Desorption Efficiency Research Articles

Effects of microplastics on polycyclic aromatic hydrocarbons migration in Baiyangdian Lake, northern China: Concentrations, sorption–desorption behavior, and multi-phase exchange

Microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) have been found in all environment matrices and are of concern worldwide. In this study, PAHs were determined in Baiyangdian Lake, China, and the effects of MPs on the migration of PAHs at the lake interfaces were analyzed. The average abundances of detected MPs were 9595 items m−3 for water and 1023 items kg−1 for sediment. The detected MPs were polyamide 6, polypropylene, polyethylene, and polyethylene terephthalate. The average Σ16PAHs in the water, sediment, and air were 1338 ng L−1, 751 ng g−1 dry weight, and 395 ng m−3, respectively. At the air–water interface, naphthalene, and phenanthrene volatilized from water to air, whereas benzo(b)fluoranthene, benzo(k)fluoranthene, and dibenzo(a,h)anthracene deposited from air to water. The fugacity fraction between sediment and bottom water ranged from 0.88 to 0.99, which indicated net volatilization at the water–sediment interface. The adsorption capacities of the four MPs for the PAHs ranged from 39.4 to 99.8 μg g−1 with a desorption efficiency range of 0.01%–44.3% under oscillation. According to the distribution of PAHs on the MPs, the exchange fluxes of PAHs at the water–air and sediment–water interfaces were recalculated. The results showed that the MPs could increase deposition of the PAHs from air to the water (ΔFA–W: −221×10−2 to −0.01×10−2 ng m−2 d−1) and the volatilization of PAHs from sediment to water (ΔFW–S: −79.7×105 to 180×105 ng m−2 d−1), which suggests that MPs increase the risk of PAHs in water and to aquatic organisms.

Engineered Mg-modified biochar-based sorbent for arsenic separation and pre-concentration

The utilization of biochar as a relatively efficient sorbent or stationary phase for the separation and preconcentration of a wide range of analytes represents an innovative approach in current sample pretreatment methods. Appropriate pre- and post-pyrolysis modification of the input precursor and pyrolysis product, respectively, allows targeted design of the physicochemical properties and sorption characteristics of the resulting sorbent. The present work deals with the preparation of pyrolysis materials based on unmodified cattail leaf biomass (BC) and its Mg-modified analogue (MgBC) by a slow pyrolysis process at 500 °C and a residence time of 1 h in a pyrolysis reactor. Physicochemical characterization of BC and MgBC carried out by pH, total C, N, surface size analysis (SSA), 13C NMR, SEM-EDX and XRD confirmed significant morphological and mineralogical differences between the prepared sorbents. By performing sorption experiments using a model anionic analyte (As) and application of Langmuir isotherm, we found that the predicted maximum sorption capacity of MgBC for As is 13.5-fold higher than that of BC. The sorption process of As by both sorbents is best described by the Sips adsorption isotherm (R2 ≥ 0.995) and a pseudo-nth order kinetic model (R2 ≥ 0.997). The optimum pH for As sorption by BC and MgBC sorbents is in the interval 5–6. The presence of competitive phosphate anions (equimolar concentration of 1:1) in the solution significantly reduces the sorption capacity of MgBC for As by 40% for BC by 70%. The presence of Cl- ions showed no significant effect on the sorption capacity of Bc and MgBC for As. Both sorbents were best recovered using 0.1 mol/L NaOH solution when the desorption efficiency for both sorbents was more than 95%. The MgBC sorbent showed 35% retention of As from the real sample in the model SPE column at a flow rate of 0.12 mL/s. Based on the obtained knowledge, it is evident that biochar-based sorbent prepared from Mg-modified precursor represents an effective sorbent for anionic forms of analytes and opens the possibility of its use also in preconcentration and separation techniques.

Coupling [Bmim]PF6 and Pd NPs Modulated MOF-Based Material for Synergetic Regulating Electrocatalytic CO2 Reduction.

Metal-organic frameworks (MOFs) with a large number of active sites and high porosity are considered to be good platforms for the carbon dioxide electroreduction reaction (CO2RR) but with confined low conductivity or low efficiency. Here, Pd-[Bmim]PF6/Cu-BTC with exceptional selectivity and electron-transfer ability is elaborately designed by introducing ionic liquids (ILs) into the MOFs. ILs favor promoting the overall current density of the catalysts, and the introduction of Pd atoms combined with O atoms on the catalyst surface reconfigures into strong Pd-O bonds, improving the desorption efficiency of *CO. The unique structure of the catalyst Pd-[Bmim]PF6/Cu-BTC leads to a significant improvement of the C1 product with a high Faraday efficiency (FE) of 99.36%, especially for carbon monoxide (CO) with an FE of 93.18% (-1.1 VRHE). The exceptional performance of the catalyst is verified by density functional theory (DFT) calculations, and the reduction of the free energy required by *HOCO as a key intermediate for CO production was only 0.12 eV, providing new insights to improve the electrocatalytic performance of MOF-based materials for the CO2RR. In this research, an effective and promising strategy that configures active sites by larger current density is proposed to enhance the efficiency of the CO2RR.

Towards Sustainable Battery Recycling: Selective Desorption of Nickel(II) and Cobalt(II) from Amino‐Polycarboxylate Derivate Ligands in Model Systems

AbstractInter alia due to the high demand for lithium‐ion batteries, the required critical heavy metals have become a scarce resource. Consequently, effective recycling processes that enable the recovery of such materials are of high interest. A silica adsorbent functionalized with amino‐polycarboxylate derivate ligands (HSU331) was applied in order to selectively adsorb nickel(II) and cobalt(II). Subsequently, suitable parameters for a pH‐swing desorption were investigated. Maximum desorption efficiencies for Co(II) were achieved at pH = 2.7 (72 %) and for Ni(II) at pH = −0.5 (94 %). These results were used for the design of a pH‐shift desorption process in order to selectively recover Co(II) and regenerate the adsorbent after simultaneous adsorption of Co(II) and Ni(II).

Insights Into the Adsorption Behavior of Polyethylene Microplastics Towards Lead(II) Ions

ABSTRACTMicroplastics and metals represent widespread contaminants which can cause significant damage to aquatic ecosystems and organisms. However, the complex interactions between microplastics and various metals in water environments remains to be understood. This study aims to investigate the interaction dynamics between lead(II) ions and polyethylene in freshwater environments. Adsorption trials were conducted systematically by adjusting operational parameters such as initial Pb(II) concentration, equilibrium pH value, and residence times. An in‐depth characterization study using scanning electron microscopy (SEM), x‐ray diffraction and Fourier transform infrared (FTIR) analysis was conducted to explain the adsorption mechanism of polyethylene microplastics (PEM). The data indicated the porous surface of PEM, highlighting the presence of diverse functional groups. According to the Langmuir model, the PEM exhibited maximum Pb(II) uptake of 3.69 mg/g at pH 4.5. The pseudo‐first‐order model demonstrated superior fitting to Pb(II)‐PEM kinetics. Desorption trials were performed to assess the release of Pb(II) from Pb(II)‐bounded PEM using various chemical agents. It was observed that 0.01 M HNO₃ desorbed Pb(II) ions optimally, achieving a desorption efficiency exceeding 99.9%. Consequently, desorption trials provided evidence that Pb(II)‐bounded PEM may release Pb(II) ions in acidic environments, facilitating the transfer of Pb(II) to the digestive tracts of aquatic organisms.

Hierarchically-porous resin for the adsorption of organic matter in raffinate produced by solvent extraction from the vanadium industry

Solvent extraction wastewater contains high concentrations of organic pollutants and metal ions, making it difficult to treat. This paper presents a method of using hierarchically-porous adsorption resin to recover organics from raffinate and regenerate the resin, addressing secondary pollution in extraction processes. The chosen resin, WS6108, removes over 95 % of organics from raffinate, with high metal ion concentrations enhancing its adsorption efficiency. The article conducted an optimization experiment and mechanism study on WS6108 resin for adsorbing organic matter in vanadium raffinate (OIVR), followed by desorption and recycling tests. Results showed WS6108 resin achieved a 96.7 % adsorption efficiency at a solid–liquid ratio of 24 g/L after optimization. The chosen methanol desorbent achieves over 99 % desorption efficiency for the WS6108 cycle under specific conditions. The resin’s performance remains stable for up to 45 cycles. Adsorption isotherms and kinetic experiments indicate that OIVR adsorption by WS6108 resin is endothermic, non-spontaneous and entropy increasing. Moreover, the adsorption kinetics of OIVR by WS6108 resin followed a pseudo-second-order model, based on the activation energy, liquid film diffusion was considered the main rate-controlling step. A column experiment was conducted to verify that WS6108 resin can be used in real vanadium raffinate to remove organics. Density functional theory (DFT) revealed that strong hydrogen bonding, π-π stacking and excellent adsorption diffusion behavior drive OIVR adsorption. This study aims to increase the use of adsorption to treat oily wastewater generated by solvent extraction.

Experimental and theoretical investigation of a novel multi-amino-functionalized ionic phase change absorbent for highly efficient CO2 capture

A great potential for CO2 capture is that combining the advantages of both the structural tunability of functionalized ionic liquids and low energy consumption of phase change absorbent. In this study, a novel multi-amino groups functionalized ionic liquids [TEPAH][Lys] was synthesized and dissolved in NPA and H2O to achieve high absorption loading with low energy consumption. The experimental results demonstrated that the [TEPAH][Lys]/NPA/H2O exhibited a remarkable CO2 absorption loading of 2.93 mol CO2 ·mol absorbent−1 with 97.54 % of the CO2 products were concentrated in the lower phase, while the volume fraction was only 38 %. Meanwhile, the lower phase displayed low viscosity and excellent fluidity. The first desorption efficiency was as high as 81.19 % when the volume ratio of the added upper phase to the lower phase is 26.32 %, and the recycling efficiency could maintain above 81.15 % after fifth absorption–desorption cycles.13C NMR analysis revealed that the [TEPAH][Lys]/NPA/H2O absorbent was able to react with CO2, the CO2 products of carbamate, protonated amine, and propyl carbonates were presented only in the lower phase while the upper phase was almost exclusively NPA. The quantum chemical calculations revealed that CO2 products have greater polarity and density, resulting in higher solubility in water than NPA. The energy consumption was estimated as 2.60 GJ·ton-1 CO2, which was approximately 33.50 % lower than that of 30 % MEA (3.91 GJ·ton-1 CO2) under similar conditions. Overall, [TEPAH][Lys]/NPA/H2O phase change absorbent exhibits high CO2 absorption loading and low energy consumption, making it extremely potential for industrial carbon capture applications.

Electrochemically Switchable Sulfurized Polyacrylonitrile for Controllable Recovery of Copper in Wastewater Based on Reversible Adsorption/Desorption Regulation.

Within the context of circular economy and industrial ecology, adsorption offers an effective manner for recycling resources from wastewater, but controllable desorption remains a challenge. Inspired by metal-thiol binding and reversible thiol-disulfide redox transformation in biological systems, this study reports the development of a reversible adsorption/desorption (RAD) system for controllable recovery of copper based on electrochemically switchable sulfurized polyacrylonitrile (SPAN). Density functional theory calculations offered theoretical prediction for the formation of S-Cu bonds and reversible weak interaction between S-S bonds and Cu2+. The SPAN anchored onto titanium suboxide ceramic foam (SPAN@TiSO) could regulate Cu2+ adsorption/desorption stimulated by the electrode potential, indicated by the adsorption capacity of 243.3 mg g-1 (30 min) at 0.2 V vs SHE and a desorption efficiency of 98.4% (5 min) at 0.8 V vs SHE. Electrochemical analysis revealed that the reversible redox transformation of S-S/-S- groups in SPAN was responsible for selective adsorption and rapid desorption in response to the electrode potential. This study provides a proof-of-concept demonstration of an electrochemically switchable polymer to build up a reversible RAD system for controllable recovery of heavy metals in wastewater, making value-added resource recovery more efficient, more intelligent, and more sustainable.

How do polyhydroxyalkanoates aged by aerobic compost interact with steroidal estrogens to alter their adsorption and transport characteristics? Kinetics, isotherms, and influencing factors

Despite evidence indicating a substantial presence of microplastics (MPs) in organic fertilizers, research exploring the differences of MPs among various types of organic fertilizers remains limited. Additionally, MPs can act as carriers for organic pollutants, influencing their environmental behaviors. This study investigated the presence of MPs in organic fertilizers and their effects on the environmental behaviors of steroidal estrogens. We compared the adsorption of estrone (E1) and estrone sulfate sodium (E1-3S) by original PHA and PHA aged through cattle manure-straw compost (CS) and vermicompost (VC). PHA-CS exhibited the highest adsorption capacities for E1 (47.97 ± 2.20μgg-1) and E1-3S (64.32 ± 2.09μgg-1). Dissolved organic matter (DOM) from CS and VC profoundly affected estrogen adsorption onto PHA, with VC-derived DOM inhibiting and CS-derived DOM promoting adsorption. In simulated avian digestive fluid, the desorption efficiency of E1 was 72.46% to -93.43% higher than that of E1-3S, indicating increased toxicity and bioavailability of E1 upon bird ingestion. Transport experiments strongly suggested that estrogens could be more easily retained in porous media containing aged PHA. This study advances our understanding of the adsorption mechanisms of aerobic compost-derived PHA on estrogens and their desorption behaviors under different environmental conditions.

Improving the solid–liquid phase transition of low energy-consuming biphasic solvent through the introduction of H2O

Non-aqueous biphasic absorbents have excellent energy-saving features in capturing CO2. However, the high hygroscopicity of chemical absorbents and the moisture content in flue gas can alter the moisture content of absorbents, thereby affecting their carbon capture performance and stability. In this research, an absorbent for solid–liquid phase transition composed of N-Aminoethylpiperazine (AEP) and dimethyl sulfoxide (DMSO) was developed. The influence of H2O content on CO2 capture capacity and phase transition behavior was explored. The introduction of H2O could not only reduce the viscosity to achieve fast CO2 capture and large CO2 absorption capacity (1.05 mol·mol−1) but also generate dispersed solid particles, allowing for quick sedimentation of the solids, thus enhancing the rate of phase separation. The desorption efficiency of this biphasic solvent was maintained above 83 % after four cycles. It could be desorbed in the middle stage of absorption without waiting for absorption saturation, greatly saving time and cost. Finally, the principle of the CO2 absorption process in this system and the regulatory effect of H2O on the solid–liquid phase were studied through characterization and quantum calculation.

Insights into the relationship between Nitrilotri(methylphosphonic acid) (NTMP) adsorption and physicochemical properties of iron oxides

Non-reactive phosphorus (e.g., phosphonate) contributes to eutrophication, while little attention has been paid to its control. The iron-based materials are highly efficient in orthophosphate removal from water, while the correlation between their physicochemical properties and selective phosphonate (e.g. Nitrilotri(methylphosphonic acid) (NTMP)) adsorption is still unclear. In this study, Fe3O4 (magnetite), FeOOH (goethite) and Fe2O3 (hematite) with different crystal structures, particle sizes and surface area were synthesized for NTMP adsorption. The physicochemical properties of the three kinds of iron oxides were characterized. The batch experiments were applied to explore the NTMP adsorption and desorption performance. The maximum adsorption capacity of NTMP on Fe3O4, FeOOH and Fe2O3 were 4.14, 1.91 and 0.99 mg-P/g, respectively. Results implied the crystal structure and surface area of iron oxides determined the maximum NTMP adsorption capacity. The NTMP adsorption on the three iron oxides was spontaneous, endothermic and randomness increase. The iron oxides showed high selectivity towards NTMP adsorption in water containing anions, while the co-existing Ca2+ and Mg2+ remarkably increased the adsorption capacity. The successive adsorption-desorption cycles suggested a favorable reusability of the above iron oxides and a high NTMP desorption efficiency. The specific NTMP adsorption capacity followed the sequence of FeOOH > Fe2O3 > Fe3O4, and was highly dependent on surface OH− proportion. The NTMP adsorption mechanism was mainly attributed to inner-sphere complexation. This study provides insights into the iron-based adsorbents design for selective phosphonate adsorption in the future.

Desorption efficiency and holding capacity of acid-treated filters for nicotine sampling in vape shops.

Efficient sampling materials are essential for assessing nicotine levels in vape shops and other settings where nicotine exposures may exist. Two different treatments of Whatman glass fiber type A (GF/A) filters (sodium bisulfate treated and citric acid treated) were evaluated for nicotine capture, desorption efficiency, and holding capacity using Gas Chromatography-Mass Spectrometry (GC-MS). The Filters were treated with 0.8mL of 0.1 M sodium bisulfate or citric acid solution and oven-dried (80 °C) for 30min. Nicotine was desorbed off the filters using a modified analytical method. The average nicotine desorption efficiency for sodium bisulfate-treated GF/A filters (98.4%) was significantly higher than that of citric acid-treated GF/A filters (60.9%) over a range of 1-100 µg nicotine. Sodium bisulfate-treated and citric acid-treated GF/A filters experienced a 10% nicotine breakthrough after being dosed with about 550 and 2,750 µg of nicotine, respectively compared to 75 µg for untreated GF/A filters. Citric acid-treated GF/A filters had a much greater nicotine-holding capacity, but nicotine desorption from citric acid-treated GF/A filters was below the recommended criteria. Therefore, we recommend that sodium bisulfate-treated GF/A filters are employed for sample of nicotine with the GC-MS method.

Solid-Phase Microextraction Mediated Solid-Phase Dielectric Barrier Discharge Vapor Generation-Atomic Fluorescence Spectrometry for Sensitive Determination of Mercury in Seawater.

A novel method coupling solid-phase microextraction (SPME) to solid-phase dielectric barrier discharge (SPDBD) vapor generation was proposed and used for the sensitive detection of trace mercury (Hg) in seawater with atomic fluorescence spectrometry (AFS) in this work. The method proposed herein offers the unique advantages of integrating desorption and chemical vapor generation into one step, eliminating the use of elution reagents, and reducing the analysis time. SPME with multiwalled carbon nanotubes (MWCNTs) coated on the glass tube was used to extract Hg2+ in seawater. The Hg2+ was then desorbed and reduced to Hg0 vapor by SPDBD, which was detected by cold vapor AFS. The parameters affecting Hg2+ extraction, desorption, and vapor generation were studied. The detection limit of Hg2+ was 0.0003 μg L-1, and the relative standard deviation at a Hg2+ concentration of 0.05 μg L-1 was 4.4%. This method also has excellent antimatrix interference ability for Hg2+ determination with recoveries between 91.8% and 101.1% in the presence of extremely high concentrations (two million times excess) of coexisting ions. The practicality of this method was also evaluated by analyzing two different certified reference materials of Hg2+ in water and several seawater samples with good spike recoveries (94.0%-107.4%). Compared with solid-phase photothermo-induced vapor generation, this method has higher extraction efficiency and higher desorption efficiency without the assistance of heating as well as a lower detection limit of Hg2+, which is capable of performing trace Hg analysis in seawater.

PH-Responsive Alginate/Chitosan Gel Films: An Alternative for Removing Cadmium and Lead from Water.

Biosorption, a non-expensive and easy method for removing potentially toxic metal ions from water, has been the subject of extensive research. In this context, this study introduces a novel approach using sodium alginate and chitosan, versatile biopolymers that have shown excellent results as biosorbents. The challenge of maintaining high efficiencies and reuse is addressed by developing alginate/chitosan-based films. These films, prepared using solvent casting and crosslinking methods, form a hydrogel network. The alginate/chitosan-based films, obtained using the eco-friendly polyelectrolyte complex method, were characterized by FTIR, SEM, TGA, and DSC. The study of their swelling pH response, adsorption, and desorption behavior revealed promising results. The adsorption of Pb was significantly enhanced by the presence of both biopolymers (98%) in a shorter time (15 min) at pH = 6.5. The adsorption of both ions followed a pseudo-second-order kinetic and the Langmuir isotherm model. The desorption efficiencies for Cd and Pb were 98.8% and 77.6% after five adsorption/desorption cycles, respectively. In conclusion, the alginate/chitosan-based films present a highly effective and novel approach for removing Cd and Pb from water, with a promising potential for reuse, demonstrating their strong potential in potentially toxic metal removal.

The role of the activation heating source on the carbon capture performance of two new adsorbents produced from household-mixed-plastic waste

This study reveals the impact of the activation with microwave and conventional heating sources on textural properties and CO2 uptake of a mixed plastic-based char. Two mixed plastic-based adsorbents, one activated using microwaves and the other using conventional heating, were produced at optimum activation conditions, and subsequently compared. The findings show that both heating sources produced microporous adsorbents, but activation heating sources influenced their physicochemical properties and CO2 uptake. The microwave-produced activated carbon (AC) displayed superior BET surface area, total, micro- and ultra-micropore volumes compared to the conventionally produced AC. The microwave-produced AC possessed CO2 adsorption capacities of 1.66 and 2.37 mmol/g under dynamic and equilibrium conditions, respectively, at 25 °C and 1 bar. These capacities represent an 8 and 30 % higher uptake, respectively, compared to the 1.53 and 1.66 mmol/g displayed by the conventionally prepared AC under the same adsorption conditions. Both samples displayed stable and excellent CO2 recyclability over 10 adsorption-desorption cycles, with desorption efficiencies ranging from 93.46 % to 96.72 % (microwave- and conventionally- produced ACs respectively). The Avrami model most accurately described the experimental CO2 adsorption data under dynamic conditions, while the Sip model gave the best fit for equilibrium conditions. These findings apply to both types of ACs at various temperatures, irrespective of the heating source. Overall microwave heating is more efficient than conventional heating, requiring 300°C lower temperature, 115 minutes shorter time, 0.79 kWh less energy, and less KOH. It improves CO2 uptake and reduces production costs by 80 %, offering a sustainable alternative for CO2 adsorbent production.

The adsorption and separation of tungsten and molybdenum by chitosan and chitosan-D301: Experiments and DFT theoretical calculation

The adsorption and separation of tungsten and molybdenum are important for efficient recycling of W-Mo resources, which requires green and efficient adsorbents. In this paper, Chitosan (CS)-D301 material was obtained by impregnation method and was applied to adsorb and separate W and Mo in solutions. The adsorption optimization results indicated that W was adsorbed by CS-D301, the separation factor of W/Mo increased to 26.45 compared with that of CS 21.34. The desorption efficiency was still above 94 % after five adsorption–desorption cycles. FT-IR, XPS and DFT theoretical calculations indicated that the surface group N+-R of CS-D301 showed more affinity for W, making it easier to selectively adsorb W over Mo than CS only. N was the surface-active adsorption site, and the adsorption process belonged to chemical adsorption with an adsorption energy of Eads = −957.64 kcal/mol. CS-D301 was expected to become green adsorbent for efficient separation of W and Mo to support resource recovery, protection and sustainable development.

Synthesis and characterization of allyl mannitol cross-linker based novel hydrogel for capturing of toxic metal ions from aqueous solution

ABSTRACT Three grades of allyl-mannitol cross-linker-based hydrogel (AMCLHs hydrogel) have been synthesized with the help of acrylic acid and acrylamide monomers using a free radical co-polymerization technique. The three prepared grades of AMCLHs hydrogel have been referred to as AMCLHs-1, AMCLHs-2, and AMCLHs-3, respectively. The prepared AMCLHs hydrogels have been characterized by several analytical techniques viz. Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TG) analysis, point of zero charge (ΔpHPZC), analysis, and scanning electron microscope (SEM) analysis, respectively. The synthesized hydrogels have been utilized for the elimination of Cu2+ and Co2+ ions from wastewater. The properties of prepared AMCLHs hydrogels, i.e. swelling and water retention ratio have been studied in distilled water under optimized conditions. The maximum swelling ratio of the best grade of hydrogel (AMCLHs-1) has been found to be 400.5 g/g with the water retention ratio of 75.09% during 24 h. These findings indicate the AMCLHs-1 hydrogel has remarkable swelling and water retention capacity. The maximum metal ion removal efficiency of AMCLHs-1 hydrogel from aqueous solutions has been found to be 96.6% for Cu2+ and 94.2% for Co2+ ions under optimum conditions. The experimental data fitted well with the Langmuir and Freundlich adsorption models, revealing maximum adsorption capacities of 431.03 mg/g for Cu2+ ions and 414.93 mg/g for Co2+ ions, respectively. In addition, the rate for the adsorption of Cu2+ and Co2+ ions onto AMCLHs-1 hydrogel follows both Pseudo first and second-order kinetic models. The negative ΔG values indicate that the adsorption process occurs spontaneously, while positive ΔH values suggest that the adsorption process is exothermic in nature. The prepared AMCLHs hydrogel is reusable and exhibits high desorption efficiency with 87.63% for Cu2+ and 85.21% for Co2+ metal ions even after the fourth cycle. Overall, AMCLHs hydrogel is a cost-effective and reusable adsorbent that possesses a significant potential for heavy metal ion removal from aqueous solutions.

Extremely Fast Wicking Self‐Layered Interpenetrating Network Hydrogel for Rapid All Day Collection of Atmospheric Water

AbstractHygroscopic salt hydrogel photothermal composites and related technology are a promising pathway for water harvesting. However, due to the overly cumbersome preparation process, the distribution of the surface photothermal layer is difficult to control and the photothermal efficiency is low. In this paper, a method is proposed to greatly simplify the preparation process of photothermal layer hydrogels and improve their atmospheric water harvesting performance by constructing temperature‐sensitive interpenetrating networks. Due to the decomposition of some reversible hydrated structures in the network during heating and warming, carbon nanotubes move autonomously to form a layered structure with a photothermal effect on the upper surface, which can return to its original state after cooling and remain stable at room temperature or under solar illumination. Compared with hydrogels with general layered structure or overall distribution of photothermal materials, agar/GG/PAM/CNT hydrogel has faster moisture adsorption efficiency and higher desorption efficiency, and during the 24 h continuous sorption–desorption cycle is capable of achieving high water yield of 2.57 Lwater kgsorbents−1 day−1, superior to most recent hydrogel adsorbents. Simplifying the preparation process while maintaining high efficiency, while greatly improving photothermal performance, paves the way for cost‐effective mass production applications for a wide range of hygroscopic salt‐hydrogel photothermal composites.

Reconfiguring closed-loop desorption for industrial solvent recycling by retaining post-condensation volatile organic compounds

Massive emissions of volatile organic compounds (VOCs) from industrial solvent evaporation have exacerbated atmospheric pollution. As high-value pollutants, VOCs can be concentrated and condensed into liquid solvents for reuse instead of destructive elimination, minimizing environmental threats and treatment costs. However, classical thermal swing adsorption (TSA) using nitrogen as the purge gas are inclined to be in closed form to economize on nitrogen, which results in desorption residues at the outlet of the adsorber and leads to environmental risks. In this study, one-step closed-loop desorption (OCD) and two-step closed-loop desorption (TCD) were proposed for industrial solvent recovery by reconfiguring TSA and condensation to improve desorption efficiency and recovery performance. A detailed mathematical model was developed and validated experimentally to describe dynamic behaviors of closed-loop desorption. The results showed that the standby adsorber connected to the thermal desorption process effectively retained the post-condensation VOCs and reduced the desorption residual for the re-absorption efficiency. By using the orthogonal experimental design, desorption temperature, condensation temperature, and feed concentration were proved to be more significant on recovery capacity than packing height and purge velocity. A broader feasible recovery domain was achieved by the TCD cycle, with an increase of 48.15 % compared to the OCD cycle at low feed concentrations. The OCD cycle was more energy-efficient, except in scenarios of low adsorption loading and low-grade energy sources. The findings provide new insights and promising approaches for achieving synergies between industrial exhaust treatment and organic solvent recovery.

CO2 capture performance of AMP-EAE amine blends: Absorption in the microchannel and desorption from saturated solutions

Blended organic amine solutions are considered an effective strategy for developing highly efficient and low energy-consuming absorbents due to the possibility of combining the advantages of single amine. The 2-amino-2-methyl-1-propanol (AMP) and 2-(ethylamino)ethanol (EAE) amine blends were prepared in three molar ratios: blend-1 (nAMP:nEAE = 3:1), blend-2 (nAMP:nEAE = 1:1), and blend-3 (nAMP:nEAE = 1:3). The impacts of gas-liquid flow rate, amine concentration, molar ratio, temperature, and CO2 concentration on absorption performance were investigated using the serpentine microchannel. Additionally, the effects of amine concentration and molar ratio on the desorption performance of saturated solutions were also explored. The performance of amine blends in absorption and desorption was evaluated by measuring absorption rate, efficiency, and loading, as well as desorption efficiency, energy consumption, cycle capacity, and average desorption rate. The desorption results were compared to those of the benchmark solvent, 30 wt% MEA, under identical operating conditions. The results indicate that the 25 wt% blend-2 solution performs exceptionally well, exhibiting a 15 % increase in absorption efficiency compared to the AMP aqueous solution at a gas-liquid ratio of 20. Additionally, the cycle capacity and average desorption rate are 1.7 times higher than those of the 30 wt% MEA solution. Notably, the energy consumption of the 25 wt% blend-2 solution for desorption is only 60 % of the 30 wt% MEA solution.