Desorption Experiments Research Articles

The in situ green synthesis of metal organic framework (HKUST-1)/cellulose/chitosan composite aerogel (CSGA/HKUST-1) and its adsorption on tetracycline

Abstract In this work, a strategy of in situ 3D hierarchical porous HKUST-1/cellulose/chitosan (CSGA/HKUST-1) composite aerogels were synthesized using ethylene glycol diglycidyl ether (EGDE) as a cross-linking agent. The effect of EGDE on CSGA/HKUST-1 and the adsorption of tetracycline (TC) was investigated: the composite aerogel (CSGA) was produced by the ring-opening reaction of the epoxy group of EGDE in alkaline solution. The chemical structure of CSGA/HKUST-1 composite aerogel was characterized by FT-IR, XRD and XPS.49.33 % mass loading of CSGA1/HKUST-1 was achieved and N2 adsorption and desorption experiment showed the BET specific surface area reached 694.514 m2 g−1. SEM observed the CSGA/HKUST-1 composite aerogel pores were filled with a large number of octahedral HKUST-1 crystal particles. CSGA/HKUST-1 composite aerogel has excellent tetracycline adsorption capacity (285.7 mg g−1), and the removal efficiency remained at 92.7 % after five cycles of adsorption–desorption. The pseudo-second-order kinetic model and Langmuir model adsorption mechanism was successfully concluded. This study can provide ideas for in situ synthesis of MOFs on 3D composite aerogel to prepare adsorption materials, improve the mass loading rate of MOFs and prevent MOFs from falling off, etc., and enrich the application of MOFs materials in the treatment of antibiotic pollutants.

Fabrication and application of aminated metal–organic cages doped monolithic column for pipette tip micro solid-phase extraction of eight phenolic compounds in milk

A Zr-based metal–organic tetrahedron (ZrT-1-NH2) doped monolithic column was sythesized and applied for pipette tip micro solid-phase extraction (PT-μSPE) of 8 phenolic compounds. Scanning electron microscopy, energy dispersive spectrometry, Fourier transform infrared spectroscopy, thermogravimetric analysis and N2 adsorption and desorption experiment were employed to characterize the morphology, composition, structure and thermal stability of the monolithic column. The experimental results showed that the monolithic column had good stability and excellent adsorption selectivity for phenolic compounds. The adsorption mechanism was speculated to be π-π stacking and H-bond interaction based on ESP maps. After the extraction conditions were optimized, a PT-μSPE-high performance liquid chromatography-ultraviolet detector (HPLC-UV) method was established for the detection of 8 phenolic compounds in milk. The PT-μSPE-HPLC-UV method has wide linearities (0.3–1000 μg L−1) (R2 > 0.997), low limits of detection (0.1–0.3 μg L−1), satisfactory recoveries (80.5–113.6 %) and high precision (RSDs < 6.7 %). Thus, the ZrT-1-NH2 doped monolithic column is an ideal medium for the separation and determinaton of phenolic compounds in milk.

Identification of cadmium-tolerant plant growth-promoting rhizobacteria and characterization of its Cd-biosorption and strengthening effect on phytoremediation: Development of a new amphibious-biocleaner for Cd-contaminated site

The use of plant growth-promoting rhizobacteria (PGPR) in decontaminating cadmium-contaminated soil and water is a sustainable and eco-friendly approach. This study aimed to isolate a PGPR strain from the rhizosphere soil of Solanum nigrum and evaluate its potential and mechanisms in remediating Cd-contaminated environments. The results showed that the isolated strain, Klebsiella sp. AW2, can tolerate 240 mg/L Cd2+. Batch biosorption experiments indicated that the optimal conditions for PGPR biosorption were a pH of 5.0, a biosorbent dosage of 1.0 g/L, and a Cd2+ concentration of 10 mg/L, resulting in a biosorption rate of 40.99%. Model fitting results revealed that the Cd biosorption process followed a uniform surface monolayer chemisorption mechanism, likely involving complexation with functional groups such as -NH, -OH, and -C=O, according to Fourier transform infrared spectrometer and desorption experiments. Furthermore, pot experiments demonstrated that PGPR application significantly enhanced the phytoremediation efficiency of Cd-contaminated soil, increasing the phytoextraction ratio by 32.41%. This improvement was primarily achieved by promoting S. nigrum growth and facilitating Cd horizontal transfer from rhizosphere soil to plants through influencing the rhizosphere soil physicochemical properties and Cd2+ influx in roots. In addition, the copy number of the 16S rRNA gene of the PGPR revealed that the PGPR was predominantly localized in the rhizosphere soil, directly leading to increased availability of Cd for plant uptake. Overall, these findings indicate that Klebsiella sp. AW2 is a promising biocleaner for Cd-contaminated environments and provide valuable insights into the application of biosorbents in phytoremediation efforts.

Factors contributing to phosphorus sorption reversibility from iron-desalinization treatment residue (Fe-DTR)

Phosphorus (P), a non-renewable nutrient, requires effective, innovative recycling practices, especially because of predicted future scarcity. This study focused on the adsorption-desorption of P from iron desalinization treatment residue (Fe-DTR) mixed with dairy wastewater to create an alternative fertilizer (P-Fe/O-DTR). Sequential extraction indicated that P adsorption onto Fe-DTR, at pH 3, predominantly favored adsorption onto iron oxides collected in summer (72 %) versus winter (59 %), due to the elevated use of FeCl3 coagulant in summer in the desalinization pre-treatment. Desorption experiments indicated that the irreversibility of sorption (apparent hysteresis index) was highest under aerobic conditions, using a synthetic P solution, ambient temperature and pH range of 7–3 (98.9–98.3 %). Irreversibility was lowest under anaerobic conditions, using dairy wastewater as a P source, at pH 7 and 40 °C (76.6 %). This suggests that loading settings of organic solution as a P source and high temperature at the sorption stage are favored for extracting P from P-Fe/O-DTR with the greatest potential for release and reuse. Desorption experiments of 3 d, 1 week and 9 weeks indicated that the initial equilibrium forms within 72 h, but resorption and precipitation processes establish a new equilibrium over time (week). Phosphorus desorption was strongly affected by the aeration conditions of the experiment followed by the size of the sorbed reservoir and the nature of the solution (wastewaters versus synthetic solution). Under anaerobic conditions, temperature exerted a high influence on the sorbed P available for desorption.

Modeling of an adsorption study of a synthesized hematite composite for the removal of lead and cadmium from contaminated water

The use of enormous nanomaterials with enhanced functionality, and improved structural morphology is thought of this era for water pollution treatment. Loaded nanomaterials using different low-cost and wasted biomass could be synthesized for efficient functional properties. .Nanostructures with different structures and morphology have been prepared with efficiency to handle single and multi-component aqueous solutions. Iron oxide-loaded rice husk biochar, named hematite nanomaterial (HLRHBC) was used for lead and cadmium removal and its surface removal capacity was compared with raw rice husk (RH) and rice husk biochar (RHBC) adsorbents. Biochar was obtained by pre-pyrolysis at 400-500 °C and nanocomposite was then prepared by loading on biochar surface. The 89.45% removal efficiency was obtained for lead remediation by nanomaterial and 89.3%, and 88.3% by rice husk biochar and raw form of rice husk respectively. For cadmium adsorption 73.4%, 70.6% and 54.76% were removal efficiency for nanomaterials, rice husk biochar, and rice husk respectively. Isothermal calculations were applied to experimental data and it revealed favorable adsorption results by Freundlich, Dubinin–Radushkevich, and Temkin isotherms as indicated by their R 2 values approaching near 1, efficient adsorption capacity values and constant calculations within favorable approach revealed nanomaterial suitable for adsorption purposes. Error analysis favored nanomaterial adsorption results by limiting value to small error results. Kinetic calculations revealed maximum Qe (mg/g) value 22.57 ± 0.013 mg/g in case of lead adsorption and 22.93 ± 0.013 mg/g for cadmium adsorption HLRHBC. Kinetic and thermodynamic calculations proved spontaneous physicochemical sorption experiments. Desorption experiments separated metal and adsorbent for recovery and reuse of nanomaterial. Hematite biomass composite was found efficient and novel sorbent for lead and cadmium uptake and recovery.

Exploring of laccase-like nanozyme and membrane filters for efficient removal of tetracycline hydrochloride

Laccase is utilized as green catalyst in the environmental catalysis. Nevertheless, the drawbacks such as poor stability and difficulty in recycling have seriously restricted its application. Here, we simulated the binding pocket and catalytic active site of nature laccase, and designed a laccase-mimicking nanozyme (named as GA-Cu and the average diameter was 600 nm) with high activity and stability by using Cu2+ as the active center, 2-aminoimidazole as well as glutathione (GSH) as the ligand. Compared with natural laccase, the GA-Cu nanozymes showed excellent stability and reusability under extreme conditions. Furthermore, to overcome the problems of difficult recycling and easy secondary contamination, we innovatively proposed to load GA-Cu nanozymes onto nylon membranes (GA-Cu@CS/GA-Cu/nylon membranes) by vacuum-assisted filtration using chitosan (CS) as a binder to degrade tetracycline hydrochloride (TC) by filtration. Encouragingly, 50 mg/L of TC was almost completely removed by filtration once at 0.15 MPa pressure. The results have showed that the GA-Cu@CS/GA-Cu/nylon membrane removed TC mainly through degradation, and more than 80 % of TC was degraded through desorption experiments. Finally, some degradation products were identified by LC-MS and three possible degradation pathways were proposed. These findings demonstrate the potential of GA-Cu@CS/GA-Cu/nylon membrane for environmental remediation, and will be a general and important strategy for the design of membrane filters based on the excellent performance of nanozyme.

Development of an impressive method for the synthesis of α-MoO3 nanobelts as an efficient catalyst for biodiesel production.

This work presents a novel and eco-friendly technique for the first time to create α-MoO3 nanobelts (NBs) by employing a straightforward procedure with glycerol and ascorbic acid acting as green complexing and polymerizing agents, respectively. The produced α-MoO3 NBs were characterized using a range of analytical techniques, including thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The NBs were used as a catalyst in the manufacturing of biodiesel. To assess the acidity strength of the catalyst, NH3 was used in a temperature-programmed desorption (NH3-TPD) experiment. Biodiesel was effectively produced from oleic acid and ethyl alcohol by the α-MoO3 NBs. Response surface methodology (RSM) was employed in the experimental design and optimization to get the ideal circumstances. Important variables, including temperature, reaction time, catalyst dosage, reaction time, temperature, and the molar ratio of alcohol to fatty acid, were examined. The outcomes demonstrated that the biodiesel production might approach 85% at ideal temperatures of 75 °C, 50 min of reaction time, a 30:1 molar ratio of alcohol to oleic acid, and 0.007 g of catalyst. The results also showed no appreciable activity loss throughout the catalyst's efficient recovery and reuse for four cycles.

Spent coffee ground biochar for phosphate adsorption in water: Influence of pyrolysis temperature and iron-coating activation method

A substantial portion of the phosphorus utilized in crop and food production is dispersed into soil and water, posing a challenge to the management of eutrophication and sustainable nutrient recovery. This research focuses on the reclamation of phosphate from polluted water through affinitive adsorption on biochar derived from spent coffee grounds (SCG). SCG were subjected to pyrolysis within a N2-purged vertical furnace across a temperature range of 300–550 °C, with a 1-h holding time. The adsorption capability of SCG biochar was systematically investigated and experimental data were interpreted using Langmuir and Freundlich isotherm models. Notably, the biochar pyrolyzed at 450 °C and activated with a Fe/biochar mass ratio of 2:1 demonstrated the highest adsorption capacity (0.87 mg P/g biochar) when exposed to the highest initial phosphate concentration in the solution (15 mg P/L). Comparative analyses revealed that the removal efficiency of non-activated SCG biochar was considerably lower (5.7%) compared to the corresponding activated biochar (up to 17.3%). This highlights the significant increase in adsorption capacity facilitated by the introduction of ferric chloride. Furthermore, phosphate desorption experiments were conducted to assess the biochar's phosphorus release characteristics and stability. The results demonstrate the positive outcomes of upcycling SCG waste material as a pollutant sorbent and the potential to diminish reliance on chemical fertilizers through the recovery of Fe-phosphate-enriched SCG biochar.

Fine-Tuning Porous Structure of Zirconium-Based Metal-Organic Frameworks for Efficient Separation and Purification of Astaxanthin by Defect Engineering.

Efficient separation of bioactive compounds from nature source, particularly that of astaxanthin (AXT), remains challenging due to their low content in complicated matrix and readily degradable structure. Herein, a modulator-induced defect engineering is presented on the stable zirconium-based metal-organic frameworks (Zr-MOFs) to optimize pore size and pore chemistry for the efficient separation and purification of AXT for the first time. High adsorption capacity of 26.21mgg-1 is achieved on the best-performing defect Zr-MOF (d-UiO-67-4), superior over the other reported adsorbent for AXT. Meanwhile, d-UiO-67-4 exhibits the selective adsorption of AXT over other carotenoids analogues with similar structure and properties. This is attributed to the preferential non-covalent interactions between defect framework and AXT revealed by the spectroscopy analysis and density functional theory (DFT) calculations. High purity of AXT with 89.0%±2.3% extraction efficiency can be realized after the purification of AXT by d-UiO-67-4. The practical separation performance of d-UiO-67-4 for AXT extracted from Haematococcus pluvialis is demonstrated by fixed-bed column-based dynamic adsorption and desorption experiments. This work broadens the preparation methods for thermosensitive active substances and provided new research ideas for the controlled adsorption of functional food factors.

Initial Desorption Characteristics of Gas in Tectonic Coal Under Vibration and Its Impact on Coal and Gas Outbursts

The rapid desorption of gas in coal is an important cause of gas over-limit and outbursts. In order to explain the causes of coal and gas outbursts induced by vibration, this paper studies the gas desorption experiments of tectonic coal with different particle sizes and different adsorption equilibrium pressures under 0~50 Hz vibration. High-pressure mercury intrusion experiments were used to measure the changes in pore volume and specific surface area of tectonic coal before and after vibration, revealing the control of pore structure changes on the initial desorption capacity of gas. Additionally, from the perspective of energy transformation during coal and gas outbursts, the effect of vibration on the process of coal and gas outbursts in tectonic coal was analyzed. The results showed that tectonic coal has strong initial desorption capacity, desorbing 29.58% to 54.51% of the ultimate desorption volume within 10 min. Vibration with frequencies of 0~50 Hz increased both the gas desorption ratios and desorption volume as the frequency increased. The initial desorption rate also increased with the vibration frequency, and vibration can enhance the initial desorption capacity of tectonic coal and delay the attenuation of desorption rate. Vibration affected the changes in the initial gas desorption rate and desorption rate attenuation coefficient by increasing the pore volume and specific surface area, with the changes in macropores and mesopores primarily affecting the initial desorption rate and 0~10 min desorption ratios, while the changes in micropores and minipores mainly influenced the attenuation rate of the desorption rate. Vibration increased the free gas expansion energy of tectonic coal as the frequency increased. During the incubation and triggering processes of coal and gas outbursts, vibration has been observed to accelerate the fragmentation and destabilisation of the coal body, while simultaneously increasing the gas expansion energy to a point where it reaches the threshold energy necessary for coal transportation, thus inducing and triggering the coal and gas protrusion. The study results elucidate, from an energy perspective, the underlying mechanisms that facilitate the occurrence of coal and gas outbursts, providing theoretical guidance for coal and gas outburst prevention and mine safety production.

Removal of Phosphate from Water by Iron/Calcium Oxide-Modified Biochar: Removal Mechanisms and Adsorption Modeling

Phosphorus (P) pollution is a leading cause of water eutrophication, and metal-modified biochar is an effective adsorbent with the ability to alter the migration capacity of phosphorus. This study uses bamboo as the raw material to prepare metal-modified biochar (ZFCO-BC) loaded with Fe and Ca under N2 conditions at 900 °C, and investigates its adsorption characteristics for phosphate. Batch experimental results show the adsorption capacity of the ZFCO-BC gradually increases (from 4.0 to 69.1 mg/g) as the initial phosphate concentration increases (from 2 to 900 mg/L), mainly through multilayer adsorption. Additionally, as the pH increases from 1 to 7, the adsorption capacity of the ZFCO-BC climbs to reach its maximum value of 48.4 mg/g with an initial phosphate concentration of 150 mg/L. At this pH, phosphate primarily exists as H2PO4− and HPO42−, which both readily react with Fe3+ and Ca2+ in the biochar. Furthermore, the addition of CO32−, HCO3−, NO3−, SO42−, F−, and Cl− each affect the removal rate of phosphate by less than 10%, indicating the ZFCO-BC has a highly efficient and selective phosphate adsorption capacity. A multi-column adsorption experiment designed to achieve long-term and efficient phosphorus removal treated 275.5 pore volumes (PVs) of water over 366 h. The cyclic adsorption–desorption experiment results show that 0.5 M NaOH can effectively leach phosphate from the ZFCO-BC. Observations at the molecular level from P K-edge XANES spectra confirm the removal of low-concentration phosphate is primarily dominated by electrostatic attraction, while the main removal mechanism for high-concentration phosphate is chemical precipitation. This study demonstrates that ZFCO-BC has broad application prospects for phosphate removal from wastewater and as a potential slow-release fertilizer in agriculture.

Phosphorus Availability from Rock Phosphates and Adsorption-Desorption Phenomenon in Red and Alluvial Soil as Affected by Phosphorus Solubilizing Bacteria (PSB), FYM and Vermicompost Application

ABSTRACT Phosphorus (P) is typically fixed in red soils (as Fe-P and Al-P). P release from different sources i.e. Rock-phosphate (RP), Farm Yard Manure (FYM), and Vermicompost (VC) is mainly governed either by adsorption, desorption, fixation, or ligand exchange. The present study was undertaken using phosphorus solubilizers Burkholdaria cariabensis (PSB1) and B. cepacia (PSB2), inorganic sources Udaipur Rock-phosphate (RP1) and Purulia Rock-phosphate (PR2) and organic sources (FYM and VC) applied in red and alluvial soils. Results showed that pH statistically on par and available P content were significantly varied in both soil type under laboratory incubation experiment at 15, 30, 45, and 60 days intervals. P adsorption and desorption experiments were also carried out taking heavy suspension of two P-solubilizers. Results showed that higher soluble P was recorded in FYM amended soils (T8, T9, T10 and T11) over the VC treated soils (T12, T13, T14 and T15) in both soils. Data showed that the RP1 have higher (34.00%) total P concentration as compared to RP2 (10.87%). Meanwhile, it was observed that higher P adsorption observed in red soils as compared to alluvial soils and vice-versa in case of desorption maxima, similarly higher P adsorption in PSB1 as compared to PSB2. A quantitative and qualitative study on organic acid secretions by Burkholdaria cariabensis and Burkholdaria cepacia needs to be carried out in the future.

Highly efficient recovery of gold by thermally modified pyrite and its mechanism

Gold recovery from wastewater should be cost-effective, efficient, and environmentally friendly. In this study, adsorbents containing Fe(II,III) systems were prepared via thermal modification of pyrite. The effects of thermal modification temperature, the source of pyrite, pH, ionic strength, adsorbent solid–liquid ratio, and coexisting metal ions on adsorption were investigated. Further, the removability of iron ions was explored, and multiple adsorption–desorption experiments were conducted to verify the stability and recyclability of the adsorbent. The adsorption law and mechanisms were analyzed using adsorption isotherms, thermodynamics, kinetics, and spectroscopy. The results revealed that the natural pyrite modified at 300°C ( N-Py-300) was a more suitable gold adsorbent with a maximum adsorption of 1055.2 mg/g at 25 °C. When coexisting with other metal ions, N-Py-300 exhibited highly selective adsorption of Au(III). Using a mixture of 10 % thiourea and 2 % HCl as a desorbent facilitated the desorption of almost all Au from N-Py-300, resulting in the recovery of Au and the reuse of N-Py-300. The Fe ions released from the adsorbent were effectively reduced by the addition of Ca(OH)2. The adsorption kinetics and isotherm data were in strong agreement with the pseudo-secondary and Langmuir models, indicating that Au(III) was chemisorbed on N-Py-300 as a monolayer and that Au(III) was reduced to Au(0) and Au(Ⅰ). The pH and IS also affected the adsorption behavior, implying that an electrostatic effect exists. Our findings provide that the thermally modified pyrite can be used to recover precious metals from wastewater efficiently, and provides an experimental basis for the resourceful use of pyrite.

Influence of flue gas components on SO2 adsorption by activated carbon at low temperature

Activated carbon can adsorb SO2 in flue gas, whose performance is significantly enhanced when lowering the adsorption temperature; however, the characteristics and mechanism of SO2 adsorption under the action of complex flue gas components at low temperatures remain unclear. In this study, adsorption experiments were conducted to investigate the characteristics of SO2 adsorption on activated carbon and the impact of O2, H2O, and NO within −20 to 20 °C. The saturated adsorption of SO2 showed a 2.21-fold increase when the temperature was lowered from 20 °C to −20 °C. Within this temperature range, physical adsorption was dominant, accounting for 73.7–91.0 %. O2 and H2O inhibited the physical adsorption of SO2 and promoted its chemical adsorption. As the temperature was lowered, the promoting effect of O2 increased, while the influence of H2O shifted from promotion to inhibition. NO affects SO2 adsorption only when co-existing with O2. As the temperature decreased, the promoting effect of NO on both physical and chemical adsorption strengthened and was significantly higher than that of O2 and H2O. Based on desorption experiments and quantum chemical calculations, the mechanisms by which H2O and NO affect SO2 adsorption were proposed·H2O and SO2 share the same physical adsorption sites, with H2O being more strongly adsorbed, thus significantly inhibiting the SO2 physical adsorption. When NO coexists with O2, gaseous SO2 reacts with the NOx adsorption configurations to form C-SO3 and C-HSO3. Active atoms near C-SO3 and C-HSO3 can adsorb NO2, forming a co-adsorption configuration, which in turn enhances the nearby physical adsorption of SO2. Enhancing the catalytic oxidation and adsorption of NO through surface modification of activated carbon can improve the low-temperature adsorption performance of SO2.

The low-cost biosorbents of Mangosteen (Garcinia mangostana Linn) doped magnesium oxide and titanium dioxide beads for eliminating methylene blue dye

Two methylene blue (MB) dye adsorbents were synthesized from mangosteen peels modified by magnesium oxide and titanium dioxide called mangosteen peel doped magnesium oxide beads (MMB) and mangosteen peel doped titanium dioxide beads (MTB) to examine which material could greater adsorb MB dye. In addition, several techniques of BET, XRD, FESEM-FIB, EDX, and FT-IR were used for their characterizations. Their MB dye removal efficiencies were investigated by batch experiments, desorption experiments, adsorption isotherms, kinetics, and thermodynamic studies. MTB had a higher specific surface area (15.24 m2/g) and smaller pore size (1.69 nm) than MMB. The results of XRD, FESEM-FIB, EDX, and FT-IR demonstrated the successful additions of magnesium oxide and titanium dioxide into MMB and MTB because they found the specific peaks, characteristic structures, elements, and functional groups of magnesium oxide and titanium dioxide in MMB and MTB. Batch experiments showed they had high MB dye removal efficiencies of more than 97 %, and they could reuse more than three cycles. Freundlich and pseudo-second-order kinetic models were good explanations for their adsorption patterns correlated to chemisorption and their mechanisms to be a chemisorption process. In addition, they were an endothermic process since their MB dye adsorptions increased with increasing temperature.

Synthesis, characterization and study of Sb(Ⅲ) adsorption from aqueous solution by iron-aluminum pillared attapulgite

In this study, a simple, environmentally friendly and inexpensive adsorbent for Sb(III) in aqueous solution was prepared by the copolymerization method using attapulgite as the matrix, FeCl3 and AlCl3 as the metal sources. The morphology and structure of iron-aluminum pillared attapulgite were analyzed through various characterization methods. The conditions and influencing factors of iron-aluminum pillared attapulgite preparation and Sb(III) adsorption were studied. The saturated adsorption capacity of Sb(III) could reach 60.44 mg·g−1 for 180 min at pH 7 and 298 K. The adsorption process is conformed to Langmuir isothermal model and pseudo-second-order kinetic model, and the thermodynamic investigation suggested a spontaneous and endothermic adsorption process. It was revealed by X-ray photoelectron spectroscopy analysis and Zeta potential analysis that Sb(III) was first electrostatically adsorbed by the adsorbent, part of Sb(III) was oxidized to Sb(V) by Fe(III) and then antimony was complexed with iron and aluminum hydroxides to form surface complexes. In addition, a small amount of antimony migrated through intra-particle diffusion into the internal micropores and reacted with hydroxyl groups. Most coexisting components under the chosen conditions had no influence on Sb(III) adsorption, and PO43−, AsO33−, C6H8O7 and H2C2O4 had a negligible effect. However, the adsorption capacity of over 90 % without interference showed that the material has a strong selectivity for Sb(III) adsorption. The findings of the desorption experiment showed that the adsorption product has a considerable degree of desorption at increased hydrochloric acid concentrations. It may be concluded that the adsorption product is more stable in the overall polluted water environment since the actual acidity of the polluted water environment is significantly lower than the desorption experiment acidity. Overall, iron-aluminum pillared attapulgite has great potential for application in removing Sb(III).

Molecule‐level Design to Form Pocket Structures for Improving Amine Efficiency in CO2 Capture

AbstractSolid amine adsorbents represent a promising class of CO2 sorbents, but their amine efficiency is limited by the inaccessibility of peripheral amines. The surface of mesocellular silica foam (MCF) is functionalized with the mixture of short‐chain 3‐Glycidyloxypropyl) triethoxysilane (GPTES) and long‐chain Octadecyltrimethoxysilane (OTMS), forming pocket structures on the support surface, thereby exposing more amine sites and enhancing the amine efficiency of polyethylenimine (PEI). The resulting adsorbent demonstrates a high CO2 adsorption capacity (5.02 mmol g−1 at 50 °C, 10 vol.% CO2, and 50%RH), high amine efficiency (0.43 at the dry condition), outstanding cyclic stability (0.5% performance decline per cycle under the conditions of dry CO2 regeneration), and fast adsorption kinetics (15 min for adsorption saturation at 50 °C). First‐principles calculations and CO2 temperature‐programmed desorption (TPD) experiments demonstrate that the introduction of GPTES and OTMS is beneficial to decreasing adsorption energy and forming paired carbamic acid states and ammonium carbamate states.

A novel hollow flower shaped Cu9S8 antibacterial agent for removing sulfonamide in water environment: effects of composite with magnetic biochar, differential adsorption, and mechanism study.

In this study, hollow nanoflower spherical Cu9S8 and Cu9S8/Fe3O4@BC with adsorption and antibacterial properties was prepared by coprecipitation and solvothermal method, respectively. The adsorption results showed that the Cu9S8 exhibited excellent adsorption performance on sulfonamide antibiotics (SAs), especially for sulfamethoxazole (SMZ). The optimal addition amount of Cu9S8 is 0.2 g, which results in a maximum adsorption capacity of 33.4 mg/g for SMZ within 120 min. The fitting results of adsorption and desorption kinetics and thermodynamics, as well as the conditions such as pH value and ionic strength were compared. It was found that different interactions led to the differential adsorption of SAs by Cu9S8. The desorption experiment further elucidated its adsorption mechanism. The large desorption capacity indicates that SAs on Cu9S8 can be further recovered and treated. The auto-deposition characteristics of Cu9S8 and the hysteresis loop of Cu9S8/Fe3O4@BC were studied to effectively recover Cu9S8 from aquatic environments. Additionally, more than 99% of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were exterminated by Cu9S8 and Cu9S8/Fe3O4@BC within 20 min. The above results suggested that the hollow nanoflower spherical Cu9S8 and Cu9S8/Fe3O4@BC composite materials can provide a new strategy for solving pollution problems and waste treatment.

Field versus laboratory measurements of PFAS sorption by soils and sediments

Sorption by soils and sediments is an important process that influences the distribution, transport, and fate of per and polyfluoroalkyl substances (PFAS) in the environment. Many laboratory studies have been conducted to quantify magnitudes of PFAS sorption as a function of the properties of the PFAS, solutions, and porous media. A critical question is how representative are laboratory-measured sorption magnitudes for field applications. To address this question, log Koc data were compiled from the literature for a range of PFAS of different chain lengths and functional groups. The aggregated field-based data consisted of two types, in-situ measurements comprising paired soil/sediment and water samples and ex-situ measurements obtained from laboratory desorption experiments employing field-contaminated media. These two sets of field-based measurements were compared to a comprehensive data set of standard laboratory batch-type measurements. The compiled data sets represent an extremely wide range of soil and sediment properties. One important novel outcome is the observation that the enhanced sorption of short-chain PFAS observed in several prior laboratory studies is also observed for the field data. This differential enhanced sorption should be accounted for in site investigations and modeling studies. Another relevant outcome is the observation of consistency between measurements obtained with standard batch adsorption experiments and those from desorption studies employing either field-contaminated or artificially-contaminated media. The mean log Koc values determined for the in-situ measured field data were generally larger than the mean laboratory-determined values, particularly for the short-chain PFAS. Notably, however, values for subsets of the laboratory data representing measurements for lower aqueous concentrations or for soils with low organic-carbon contents (<1 %) compared well to the in-situ field data. Measurements compiled for anionic-polyfluoroalkyl, neutral, and cationic PFAS compared well to those for PFCAs and PFSAs. Overall, the results indicate that the laboratory measurements of PFAS sorption were generally representative of the field-derived magnitudes when compared on a consistent basis.

Analysis of Water Adsorption Capacity, Thermal Behavior, Antioxidant Activity, and Smoke Volume by Polyol Ester in Reconstituted Tobacco.

A series of ester derivatives with hydroxyl groups were created by esterification of 1,2-propanediol and glycerol with o-toluoyl chloride via the catalyst 4-dimethylaminopyridine (DMAP). All the compounds were verified using nuclear magnetic resonance (1H NMR, 13C NMR), infrared spectroscopy, and high resolution mass spectrometry. Moisture absorption and desorption experiments were carried out on the compounds' pure systems and their systems in reconstituted tobacco, while their hygroscopicity and moisturizing properties were evaluated using low-field nuclear magnetic resonance imaging. Two compounds with better absorption and moisture retention were selected: 4 (1-hydroxypropan-2-yl 2-methylbenzoate) and 6 (2,3-dihydroxypropyl 2-methylbenzoate), respectively. Moreover, the thermal stability of compounds 4 and 6 were investigated using thermogravimetric (TG) analysis. The results of TG-DTG showed that the maximum mass loss rate of compound 4 appeared at 251.67 °C, with a mass loss rate of 87.61%. At the peak temperature of 291.83 °C, 6 showed the highest decomposition rate with 49.23% mass loss rate. To explore the antioxidant properties, we constructed three different antioxidant systems. Furthermore, compound 6 showed excellent effects, with scavenging rates reaching 69.28%, 71.92%, and 75.93%, respectively. Smoke volume results indicated that the compounds optimally replaced propanediol and glycerol at a rate of 40%. The results provide a theoretical reference for the development of new moisturizing agents based on polyol esters in the tobacco industry.