Search

Based on the Lennard-Jones potential function, a theoretical model of atoms/ions interaction with finite-size (doped) graphene is presented to investigate the mechanical behaviors of atoms/ions adsorption and migration on the surface of finite-size boron, nitrogen and boron nitride doped graphene. The results show that boron, nitrogen and boron nitride doping can change the interaction between atoms/ions and graphene, and the type, position and domain size of doping elements have significant effects on the adsorption sites and adsorption energy of atoms/ions. The stable adsorption sites, adsorption heights and adsorption energy of atoms/ions on the surface of doped graphene can be controlled by regulating the doping elements. Meanwhile, boron, nitrogen and boron nitride doping can affect the energy period and energy barrier of atoms/ions migration on graphene surface. The proper design of boron, nitrogen and boron nitride doping position, size and distribution can effectively control the atom/ion migration behavior on graphene surface. This research work can provide a theoretical reference for atoms/ions carriers, molecular sieves and ion battery electrodes based on doped graphene and graphene heterostructures. [ABSTRACT FROM AUTHOR]

By assembling CoII ions and a combination of 5-(4-pyridyl)tetrazole (4-ptz) and formate ions, two distinct metal-organic frameworks, [Co3(4-ptz)5(HCOO)(H2O)2] and [Co3(4-ptz)4(dmf)2(HCOO)2 ] (dmf= N, N′-dimethylformamide), were synthesized. They were both characterized by single-crystal X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and powder X-ray diffraction. Structural analyses revealed that by slightly modulating the coordination environment of the trinuclear cobalt cluster, two complexes were formed featuring unusual six-connected nets reminiscent of a pyrazole-type linear trinuclear cobalt cluster as compared with the classic eight-connected bcu topology. In addition, [Co3(4-ptz)5(HCOO)(H2O)2] interacted strongly with CO2, with an adsorption enthalpy of 29.2 kJ mol−1, and in a selectivity study, the uptake ratios of CO2/N2 (from a 15:85 mixture) and CO2/CH4 (50:50 mixture) were 77.6 and 37.7, respectively. Magnetic studies on both complexes revealed weak antiferromagnetic coupling between the CoII ions. [ABSTRACT FROM AUTHOR]

Spiro(fluorene-9,9′-xanthene)-based polymeric monodisperse spheres have been prepared through a surfactant-free Suzuki coupling polymerization in a single-phase. The polymer (PSFX) exhibits permanent microporous nature with Brunauer–Emmett–Teller specific surface area up to 610 m2g−1. Its hydrogen storage can reach to 1.20 wt% (1.0 bar and 77 K) and the uptake capacity for carbon dioxide is 11.8 wt% (1.0 bar and 273 K).PSFXis a highly hydrophobic material with good sorption capacity for toluene (887 mg g−1at saturated vapor pressure and room temperature), which makes it show potential use in elimination of harmful small aromatic molecules in the environment. Interestingly,PSFXexhibits a remarkable fluorescent emission property in the suspension. Fluorescence detection of explosive chemical (TNT) was performed through a series of spectrofluorometric titration using the suspension ofPSFXas the probe. [ABSTRACT FROM AUTHOR]

• A novel strategy was developed to prepare nitrogen rich biochar. • APBC has high affinity and strong sorption ability towards Pb(II). • APBC contains abundant nitrogen and oxygen-containing groups. • Sorption of Pb(II) is mainly dominant by inner–sphere surface complexation. Biochar was prepared by torrefaction of ammonium persulphate pretreated bamboo (labeled as APBC) and applied into elimination of Pb(II) from water solutions. APBC was characterized by N 2 adsorption–desorption isotherms, elemental and Zeta potential analyses, SEM-EDS, XPS, and FTIR. Abundant N- and O-containing groups appeared atop APBC. Batch sorption assays revealed that APBC had high affinity and strong sorption ability towards Pb(II). The high Pb(II) adsorbing ability was attributed to the high contents of N- and O-containing functional groups of APBC. The adsorption mechanism mainly occurred by inner–sphere surface complexation. Hence, torrefaction of ammonium persulphate pretreated bamboo is a promising strategy for producing efficient biochar that is applicable for industrial wastewater treatment. [ABSTRACT FROM AUTHOR]

Abstract: Spirobixanthene-based polymeric monodisperse spheres with particle sizes about 600nm in diameter have been prepared through surfactant-free Suzuki coupling polymerization in a single-phase. The polymer (PSBX) exhibits permanent microporous nature with high Brunauer–Emmett–Teller specific surface area up to 1020m2 g−1. Its hydrogen storage can reach upto 1.67wt% (1.0bar and 77K) and the uptake capacity for carbon dioxide is 12.0wt% (1.0bar and 273K). Interestingly, PSBX is a highly hydrophobic material but with a high methanol uptake (574mgg−1 at saturated vapor pressure and room temperature). The good sorption capacity of PSBX for toluene (887mgg−1 at saturated vapor pressure and room temperature) makes it potent for use in the elimination of harmful small aromatic molecules in the environment. [Copyright &y& Elsevier]

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]

Abstract: A new hybrid compound based on porous metal–organic frameworks and polyoxometalates H4[(Cu4Cl)3(BTC)8]2[SiW12O40]·(C4H12N)6·3H2O (NENU-15, BTC=1, 3, 5-benzenetricarboxylate) has been hydrothermally synthesized and its crystal structure, stability and porosity have been characterized. The experimental results showed that the introduction of polyoxometalates improved the integral stability of the compound. In addition, NENU-15 was employed in NO removal for the first time. By virtue of the synergistic effect between host frameworks and guest polyoxometalates, it not only displayed good adsorption behavior for NO, but also exhibited superior activity in NO decomposition. [Copyright &y& Elsevier]

• Solvothermal treatment enhanced the quantity of active groups (OH, NHR and R N C O) and amorphous carbon structure. • The SRHH-180 displayed superior dye adsorption and degradation performance itself. • Up to 93% removal efficiency was reached during entirely reaction system. • Both pseudo-second-order and intraparticle diffusion models fitted well with actual adsorption process. In this study, an activated biochar derived from Spartina alterniflora (SRHH) was innovatively synthesized to efficiently remove dye contaminants from aqueous solution. A series of characterizations exhibited that solvothermal process effectively increased the mesopores and functional group structure (OH, NHR, C O, C O and R N C O) of the nanomaterial, which could also acquire amorphous carbon-doped biochar with less energy consumption. Moreover, the results showed that the as-prepared sample in a solvothermal kettle at 180 °C displayed superior dye adsorption and degradation performance, and the removal efficiency entirely could reach up to 93% within 4 h at neutral condition. The adsorption process was both consistent well with the pseudo-second-order and intraparticle diffusion models, indicating that diffusion resistance within the particle pore size and chemical action might be predominantly controlled factor. Therefore, the prepared catalyst has enormous potential in the removal of organic pollution as a low-cost and economical in-situ remediation material. [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]

[Display omitted] • Acrylate-modified hydrochar with excellent adsorption properties was prepared easily. • The removal amounts of Pb(II) and methylene blue exceed 291.96 and 1014.96 mg/g. • Acrylate plays a key role in the adsorption process. • The acrylate content was more influential on adsorption than specific surface area. • The structure of hydrochar significantly affects its functional modification. Hydrochars are promising sorbents for wastewater treatment. Herein, two acrylate-modified hydrochars (AMHC 1 and AMHC 2) were obtained by grafting acrylic acid on the surface of two hydrochars (MHC 1 and MHC 2 hydrothermally carbonized in water and acidic medium respectively) with free radical polymerization. Characterizations show that MHC 2 is more prone to free radical polymerization than MHC 1 does, and has higher carboxylate content after modification. The adsorption amounts of AMHC 2 over methylene blue (MB) and Pb(II) are much higher than those of AMHC 1. Pseudo-second-order kinetic and Langmuir isotherm equations well fit the Pb(II) and MB sorption data of AMHC 2. The Pb(II) adsorptive mechanism is mainly inner-surface complexation accompanied by ion exchange and cation-π interaction. MB adsorption involves ion exchange, electrostatic interaction, H-bonding and π-π interaction. Hence, the one-step modification method of free radical polymerization under alkaline condition has great potential for preparing carboxylate-modified hydrochars to adsorb cationic pollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • IFHC was prepared from one-step solvent-free radical copolymerization. • IFHC has rich carboxylate and effectively adsorbs cationic contaminants. • The sorption amounts of Pb(II) and MB exceed 291 and 1036 mg/g respectively. • Carboxylate plays a key role in the removal of cationic contaminants. • Solvent-free radical copolymerization can effectively functionalize hydrochar. An itaconate-functionalized hydrochar (IFHC) was prepared from one-step solvent-free radical copolymerization of bamboo hydrochar, itaconic acid, ammonium persulphate and sodium hydroxide in solvent-free environment, and was employed to absorb methylene blue (MB) and Pb(II) from wastewater. Characterizations show IFHC has rich carboxylate and tends to adsorb cationic contaminants. The largest adsorbed quantities of MB and Pb(II) by IFHC are up to 1036 and 291.8 mg·g−1 at 298 K respectively as per the Langmuir isotherm. Sorption of MB and Pb(II) onto IFHC can be expressed well by Langmuir isotherm and pseudo-2nd-order kinetics equations. The high sorption performance depends on the rich carboxylate, which can adsorb MB/Pb(II) through an electrostatic interaction/inner-surface complexation mechanism. The sorptive capacity of regenerated IFHC decreased below 10% after 5 desorption-resorption cycles. Thus, the solvent-free free radical copolymerization is an environmentally-friendly strategy to synthesize novel efficient sorbents that can clean cationic contaminants from wastewater. [ABSTRACT FROM AUTHOR]

• Fe 3 O 4 -loaded hydrochar was prepared by HTC and precipitation. • FeCl 3 plays at least two roles as a catalyst and an oxidant in HTC. • Electrostatic interaction was the primary mechanism of MB sorption by HC-Fe 3 O 4. • Fe 3 O 4 -loaded hydrochar can be stably recycled for at least 5 consecutive cycles. • Adsorption follows Langmuir isotherm and pseudo-second-order kinetics. Highly efficient and cheap magnetic materials have application prospects in wastewater treatment. Herein, Fe 3 O 4 -loaded hydrochar (HC-Fe 3 O 4) was obtained from hydrothermal carbonization (HTC) of bamboo with FeCl 3 and then added with FeCl 3 to form a magnetic sorbent via simple precipitation. The HC-Fe 3 O 4 was characterized with various instruments. The characterizations show FeCl 3 plays at least two roles as a catalyst and an oxidant in HTC. The specific surface area of hydrochar enlarged from 39.9731 to 60.9887 m2·g−1 after the addition of FeCl 3 during HTC, which showed FeCl 3 acted as a catalyst in HTC. XRD indicated Fe 3 O 4 was formed by the structure of HC-Fe 3 O 4 , which indicated Fe(III) was reduced to Fe(II) during HTC. Sorption of methylene blue (MB) onto HC-Fe 3 O 4 was better fitted by the Langmuir isotherm and pseudo-second-order kinetic models. Sorption is a spontaneous thermodynamic endothermic process and HC-Fe 3 O 4 is easily separated by an applied magnetic field and reused. [ABSTRACT FROM AUTHOR]

Abstract: The functionalization of porous metal–organic frameworks (Cu3(BTC)2) was achieved by incorporating Keggin-type polyoxometalates (POMs), and further optimized via alkali metal ion-exchange. In addition to thermal gravimetric analysis, IR, single-crystal X-ray diffraction, and powder X-ray diffraction, the adsorption properties were characterized by N2 and volatile organic compounds (VOCs) adsorption measurements, including short-chain alcohols (C<4), cyclohexane, benzene, and toluene. The adsorption enthalpies estimated by the modified Clausius–Clapeyron equation provided insight into the impact of POMs and alkali metal cations on the adsorption of VOCs. The introduction of POMs not only improved the stability, but also brought the increase of adsorption capacity by strengthening the interaction with gas molecules. Furthermore, the exchanged alkali metal cations acted as active sites to interact with adsorbates and enhanced the adsorption of VOCs. [Copyright &y& Elsevier]