Adsorption of nickel on husk of Lathyrus sativus: behavior and binding mechanism

Husk of Lathyrus sativus (HLS) has been found to be a good sorbent for the removal of nickel(II) from its aqueous solution. The adsorption process depends on pH of the solution with an optimum at 5.0, and follows Langmuir isotherm model (correlation coefficient 0.998). Initial adsorption rate is very fast and reaches equilibrium following pseudo-second order kinetics within 60 min. Amino, carboxyl, hydroxyl and phosphate groups of the biomass are involved in chemical interaction with nickel ions as revealed from SEM-EDX and FTIR studies. Chemical modifications of the functional groups of the biosorbent show that amino groups contribute largely (approximately 57%) for the binding of nickel ions and probably undergo chelation through dative bond formation. HLS biomass has been found to adsorb both nickel and cadmium equally from their mixed solution to the extent of approximately 70% indicating the importance of this sorbent in industrial effluent treatment.     

微波辅助有机过氧化物功能化修饰单壁碳纳米管

本文报道了微波辅助下,利用过氧化月桂酰分解得到的十一烷基,化学功能化修饰单壁碳纳米管。这种快速、高效的方法将反应时间缩短至10分钟,并得到了比传统回流方法具有更高接枝率的产物。利用傅立叶变换红外光谱(FT-IR),热失重分析(TGA),拉曼光谱,探究了不同的反应时间和微波功率对单壁碳纳米管的接枝率的影响。结果表明：过长的反应时间会导致部分的去功能化的发生,而过高的微波功率(大于900瓦),则会将单壁碳纳米管上起初键连上的十一烷基剥落下来。分散性照片和高分辨率透射电子显微镜(HRTEM)照片显示出,功能化后的单壁碳纳米管与原始的碳管相比,在有机溶剂中的分散性有了明显的提高。     

Covalent Functionalization of Pristine and Ga-Doped Boron Phosphide Nanotubes with Imidazole

Abstract

Density functional theory (DFT) calculations at the B3LYP/6–31G* level were performed to investigate covalent functionalization of imidazole on pristine (in gas and H₂O phases) and Ga-doped BPNT models in terms of energetic, geometric, and electronic properties. The results show that imidazole, as a functional group, prefers to be adsorbed via its nitrogen atom on the pristine, Ga_B, and Ga_P nanotube models. The adsorption energy of imidazole on the (6,0) zigzag BPNT in gas and solvent phases is ?0.76 and ?1.11 eV, respectively, and about 0.38 and 0.43 electron are transferred from the imidazole to nanotube in the phases. The presence of a polar solvent increases the electron donor of imidazole molecule. The results show that Ga doping can significantly enhance the adsorption energy of imidazole on the nanotube models to about 95%.

Moreover, the imidazole adsorption on the pristine and Ga-doped BPNT models has not significant changes in the energy gap of the nanotube models and it is slightly changed after covalent functionalization process. This study may provide new insight to the development of functionalized boron phosphide nanotubes for generation of the new hybrid compounds especially in drug delivery systems for virtual applications.     

Effect of interaction between poly(ethylene terephthalate) and carbon nanotubes on the morphology and properties of their nanocomposites

Poly(ethylene terephthalate) (PET) nanocomposites were prepared by melt‐extruding mixtures of PET and functionalized multiwalled carbon nanotubes (MWNTs) with some interaction with PET molecules. For the functionalization of MWNTs, benzyl isocyanate and phenyl isocyanate with different molecular flexibility were employed on the surface of the MWNTs via chemical modification, respectively. The reaction for functionalization of MWNTs was confirmed by FTIR and transmission electron microscopy (TEM) measurements. TEM observations indicated that both benzyl and phenyl isocyanate groups covered the surface of the MWNTs after functionalization. The PET nanocomposites containing isocyanate groups showed improved mechanical properties, including the tensile strength and tensile modulus, compared with those with pristine and acid‐treated nanotubes. These improvements were ascribed to π–π interactions between the aromatic rings of PET molecules and the isocyanate group in MWNTs. The functionalized MWNTs showed a better dispersion of carbon nanotubes in the matrix polymer and a different fractured cross‐section morphology in scanning electron microscope measurements relative to the pristine MWNTs. The crystallinity of the functionalized MWNT‐PET nanocomposites was significantly higher than that of the pristine and acid‐treated MWNTs. FTIR results indicated that the presence of carbon nanotubes induced trans‐conformation of PET chains, and trans conformation was particularly dominant in PET composites incorporating MWNT‐phenyl. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 900–910, 2008     

Insights from the Adsorption of Halide Ions on Graphene Materials

Graphene has recently found applications in a wide range of fields. Density functional calculations show that halide ions can be adsorbed on pristine graphene, but only F^? has an appreciable binding energy (?97.0 kJ mol^?1). Graphene materials, which are mainly electron donors, can be made strong electron acceptors by edge functionalization with F atoms. The binding strengths of halide ions are greatly enhanced by edge functionalization and show direct proportionality with the degree of functionalization Θ and increased charge transfer. In contrast, the adsorption strengths of metal ions on pristine graphene are clearly superior to those of halide ions but decline substantially with increasing degree of edge functionalization, and for Θ=100 %, the binding energies of ?95.7, ?44.8, and ?25.9 kJ mol^?1 that are calculated for Li⁺, Na⁺, and K⁺, respectively, are obviously inferior to that of F^? (?186.3 kJ mol^?1). Thus, the electronic properties of graphene are fundamentally regulated by edge functionalization, and the preferential adsorption of certain metal ions or anions can be facilely realized by choice of an appropriate degree of functionalization. Adsorbed metal ions and anions behave differently on gradual addition of water molecules, and their binding strengths remain substantial when graphene materials are in the pristine and highly edge functionalized states, respectively.     

Separation of alkanes and aromatic compounds by packed column gas chromatography using functionalized Multi-Walled Carbon Nanotubes as stationary phases

In the present work, we show a novel application of pristine and functionalized Multi-Walled Carbon Nanotubes (MWCNTs) as stationary phase in low-cost packed columns for the gas chromatographic separation of alkanes and aromatic hydrocarbons. The MWCNTs were deeply investigated by means of physical and chemical methods, like thermal analysis, IR and atomic force microscopy, and Inverse Gas Chromatography (IGC) in order to correlate the adsorption process and surface properties with the material purity level and functionalization degree. The derivatization process of the pristine nanotubes was a key factor to achieve a successful separation of both the light n-alkanes (C₃–C₅) and the related isomers (C₄–C₅ branched alkanes). Satisfactory results were similarly obtained in the case of separation of aromatic hydrocarbons (BTX).     

2-Mercaptoimidazole selectively etching and thiol-functionalized ZIF-8 metal–organic framework to serve as a multifaceted platform for radical scavenging and Au loading

Zeolite imidazole frameworks (ZIF-8) are a group of metal–organic frameworks (MOFs) that harbor application potential due to their unique high porosity and other physicochemical properties. However, the small cavities, unstable dispersion, and the lack of surface functional groups hinder the practical application of ZIF-8. In this study, we aimed to develop a ZIF-8-based multifaceted platform with hollow structure and abundant functional groups via a simple one-pot method. We synthesized the ZIF-8 with thiol functionalization (ZSH), while 2-mercaptoimidazole was served as both etching agent and functional counterpart. The hollow morphology and the thiol-groups modification were validated by scanning electron microscopy, transmission electron microscopy with energy-disperse X-ray mapping and X-ray photoelectron spectroscopy. The interparticle structure was estimated by Brunauer–Emmmett–Teller and ultraviolet–visible spectroscopy. The hollow architecture, colloidal stable, and thiol-abundant surface endow ZSHs exploiting the antioxidant and anti-inflammatory ability than pristine ZIF-8 toward a broad scale of morphological change with high functionalization degree. Moreover, ZSHs can specifically encapsulate gold nanoparticles in large quantities for further applications. Finally, ZSHs possess good biocompatibility in human cells and in vivo zebrafish model and could potentially protect human cells against oxidative stress. This concept valuably elucidated the new era for functionalized ZIF-8 to apply as the next generation of multifunctional biomaterials.     

Addition of Sulphur to Graphene Nanoflakes Using Thermal Plasma for Oxygen Reduction Reaction in Alkaline Medium

A batch process is developed to generate sulphur functionalized graphene nanoflakes (S-GNFs), corresponding to nanoparticles of stacked graphene. The growth and functionalization of the catalysts are done in a single thermal plasma reactor. The GNFs are first grown through the decomposition of methane in the thermal plasma volume followed by homogeneous nucleation of the nanoparticles in the well-controlled recombining plasma stream allowing the 2-dimensional evolution of the nanoparticle morphology. The precursor feeding conditions are then changed to liquid carbon disulphide in order to generate sulphur-based functional groups on the nanoparticles. The plasma conditions and carbon disulphide injection are varied, and samples with tuneable amount of sulphur between 4 and 28 at% are obtained. The functional groups generated include polythiophene polymer partly covering the GNFs, sulphur functionalities implemented directly on the graphitic structure, and traces of orthorhombic sulphur. The S-GNFs exhibit higher electrocatalytic activity toward the oxygen reduction reaction in alkaline medium for the samples containing the highest amounts of sulphur.     

Functionalized SBA-15 materials as carriers for controlled drug delivery: influence of surface properties on matrix-drug interactions

Mesoporous SBA-15 materials were functionalized with amine groups through postsynthesis and one-pot synthesis, and the resulting functionalized materials were investigated as matrixes for controlled drug delivery. The materials were characterized by FTIR, N(2) adsorption/desorption analysis, zeta potential measurement, XRD, XPS, and TEM. Ibuprofen (IBU) and bovine serum albumin (BSA) were selected as model drugs and loaded onto the unmodified and functionalized SBA-15. It was revealed that the adsorption capacities and release behaviors of these model drugs were highly dependent on the different surface properties of SBA-15 materials. The release rate of IBU from SBA-15 functionalized by postsynthesis is found to be effectively controlled as compared to that from pure SBA-15 and SBA-15 functionalized by one-pot synthesis due to the ionic interaction between carboxyl groups in IBU and amine groups on the surface of SBA-15. However, SBA-15 functionalized by one-pot synthesis is found to be more favorable for the adsorption and release of BSA due to the balance of electrostatic interaction and hydrophilic interaction between BSA and the functionalized SBA-15 matrix.     

Separation of single-walled carbon nanotubes on silica gel. Materials morphology and Raman excitation wavelength affect data interpretation

In this report, procedures are discussed for the enrichment of single-walled carbon nanotube (SWNT) types by simple filtration of the functionalized SWNTs through silica gel. This separation uses nanotube sidewall functionalization employing two different strategies. In the first approach, a crude mixture of metallic and semiconducting SWNTs was heavily functionalized with 4-tert-butylphenyl addends to impart solubility to the entire sample of SWNTs. Two major polarity fractions were rapidly filtered through silica gel, with the solvent being removed in vacuo, heated to 700 degrees C to remove the addends, and analyzed spectroscopically. The second approach uses two different aryldiazonium salts (one with a polar grafting group and one nonpolar), appended selectively onto the different SWNTs by means of titration and monitoring by UV analysis throughout the functionalization process. The different addends accentuate the polarity differences between the band-gap-based types permitting their partial separation on silica gel. Thermal treatment regenerated pristine SWNTs in enriched fractions. The processed samples were analyzed and characterized by Raman spectroscopy. A controlled functionalization method using 4-fluorophenyl and 4-iodophenyl addends was performed, and XPS analyses yielded data on the degree of functionalization needed to affect the van Hove singularities in the UV/vis/NIR spectra. Finally, we demonstrate that relative peak intensity changes in Raman spectra can be caused by morphological changes in SWNT bundling based on differing flocculation or deposition methods. Therefore a misleading impression of separations can result, underscoring the care needed in assessing efficacies in SWNT enrichment and the prerequisite use of multiple excitation wavelengths and similar flocculation or deposition methods in comparative analyses.     

Noncovalent Functionalization and Charge Transfer in Antimonene

Antimonene, a novel group 15 two‐dimensional material, is functionalized with a tailormade perylene bisimide through strong van der Waals interactions. The functionalization process leads to a significant quenching of the perylene fluorescence, and surpasses that observed for either graphene or black phosphorus, thus allowing straightforward characterization of the flakes by scanning Raman microscopy. Furthermore, scanning photoelectron microscopy studies and theoretical calculations reveal a remarkable charge‐transfer behavior, being twice that of black phosphorus. Moreover, the excellent stability under environmental conditions of pristine antimonene has been tackled, thus pointing towards the spontaneous formation of a sub‐nanometric oxide passivation layer. DFT calculations revealed that the noncovalent functionalization of antimonene results in a charge‐transfer band gap of 1.1 eV.     

Monitoring bisphosphonate surface functionalization and acid stability of hierarchically porous titanium zirconium oxides

To take advantage of the full potential of functionalized transition metal oxides, a well-understood nonsilane based grafting technique is required. The functionalization of mixed titanium zirconium oxides was studied in detail using a bisphosphonic acid, featuring two phosphonic acid groups with high surface affinity. The bisphosphonic acid employed was coupled to a UV active benzamide moiety in order to track the progress of the surface functionalization in situ. Using different material compositions, altering the pH environment, and looking at various annealing conditions, key features of the functionalization process were identified that consequently will allow for intelligent material design. Loading with bisphosphonic acid was highest on supports calcined at 650 °C compared to lower calcination temperatures: A maximum capacity of 0.13 mmol g(-1) was obtained and the adsorption process could be modeled with a pseudo-second-order rate relationship. Heating at 650 °C resulted in a phase transition of the mixed binary oxide to a ternary oxide, titanium zirconium oxide in the srilankite phase. This phase transition was crucial in order to achieve high loading of the bisphosphonic acid and enhanced chemical stability in highly acidic solutions. Due to the inert nature of phosphorus-oxygen-metal bonds, materials functionalized by bisphosphonic acids showed increased chemical stability compared to their nonfunctionalized counterparts in harshly acidic solutions. Leaching studies showed that the acid stability of the functionalized material was improved with a partially crystalline srilankite phase. The materials were characterized using nitrogen sorption, X-ray powder diffraction, and UV-vis spectroscopy; X-ray photoelectron spectroscopy was used to study surface coverage with the bisphosphonic acid molecules.     

Density functional study on the functionalization of BN nanotubes with nitramide

Chemical functionalization of a boron nitride nanotube (BNNT) with nitramide molecule (H₂NNO₂) has been investigated using density functional theory. It was found that the molecule prefers to be adsorbed and dissociated on a diagonal B-N bond of the tube surface so that the -NH₂ and -NO₂ groups are attached on B and N atoms, releasing energy of 0.50 eV. The results show that the functionalized BNNT is more soluble than the pristine one which may render the chemical modification process to be an effective way for purification of the BNNTs. Depending on the cleavage behavior of nitramide on the tube, HOMO/LUMO gap of the system can be either decreased or increased while the chemically modified BNNT is still a semiconductor. Furthermore, the chemical functionalization results in hindered field emission in the tube by raising the potential barrier of the electron emission.     

碳点的功能化及其在食品安全领域的应用

作为新型的传感材料,碳点在过去10年中受到了广泛的关注。由于制备方法相对单一,未经功能化碳点的表面有效传感作用位点的种类受到了限制（多为羧基、羟基、醛基等含氧官能团）,导致其选择性和灵敏度不佳。因此,功能化在开发碳点传感器中扮演了重要的角色。碳点的功能化主要分为两大类：掺杂改性及表面修饰。掺杂改性是在碳点的骨架结构中引入新的元素,一方面能够实现碳点的光学改性,另一方面也可以在其表面形成新的作用位点用于传感。表面修饰是在碳点表面原有结构的基础上,通过共价或非共价的形式与其他功能结构相结合,从而拓展碳点的选择性并提升其灵敏度。本文对近8年来碳点功能化及其在食品安全检测领域应用的相关研究进展进行了系统性的梳理,为开发基于功能化碳点的食品快检设备提供一些新的思路。     

Detection of homogeneous distribution of functional groups in mesoporous silica by small angle neutron scattering and in situ adsorption of nitrogen or water

The distribution of SO(3)H-functional groups attached to the ordered inner pore walls of mesoporous Si-MCM-41 materials based on SiO(2) was investigated by gas adsorption combined with in situ small angle neutron scattering (SANS). The functionalization was performed by two different methods, (i) grafting and (ii) co-condensation. The adsorbates N(2) at 77 K or a H(2)O/D(2)O mixture of 42:58 at 298 K possess neutron scattering length densities (SLD) similar to that of SiO(2) and therefore quench the diffraction signals of the nonmodified silica. SANS measurements show that N(2) matches completely not only with the pristine mesoporous Si-MCM-41 but also with Si-MCM-41-SO(3)H functionalized by grafting. Thus, full access of adsorbate into the entire length of the pores is proven. For the analysis of the distribution of functional groups within the pores in dependence on the used functionalization method, grafting or co-condensation, however, the more specific adsorbate H(2)O/D(2)O (42:58) is necessary, because it reacts more sensitively toward small changes in the SLD of the host material. For grafted Si-MCM-41-SO(3)H materials, an incomplete quenching was observed, indicating that only some regions, probably the pore mouths, have been modified. For a sample functionalized by co-condensation, almost no quenching of the neutron diffraction was found, indicating a very homogeneous distribution of the functional groups along the entire pores.     

Ab initio theoretical study of non-covalent adsorption of aromatic molecules on boron nitride nanotubes

We have studied non-covalent functionalization of boron nitride nanotubes (BNNTs) with benzene molecule and with seven other different heterocyclic aromatic rings (furan, thiophene, pyrrole, pyridine, pyrazine, pyrimidine, and pyridazine, respectively). A hybrid density functional theory (DFT) method with the inclusion of dispersion correction is employed. The structural and electronic properties of the functionalized BNNTs are obtained. The DFT calculation shows that upon adsorption to the BNNT, the center of aromatic rings tend to locate on top of the nitrogen site. The trend of adsorption energy for the aromatic rings on the BNNTs shows marked dependence on different intermolecular interactions, including the dispersion interaction (area of the delocalized π bond), the dipole-dipole interaction (polarization), and the electrostatic repulsion (lone pair electrons). The DFT calculation also shows that non-covalent functionalization of BNNTs with aromatic rings can give rise to new impurity states within the band gap of pristine BNNTs, suggesting possible carrier doping of BNNTs via selective adsorption of aromatic rings.     

Atomic layer deposition of metal oxides on pristine and functionalized graphene

We investigate atomic layer deposition (ALD) of metal oxide on pristine and functionalized graphene. On pristine graphene, ALD coating can only actively grow on edges and defect sites, where dangling bonds or surface groups react with ALD precursors. This affords a simple method to decorate and probe single defect sites in graphene planes. We used perylene tetracarboxylic acid (PTCA) to functionalize the graphene surface and selectively introduced densely packed surface groups on graphene. Uniform ultrathin ALD coating on PTCA graphene was achieved over a large area. The functionalization method could be used to integrate ultrathin high-kappa dielectrics in future graphene electronics.     

Functionalized silica matrices for controlled delivery of cephalexin

The surface of SBA-15 ordered mesoporous silica was functionalized with sulphonic and amine functional groups to determine the effect of changes in surface acidity on cephalexin adsorption and subsequent release. Cephalexin (CPX), which belongs to the group of cephalosporins or β-lactam antibiotics, was impregnated on functionalized SBA-15. The functionalized silica materials were characterized by SEM, TGA, FTIR and N₂ adsorption, and an in vitro drug delivery test was performed. SEM micrographs showed the packed cylinders correspond to SBA 15 materials. Likewise, N₂ adsorption–desorption isotherms demonstrated that the SBA-15 structure was obtained when IV-type isotherms were displayed. The inalterable stabilization of the drug was confirmed by FTIR spectroscopy. For all the samples studied, the delivery profiles exhibit two steps. A fast initial stage was obtained over the first 5 h, followed by a slower one. Regarding this second stage, the time needed to attain a plateau was undoubtedly altered by the surface functionalization.     

A density functional study of the 13C NMR chemical shifts in functionalized single-walled carbon nanotubes

The 13C NMR chemical shifts for functionalized (7,0), (8,0), (9,0), and (10,0) single-walled carbon nanotubes (SWNTs) have been studied computationally using gauge-including projector-augmented plane-wave (GIPAW) density functional theory (DFT). The functional groups NH, NCH3, NCH2OH, and CH2NHCH2 have been considered, and different sites where covalent addition or substitution may occur have been examined. The shifts of the carbons directly attached to the group are sensitive to the bond which has been functionalized and may, therefore, be used to identify whether the group has reacted with a parallel or a diagonal C-C bond. The addition of NH to a parallel bond renders the functionalized carbons formally sp3-hybridized, yielding shifts of around 44 ppm, independent of the SWNT radius. Reaction with a diagonal bond retains the formal sp2 hybridization of the substituted carbons, and their shifts are slightly lower or higher than those of the unsubstituted carbon atoms. The calculated 1H NMR shifts of protons in the functional groups are also dependent upon the SWNT-group interaction. Upon decreasing the degree of functionalization for the systems where the group is added to a parallel bond, the average chemical shift of the unfunctionalized carbons approaches that of the pristine tube. At the same time, the shifts of the functionalized carbons remain independent upon the degree of functionalization. For the SWNTs where N-R attaches to a parallel bond, the average shift of the sp2 carbons was found to be insensitive to the substituent R. Moreover, the shifts of the functionalized sp3 carbons, as well as of the carbons within the group itself, are independent of the SWNT radius. The results indicate that a wealth of knowledge may be obtained from the 13C NMR of functionalized SWNTs.     

Functionalization of halloysite with N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane

In order to increase the affinity of the halloysite mineral to 3d-metal ions, its surface was functionalized with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. A significant influence of the nature of the solvent and silane concentration on the degree of functionalization of halloysite was revealed. According to the data of elemental analysis, FTIR spectroscopy, and thermogravimetry, it was found that the most efficient solvents were tetrahydrofuran and acetonitrile at an equimolar silane to halloysite ratio. The functionalization of halloysite with N-(2-aminoethyl)-3-aminopropylsilyl groups significantly increases the sorption capacity of the material in comparison with both unmodified halloysite and halloysite functionalized with non-chelating 3-aminopropylsilyl groups.