygen sites for efficient hydrogen evolution in acidic conditions

PtNC single-atom catalysts (SACs) single-atom catalysts (SACs) are promising for acidic hydrogen evolution reaction (HER) but suffer from instability at high current densities, limiting their large-scale application. Herein, PtO bonds are constructed to securely anchor atomically dispersed Pt for single-atom (SA) catalysis, utilizing etched vertical graphene (EVG) nanosheets as monolithic supports (Pt-SAs/EVG). Compared to PtNC, the resultant PtO4 coordination demonstrates improved stability while maintaining significant catalytic activity. When applying this catalyst in the acidic HER, a high turnover frequency (34.6 s−1) is achieved at 70 mV, accompanied by exceptional durability exceeding 100 h at −100 mA cm−2. Theoretical analyses indicate that the PtO bonds confer stability to the Pt atoms, facilitating the efficient adsorption of protons and the subsequent desorption of hydrogen. The prepared Pt-SAs/EVG can also be directly employed as the cathode to afford stable operation at 0.5 A cm−2 in a proton exchange membrane electrolyzer cell. This study offers novel insights into enhancing the performance of SACs for industrial applications in electrocatalysis.

High mixing enhancement for continuous uniformity Li/Al-LDHs in lithium extraction from low grade salt lakes

The enhancement of lithium extraction from low grade salt lake through the development of advanced adsorbents has become a primary focus in current research. A new method was developed in this work for the continuous fabrication of ultra-highly uniform lithium-aluminum layered double hydroxides (H-LDHs), used as lithium adsorbents, through a high mixing reactor. These H-LDHs featured a more consistent particle size distribution, which facilitated an enhanced vibrational density. This not only significantly increased the powder content in granules but also improved lithium adsorption efficiency. Computational fluid dynamics (CFD) modeling showed that the reactor reached peak mixing efficiency with a minimal gap size of 1 mm. The analysis further indicated that a Reynolds number of 75 led to enhanced mixing effects and stronger flow dynamics. Experiments with Qarhan salt lake brine demonstrated that the H-LDHs powders reached a lithium adsorption capacity of up to 7.27 mg/g, while the volumetric adsorption capacity of these H-LDHs granules exceeded that of traditional granules by 1.179 times. Subsequent desorption and cycling experiments verified the material’s enduring lithium adsorption efficacy and structural integrity, underscoring its considerable potential for industrial use.

Programmable Oxygen Reduction Reaction Performance of Atomic Ir-Clusters Anchored Pd Nanoparticles on the Ni-Oxide Support

Fuel cells is severely restricted by the sluggish oxygen reduction reaction (ORR) kinetics at the cathode side, which demands highly active and enduring catalysts for producing adequate rates. Herein, we report a systematic study to investigate the effect of structure configuration on the oxygen reduction reaction (ORR) activity of tri-metallic nanocatalysts (NC)s comprising atomic Ir-clusters (0.5 wt.% of Ir) anchored Pd nanoparticles on the tetrahedral symmetric Ni-oxide support (denoted as NPI). The electrochemical activities of NPI NCs are programmable via a temperature-controlled wet chemical reduction method. For the optimum condition when the Ni-crystal impregnation temperature is 40oC, the Ir-clusters decorated Ni@Pd nanoislands are formed (hereafter denoted as NPI-40), outperforming the commercial J.M.-Pt/C (20 wt.% Pt) catalyst by ~180-folds with an unprecedented high mass activity of ~12,000 mAmgIr -1 at 0.85 V vs RHE in 0.1 M KOH. More importantly, NPI-40 NC retained 100 % ORR performance with no degradation up to 20k accelerated degradation test cycles, while only a 5 mV loss in half-wave potential (E1/2 ) is observed after 30k ADT cycles. The results of physical structure inspections and electrochemical analysis suggest that such an exceptional ORR performance of NPI-40 NC originates from the potential synergetic effect between the high density of occupied Ir-d-orbital and adjacent compressively strained Ni-Pd interface. With this structure configuration, Ir-sites offer optimal adsorption energy for O2 splitting and Ni-Pd interface facilitates the subsequent desorption of hydroxide ions (OH-). We believe that the obtained results will open new approach for the design of Pt-free NCs for fuel cell cathode. Keywords: Oxygen reduction reaction, Fuel cells, Mass activity, Ir clusters

Prediction of the catalytic mechanism of hydrogen evolution reaction enhanced by surface oxidation on FCC_CoCrFeNi and Co0.35Cr0.15Fe0.2Mo0.1Ni0.2 multi-principal element alloys based on site preference

Some multi-principal element alloy (MPEA) catalysts may exhibit the ability to promote the hydrogen evolution reaction (HER) and maintain stability under acidic conditions. Here, we investigated the impact of ordered behavior and surface oxidation of FCC_CoCrFeNi and Co0.35Cr0.15Fe0.2Mo0.1Ni0.2 MPEAs on HER performance through first-principles calculations. The ordering behaviors of MPEAs were described using L12_AuCu3 sublattice model and the predicted site occupying fractions (SOFs). And we found that the catalytic activity of single intermediate *H at top or bridge adsorption sites surpassed that at the hollow site. However, the hollow site exhibits strong adsorption towards *H, resulting in the transfer of *H from other sites to hollow site. Meanwhile, compared to those containing only hydrogen, MPEAs with both hydrogen and oxygen exhibit lower overpotentials, primarily due to oxygen facilitating hydrogen adsorption and subsequent desorption from MPEA surfaces, thus, such fundamental finding highlights the beneficial role of alloy surface oxidation in promoting HER performance. Furthermore, the overpotential values of the three slab models based on SOFs are similar, demonstrating considerably consistent atomic distribution behaviors, thereby better reflecting the overall catalytic performance of ordered MPEAs. These explorations bring new insights into the ordered behavior and surface oxidation of MPEAs in HER catalysis.

Limitations and insights regarding atmospheric mercury sampling using gold

BackgroundAtmospheric mercury (Hg) concentrations are quantified primarily through preconcentration on gold (Au) cartridges through amalgamation and subsequent thermal desorption into an atomic fluorescence spectrometry detector. This procedure has been used for decades, and is implemented in the industry-standard atmospheric Hg analyzer, the Tekran 2537. There is ongoing debate as to whether gaseous elemental mercury (Hg0) or total gaseous mercury (TGM, Hg0 + HgII) is measured using Au cartridges. The raw Hg signal processing algorithms for the Tekran 2537 analyzer have also been questioned. The objective of this work was to develop a better understanding of what forms of Hg are collected on gold cartridges through the use of permeation tube-based calibrators, that release known amounts of Hg0 and HgII. The potential differences between different Tekran analyzer models (i.e., 2537B versus 2537X) Hg signal processing algorithms, and Hg0 calibration methods were also investigated. ResultsExperiments were performed using Hg0 and HgII permeation calibrators. Validation tests showed that the HgII calibrator produced a reproducible and stable HgII permeation rate (2.2 ± 0.2 pg min−1). Results of HgII sampling and analysis using Au amalgamation showed the gold cartridges measured up to 75 % HgII, with the value at the beginning of the HgII measurement being much lower (as low as 10 %) due to HgII adsorption on analyzer surfaces and the Tekran particulate filter. Furthermore, thermal desorption of Hg from Au reduced only 80 % of HgII to Hg0, resulting in additional HgII that was not measured by the analyzer. By adding a thermolyzer upstream of the analyzer, 97 % of HgII was measured as Hg0. Additionally, Hg0 measurements using Tekran 2537 B and X models using a newly developed signal processing algorithm, different peak integration methods, and two Hg0 sources were compared. Results showed the 2537X model was not affected by the integration type, while the 2537B model was. Bell jar calibration based on the Dumarey equation resulted in 6 % ± 7 % (mean ± SD) underestimation of measured Hg0 concentrations compared to the calibration with a permeation calibrator. SignificanceGold cartridges measured an atmospheric Hg fraction somewhere between Hg0 and TGM due to HgII adsorption and inefficient reduction of HgII to Hg0 during thermal desorption from Au. Since HgII in ambient air can be 25 % of total Hg, distinguishing between Hg0 and TGM is important. The use of a thermolyzer or a cation exchange membrane upstream of gold cartridges is recommended to enable TGM or Hg0 measurements, respectively. Observations showed that traceable multipoint calibrations of atmospheric Hg measurements are needed for Hg quantification, and that different Hg0 calibration methods can produce significantly different results for measured atmospheric Hg concentrations.

Iridium Single Atoms to Nanoparticles: Nurturing the Local Synergy with Cobalt-Oxide Supported Palladium Nanoparticles for Oxygen Reduction Reaction.

A ternary catalyst comprising Iridium (Ir) single-atoms (SA)s decorated on the Co-oxide supported palladium (Pd)nanoparticles (denoted as CPI-SA) is developed in this work. The CPI-SA with 1wt.% of Ir exhibits unprecedented high mass activity (MA) of 7173 and 770mA mgIr -1, respectively, at 0.85 and 0.90V versus RHE in alkaline ORR (0.1m KOH), outperforming the commercial Johnson Matthey Pt catalyst (J.M.-Pt/C; 20wt.% Pt) by 107-folds. More importantly, the high structural reliability of the Ir single-atoms endows the CPI-SA with outstanding durability, where it shows progressively increasing MA of 13 342 and 1372mA mgIr -1, respectively, at 0.85 and 0.90V versus RHE up to 69 000 cycles (3 months) in the accelerated degradation test (ADT). Evidence from the in situ partial fluorescence yield X-ray absorption spectroscopy (PFY-XAS) and the electrochemical analysis indicate that the Ir single-atoms and adjacent Pd domains synergistically promote the O2 splitting and subsequent desorption of hydroxide ions (OH-), respectively. Whereas the Co-atoms underneath serve as electron injectors to boost the ORR activity of the Ir single-atoms. Besides, a progressive and sharp drop in the ORR performance is observed when Ir-clusters and Ir nanoparticles are decorated on the Co-oxide-supported Pd nanoparticles.

Photoelectrochemical catalytic CO2 reduction enhanced by In-doped GaN and combined with vibration energy harvester driving CO2 reduction

Photoelectrochemical (PEC) technology seamlessly integrates and optimizes the merits of photocatalysis and electrocatalysis, facilitating charge separation and enhancing solar conversion efficiency. It stands out as a promising approach for CO2 treatment. GaN as III-Ⅴ semiconductor, has garnered substantial attention in the realm of PEC CO2 reduction reactions (RR). In this study, GaN and In/GaN micro-rods were prepared via straightforward hydrothermal synthesis. Attaining a current density of approximately 10 mA/cm2 and CO Faradaic Efficiency (FE) of ∼45 % at −0.75 VRHE (Reversible Hydrogen Electrode, RHE), In/GaN exhibited exceptional stability over a 2 h PEC CO2 RR. The introduction of In into GaN significantly augmented CO2 adsorption capacity and light harvesting. Additionally, Density Functional Theory (DFT) calculations elucidated that In-doped GaN can diminish the adsorption of intermediate CO, favoring subsequent CO desorption. Furthermore, the N-vacancy increased with In doping, resulting in a rise in the number of unpaired electrons, facilitating carrier transport. Herein, vibration energy harvester was introduced to drive CO2 RR, marking a significant advancement in development of PEC CO2 RR for future green energy applications.

Enhanced CO2 absorption in amine-based carbon capture aided by coconut shell-derived nitrogen-doped biochar

The sluggish CO2 absorption kinetics and constrained CO2 absorption capacity diminish the practicality of using amine-based absorption for CO2 capture, impeding progress toward carbon neutrality goals. This study aims to develop a catalytic CO2 absorption process to promote CO2 absorption by introducing a solid base catalyst, namely, coconut shell-derived nitrogen-doped biochar (NBC), into an amine-based solution. The coconut shells were modified with urea and activated with KOH to prepare an NBC catalyst with improved basic characteristics. The findings showed that compared to non-catalytic absorption, the NBC catalyst increased the CO2 absorption amount, CO2 absorption rate, and absorption efficiency of the monoethanolamine (MEA) solution by 16.9 %, 43.4 %, and 13.1 %, respectively. The basic sites on the NBC surface provided extra electrons to motivate the formation of MEACOO- and HCO3-. NBC’s large surface area and porous structure also advanced the gas–liquid mass transfer, accelerating the CO2 absorption rate. Furthermore, the NBC exhibited excellent cyclic stability and facilitated the subsequent CO2 desorption process. This work develops a promising and practical approach to significantly improve the amine-based absorption and reuse of waste biomass resources for efficient CO2 capture.

Low-temperature desorption in thermomorphic solvents for CO2 capture: Systems with N-methylcyclohexylamine and N,N-dimethylcyclohexylamine

The significant energy consumption associated with the carbon capture process has long posed a substantial obstacle to the extensive industrial utilization of amine solutions. Therefore, it is imperative to investigate a low-energy-consumption carbon capture solvent. This study meticulously examined thermomorphic absorbents composed of N-methylcyclohexylamine(MCA) and N,N-Dimethylcyclohexylamine(DMCA), delving into its absorption and desorption performances. Initially, focusing on absorption efficiency, we tested six varying concentration ratios of absorbents for CO2 absorption, scrutinizing their absorption rate and capacity. The analysis revealed that the rapid saturation of the absorbent stemmed from its limited absorption capacity. Notably, the MCA:DMCA=1 M:1 M ratio exhibited outstanding absorption capability, at 0.7015 mol CO2/mol amine, surpassing the absorption capacity of 30 wt% Monoethanolamine by a factor of 1.525. Subsequent desorption trials on MCA:DMCA=1 M:1 M at temperatures of 333 K, 348 K, and 363 K indicated successful desorption at 333 K, achieving an efficiency of 82.77 %, which rose with increasing temperature. Lastly, the estimated energy consumption for the latent heat and evaporation heat of this absorbent was approximately 0.342GJ/t CO2, marking a ∼61.1 % decrease compared to liquid-liquid phase change absorbents. These findings underscore the industrial promise of thermomorphic absorbents as a viable option for carbon capture applications.

Hydrogen‐Bond‐Enhanced Photoreforming of Biomass Furans over a Urea‐Incorporated Cu(II) Porphyrin Framework

AbstractSolar‐driven upgrading of biomass‐derived 5‐hydroxylmethylfurfural (HMF) to 2,5‐furandicarboxylic acid (FDCA) holds great promise for sustainable production of bio‐plastics and resins. However, the process is limited by poor selectivity and sluggish kinetics due to the vertical coordination of HMF at relatively strong metal sites. Here, we purposely developed a Cu(II) porphyrin framework featuring side‐chain incorporated urea linkages, denoted as TBUPP−Cu MOF, to render HMF a weak hydrogen bond at the urea site and flat adsorption via π–π stacking with the benzene moiety. The unique configuration promotes the approaching of −CHO of HMF to the photoexcited porphyrin ring towards kinetically and thermodynamically favourable intermediate formation and subsequent desorption. The charge localisation and orbital energy alignment enable the selective activation of O2 over the porphyrin to generate ⋅O2− and 1O2 instead of highly oxidative H2O2 and ⋅OH via spin‐flip electron transfer, which drive the ambient oxidation of proximal −CHO. The effective utilisation of redox species and circumvented over‐oxidation facilitate a FDCA selectivity of >90 % with a high turnover number of 193 molHMF molCu−1. The facile purification of high‐purity FDCA and zero‐waste recycling of intermediates and durable catalyst feature TBUPP−Cu MOF a promising photo‐oxidation platform towards net‐zero biorefining and organic transformations.

Hydrogen-Bond-Enhanced Photoreforming of Biomass Furans over aUrea-Incorporated Cu(II) Porphyrin Framework.

Solar-driven upgrading of biomass-derived 5-hydroxylmethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) holds great promise for sustainable production of bio-plastics and resins. However, the process is limited by poor selectivity and sluggish kinetics due to the vertical coordination of HMF at relatively strong metal sites. Here, we purposely developed a Cu(II) porphyrin framework featuring side-chain incorporated urea linkages, denoted as TBUPP-Cu MOF, to render HMF a weak hydrogen bond at the urea site and flat adsorption via π-π stacking with the benzyl moiety. The unique configuration promotes the approaching of -CHO of HMF to the photoexcited porphyrin ring towards kinetically and thermodynamically favourable intermediate formation and subsequent desorption. The charge localization and orbital energy alignment enable the selective activation of O2 over the porphyrin to generate ·O2- and 1O2 instead of highly oxidative H2O2 and ·OH via spin-flip electron transfer, which drive the ambient oxidation of proximal -CHO. The effective utilisation of redox species and circumvented over-oxidation facilitate a FDCA selectivity of >90% with a high turnover number of 193 molHMF molCu-1. The facile purification of high-purity FDCA and zero-waste recycling of intermediates and durable catalyst feature TBUPP-Cu MOF a promising photo-oxidation platform towards net-zero biorefining and organic transformations.

Exploring flavor separation in soy protein enzymatic hydrolysates via resin adsorption/desorption: A study on physicochemical characteristics and mass transfer dynamics

The green separation of soy protein enzymatic hydrolysates (SPEH) with different flavors can enhance the application of SPEH in the food industry. This study investigated the detailed process of separating and purifying SPEH by utilising the interaction between SPEH and adsorptive resins, and the mass transfer behaviour of SPEH in the adsorptive resin was explored by a mathematical model. Initially, soybean meal underwent hydrolysis by papain. Subsequently, the resulting SPEH was adsorbed onto the resin under various pH conditions and then desorbed. In general, SPEH exhibited a greater ability to bind with the resin under protonation treatment (pH 3.0) compared to deprotonation treatment (pH 9.0). The equilibrium adsorption capacity at pH 3.0 and 9.0 was 33.1 ± 1.7 mg g−1 and 24.1 ± 0.9 mg g−1, respectively. At the same time, SPEH exhibited greater surface diffusivity within the resin during adsorption at pH 3.0 (2.83 × 10−8 cm2 s−1) compared to pH 9.0 (2.41 × 10−8 cm2 s−1). Due to the robust binding affinity of SPEH with the resin in the acidic environment, a smaller quantity of SPEH was released from the resin during the subsequent desorption process. Furthermore, the bitter SPEH, characterised by an abundance of random coil and β-turn structures, demonstrated greater affinity for binding with the adsorptive resin compared to the salty and umami SPEH, which exhibited a higher proportion of β-sheet structure. After adsorption at pH levels ranging from 3.0 to 9.0 and subsequent desorption, the recovery of SPEH ranged from 30.4 % to 35.7 %, with purities between 57.5 % and 62.3 %. Overall, this study offers valuable insights into the targeted separation of various flavor components from SPEH, shedding light on the intricate dynamics of adsorption and desorption processes under different pH conditions.

Desorption of Polycyclic Aromatic Hydrocarbons from Microplastics in Human Gastrointestinal Fluid Simulants-Implications for Exposure Assessment.

Microplastics have been detected in various food types, suggesting inevitable human exposure. A major fraction may originate from aerial deposition and could be contaminated by ubiquitous pollutants such as polycyclic aromatic hydrocarbons (PAHs). While data on the sorption of pollutants to microplastics are abundant, the subsequent desorption in the gastrointestinal tract (GIT) is less understood. This prompted us to systematically investigate the release of microplastics-sorbed PAHs at realistic loadings (44-95 ng/mg) utilizing a physiology-based in vitro model comprising digestion in simulated saliva, gastric, and small and large intestinal fluids. Using benzo[a]pyrene as a representative PAH, desorption from different microplastics based on low density polyethylene (LDPE), thermoplastic polyurethanes (TPUs), and polyamides (PAs) was investigated consecutively in all four GIT fluid simulants. The cumulative relative desorption (CRD) of benzo[a]pyrene was negligible in saliva simulant but increased from gastric (4 ± 1% - 15 ± 4%) to large intestinal fluid simulant (21 ± 1% - 29 ± 6%), depending on the polymer type. CRDs were comparable for ten different microplastics in the small intestinal fluid simulant, except for a polydisperse PA-6 variant (1-10 μm), which showed an exceptionally high release (51 ± 8%). Nevertheless, the estimated contribution of microplastics-sorbed PAHs to total human PAH dietary intake was very low (≤0.1%). Our study provides a systematic data set on the desorption of PAHs from microplastics in GIT fluid simulants.

Enhanced Nitrate Nitrogen Removal from Wastewater Using Modified Reed Straw: Adsorption Performance and Resource Utilization

This paper presents a study on the efficient removal of nitrate nitrogen from wastewater using modified reed straw (MRS) and its subsequent resource utilization. The modification of the reed straw involved the introduction of branching quaternary amine groups to enhance its adsorption capacity for nitrate nitrogen. Experimental investigations were conducted to analyze the impact of packing height, flow rate, and initial solution concentration on the dynamic adsorption performance of the MRS. The results revealed that the maximum dynamic adsorption capacity of the MRS for nitrate nitrogen reached 14.76 mg/g. Furthermore, valuable nitrate nitrogen nutrient solution was successfully recovered through subsequent desorption experiments for resource recycling. Moreover, the application of the MRS led to notable enhancements in column height, fresh weight, chlorophyll content, and nitrogen content of the treated plants, indicating its efficacy in promoting plant growth. Overall, the findings demonstrate that MRS serves as a versatile adsorbent capable of efficient nitrate nitrogen removal and subsequent resource utilization.

Deciphering the factors influencing electric field mediated polymerization and depolymerization at the solution–solid interface

Strong and oriented electric fields are known to influence structure as well as reactivity. The strong electric field (EF) between the tip of a scanning tunneling microscope (STM) and graphite has been used to modulate two-dimensional (2D) polymerization of aryl boronic acids where switching the polarity of the substrate bias enabled reversible transition between self-assembled molecular networks of monomers and crystalline 2D polymer (2DP) domains. Here, we untangle the different factors influencing the EF-mediated (de)polymerization of a boroxine-based 2DP on graphite. The influence of the solvent was systematically studied by varying the nature from polar protic to polar aprotic to non-polar. The effect of monomer concentration was also investigated in detail with a special focus on the time-dependence of the transition. Our experimental observations indicate that while the nucleation of 2DP domains is not initiated by the applied electric field, their depolymerization and subsequent desorption, are a consequence of the change in the polarity of the substrate bias within the area scanned by the STM tip. We conclude that the reversible transition is intimately linked to the bias-induced adsorption and desorption of the monomers, which, in turn, could drive changes in the local concentration of the monomers.