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Covalent organic frameworks (COF) is crystalline organic polymers with periodic architectures and well-defined pores, enabling various applications such as gas storage and separation, catalysis, sensor and energy storage. Crystallinity and porosity are two important properties that determine the performance of COF, and the preparation of COF with high crystallinity and specific surface area has been a key issue in the synthesis of COF. Herein, a novel methylated covalent organic framework material (COF-946) was constructed using 2,4,6-trimethyl-benzene-1,3,5-tricarbaldehyde and 2,5- dimethyl-p-phenylene diamine as building blocks. The methylation not only significantly enhances the crystallinity and porosity by preventing pore collapse, but also allows COF-946 to be prepared in a variety of solvent systems. The basic structure and properties of COF-946 were characterized using Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), nitrogen adsorption/desorption isotherms, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results show that COF-946 with high crystallinity and specific surface area can be prepared in a wide range of solvents and within a short period of time (SBET > 700 m²/g in 0.5 h). In addition, COF-946 has a high iodine vapor adsorption capacity (5.65 g/g) and adsorption rate (0.78 g/(g·h)), and can maintain more than 90% of the original adsorption capacity after five cycles. [ABSTRACT FROM AUTHOR]

Herein, poly (allylamine hydrochloride) (PAH)/ poly (styrene sulfonic acid) sodium salt (PSS) microcapsules of (PAH/PSS)2PAH (P2P MCs) and (PAH/PSS)2 (P2 MCs) were obtained by a layer-by-layer method. The P2 MCs show high adsorption capacity for Rhodamine B (642.26 mg/g) and methylene blue (909.25 mg/g), with an extremely low equilibrium adsorption time (~20 min). The P2P MCs exhibited high adsorption capacities of reactive orange K-G (ROKG) and direct yellow 5G (DY5G) which were 404.79 and 451.56 mg/g. Adsorption processes of all dyes onto microcapsules were best described by the Langmuir isotherm model and a pseudo-second-order kinetic model. In addition, the P2P MCs loaded with reactive dyes (P2P–ROKG), could further adsorb rhodamine B (RhB) dye, and P2 MCs that had adsorbed cationic MB dyes could also be used for secondary adsorption treatment of direct dye waste-water, respectively. The present work confirmed that P2P and P2 MCs were expected to become an excellent adsorbent in the water treatment industry. [ABSTRACT FROM AUTHOR]

The design and synthesis of porous framework materials with strong affinity and selectivity for uranyl ion are extremely appealing for the efficient extraction of uranium from seawater. Herein, rectangular porous framework cage(denoted as Co16) is prepared by using p-tert-butylsulfonylcalix［4］arene, CoCl2·6H2O and 1,3-bis(2H-tetrazol-5-yl)benzene (H2L) ligands under solvothermal conditions. Further, the Co16 is used for uranium extraction. As the result, the Co16 exhibits short adsorption equilibrium time(≈90 min) and is in accordance with the pseudo-second-order kinetic model. Robust framework and active U(Ⅵ) adsorption in the wide pH range are displayed. Besides, Co16 adsorbents exhibit high U(Ⅵ) uptake capacity(547.31 mg/g) and well fit the Langmuir model. Adsorption thermodynamics research has clearly demonstrated that the adsorption process is endothermic and spontaneous. Furthermore, Co16 achieves a high uranium adsorption capacity(4.88 mg/g) after immersing in real seawater for 20 days. Overall, these advantages of Co16 adsorbents highlight the potential candidate for the selective capture of U(Ⅵ) from seawater.

[Display omitted] • Amination modified Fe-BTC with high capacity and rapid adsorption was fabricated. • The maximum adsorption capacity of amination modified MOFs for arsenic was 1748.50 mg/g. • DETA-Fe-BTC showed high adsorption capacity in the arsenic concentration range of 11 ∼ 1000 mg/L. • The adsorbent has strong recycling and regeneration ability. DETA-Fe-BTC MOFs with an irregular porous structure is fabricated by a hydrothermal method combining with Diethylenetriamine (DETA) modification and investigated in batch adsorption experiments for arsenic removal from wastewater. DETA-Fe-BTC show high adsorption ability in wide pHs ranged from 2 to 12 and a wide arsenic concentration range from 1 mg/L to 1000 mg/L. The maximal arsenic adsorption capacity reaches 1748.50 mg/g at a pH of 10. Besides, the MOFs reveal a super-fast arsenic-removal rate. 90.58 % of arsenic was removed from wastewater with an initial arsenic concentration of 40 mg/L in 5 s. Arsenic adsorption kinetics and isotherms follow a chemical adsorption mode and a single-molecule adsorption mode that the MOFs offer abundant Fe3+ active cites forming Fe-O-As coordination with arsenate or arsenite. Considering its strong recyclability and high efficiency, DETA-Fe-BTC will be used as a potential arsenic scavenger for the disposal of arsenic contaminated groundwater or industrial wastewater. [ABSTRACT FROM AUTHOR]

Herein, poly (allylamine hydrochloride) (PAH)/ poly (styrene sulfonic acid) sodium salt (PSS) microcapsules of (PAH/PSS)2PAH (P2P MCs) and (PAH/PSS)2 (P2 MCs) were obtained by a layer-by-layer method. The P2 MCs show high adsorption capacity for Rhodamine B (642.26 mg/g) and methylene blue (909.25 mg/g), with an extremely low equilibrium adsorption time (~20 min). The P2P MCs exhibited high adsorption capacities of reactive orange K-G (ROKG) and direct yellow 5G (DY5G) which were 404.79 and 451.56 mg/g. Adsorption processes of all dyes onto microcapsules were best described by the Langmuir isotherm model and a pseudo-second-order kinetic model. In addition, the P2P MCs loaded with reactive dyes (P2P–ROKG), could further adsorb rhodamine B (RhB) dye, and P2 MCs that had adsorbed cationic MB dyes could also be used for secondary adsorption treatment of direct dye waste-water, respectively. The present work confirmed that P2P and P2 MCs were expected to become an excellent adsorbent in the water treatment industry.

Nanoscale metal-organic frameworks (MOFs) have appeared as potential materials in biomedical and sensing applications. In this work, a nano Zn-BDC-NH2 encoded MOF was effectively synthesized using the co-surfactants strategy and characterized for the curcumin adsorption. The analysis of the synthesized MOF by using characterization techniques, including XRD, SEM, N2 isotherm sorption, TGA, and FT-IR revealed that the nanomaterial exhibited similar structure structural and other physical properties to the original framework, but its particle size was very small of about 50 nm. As a result of the curcumin (CUR) adsorption investigation, the nanomaterial showed a high adsorption capacity on Zn-BDC-NH2 up to 179.36 mg·g−1 and faster adsorption in comparison with reported adsorbents. The results suggest that the nano Zn-BDC-NH2 MOF can be considered as a promising material for bio-applications.

The nanoporous activated carbon (AC) was prepared from the eucalyptus leaves via chemical activation with KOH, then treated with nitric acid/ /urea (NOAC) and finally used as a new adsorbent for simultaneous ultrasound- assisted removal of basic red 46 (BR46) and basic yellow 13 (BY13) dyes from binary aqueous solutions. The NOAC nano-adsorbent was characterized with SEM, TEM, Raman, BET, FTIR, CHN, pHpzc and Boehm titration analysis. Both of the AC and NOAC samples had superior BET surface area of 2222 and 1572 m2 g-1 with average micropore volume of 0.81 and 0.50 cm3 g-1, respectively. First order derivative spectrophotometric method was used for analysis of BY13 in binary mixtures. Small amount of the adsorbent (30 mg) was capable to remove high percentage of dyes (>99 %) in a very short time (8 min). The adsorption of dyes follows the Langmuir isotherm and the pseudo- -second-order kinetics. The adsorption capacities of NOAC for single solutions of BR46 and BY13 were 1111 and 1250 mg g-1 as well as for binary solutions were 769 and 909 mg g-1, respectively. The adsorption thermodynamics were also explored. Exhausted NOAC was regenerated using HCl (2 M) and reused for five adsorption-desorption cycles with high performance.

Polymer/Fe3O4 composite was synthesized via radical polymerization. Acrylamide was used as monomer and copolymerized with 1,3,5-triacryloylhexahydro-1,3,5-triazine in the presence of Fe3O4 particles. The obtained polymer was hydrolyzed by N,N,N',N'-tetramethylethylenediamine to increase ionized groups amount. Dried and powdered composite was used for removal of Cd2+, Pb2+ and Cr3+ in batch mode. Also, the synthesized composite was trapped in a cellulose acetate membrane filter. The removal occurred in 3–5 s by using a syringe filter system. 97.9% for Cd2+, 95.7% for Cr3+ and 99.8% for Pb2+ removal rates were obtained in the experiment using 2.5 ppm of Cd2+, Cr3+, Pb2+ added to tap water at pH 6. The synthesized composite was characterized by Fourier Transform Infrared. The metal ion concentrations were measured by ICP-OES. The effects of pH, interaction time, shaking speed, ambient temperature, initial metal ion concentration, and amount of composite were also investigated. The reached removal percentage was 100% for Cd2+, Cr3+, Pb2+ under optimal conditions by using 0.25 g of composite in batch mode. The used initial metal ion concentration was 2.5 mg/L. [ABSTRACT FROM AUTHOR]

The performances of two FAU-type zeolites with different SiO 2 /Al 2 O 3 ratios were evaluated for the removal of antibiotics of three different classes, namely azithromycin, ofloxacin, and sulfamethoxazole, from aqueous solutions. Commercial zeolites were used, without any previous treatment. Use of a small adsorbent dosage resulted in fast antibiotic adsorption that followed pseudo-second order kinetics. The removals of azithromycin and sulfamethoxazole were highly pH-dependent, with low removal percentages observed under acid (pH 2.5–4.5) and basic (pH 8.5–10.5) conditions, respectively. The Freundlich isotherm model provided the best fits to the adsorption data. The adsorption mechanisms appeared to involve both electrostatic and H-bonding interactions. Using an antibiotics mixture, percentage removals of azithromycin and ofloxacin onto the zeolites of up to 79% were obtained. Both materials presented good adsorption (>50%) of azithromycin and ofloxacin from a real sample of effluent wastewater. The results showed that zeolites with FAU structure can be used as effective adsorbents for the removal of antibiotics with different physicochemical properties, including molecules with large volumes, such as azithromycin. [ABSTRACT FROM AUTHOR]

Magnetic metal/carbon nano-materials are attractive for pollutant adsorption and removal. In this study, ultrafine nickel/carbon nanoparticles are successfully prepared via electrical wire explosion processing in ethanol media for the elimination of pollutant organic dyes such as Rhodamine B and methylene blue in aqueous solutions. High specific surface areas originating from both the nano-sized particles and the existence of carbon on the surface of Ni nanoparticles enhance dye adsorption capacity. In addition to this, the excellent dispersity of Ni/C nanoparticles in aqueous dye solutions leads to superior adsorption rates. The adsorption kinetics for the removal of organic dyes by Ni/C nanoparticles agree with a pseudo-second-order model and follow Freundlich adsorption isotherm behavior. [ABSTRACT FROM AUTHOR]

A novel porous adsorbent with high surface area and rigid structure was prepared by crosslinking oxidized microcrystalline cellulose particles with tetrafluoroterephthalonitrile. N adsorption-desorption measurements revealed the surface area to be 88.32 m g for the porous adsorbent, while it was only 25.74 m g for the sample crosslinked using epichlorohydrin. This porous adsorbent showed excellent performance for fast and efficient removal of low-concentration heavy metals from aqueous solution. Adsorption kinetic study demonstrated that, within 5 min, the removal efficiency for Pb, Cu, and Cd with initial concentration of 10 mg L by this adsorbent was 93.2, 87.5, and 72.3 %, respectively. Moreover, the pseudo-second-order model correlated better to the adsorption kinetic data than the pseudo-first-order model. The effects of other factors, e.g., initial solution pH, adsorption temperature, initial metal concentration, and background electrolytes, on the removal efficiency were also analyzed. Additionally, desorption experiments indicated that this adsorbent could be effectively regenerated using dilute HCl solution. [ABSTRACT FROM AUTHOR]

Antibiotics are used widely in human and veterinary medicine and are ubiquitous in environmental matrices worldwide. The influence of the concentration of antibiotics on adsorption kinetics is still unclear. This study used sulfamethoxazole (SMX) and ofloxacin (OFL) as adsorbates to investigate the adsorption kinetics on sediment affected by varying concentrations of antibiotics adsorbable species. At the experimental pH values, the major adsorbed species of SMX and OFL on sediment were SMX 0 and OFL + by hydrophobic interaction and electrostatic attraction, respectively. The apparent adsorption rate of SMX was not affected by the initial concentration and the pH values because the hydrophobic interactions were concentration-independent and charge-independent. However, the apparent adsorption rate of OFL significantly slowed down as the initial concentration increased. The adsorbed OFL + effectively neutralized the negative charges of the sediment, leading to a reduced adsorption rate of subsequent OFL + . The neutralization effect was greatly enhanced due to the increased OFL + with the increasing OFL concentration. Additionally, the apparent adsorption rate of OFL significantly increased at higher pH due to the reduced neutralization effect that resulted from the decreased OFL + and increased negative charges of the sediment surface. This study implied that the adsorption kinetics of antibiotics was greatly dominated by the concentration of adsorbable species rather than apparent overall concentration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three Ca-MOFs with specific structures were employed as precursors to obtain nano CaO through a two-step thermal transition process. • LAC MOF-derived CaO spheres with an average size of 100 nm achieved a fast adsorption capacity of 11.8 mmol g−1 after 4 cycles. • The structure transition from LAC MOF to CaO spheres was deeply investigated. Calcium looping is considered to be one of the best approaches for industrial CO 2 high-temperature capture, whereas current CaO-based sorbent suffers poor cyclic performance, especially the relations between precursor structure and CO 2 fast adsorption capacity still need to be further revealed. In this work, three calcium-based metal frameworks (Ca-MOFs) with specific structures were employed as precursors to obtain nano CaO through a two-step thermal transition process. It was found that LAC MOF-derived CaO achieved a fast adsorption capacity of 11.8 mmol g−1 (78 % of total adsorption) after 4 cycles. This was because the fiber bundle-like original LAC MOF structure changed gradually to nanosheets after 600 °C pyrolysis and finally formed regular CaO spheres with an average size of 100 nm after an 800 °C -calcination, thereby preventing further aggregation of CaO particles during the thermal transition process. In addition, the adsorption performance did not rely on pore structure, and thus pore-blocking showed little influence on the performance of CO 2 capture. Hence, high stability can be achieved simply by avoiding particle sintering. The systematic study marks the significance of precise tailoring of nano-CaO for achieving the desired performance of CO 2 fast adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu nanoporous aerogel (Cu-NPA) was synthesized for iodide removal from water. • Cu-NPA showed good antioxidant properties. • The adsorption capacity could reach as high as 1384 mg/g. • The I 2 (1200 mg/L) could be almost completely removed within 10 min. The effective capture and storage of the generated radioactive contaminant (iodine) are of great significance with the extensive use of nuclear energy. In this work, a novel Cu nanoporous aerogel (Cu-NPA) was prepared by using inorganic Cu salt as precursors. The as-prepared Cu-NPA was fully characterized in detail, and the I 2 adsorption and stability capability of Cu-NPA has been investigated in the solution. The results showed that Cu-NPA has high specific surface area and porosity. The structure of hierarchical pores is conducive to the rapid enrichment of pollutants in water. Adsorption experiments showed that Cu-NPA had ultra-high I 2 adsorption capacity (1384 mg/g) and fast equilibrium adsorption time (10 min). The I 2 in the solution (c < 1200 mg/g) can be almost completely removed. In addition, Cu-NPA exhibits good stability in the air and can be exposed to air for a long time. In general, our work demonstrated the preparation of Cu-NPA and its great potential in the field of rapidly eliminating radioactive I 2. [ABSTRACT FROM AUTHOR]

In order to improve the adsorption speed of iodine from water, MIL-101 with extra-large specific surface area (3054 m 2 /g) was chosen as a base material, and then, Ag was doped into MIL-101 to enhance its adsorption capacity through an incipient-wetness impregnation method. With the characterization of SEM-EDS, TEM, XRD, XPS, TGA, IR, and BET techniques, the resulting Ag was identified to be stay in the framework of MIL-101 stably in the form of Ag II (generally, Ag II cation is not stable). However, after the adsorption of I − anions, Ag II stay in the cages of MIL-101 in the form of AgI/AgI 3 . It is important to note that, all adsorbents show high adsorption speed of iodine in solution. The equilibrium adsorption time of the adsorbents were acquired by only a few minutes, which can be attributed to its large BET surface area. An interesting note is that, when the doping amount of Ag is less than 9%, the iodine anions adsorption capacity of Ag@MIL-101 is greater than its theoretical adsorption capacity. It shows that both physical adsorption and chemical adsorption are existed in the adsorption process. This study hopefully leads to a new and highly efficient Ag-based adsorbent for iodide adsorb from solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Disposable MOF membrane was facile synthesized by one-pot method. • MOF membrane can adsorb organophosphorus pesticides fast. • Adsorption mechanism includes π-π interaction, the affinity of –NH 2 and Ti for P. • MOF membrane can remove organophosphorus pesticides efficiently in actual spinach samples. Metal-organic frameworks (MOFs) have great potential to remove pesticide residues. However, the lack of affinity between the materials and target and the process of trivial sample preparation resulted in limited removal efficiency. Here, we report a one-pot method for the fast preparation of NH 2 -MIL-125 (Ti)-based filter paper to synthesise NH 2 -MIL-125 (Ti)-based filter paper membranes. The NH 2 -MIL-125 (Ti)-based filter paper membrane takes advantage of π-π interactions between the organophosphorus pesticides (OPPs) and the benzene ring of MOFs. The affinity of amino groups and metal Ti for phosphorus atoms in the OPPs exhibits rapid removal efficiency for three OPPs, imidan, fenthion, and fenitrothion. The isothermal adsorption results for imidan, fenthion, and fenitrothion were consistent with the Langmuir, Freundlich, and Langmuir models, respectively. The kinetic results for imidan, fenthion, and fenitrothion agreed with the pseudo-second-order kinetic model, and the removal efficiency reached equilibrium within 1 min. There was no significant change in the adsorption capacity of OPPs in different pH solutions (pH = 2–10). Compared with that of MOFs, the NH 2 -MIL-125 (Ti)-based filter paper membrane removal efficiency of OPPs is the same, and it also has better removal efficiency in actual spinach samples. As a result, the sample pretreatment procedure was simplified using a low-cost and simple-to-synthesize disposable NH 2 -MIL-125 (Ti)-based filter paper membrane, samples' quick separation and the simultaneous fast removal of OPPs. [ABSTRACT FROM AUTHOR]

Cu-based functional materials are excellent candidates for the elimination of iodine anions. However, the low utilization rate of Cu and its unsatisfactory adsorption performance limit its large-scale practical applications. This paper proposes a co-gelation method to obtain Cu/Al 2 O 3 aerogels with a high specific area (537 m 2 /g). Cu/Al 2 O 3 aerogels have a hierarchical porous structure and contain a high proportion of Cu (20.5 wt%). The high dispersibility of Cu, which is based on an in-situ gel process, provides conditions for the high-efficiency elimination of iodide anions. We conducted adsorption experiments that demonstrated that the fabricated Cu/Al 2 O 3 aerogel had an ultrahigh adsorption capacity (407.6 mg/g) and a fast adsorption equilibrium time (0.5 h) for iodide anions. Additionally, the Cu/Al 2 O 3 aerogel could selectively capture iodine anions even in the presence of high concentrations of competing ions (NO 3 - , SO 4 2- , and Cl - at 60 mmol/L). Importantly, the aerogel can operate in a wide pH range of 3-11 without causing secondary pollution. This work demonstrates that low-cost Cu/Al 2 O 3 aerogels exhibit great potential for eliminating radioactive iodine anions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

In this study, a novel adsorbent (PA-β-CD) capable of fast and efficient adsorption of cationic dyes was successfully prepared by the poly-condensation reaction of phytic acid (PA) and β-cyclodextrin (β-CD). Results showed that PA-β-CD exhibited high adsorption capacities of 1095, 2005.58, 1736.32, and 1930.23 mg/g for methylene blue (MB), basic green 4 (MG), astrazon pink FG (FG), and crystal violet (MV), respectively. In addition, the adsorption of cationic dyes on PA-β-CD was very fast, and most of cationic dyes were adsorbed in the first 2 min. Moreover, PA-β-CD could selectively adsorb the cationic dye from a cationic/anionic dye mixture. Adsorption data revealed that the adsorption kinetics fitted the pseudo-second-order model well, and the isotherms were well described by a Langmuir isotherm model. The regeneration efficiency of the adsorbent remained above 90% after the fifth cycle. The present work confirmed that PA-β-CD shows great potential in the treatment of dye wastewater. [Display omitted] • A novel adsorbent (PA-β-CD) was successfully prepared by the poly-condensation reaction of phytic acid and β-cyclodextrin. • PA-β-CD exhibited high adsorption capacities for cationic dyes. • The adsorption of cationic dyes on PA-β-CD was very fast, and most of cationic dyes were adsorbed in the first 2 min. • PA-β-CD could selectively adsorb the cationic dye from a cationic/anionic dye mixture. • The regeneration efficiency of PA-β-CD remained above 90% after the fifth cycle. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chemical oxidation weakened the adsorption of BPA but enhanced that of MB on AC. • Fast adsorption constant positively related to the log K ow of organic compounds. • Enhanced dispersibility of oxidized CNTs was confirmed via 1H NMR relaxation. • Structural dependence should be considered during modified carbonaceous materials. Chemical oxidation is often used to modify the surface properties of carbonaceous materials and improve their environmental benefits in removal of organic pollutants. However, there are some controversial observations and explanations about the influence of chemical oxidation on the adsorption performance of carbonaceous materials that need to be revisited. We studied the influence of chemical oxidation on the adsorption of methylene blue (MB) and bisphenol A (BPA) as model compounds on activated carbon (AC) and carbon nanotubes (CNTs). The kinetics results showed that chemical oxidation prolonged the adsorption of MB and BPA on AC and CNTs, and it accelerated the overall adsorption on CNTs. The adsorption of BPA on oxidized AC was weaker, whereas that of MB was stronger. Furthermore, oxidation treatment of dispersible CNTs greatly increased the adsorption rate and capacity of the CNTs for BPA. The adsorption kinetics and capacity of AC and CNTs are closely related to their structural characteristics (non-dispersibility vs. dispersibility). 1H NMR relaxation measurements showed that the dispersibility of oxidized CNTs can be increased in a liquid environment. After oxidation, significantly more adsorption sites are exposed, which are responsible for the increased sorption capacity and adsorption rate. This work clarifies the structural dependence of the adsorption performance of modified carbonaceous materials via chemical oxidation. [ABSTRACT FROM AUTHOR]

The decrement of low concentration of fluoride to below standard (< 1 mg/L) is one of the current research hotspots. In this work, reed biochar beads cross-linked with cerium alginate were prepared by the gelation-spheroidization-carbonization method to serve as an efficient fluoride adsorbent. The results of batch adsorption experiments showed that RBM-Ce (dosage of 1 ± 0.01 g/L) could rapidly remove fluoride (concentration of around 10 mg/L) over a wide range of pH 3–9, and showed trace leaching amount of Ce ions during adsorption. The maximum adsorption capacity was 34.86 mg/g at normal temperature (20 ℃), and the most consistent curve was Langmuir model in adsorption isotherms. In adsorption kinetics experiments, RBM-Ce showed a rapid adsorption rate capable of treating fluoride under certain standard within 15 min, and the fit was consistent with the pseudo-second order model. The SEM, EDS and XRD characterization indicated that CeO 2 nanoparticles was dispersed and immobilized on the surface of biochar beads. From zeta potential, XPS, FTIR and Raman analyses, the adsorption mechanisms included ion exchange, electrostatic attraction, hydrogen bonding and complexation. All characterization and adsorption experiments pointed to RBM-Ce beads as promising adsorbents for fluoride removal. [Display omitted] • RBM-Ce maintained high adsorption capacity over wide range of pH 3–9. • RBM-Ce adsorbed low concentration of fluoride to reach equilibrium within 15 min. • CeO 2 could dispersedly loaded on the porous biochar skeleton. • Electrostatic attraction and ion exchange were the main adsorption mechanism. [ABSTRACT FROM AUTHOR]

Kapok fiber, a natural hollow fiber with thin shell and large cavity, has rarely been used as adsorbent for heavy metal ions. In this paper, kapok fibers were modified with diethylenetriamine pentaacetic acid (DTPA) after hydrophilicity treatment. The adsorption behavior of the resultant kapok-DTPA influenced by pH, adsorption time and initial concentration of metal ion was investigated. The results demonstrate that adsorption equilibrium was reached within 2 min for Pb and Cd. Adsorption kinetics showed that the adsorption rate was well fitted by pseudo-second-order rate model. The adsorption isotherms were studied, and the best fit was obtained in the Langmuir model. The maximum adsorption capacities of kapok-DTPA were 310.6 mg g for Pb, 163.7 mg g for Cd, 101.0 mg g for Cu, respectively. After eight desorption and re-adsorption loops, the lost adsorption capacities for Pb and Cu were less than 10 %. Because of the large specific area derived from the hollow fiber structure, kapok-DTPA exhibited much better adsorption capacity compared with many other reported adsorbents based on natural materials. [ABSTRACT FROM AUTHOR]

Organic dyes can enter water bodies through industrial wastes and may pose a threat to the health of aquatic organisms and human. Metal organic framework derived carbon materials (CMOFs) have shown excellent performance for aqueous dye adsorption. However, few have studied multimetallic CMOFs for dye removal. Herein, a ternary metal oxide embedded carbon derived from amino-modified metal organic framework (CMOF(Fe/Al/Ni 8/7/5)-NH 2) has been developed as an efficient adsorbent to remove aqueous methylene blue (MB) and acid red 73 (AR-73). CMOF(Fe/Al/Ni 8/7/5)-NH 2 reached adsorption equilibrium for both MB and AR-73 within 30 min at neutral pH condition. It also achieved 18 and 24 times higher adsorption than commercial activated carbon (AC) in 10 min for MB and AR-73, respectively. Compared to other CMOFs-NH 2 , CMOF(Fe/Al/Ni 8/7/5)-NH 2 had the highest adsorption capacity for both cationic MB and anionic AR-73. In addition, CMOF(Fe/Al/Ni 8/7/5)-NH 2 had < 0.15% metal leaching in 90 min in the pH range of 4–10, and it also maintained 89% and 95% adsorption capacity for MB and AR-73 in five consecutive adsorption batches, respectively. Electrostatic interaction was identified as the primary interaction between CMOFs-NH 2 and the dyes, and the embedded crystalline metal oxides with different points of zero charge (PZCs) were identified to be the key adsorption sites. A uniformly distributed surface charge model was proposed to explain the exceptional adsorption capacity of CMOF(Fe/Al/Ni 8/7/5)-NH 2. With fast kinetics, high adsorption capacity, wide applicability and good stability, CMOF(Fe/Al/Ni 8/7/5)-NH 2 may be an effective adsorbent for many other ionic organic pollutants. [Display omitted] • Metal oxide embedded CMOFs-NH 2 were prepared by pyrolysis of MOF-NH 2 precursors. • CMOF(Fe/Al/Ni 8/7/5)-NH 2 had ∼20 times higher dye adsorption than AC in 10 min. • CMOF(Fe/Al/Ni 8/7/5)-NH 2 efficiently adsorbed both cationic MB and anionic AR-73. • Adsorption behavior of CMOFs-NH 2 was well accounted for by surface chemistry. • A surface model was proposed for the performance of CMOF(Fe/Al/Ni 8/7/5)-NH 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • The magnetically separable ethanolamine-functionalized graphene was synthesized. • The Fe 3 O 4 and AE co-modified graphene (MAEGO) can achieve ultra-fast adsorption. • In only five minutes, the adsorption capacities of MAEGO for TC is 315.25 mg/g. • MAEGO can remove tetracycline, levofloxacin, methylene blue, methyl orange rapidly. • When the adsorption of TC reached equilibrium, the removal rate was 97.80%. Frequent organic pollution threatens people and the environment. Achieving rapid on-site adsorption and removal of pollutants is therefore of great significance to quickly alleviate pollution and reduce harm to life and the environment. In this study, we used organic covalent, supramolecular self-assembly and soft chemistry to construct a magnetically separable ethanolamine (AE)-functionalized graphene adsorption material (MAEGO). Due to synergy between AE and Fe 3 O 4 nanoparticles, the adsorption active centers generated in MAEGO are highly exposed, which greatly improves the adsorption and migration of pollutants. In only five minutes, the adsorption capacities of MAEGO for tetracycline (TC), levofloxacin, methylene blue and methyl orange were 315.25, 229.53, 500 and 257.14 mg/g, respectively. The corresponding pollutant removal rates were 63.20%, 49.74%, 100% and 45.33%, respectively. When the adsorption of TC reached equilibrium (1440 min), the removal rate was 97.80%. The adsorption data fitted the pseudo-second-order and Langmuir models well. MAEGO is an efficient and promising adsorbent for rapid removal of organic pollutants. [ABSTRACT FROM AUTHOR]

• A pH-sensitive nanoparticle (NC-PEI/GA) was synthesized via a single-graft method. • NC-PEI/GA was most sensitive to pH condition, especially at pH 3. • The maximum capacity of NC-PEI/GA reached approximately 255.19 mg g−1. • The adsorbent displayed excellent performance even after eight regeneration cycles. • The new potential application of kapok fibers and nanocellulose were expanded. This study reported a facile method to synthesize novel pH-sensitive nanoparticle based on nanocellulose, involving cross-linking polyethyleneimine and glutaraldehyde. The adsorbent was characterized and found to be sensitive to the solution pH, especially at pH 3. Additionally, the biosorbent exhibited rapid adsorption during the initial 10 min and the As(V) adsorption capacity of the nanoparticles reached approximately 255.19 mg g−1 at pH 3, which was five times greater than that achieved with the As(V) solution at its initial pH (44.33 mg g−1). To reflect its performance in actual acidic wastewater, the effects of coexisting anions were also investigated, showing that these anions had little influence on As(V) adsorption. Meanwhile, the adsorbent displayed excellent performance even after eight regeneration cycles. This novel material demonstrates enormous potential for the removal of arsenic contaminants and for the development of pH-sensitive materials. [ABSTRACT FROM AUTHOR]

Hydrothermally synthesized WO 2.72 nanowires with oxygen vacancy possess super selective adsorption, fast adsorption, high capacity and excellent reusability for methylene blue (MB). • Super selective WO 2.72 nanowires have fast adsorption and high capacity (547.3 mg/g). • The adsorption data fit well with the pseudo-second order and Langmuir model. • Thermodynamics revealed the adsorption process is spontaneous and exothermic. • The adsorption efficiency can still reach 86.54% after five reusability experiments. • Electrostatic absorption was conceived as the main adsorption mechanism. Hydrothermally prepared nonstoichiometry tungsten oxide (WO 2.72) nanowires possess super selective adsorption performance for methylene blue (MB). The effects of dye concentration, contact time, pH and temperature on the adsorption properties of WO 2.72 were investigated. The experimental results indicated that WO 2.72 nanowires have a high adsorption capacity (547.32 mg/g) under neutral pH and a fast adsorption rate (adsorbing 100% within 6 min) for MB dye. The kinetic data showed good correlation coefficient (R2 > 0.99) for the pseudo-second-order. The equilibrium data suggesting the monolayer coverage of adsorbate as it fits well with the Langmuir isotherm model (R2 > 0.99). The energy functions of chemical thermodynamics revealed the adsorbate transport across the phase boundary is spontaneous and exothermic. Electrostatic absorption was proposed as the main adsorption mechanisms. Calcination treatment was utilized to decompose MB adsorbed on WO 2.72 and regenerate WO 2.72. The adsorption efficiency of WO 2.72 nanowires can still reach 86.54% after recycling five times, which indicated that as-obtained WO 2.72 nanowires are a very promising high-efficiency adsorbent for practical purification of dyeing waste water. [ABSTRACT FROM AUTHOR]

• Chitin and chitosan were functionalized with APTES (3–aminopropyltriethoxysilane). • Modified and unmodified materials were used for sunset yellow dye adsorption. • APTES functionalized chitosan presented more than 99% of dye removal. • Functionalization provided a faster adsorption rate. The biopolymers chitin (CTN) and chitosan (CTS) were functionalized with APTES (3–aminopropyltriethoxysilane) in order to enhance its adsorption potential for sunset yellow dye (SYD). The functionalization was proved by several techniques like FTIR (Fourier transform infrared spectroscopy), XRD (X–ray diffraction), N 2 adsorption/desorption isotherms, SEM (scanning electron microscopy) and EDS (energy dispersive spectroscopy). The insertion of APTES in the biopolymers has improved the adsorption properties of both, CTN and CTS. The best performance was obtained using CTS functionalized with APTES (CTS–AP), at pH of 4.0, where, more than 99% of the SYD was removed from the solution. Adsorption of SYD on CTS–AP and CTS followed the n–order kinetic model, being that, the use of CTS–AP provided a much faster rate. Freundlich model has better described the isotherms of SYD adsorption on CTS–AP and CTS. An endothermic and physical adsorption was verified. The maximum adsorption capacities were 85 and 95 mg g–1 for CTS and CTS–AP, respectively. The functionalization of CTS with APTES was able to improve the adsorption capacity. However, the main roles of the functionalization was provides a faster adsorption rate, decreasing in 50% the equilibrium time, and, a great recyclability for the adsorbent. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) gas is well-known as a greenhouse gas that leads to global warming. Many efforts have been made to capture CO2 from coal-fired power plants, as well as to reduce the amounts of excess CO2 in the atmosphere to around 400 ppm. However, this is not a simple task, particularly in the lower pressure region than 1000 ppm. This is because the CO2 molecule is chemically stable and has a relatively low reactivity. In the present study, the CO2 adsorption at room temperature on MFI-type zeolites exchanged with alkaline-earth-metal ions, with focus on CO2 concentrations <1000 ppm, was investigated both experimentally and by calculation. These materials exhibited a particularly efficient adsorption capability for CO2, compared with other presented samples, such as the sodium-form and transition-metal ion-exchanged MFI-type zeolites. Ethyne (C2H2) was used as a probe molecule. Analyses were carried out with IR spectroscopy and X-ray absorption, and provided significant information regarding the presence of the M(2+)-O(2-)-M(2+) (M(2+): alkaline-earth-metal ion) species formed in the samples. It was subsequently determined that this species acts as a highly efficient site for CO2 adsorption at room temperature under very low pressure, compared to a single M(2+) species. A further advantage is that this material can be easily regenerated by a treatment, e.g., through the application of the temperature swing adsorption process, at relatively low temperatures (300-473 K).