Search

In this paper, two 3D anionic metal-organic frameworks, [(CH3CH2)2NH2]·[Zn(BTC)1/3(PyC)]·1/2CH3CN·2H2O (NKU-102) and [(CH3CH2)2NH2]·[Zn2(BTC) (PyC)]·1.5H2O·DEF (NKU-103), were constructed from the same reaction system at different temperature. Though both are of anionic framework, NKU-102 possesses a sealed 3D framework based on octahedral cage and shows negligible adsorption capacity of organic dyes, whereas NKU-103 features an open triangular microchannel surrounded by two types of helical chains, and thus exhibits outstanding size-selective adsorption toward small cationic organic dyes. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are a class of nanoporous materials. The development of efficient and environmentally friendly methods for activating MOFs is of great significance for its industrial application. In this work, nanoscale magnetic core-shell Cu-BTC@Fe 3 O 4 was prepared through a secondary growth strategy. The effects of different activation solvents (dichloromethane and ethanol, respectively) and temperatures on the surface area, pore structures and the adsorption of xylene isomers on Cu-BTC@Fe 3 O 4 were investigated. Ethanol as an activation solvent could more easily displace the precursors remaining in the channels of Cu-BTC@Fe 3 O 4 than dichloromethane, while the temperature change has no significant influence on the pore structure. The adsorption separation of xylene isomers on Cu-BTC@Fe 3 O 4 composite materials was studied using the batch vapor-phase adsorption, and liquid-phase breakthrough experiments. The activated Cu-BTC@Fe 3 O 4 (CH 2 Cl 2 -200 ​°C ​− ​C 2 H 5 OH) material has the highest adsorption capacity of 210.26 ​mg ​g−1 for p -xylene (p X). Cu-BTC@Fe 3 O 4 (C 2 H 5 OH) and Cu-BTC@Fe 3 O 4 materials have excellent adsorption capacity for m -xylene (m X), with the values of 200.19 ​mg ​g−1 and 219.63 ​mg ​g−1, respectively, which is about 4 times higher than that of Cu-BTC@Fe 3 O 4 (CH 2 Cl 2). The adsorption capacity sequence of xylene on Cu-BTC@Fe 3 O 4 (C 2 H 5 OH) and Cu-BTC@Fe 3 O 4 materials is m -xylene (m X) ​> ​ p -xylene (p X) ​> ​ o -xylene (o X), and that of other materials is p X ​> ​ m X ​> ​ o X. Nanoscale magnetic core-shell Cu-BTC@Fe 3 O 4 was prepared through a secondary growth strategy towards the adsorption separation of xylene isomers. [Display omitted] • Nanoscale magnetic core-shell Cu-BTC@Fe 3 O 4 was prepared through a secondary growth strategy. • The effects of different activation solvents and temperatures on the xylene isomers adsorption of Cu-BTC@Fe 3 O 4 were studied. • Using ethanol as an activation solvent could more easily displace the precursors remaining in the channels of Cu-BTC@Fe 3 O 4. [ABSTRACT FROM AUTHOR]

[Display omitted] • Functionalized hydrochar was prepared by free radical post-synthetic modification. • Hydrochar with − N+H 2 R groups exhibited high adsorption capacity towards Cr(VI). • •Nitrogen-containing groups in hydrochar play multiple roles in adsorption procedure. Chemical modification on hydrochars can significantly improve their ability of removing heavy metal ions from wastewater, but so far no research has focused on the chemical modification through free radical reaction. In this work, a cation functionalized hydrochar (CFHC) bearing − N+H 2 R was synthesized by grafting-polymerization of glycidyl methacrylate (GMA) onto bamboo hydrochar under initiation by benzoyl peroxide, followed by the amination with the introduced epoxy group and diethylenetriamine and a subsequent hydrochloric acid treatment. The resulted CFHC exhibited a superior removal capacity of 424.09 mg·g−1 for Cr(VI), and the highest sorption occurred at pH of 2. Combining a series of characterizations and tests, it was concluded that the sorption conformed to the pseudo-second-order and Freundlich equations, indicating a multilayer chemisorption process that mainly driven by electrostatic reaction, reduction, and surface complexation. This research proved that a free radical polymerization treatment could effectively transform hydrochars into super adsorbents for wastewater treatment. [ABSTRACT FROM AUTHOR]

Based on the generalized gradient approximation of density functional theory, the geometric structure and electronic properties of the intrinsic Ti3C2 and Cu-, Pt-, Co-, Si-, F-, Cl- or Br-doped Ti3C2 are optimized, and the adsorption process of HCHO on the surface of the intrinsic Ti3C2 and doped Ti3C2 is calculated. The effects of adsorption energy, stability, DOS and doping on bond length were discussed. The results show that the adsorption energy of the intrinsic Ti3C2 crystal plane at the top site is the strongest, at −7.58 eV. The optimal adsorption sites of HCHO on various doping systems are Cu-Top, Pt-Top, Co-Top, Si-Hollow, Cl-Hollow, F-Bridge and Br-Hollow, respectively. Among the doped elements, anion (F, Cl, Br) doping at each adsorption site generally reduces the formaldehyde adsorption activity of the substrate; cationic doping (Cu, Pt, Co, Si) enhances the adsorption activity of the substrate for formaldehyde at most of the adsorption sites, indicating that the modification effect of anions on Ti3C2 is not as good as that of cations. The adsorption capacity of Si-doped Ti3C2 for formaldehyde was significantly improved. Compared with the intrinsic Ti3C2 crystal plane at the same adsorption site, the adsorption activity of HCHO was improved, and the highest adsorption energy was −8.09 eV. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two biochars were prepared from APS/KPS-pretreated bamboo. • Cation types in persulfate impact physicochemical properties of biochar. • The KPS-pretreated bamboo-derived biochar has a higher adsorptive capacity for MB. • The discrepancy in adsorption capacity of two biochar for MB was analyzed. • Electrostatic action is the main adsorption mechanism for MB onto biochars. The adsorption behaviors of biochar are largely impacted by biomass feedstock. In this study, two biochars were prepared from torrefaction of ammonium persulfate- and potassium persulfate-pretreated bamboo and then activated by cold alkali, which are named as ASBC and KSBC, respectively. The two biochars were characterized by different instruments, and their adsorption properties over cationic methylene blue (MB) were compared. The type of persulfates little affected the specific surface areas, but significantly impacted O (29.54 % vs. 35.113 %) and N (12.13 % vs. 3.74 %) contents, functional groups, and zeta potentials of biochars. MB adsorption onto ASBC/KSBC is a single-layer chemical endothermic process and ASBC/KSBC exhibit high adsorption capacity over MB (475/881 mg·g−1) at 303 K. Obviously, the sorption capacity of MB onto KSBC much surpasses that of MB onto ASBC. These results indicate biomass pre-treatment is a cheap and convenient method to prepare biochars with unique physicochemical and adsorptive properties. [ABSTRACT FROM AUTHOR]

• N-doped hydrochar was synthesized by one-step hydrothermal reaction. • Cr(VI) adsorption capacity of hydrochar was enhanced by N-doping. • NH 4 Cl acts as a catalyst and a nitrogen source in preparation of N-doped hydrochar. • N-groups can adsorb Cr(VI) by electrostatic interaction and reduce Cr(VI) to Cr(III). N-doped biochar can effectively eliminate toxic Cr(VI). Here, N-doped hydrochar (NHC) was successfully synthesized by one-pot hydrothermal carbonization (HTC) of NH 4 Cl and bamboo, and employed to adsorb Cr(VI). The specific surface area, pore volume, and carbon and nitrogen contents of NHC all increase compared with the undoped hydrochar (HC). NH 4 Cl acts as a cheap nitrogen source to enhance the nitrogen content of hydrochar and as an acid catalyst to accelerate hydrochar carbonization. Adsorption experiments show NHC has higher adsorption capacity than HC for Cr(VI). XPS and FTIR imply the dominant mechanisms of adsorbing Cr(VI) onto two hydrochars are electrostatic attraction, reduction and complexation, but the contributions of surface functional groups in two hydrochars for elimination of Cr(VI) differ. The doped nitrogen in NHC is pivotal in adsorbing and reducing Cr(VI). Hence, NHC prepared from bamboo and NH 4 Cl by one-step HTC is a cheap and efficient adsorbent to eliminate aqueous Cr(VI). [ABSTRACT FROM AUTHOR]

• The novel magnetic activated biochar nanocomposites were first time prepared using wakame. • Loading nickel on the surface of wakame biochar is conducive to its recycling. • The adsorption process is a spontaneous endothermic process. • At 293 K, the maximum adsorption capacity of MB is 479.49 mg/g. In this work, magnetic wakame biochar nanocomposites for the first time had been synthesized to investigate their adsorption to methylene blue dye. As-prepared magnetic biochar samples were obtained by the impregnation method to load nickel on wakame biochar via one-step carbonization with activation agent KOH at 800 °C. The prepared samples were characterized by BET, XRD, FTIR, Raman, SEM, TEM and so on. The results exhibited that the maximum adsorption capacity of BW(Ni)0.5 to methylene blue could reach 479.49 mg/g at 20 °C. The adsorption behavior was more suitable for Langmuir isotherm equation and the kinetic data were most consistent with the pseudo second-order model. And also, the adsorption reaction was a spontaneous and endothermic process. After five cycles, it was found that BW(Ni)0.5 had a high adsorption capacity for methylene blue (117.58 mg/g). This study demonstrated that wakame biochar could have great potential in dye wastewater treatment. [ABSTRACT FROM AUTHOR]

• The porous dawsonite is synthesized by the digestion of MOFs precursor. • Dawsonite shows a mesoporous structure with a large specific surface area. • The maximum adsorption capacity can reach 228.25 mg/g at 303 K. • OH− and CO 3 2− play an important role for Cu(II) removal. Mesoporous dawsonite was successfully synthesized using metal-organic frameworks (MOFs) as the template and precursor by direct digestion of NH 2 -MIL-53(Al) with the help of bismuththiol and Na 2 CO 3 and was applied to eliminate Cu(II) from wastewater. The mesoporous dawsonite was characterized by ICP, SEM-EDS, TEM, AFM, FTIR, XRD, XPS, EA, TGA, zeta potential and nitrogen adsorption-desorption isotherms. The influence factors on the adsorption were discussed, including initial Cu(II) concentration, temperature, solution pH, contact time, and co-cation. The results showed that the adsorption isotherm and adsorption kinetics of Cu(II) onto dawsonite obeyed Langmuir and pseudo-2nd-order kinetic equations, respectively. Thermodynamic analysis revealed adsorption of Cu(II) onto dawsonite was spontaneous and thermodynamically favorable. The efficient elimination of Cu(II) was ascribed to cation exchange and the inner-sphere complexation between Cu(II) and surface hydroxyl or carbonate groups of dawsonite. The high adsorption performance and reusability suggest the dawsonite prepared here is an efficient adsorbent to eliminate Cu(II) from wastewater. [ABSTRACT FROM AUTHOR]

In this study, modified activated fishbone charcoal (MAFC) was successfully prepared to remove emulsified oil from oily wastewater. Various characteristic techniques, including SEM, XRD, FTIR, and BET, were employed to investigate the morphology, texture, and surface properties of as-prepared samples. BET results demonstrated that the specific surface area of fishbone charcoal increased from 69.8 m2/g to 206.0 m2/g after treatment with K2CO3 as an activating agent, while the total pore volume of MAFC increased from 0.003 cm3/g to 0.3 cm3/g, accompanied by the formation of abundant pore structures. It was observed that 90.1% of emulsified oil (100 mg/L) was successfully removed by MAFC under our experimental conditions. The results of a kinetic and isotherm model analysis indicated that the adsorption experimental data were not only consistent with the Langmuir adsorption isotherm but were also well-described by the pseudo-second-order adsorption model. It is expected that this highly efficient and inexpensive MAFC can be a promising bio-adsorbent for removing organic pollutants from industrial wastewater. [ABSTRACT FROM AUTHOR]

In this study, carbonized kelp biochar (AKB) modified by KOH impregnation and photocatalytic Bi2MoO6/AKB composite (BKBC) nanomaterials were the first time successfully synthesized for efficient removal of dyes in aqueous solution. BET, XRD, FT-IR, and SEM were employed to characterize as-prepared samples. UV-vis and other test results indicated that the removal efficiency of methylene blue (MB) was 61.39% and 94.12% for BKBC and AKB, respectively, which was up to 13 times and 20 times higher in comparison with pure Bi2MoO6 (PBM). In addition, the equilibrium adsorption capacity of MB could reach up to 324.1 mg/g for AKB. This high dyes adsorption performance could be likely attributed to its high specific surface area (507.177 m2/g) and its abundant presence of various functional groups such as –OH and =C–H on AKB. Particularly, the existing of amorphous carbon and transition metal oxides, such as Fe2O3 and Mn5O8, could be beneficial for the photodegradation of MB for AKB. Meanwhile, experimental data indicated that adsorption kinetics complied with the pseudo-second order model well, and all of the tests had satisfactory results in terms of the highly efficient adsorption and photodegradation activity of AKB nanomaterials, which suggested its great potential in wastewater treatment. [ABSTRACT FROM AUTHOR]