Adsorption Regeneration Research Articles

Efficient microwave regeneration of iron-modified Na-based montmorillonite and Na-based attapulgite for enhanced adsorption of tetracycline in water

A novel iron-modified Na-based montmorillonite (Fe-MT) or iron-modified Na-based attapulgite (Fe-AT) adsorbent is successfully prepared using ion exchange method and applied to remove tetracycline (TC) in water, and the spent adsorbents saturated with organic pollutants are regenerated under microwave (MW) irradiation. The influences of the ratio of Fe3+ and cation exchange capacity, adsorption time, adsorbent dosage, MW power, and irradiation time are investigated. The possible adsorption and MW regeneration mechanism is also proposed. The results indicate that Fe-MT and Fe-AT have enhanced interlayer spacing and surface area after the Na-based montmorillonite (Na-MT) or Na-based attapulgite (Na-AT) are modified using Fe3+. 97.70 % and 95.04 % adsorption are obtained using Fe-MT and Fe-AT within 30.0 min at 298 K, respectively, while 78.54 % and 61.92 % adsorption are obtained using Na-MT and Na-AT, respectively. Also, the adsorption processes fit well with pseudo-second-order reaction kinetic and Freundlich model, signifying chemical and multilayered adsorption. The adsorption of TC using the above four adsorbents are spontaneous and endothermic. Moreover, MW regeneration can enhance the adsorption capacity of Fe-MT or Fe-AT, and the regeneration ratios can reach 98.82 % and 93.14 % under 800 W MW within 5.0 min, respectively. By comparison, the adsorption capacity, regeneration performance and reusability of Fe-MT with larger interlayer spacing and surface area are superior to that of Fe-AT. Therefore, this work provides new perspectives on the adsorption technique using modified clay minerals as adsorbents for dealing antibiotics in water and wastewater, and the MW regeneration technology for regenerating spent adsorbents saturated with organic pollutants.

Adsorption and photocatalytic regeneration property of biochar-Bi2WO6 composite

Adsorption and photocatalytic regeneration property of biochar-Bi2WO6 composite

Simultaneously enhancing toluene adsorption and regeneration process by hierarchical pore in activated coke: a combined experimental and adsorption kinetic modeling study.

Activated coke is a type of commonly used adsorbent for benzene series VOCs such as toluene, but traditional microporous activated coke usually faces the challenge of poor regeneration performance. Herein, based on self-made activated cokes with typical pore configuration, we found that adsorption and regeneration of toluene can be simultaneously enhanced by constructing hierarchical pore in activated coke. Correlations of pore configuration with toluene adsorption capacity and regeneration efficiency reveal that micropore contributes for strong toluene adsorption; meso-macropore provides mass transfer channel for toluene desorption and regeneration process. Hierarchical porous activated coke prepared from Zhundong subbituminous coal not only achieves the highest toluene adsorption capacity of 340.92mg·g-1, but also can retain more than 90% of initial adsorption capacity after five adsorption-regeneration cycles. By contrast, micropore-dominant activated cokes can only retain 70% of initial adsorption capacity. Adsorption kinetic modelling on adsorption breakthrough curves shows that hierarchical porous activated coke prepared from Zhundong subbituminous coal exhibits high adsorption and diffusion rate constants of 14.39 and 33.45min-1, respectively, much higher than those of micropore-dominant activated cokes. Due to the accelerated surface adsorption and diffusion processes induced by meso-macropore, toluene adsorption and regeneration behavior can be simultaneously improved. Results from this work validated the role of pore hierarchy in toluene adsorption-regeneration process, providing guidance for designing high-performance activated coke with synergistically improved toluene adsorption capacity and regeneration performance.

Adsorption and catalytic degradation of tetracycline hydrochloride by HCNTs /MnFe2O4

Developing efficient, stable and selective materials is essential for removing antibiotics from aquatic systems. In this study, one composite is prepared via loading of magnetic MnFe2O4 onto hydroxylated multi-walled carbon nanotubes (HCNTs) through co-precipitation, named as HCNTs/MnFe2O4. The characterization of materials was performed using various methods, such as Vibrating Sample Magnetometer (VSM), Electron Paramagnetic Resonance (EPR), etc. There are larger surface and good magnetic property, which are useful to bind adsorbate and easy separation from mixtures. The as-synthesized composite exhibited excellent adsorption capacity and ability to activate potassium persulfate (KPS) for the efficient removal of Tetracycline hydrochloride (TC) from solution. The results showed that the adsorption capacity of HCNTs/MnFe2O4 towards TC was 341 mg·g–1 at 303 K. The kinetic process can be elucidated using pseudo-second-order kinetic model while the adsorption equilibrium can be fitted by Freundlich model. The mechanism of adsorption may include electrostatic attraction, complexation, π-π stacking, etc. To initiate Fenton-like heterogeneous catalytic degradation, KPS was added to the adsorption system to degrade and remove TC from solution. The experimental results showed that HCNTs/MnFe2O4 as a catalyst could achieve up to 89 % degradation of TC in the range of pH=3–8 due to its ability to generate active species such as ‧OH, SO4‧-, ‧O2- and 1O2 as confirmed from radical capturing experiments and EPR analysis. The removal efficiency after three adsorption regeneration or degradation cycles could reach up to 56 %, confirming its good reusability properties. There are good prospects of HCNTs/MnFe2O4 for the practical removal of antibiotics from aqueous solutions.

Interplay of adsorptive properties and dielectric reactivity of graphenes upon edge functionalization

Graphenes have unique physicochemical properties that can be engineered for pollutant adsorption and their dielectric properties can facilitate subsequent microwave regeneration. First, graphenes have the potential for high-level control of oxygen content at the edges of the material without compromising the conjugated electronic structure of the basal plane. Because the basal plane contains lightly functionalized sp2-hybridized carbon atoms while sp3-hybridized ones are on the periphery of the sheets. Edges of graphenes can be oxidized while the basal plane can still be electronically stable with conjugated π-electrons perpendicular to the graphene lattice. For this, graphenes can be oxidized to attain controlled dispersion in water without disrupting the conjugated electron network on the basal plane, which is critical for pollutant adsorption. Graphenes have sheet-like surfaces that form dynamic, porous aggregates in water and can facilitate synthetic organic compound adsorption by the complex interplay of ‘pore’ accessibility and favorable intermolecular interactions. Thus, studying the role of oxidation of graphenes can help unravel the interplay between inter-sheet distance and the adsorption of synthetic organic compounds. Second, the sp2 hybridized basal planes of graphenes have mobile π-electrons that are expedient for rapid dielectric heating, which can be harvested for rapid and efficient microwave regeneration. Fundamental research on graphene chemistry can lead to a paradigm shift in the water treatment industry towards the safe and sustainable deployment of regenerable nano-scale adsorbents. This article presents a perspective on how to approach edge functionalization of graphene with an aspiration to advance their safe and sustainable use in water treatment.

Experimental PSA reactor for methanol-enhanced production VIA CO2 hydrogenation

Methanol synthesis via catalytic CO2 hydrogenation has emerged as one of the main ways to valorize CO2. The main problem is that the methanol synthesis reaction is thermodynamically controlled, and there is a parallel endothermic reaction, reverse water gas shift (RWGS), so low methanol production ratios are achieved.In this scenario, process intensification, particularly multifunctional reactors where reaction and separation occur simultaneously, is of great interest. Sorption-enhanced reaction processes (SERP) technologies are widely used in equilibrium-controlled processes to increase reagent conversion through selective product removal.Various authors have proposed SERP processes for CO2 hydrogenation to methanol, but most of them are simulations studies and it is difficult to find experimental data. The aim of the work is the experimental study of the CO2 conversion and selectivity to methanol of a SERP process based on a four-step PSA reactor. The process has been carried out with a commercial Cu/ZnO/Al2O3 catalyst and commercial 3A zeolite as adsorbent.Conversions beyond the equilibrium have been achieved in the SERP process, even complete conversion of CO2 at 50 bar, 250 °C, and 300 °C. In the cyclic process, high CO2 conversions far from equilibrium are achieved in all the range of temperatures, 200–300 °C. The best results of methanol yield are achieved at 250 °C and 50 bar, followed closely by 200 °C. It is worth mentioning that methane is detected in the transitory state at 300 °C and 50 bar. Also, the purge step has been studied, concluding that it is necessary for adsorbent regeneration, improving CO2 conversion in the cyclic steady state.

Study on the adsorption of Ce(III) on phosphonic acid functionalized ZIF-67@SiO2 magnetic porous carbon materials

A ZIF-67 composite SiO2 material (ZIF-67@SiO2) was synthesized using ethyl orthosilicate (TEOS) as a silicon source, followed by one-step carbonization to produce magnetic porous nitrogen-doped carbon material (MNPC@SiO2) using ZIF-67@SiO2 as a carbon precursor. Subsequently, the composite P-MNPC@SiO2 was obtained through functionalization with diethylphosphonoethyltriethoxysilane (DPTS), and its characteristics were analyzed. The adsorption properties of Ce(III) on MNPC@SiO2 and P-MNPC@SiO2 composites were investigated under various conditions through adsorption experiments. Kinetic, isothermal, and thermodynamic models were employed to analyze the adsorption mechanism of P-MNPC@SiO2 on Ce3+ and assess adsorbent stability and regeneration performance. The result shows that P-MNPC@SiO2 exhibited excellent adsorption capacity for Ce3+ and possessed magnetic properties conducive to recycling. Under optimized conditions, P-MNPC@SiO2 reached Ce(III) adsorption saturation within 20 min, with a maximum adsorption capacity of 342.52 mg/g, which was 1.9 times higher than that of the MNPC@SiO2 material. Data fitting shows that surface adsorption controls the rate-limiting step, and Ce(III) forms a monolayer adsorption on the surface of the adsorbent material. Furthermore, P-MNPC@SiO2 exhibits strong stability and regeneration properties.

Reusable adsorbent of magnetite in mesoporous carbon for antibiotic removal.

This study aims to evaluate the feasibility of an innovative reusable adsorbent through adsorption-degradation sequence for antibiotic removal from water. The magnetite/mesoporous carbon adsorbent was prepared using a two-step method of (i) in situ impregnation of magnetite precursor during resorcinol formaldehyde polymerization and (ii) pyrolysis at elevated temperature (800 °C). XRD spectra confirmed that magnetite (Fe3O4) was the only iron oxide species present in the adsorbent, and thermogravimetric analysis revealed that its content was 10 wt%. Nitrogen sorption analysis showed that Fe3O4/carbon features a high fraction of mesopores (> 80 vol.%) and a remarkable specific surface area value (246 m2g-1), outstanding properties for water treatment. The performance of the adsorbent was examined in the uptake of three relevant antibiotics. The maximum adsorption uptakes were ca. 76mgg-1, ca. 70mgg-1, and ca. 44mgg-1 for metronidazole, sulfamethoxazole, and ciprofloxacin, respectively. All adsorption curves were successfully fitted with Langmuir equilibrium model. The regeneration of adsorbent was carried out using Fenton oxidation under ambient conditions. After three consecutive runs of adsorption-regeneration, Fe3O4/carbon maintained its performance almost unchanged (up to 95% of its adsorption capacity), which highlights the high reusability of the adsorbent.

Machine learning approaches to predict adsorption performance of sugarcane derived-carbon dot −based composite in the removal of dyes

This study presents a sustainable and low-cost approach to uniformly blend nanofillers (TiO2) and CDs) into chitosan polymer matrices, aiming to enhance the adsorption capacity and regeneration efficiency of the composite. The effect of degree of deacetylation on the composite was examined using crosslinkers EDA and ECH, achieving a DD of 78.8 % and demonstrating improved chemical and thermal stability compared to chitosan alone. Furthermore, SEM, TEM, and EDX mapping confirmed successful dispersion of nanofillers within the crosslinked chitosan matrix, with excellent adsorption performance towards cationic and anionic dyes (1666.67 mg/g and 1630 mg/g, respectively). The study also presents a novel approach that employs machine learning techniques to accurately predict optimization results. This study combines experiments and AI techniques using Python and machine learning algorithms on a dataset of over 600 experiments, achieving high forecast accuracy with the Random Forest model, evidenced by an R2 value of 1 and the lowest mean squared error for both dyes. The adsorption process followed Freundlich and the pseudo-second-order model. The statistical physical model explained a mixed orientation of anionic dye molecules and a multi-molecular mechanism of cationic dye molecules over nanocomposite, with FTIR results indicating electrostatic attraction, π-π interaction, and hydrogen bonding as key factors in the adsorption process. The composite material used in the study showed a consistent ability to adsorb dyes over 5 regeneration cycles in the column adsorption study, indicating its reusability. The results of this comprehensive investigation contribute to advancing sustainable wastewater treatment through the development of innovative nanocomposites and the use of sophisticated modelling techniques.

Efficient wastewater decontamination using magnetic bentonite-alginate beads: A comprehensive study of adsorption dynamics, regeneration, and molecular interactions

This study enhances wastewater treatment methodologies by developing magnetic bentonite-alginate beads (MBent-A beads) for adsorbing methylene blue (MB) from aqueous solutions. Experimental and computational analyses were employed to evaluate the beads' adsorption efficiency, utilizing characterization techniques including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), point of zero charge (pHpzc), Brunauer-Emmett-Teller method (BET), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) to examine the composite’s morphology and chemistry. Findings reveal a significant adsorption capacity with the beads' specific surface area at 3.94 m2/g and a maximum adsorption capacity of 774.32 mg/g. Adsorption kinetics adhered closely to the pseudo-second-order model, indicating a rapid adsorption process, while Langmuir isotherm analysis confirmed a uniform monolayer adsorption and temperature-dependent capacities. Thermodynamic analysis showed the adsorption process to be spontaneous and exothermic, reflecting a strong affinity between MB molecules and the bead surface. The beads demonstrated durability with more than 90% removal efficiency after five regeneration cycles, highlighting a minimal decrease from 98.54% to 90.60%. In-depth theoretical investigations using density functional theory (DFT), frontier molecular orbital (FMO), reduced density gradient (RDG), and quantum theory of atoms in molecules (QTAIM) analyses identified van der Waals forces and hydrogen bonding as primary interactions driving the adsorption. The synthesis of MBent-A beads and their confirmed efficacy in dye adsorption integrates experimental research with theoretical modeling, offering a robust solution for treating dye-contaminated wastewater and underlining the potential of MBent-A beads in environmental remediation.

Green and sustainable degradation of ofloxacin in Fe3O4/clinoptilolite electro-Fenton system under neutral condition

BackgroundIn order to overcome the drawbacks of the pH value adjustment and Fe2+addition of traditional electro-Fenton in refractory organic wastewater treatment, we set up an electro-Fence system (FCC-EF) with multiple functions of adsorption, catalysis, and green regeneration for efficient and green degradation of ofloxacin (OFLO) wastewater under neutral condition. MethodsThe Fe3O4/clinoptilolite catalyst with adsorption function was prepared by hydrothermal synthesis method, and then characterized by energy dispersive spectrometer (EDS), transmission electron microscopy (TEM) and X-ray Diffractometer (XRD). The Fe3O4/clinoptilolite's chemical composition and oxidation state was investigated by X-ray photoelectron spectros (XPS). The degradation of OFLO and the total organic carbon (TOC) were determined through HPLC and a TOC analyzer, respectively. FindingsThe results indicate that in multi-cycle operation under current density of 6 mA·cm−2 and pH = 7, FCC-EF has a 100 % removal rate for OFLO and 80.4 ± 0.2 % removal rate for TOC at 165 min, while no iron ions are detected. The internal cycling of Fe3+/Fe2+ within Fe3O4 crystals is performed in FCC-EF. The green regeneration of Fe3O4/clinoptilolite and the efficient degradation of OFLO in multi-cycle operation could be simultaneously achieved under neutral condition.

Enhanced adsorption of toluene on thermally activated ZIF-67: Characterization, performance, and modeling insights

The zeolitic imidazolate framework-67 (ZIF-67) has been explored for the dynamic adsorption of toluene vapor. We synthesized ZIF-67 through a straightforward room-temperature process and characterized it using XRD, FT-IR, DLS, and SEM techniques. The synthesized ZIF-67 possessed a Brunauer–Emmett–Teller (BET) surface area of 1578.7 m2/g and 0.76 μm particle size. Thermal activation under various conditions revealed that ZIF-67, activated in dry air at 250 °C, demonstrated optimal adsorption efficacy. Its adsorption capacity, time of breakthrough, and time of equilibration were 414.5 mg/g, 420 min, and 795 min, respectively. We investigated the impact of diverse operational parameters on adsorption through breakthrough curve analysis. An increase in the toluene concentration from 100 to 1000 ppm enhanced the adsorption capacity from 171 to 414 mg/g, while breakthrough time decreased from 1260 min to 462 min, respectively.Our findings show that increasing relative humidity from 0 to 70 % reduced 53.7 % in adsorption capacity and 46.3 % in breakthrough time. The competitive adsorption of toluene and ethylbenzene revealed that ZIF-67 had a higher selectivity for toluene adsorption. A 98 % adsorbent's regeneration efficiency at the first cycle reveals its reusability. The experimental data were successfully fitted to the Yan, Thomas, and Yoon-Nelson models to describe the adsorption process. The statistical validation of the model parameters confirms their reliability for estimating adsorption parameters, thus facilitating the design of fixed-bed adsorption columns for practical applications.

Fluoride Removal from Aqueous Solution Using Thermally Treated Dolomite Powder as Adsorbent in the Fixed Bed Column

Abstract Aim: The objective of this paper was to investigate the ability of thermally treated dolomite powder (TTDP) to remove fluoride ions from wastewater in a fixed bed column system, and to understand how different operating parameters such as bed height, initial fluoride concentration, and flow rate of influent affected the performance of the system. Materials and Methods: The researchers used several different models to analyze the data collected from the column experiments, and they also characterized the TDP adsorbent using field emission scanning electron microscopy and X-ray diffraction in order to understand its surface morphology. Results: Adsorption capacity increased with the initial fluoride concentration and decreased with bed height. Saturation concentration increases with an initial concentration of fluoride and decreases with bed height and flow rate of influent. Error analysis between experimental results and model results has been done using different predefined error functions. Regeneration of TDP adsorbent is done using a 1N NaOH solution. Conclusions: The breakthrough time increases with a low flow rate of 15 ml/min, low influent concentration of 5 ppm, and higher bed depth of 20 cm. The experimental data from the fixed bed column for fluoride removal are well fitted with all classic models, and the coefficient of regression is close to unity. Regeneration studies have shown that the adsorbent (TTDP) can undergo three cycles of regeneration.

Effective microwave regeneration of natural sepiolite and montmorillonite as adsorbents for tetracycline removal and mechanism insight

Natural clay minerals such as sepiolite (Sep) and montmorillonite (Mt) are used as low-cost adsorbents to remove tetracycline (TC) in water, and the spent adsorbents saturated with TC are regenerated under microwave (MW) irradiation. The adsorption and regeneration properties of Sep and Mt are compared. The possible adsorption and MW regeneration mechanisms are proposed. The results show that 11.25 mg·g−1 and 20.74 mg·g−1 adsorption capacities of Sep and Mt are obtained, respectively, within 120.0 min at 298 K. Mt has higher adsorption capacity, faster adsorption rate and shorter adsorption time for TC than that of Sep. The adsorption processes using Sep and Mt are well-fitted to pseudo-second-order kinetics and Langmuir models. The two adsorption reactions are spontaneous and endothermic, with increased randomness at solid–liquid interfaces. Moreover, 89.76 % and 114.45 % maximum regeneration ratios are obtained for Sep and Mt, respectively. Mt exhibits superior regeneration performance than Sep. After eight adsorption-regeneration cycles, the two adsorbents can maintain excellent adsorption and regeneration performance. This work provides new perspectives on the adsorption technology using natural clay minerals to remove antibiotics and the MW regeneration technology to regenerate spent natural clay minerals saturated with organic pollutants in organic wastewater treatment.

Adsorption performance of sulfur-decorated polyamidoamine dendrimers/silica for Ag(I) and Cu(II)

Water pollution aroused by heavy metal poses great damage to environmental safety. Polyamidoamine (PAMAM) dendrimers display great advantages in preparation efficient adsorbents to decontaminate heavy metal ions. Herein, sulfur-decorated PAMAM dendrimers/silica (G0-MT, G1-MT and G2-MT) were constructed by using alkoxysilyl-containing PAMAM dendrimers as precursor. G0-MT, G1-MT and G2-MT were employed for removing Ag(I) and Cu(II) from water solution. The adsorption capacity for Ag(I) and Cu(II) follows the order of G0-MT < G2-MT < G1-MT and G0-MT < G1-MT < G2-MT, respectively. The maximum adsorption capacity of the composites for Ag(I) and Cu(II) are 1.38 and 0.78 mmol g−1, which are superior to the corresponding adsorbents that synthesized by chemical modification method. Adsorption kinetic indicates the saturated adsorption for Ag(I) and Cu(II) can be reached at 150 and 270 min. The adsorption for the ions could be boosted by raising metal ion concentration and adsorption temperature. Adsorption mechanism demonstrates S atoms dominate the adsorption, while O and N atoms participate in the adsorption. The noticeable adsorption capacity and regeneration property enable the composites to be promising candidate for efficient removing aqueous Ag(I) and Cu(II).

Simple synthesis of acyl coupling conjugated microporous polymers monolithic material for synergistic capture of PM and CO2 in flue gas and process simulation

Adsorption and separation technologies based on physical adsorbents have the advantages of simple operation, low heat of adsorption and easy regeneration. They have received much attention for the capture of CO2 and PM from flue gases. However, the inherent “trade-off” between adsorption capacity and adsorption selectivity, as well as the high gas permeation resistance after powder processing and shaping, severely limit the prospects for industrial applications. Here, acyl functional groups were strategically introduced into polymer frameworks to successfully synthesize monolithic adsorbents (AC-CMPs) with a hierarchical pore structure for PM capture and CO2/N2 selective adsorption. The three-dimensional network structure composed of aligned hollow nanotubes effectively enhances the dispersion and mass transfer of gas flow per unit volume. Based on the porous media, multiphase flow model and discrete phase model, the gas flow process of PM trapped by AC-CMPs was simulated using Fluent. The simulation dynamically revealed the relationship between permeability resistance and filtration efficiency. The highly delocalized π-π conjugated porous skeleton linked by continuous covalent bonds endowed AC-CMPs with good stability, which prevented them from degrading in humid and high-temperature environments, thus keeping the adsorption capacity unchanged. The high polarity environment generated by the open oxygen atoms within the AC-CMPs framework, along with a high micro/mesopore ratio, enable it to achieve a CO2 adsorption capacity of 2.07 mmol/g at 273 K and 1 bar. Ideal adsorption solution theory calculations (IAST) and CO2/N2 column breakthrough experiments confirmed the excellent CO2 selectivity of AC-CMPs under realistic carbon capture conditions.

Ti3C2Tx MXene-assisted solar-driven CO2 adsorption and photothermal regeneration over mesoporous SiO2

Due to the high energy consumption associated with regenerating adsorbents with high carbon dioxide adsorption capacity, utilizing renewable solar energy as an alternative to traditional thermal energy for photothermally regenerating adsorbents is a feasible approach. In this research, a solar-induced regeneration technique has been formulated, employing fumed silica as the framework, MXene as the photothermal conversion component, and (3-aminopropyl)triethoxysilane (APTES) as the site for carbon dioxide adsorption. The findings suggest that incorporating MXene can substantially enhance the photoresponsive and photothermal conversion properties of aminosilica. Beneath an brightening concentrated of 1 kW·m−2, aminosilica@MXene(7 wt%) reaches a maximum temperature of 76.8 °C, compared to only 53.4 °C when using aminosilica alone. Notably, aminosilica@MXene (7 wt%) achieves complete desorption at an illumination intensity of 2 kW·m−2. Through multiple cycling tests, aminosilica@MXene (7 wt%) demonstrates outstanding recyclability. As a result, using solar energy to power the adsorbent photothermal regeneration turns into a useful strategy for lowering the energy required for regeneration.

A novel g-C3N4-SH@konjac glucomannan composite aerogel for patulin removal from apple juice and its photocatalytic regeneration

Patulin (PAT) is a hazardous mycotoxin frequently occurs in fruit industry. A reusable g-C3N4-SH@KG composite aerogel for PAT removal in a novel “dark adsorption-light regeneration” mode was prepared by thiol(-SH) functionalization and konjac glucomannan (KG) immobilization. The g-C3N4-SH@KG was characterized by SEM, FT-IR, XPS and UV–Vis DRS, and its PAT adsorption and photocatalytic regeneration behaviors and mechanisms were investigated. The g-C3N4-SH@KG exhibited good regeneration performance, maintaining 83% of PAT initial adsorption capacity (0.92 mg/g) after 5 “adsorption-regeneration” cycles. The adsorption process was endothermic and spontaneous. •OH and h+ generated by photocatalysis were the main substances that degraded PAT into two products and regenerated -SH. The g-C3N4-SH@KG could effectively remove PAT without negative impact on juice quality. The study provided a new strategy for the regeneration of thiol-functionalized PAT adsorbents, and a new idea for the application of non-selective photocatalysis in the control of food contaminations.

Adsorption Mechanism and Regeneration Performance of Calcined Zeolites for Hydrogen Sulfide and Its Application.

Hydrogen sulfide (H2S) is a very toxic, acidic, and odorous gas. In this study, a calcined zeolite was used to investigate the adsorption performance of H2S. Among particle size, calcination temperature and time calcination temperature and time had significant effects on the adsorption capacity of H2S on the zeolite. The optimal calcination conditions for the zeolite were 332 °C, 1.8 h, and 10-20 mm size, and the maximum adsorption capacity of H2S was approximately 6219 mg kg-1. Calcination could broaden the channels, remove the adsorbed gases and impurities on the surface of zeolites, and increase the average pore size and point of zero net charge. As the zeolite adsorbed to saturation, it could be regenerated at the temperatures between 200 and 350 °C for 0.5 h. Compared with the natural zeolite, the adsorption capacities of dimethyl disulfide, dimethyl sulfide, toluene, CH3SH, CS2, CO2, and H2S were significantly higher on the calcined zeolite, while the adsorption capacity of CH4 was lower on the calcined zeolite. A gas treatment system by a temperature swing adsorption-regeneration process on honeycomb rotors with calcined zeolites was proposed. These findings are helpful for developing techniques for removing gas pollutants such as volatile sulfur compounds and volatile organic compounds to purify biogas and to limited toxic concentrations in the working environment.

Solvent-Induced In(III)-MOFs with Controllable Interpenetration Degree Performing High-Efficiency Separation of CO2/N2 and CO2/CH4.

Herein, three In(III)-based metal-organic frameworks (In-MOFs) with different degrees of interpenetration (DOI), namely In-MOF-1, In-MOF-2, and In-MOF-3, constructed by In3+ and Y-shaped ligands 4,4',4″-s-triazine-2,4,6-triyltribenzoate (H3TATB), are successfully synthesized through the ionothermal/solvothermal method. Subsequently, three novel In-MOFs, including noninterpenetration polycatenation, 2-fold interpenetrated, and 4-fold interpenetrated structure, are employed as the platform for systematically investigating the separation efficiency of CO2/N2, CO2/CH4, and CO2/CH4/N2 mixture gas system. Among them, In-MOF-2 shows the highest CO2 uptake capacities at 298 K and simultaneously possesses the low adsorption enthalpy of CO2 (26.4 kJ/mol at low coverage), a feature desirable for low-energy-cost adsorbent regeneration. The CO2/N2 (v: v = 15/85) selectivity of In-MOF-2 reaches 37.6 (at 298 K and 1 bar), also revealing outstanding selective separation ability from flue gases and purifying natural gas, affording a unique robust separation material as it has moderate DOI and pore size. In-MOF-2 shows exceptional stability and feasibility to achieve reproducibility. Aperture adjustment makes In-MOF-2 a versatile platform for selectively capturing CO2 from flue gases or purifying natural gas.