Amine Grafting Research Articles

Spherical amine grafted silica aerogels for CO2 capture.

The objective of this research was to develop a novel spherical amine grafted silica aerogel for CO2 capture. A spherical silica gel was synthesized by dropping a sodium silicate based silica sol into an oil bath. Amine grafting was achieved by bonding 3-aminopropyltriethoxysilane onto the framework of the silica gel. The spherical amine grafted silica gels were dried using vacuum drying to prepare the spherical amine grafted silica aerogels (SASAs). The synthetic mechanism of the SASAs was proposed. The structures and the CO2 adsorption performances of SASAs were researched. The amine loading of the SASAs increased with the grafting time, however, the specific surface area and pore volume sharply decreased owing to the blockage of the pore space. Excess amine loading led to the decrease of the CO2 adsorption capacity. The optimal CO2 adsorption capacity was 1.56 mmol g−1 with dry 1% CO2 and at 35 °C. This work provides a low-cost and environmentally friendly way to design a capable and regenerable adsorbent material.

Carbohydrate coated fluorescent mesoporous silica particles for bacterial imaging

This work investigated the synthesis of carbohydrate functionalized methylene blue doped amine grafted mesoporous silica nanoparticles (MB AMSN) and their application in bioimaging. A single-pot synthesis methodology was developed via a modified co-condensation sol-gel technique for simultaneous incorporation of the dye molecule in the nanoparticles, with amine grafting for subsequent functionalization. The obtained nanoparticles (∼ 450 nm) are mesoporous and have a high surface area (538 m2/g), pore-volume (0.3 cm3/g), showed excellent UV-vis absorbance, and dye encapsulation efficiency (> 75 %). These fluorescent nanoparticles were further functionalized with carbohydrate molecules before application as contrast agents in bacterial cells. In the present study, gram-positive (E. coli) and gram-negative (B. subtilis) bacteria were used as model organisms. Confocal laser microscopy results showed that the nanoparticles are highly fluorescent, and SEM of glucose conjugated MB doped nanoparticles indicated close interaction with E. coli with no toxicity observed towards either bacterial cells. The results demonstrate that by suitable surface functionalization, the methylene blue doped silica nanoparticles can be used as bioimaging agents.

Selectivity of Copper by Amine-Based Ion Recognition Polymer Adsorbent with Different Aliphatic Amines.

This paper investigates the selectivity of GMA-based-non-woven fabrics adsorbent towards copper ion (Cu) functionalized with several aliphatic amines. The aliphatic amines used in this study were ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA). The non-woven polyethylene/polypropylene fabrics (NWF) were grafted with glycidyl methacrylate (GMA) via pre-radiation grafting technique, followed by chemical functionalization with the aliphatic amine. To prepare the ion recognition polymer (IRP), the functionalized amine GMA-grafted-NWF sample was subjected to radiation crosslinking process along with the crosslinking agent, divinylbenzene (DVB), in the presence of Cu ion as a template in the matrix of the adsorbent. Functionalization with different aliphatic amine was carried out at different amine concentrations, grafting yield, reaction temperature, and reaction time to study the effect of different aliphatic amine onto amine density yield. At a concentration of 50% of amine and 50% of isopropanol, EDA, DETA, TETA, and TEPA had attained amine density around 5.12, 4.06, 3.04, and 2.56 mmol/g-ad, respectively. The amine density yield decreases further as the aliphatic amine chain grows longer. The experimental condition for amine functionalization process was fixed at 70% amine, 30% isopropanol, 60 °C for grafting temperature, and 2 h of grafting time for attaining 100% of grafting yield (Dg). The prepared adsorbents were characterized comprehensively in terms of structural and morphology with multiple analytical tools. An adsorptive removal and selectivity of Cu ion by the prepared adsorbent was investigated in a binary metal ion system. The IRP samples with a functional precursor of EDA, the smallest aliphatic amine had given the higher adsorption capacity and selectivity towards Cu ion. The selectivity of IRP samples reduces as the aliphatic amine chain grows longer, EDA to TEPA. However, IRP samples still exhibited remarkably higher selectivity in comparison to the amine immobilized GMA-g-NWF at similar adsorption experimental conditions. This observation indicates that IRP samples possess higher selectivity after incorporation of the ion recognition imprint technique via the radiation crosslinking process.

Formation and Properties of Electron- and Ion-Conducting Layers of N-Substituted PVC Derivatives Grafted onto Active Carbon

A systematization is presented of studies of carbon sorbent functionalization based on chemical modification of the active carbon surface by covalent grafting of macromolecular N-substituted cyclic amines. Thus, porous electron-conducting and luminescent layers grafted onto supports are obtained. The layers can sorb organic compounds. After sorption of acids, hydroxides, and metal salts, the layers become electron- and ion-conducting. Here, hydrogen is formed as in cathodically polarized electrochemical bridges and oxygen is formed as in anodically polarized electrochemical bridges. Principles of layer formation are considered on the surface of the material of cellulose fibers and asbestos cloth, as well as nickel filaments. Specific features of such functionalized sorbents are shown.

Effects of primary amine-based coatings on microglia internalization of nanogels

Nanogels represent a pivotal class of biomaterials in the therapeutic intracellular treatment of many diseases, especially those involving the central nervous system (CNS). Their biocompatibility and synergy with the biological environment encourage their cellular uptake, releasing the curative cargo in the desired area. As a main drawback, microglia are generally able to phagocytize any foreign element overcoming the blood brain barrier (BBB), including these materials, drastically limiting their bioavailability for the target cells. In this work, we investigated the opportunity to tune and therefore reduce nanogel internalization in microglia cultures, exploiting the orthogonal chemical functionalization with primary amine groups, as a surface coating strategy. Nanogels are designed by following two methods: the direct grafting of aliphatic primary amines and the linkage of -NH2 modified PEG on the nanogel surface. The latter synthesis was proposed to evaluate the combination of PEGylation with the basic nitrogen atom. The achieved results indicate the possibility of effectively modulating the uptake of nanogels, in particular limiting their internalization using the PEG-NH2 coating. This outcome could be considered a promising strategy for the development of carriers for drugs or gene delivery that could overcome microglia scavenging.

Uranium(VI) and zirconium(IV) sorption on magnetic chitosan derivatives – effect of different functional groups on separation properties

AbstractBACKGROUNDThe recovery of metal ions from aqueous solutions for environmental preservation or resource saving requires the development of new sorbents with enhanced separation properties. A new process has been designed for the functionalization of magnetic chitosan microparticles with grafting of either amidoxime (AO‐AHC) or hydrazinyl amine (HZ‐AHC). Their sorption properties have been tested for the recovery of uranium(VI) and zirconium(IV) from aqueous solutions.RESULTSA wide range of analytical tools is used for characterizing not only the chemical modifications but also the interaction mode between the sorbent and target metal ions; including elemental analysis and titration, Fourier‐transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS) characterizations, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) observations, energy‐dispersive X‐ray spectroscopy (EDX) analysis and textural characterization. The optimum pH values were found in the range 4–5. The maximum sorption capacities depend on the metal and the kind of functionalization: up to 1.38 mmol U g−1 for AO‐AHC and up to 1.96 mmol Zr g−1 for HZ‐AHC. The small size of magnetic particles limits the contribution of diffusion mechanisms in the overall control of uptake kinetics and the equilibrium is reached within 40–60 min. Metal desorption is highly effective (almost quantitative over five successive cycles of sorption and desorption) using 0.3 M hydrochloric acid solutions.CONCLUSIONAO‐AHC sorbent is more selective than HZ‐AHC in terms of separation of uranium(VI) from zirconium(IV), especially at pH close to 4. The results obtained in the treatment of acidic ore leachates confirm these trends. © 2019 Society of Chemical Industry

A facile synthesis of hydroxyl functionalized graphene oxide as an electrode material for energy storage devices

In this case, a facile synthesis of alcohol functionalized graphene oxide (GO) material has been made using water soluble, non-toxic, biocompatible tris buffer (TB) and diethenolamine (DEA). This functional material was characterized by various techniques such as, XRD, TEM, XPS, Raman, TGA and Cyclic voltametry (CV). The molecular level grafting of amines to graphene has been occurred due to the functionalization of alcohol by the enlargement of interlayer spacing and specific surface area. The synthesized material shows high specific capacitance value of 372 and 252 F g−1 at a current density of 1 A g−1 in 6% KOH solution.

Base‐Assisted Electrografting of Aromatic Amines

AbstractContrary to aliphatic amines, aromatic amines have received less attention for surface modification by oxidation due to the low acidity of their cation radicals. To overcome this limitation, bases are often added into the solution to facilitate or to make the grafting possible. However, there has only been a modest focus on their impact on the grafting efficiency. Here, the anodic behavior of a series of para‐substituted anilines was investigated in the presence of different bases to address this issue. From complete sets of Brønsted acidity/basicity data and H‐bond acidity/basicity factors for both para‐substituted anilines and bases, a grafting efficiency index was proposed as a practical tool to choose the most suitable base for the grafting. As a proof‐of‐concept for base‐assisted grafting of aromatic amines, two aniline/base systems were tested to modify carbon surfaces at lower potential, compared to the modification achieved from pure aniline solutions.

Solvent-Free Synthesis of Amidated Carboxymethyl Cellulose Derivatives: Effect on the Thermal Properties.

The present work explores the possibility of chemically modifying carboxymethyl cellulose (CMC), a widely diffused commercial cellulose ether, by grafting of hydrophobic moieties. Amidation of CMC, at high temperature and in heterogeneous conditions, was selected as synthetic tool for grafting on CMC a panel of commercially available amines (bearing long aliphatic chains, alkyl aromatic and heteroaromatic groups, more or less spaced from the cellulose backbone). The reaction was successfully carried out in absence of solvents, catalysts and coupling agents, providing a promising and more sustainable alternative to conventional amidation procedures. Relationships between the chemical structure of the obtained CMC derivatives and their thermal properties were carefully studied, with a particular attention to the thermal behavior. Grafting of aromatic and heteroaromatic alkyl amines, presenting a linear alkyl chain between CMC backbone and a terminal bulky moiety, allowed for efficiently separating the polysaccharide chains, improving their mobility and resulting in a consequent lowering of the glass transition temperature (Tg). The Tg values obtained (90–147 °C) were found to be closely dependent on both the size of the aliphatic spacer, the structure of the aromatic ring and the extent of amidation.

Amine grafting of acid-activated bentonite for carbon dioxide capture

A low-cost bentonite (ZBent) and acid-activated derived samples have been employed as clay adsorbents to assess their performance for pure CO2 adsorption in a thermogravemetric system. The raw bentonite reached a CO2 uptake of only 6.2 mg/g ads due to its low specific surface area and pore volume. After acid modification, an increase in its specific surface area and pore volume was observed, due to the leaching of octahedral cations and the generation of an amorphous silica phase. However, the degradation of the clay structure only improved slightly the adsorption of CO2. In a next step, raw and acid-treated clay minerals were functionalized with two different amine species (aminopropyl-trimethoxysilane; AP, and diethylene-triamine-trimethoxysilane; DT) by grafting. Unlike the case of DT species, the incorporation of AP moieties favored the chemical interaction between the amines species and the CO2 molecules in all cases. Functionalization with AP molecules increased the adsorption capacity of CO2 up to 29.2 mg/g ads at 30 °C for ZBent-24 h-AP, the material obtained after longer acid treatment time and functionalized with AP. AP-functionalized samples also had good stability and reusability during eight cyclic adsorption/desorption tests.

CuO Nanosheets Modified with Amine and Thiol Grafting for High Catalytic and Antibacterial Activities

The aim of the present study is to develop an ecofriendly and cost-effective method for the synthesis and functionalization of copper oxide (CuO) nanosheets by chemical grafting of 3-(chloropropyl)triethoxysilane (ClPTES), p-aminothiophenol (ATP) and diethanolamine (DEA). Full characterization of the resulting materials through FTIR, X-ray diffraction (XRD), scanning–transmission electron microscopy (STEM) and energy-dispersive X-ray fluorescence (ED-XRF) allowed confirmation of the grafting of ClPTES, ATP, DEA, and CuO crystalline phase and assessment of the average size of the as-prepared CuO (500 nm) and its high purity, respectively. Cu functionalization was found to confer high catalytic activity in 4-nitrophenol (4-NP) reduction into 4-aminophenol (4-AP), methylene blue (MB) degradation, and decomposition of their mixture. Besides, DEA- and ATP-modified CuO also exhibited appreciable antibacterial capacity against Staphylococcus epidermidis and Escherichia coli. These results are of great importance...

Evaluation of the thermal regeneration of an amine-grafted mesoporous silica used for CO2/N2 separation

In view of the promising applicability of adsorption to the capture of CO2 from post-combustion gases, the use of mesoporous silica functionalized with 3-aminopropyltriethoxysilane (APTES) was studied as adsorbent in a fixed bed for CO2–N2 separation under thermal swings. Characterization of the adsorbent performed before and after functionalization indicated that amine grafting was successful. Additionally, CO2 adsorption on a magnetic suspension balance showed a significant increase in uptake of the APTES-functionalized sample over the support, mainly at low relative pressures. Relatively high values of adsorption enthalpy suggest the occurrence of chemical adsorption attributed to CO2 bonding with the amines. Breakthrough curves were measured for pure CO2, N2 and the CO2/N2 (15/75% v/v) mixture, which showed good agreement with respect to the uptake of the individual gases, as determined from gravimetric tests. Full CO2 desorption from the bed required a temperature rise, which suggests that these materials may be suitable for TSA cyclic processes. A temperature of 90 °C was enough for a complete regeneration of the adsorbent during the desorption phase under dynamic conditions. The material showed very stable behavior after 20 successive cycles.

Highly recyclable cysteamine-modified acid-resistant MOFs for enhancing Hg (II) removal from water

ABSTRACT Thiol-functionalized metal-organic frameworks (MIL-101-SH and UiO-66-SH) were synthesized by a post-synthetic modification method as the proper adsorbents for Hg (II) removal from water. This facile method for the synthesis of UiO-66-SH was developed via a condensation reaction between cysteamine and carboxyl groups present in the framework of UiO-66-COOH. MIL-101 was functionalized by grafting amine group of cysteamine on coordinatively unsaturated chromium ions centres, yielding to MIL-101-SH adsorbents. These two types of thiol-functionalized MOFs samples by cysteamine-modified were characterized by XRD, XPS, FTIR and N2 adsorption–desorption isotherms respectively, which prove the successful modification of the thiol groups. The maximum adsorption capacities of mercury ions for UiO-66-SH and MIL-101-SH adsorbents were 110 and 250 mg/g at pH of 5, respectively. Moreover, the acidic medium could effectively elute Hg (II) and the adsorbents can be well reusable.

Grafting of amine functions on cellulose acetate fibers by plasma processing

The aim of this study was to graft the amine functions on the surface of cellulose acetate (CA) fibers by two kind of plasma processing; namely, inductively coupled plasma (ICP) and radiofrequency plasma, using either NH3/He or mixture of N2/H2 gases. Optical emission spectroscopy was used to examine the various chemical species of the N2/H2 ICP system. Due to the entangled morphology of the CA fibers, only X-ray photoelectron spectroscopy (XPS) was used to characterize the surface. The effects of the different experimental conditions on the grafting efficiency have been studied. The results showed that in all cases NH2 groups were successfully grafted onto the surface of the CA fibers, and it seems that the ICP process is more effective for the amine grafting than low pressure radiofrequency plasma. Ageing tests carried out under laboratory conditions on the plasma-treated CA tow showed that the density of grafted amines was almost stable over a period of 60 days.

Graphene oxide modification for enhancing high-density polyethylene properties: a comparison between solvent reaction and melt mixing

Abstract Graphene oxide (GO) was chemically modified in xylene with dodecyl amine and hydrazine monohydrate to obtain reduced functionalized graphene oxide (RFGO). Composites of high-density polyethylene (HDPE) and GO were made via solvent reaction, whereas both melt mixing and solvent reaction were used for HDPE-RFGO composites for comparison purposes. Elemental and thermal analysis showed the success of GO modification in grafting amine functionalities onto its structure and restoring most of the original graphene C=C bonds. A significant increase in mechanical properties, thermal stability, and crystallization behavior was observed for HDPE-RFGO (solvent) compared with HDPE and HDPE-GO, proving that homogeneous dispersion of RFGO in the polymer matrix and strong interactions between them resulted in facilitated stress transfer, delayed thermal degradation, and more efficient nucleating effect in inducing the crystal growth of HDPE. A comparison of HDPE-RFGO properties enhancement between the melt mixing method and the solvent reaction method showed that, apart from mechanical behavior, the RFGO contribution was the same, suggesting that the optimization of the ecofriendlier approach (melt) could eventually lead to its total use for the mass production of high-performance, cost-effective, and more environmentally friendly graphene-based thermoplastic polyolefin nanocomposites suitable for highly demanding industrial applications.

Electrochemical functionalization of single-walled carbon nanotubes with amine-terminated dendrimers encapsulating Pt nanoparticles: Toward facile field-effect transistor-based sensing platforms

We present a method for functionalization of single-walled carbon nanotubes (CNTs) with amine-terminated dendrimers encapsulating catalytic nanoparticles, and demonstrate the feasibility of functionalized CNTs as efficient field-effect transistor (FET)-sensing platforms. As a model system, we synthesized Pt dendrimer-encapsulated nanoparticles (DENs) using amine-terminated sixth-generation poly(amidoamine) dendrimers, and functionalized CNT-based FET channels with Pt DENs via electro-oxidative grafting of the terminal amines of dendrimers onto the surface of CNTs. We also demonstrated spatially-controlled surface functionalization of CNTs and subsequent modification of the functionalized CNT-based FET channels with glutamate oxidases for efficient FET-based sensing of glutamates. Our approach could facilitate the functionalization of CNTs with a variety of catalytic nanoparticles and biologically active materials, enabling the development of sensitive and selective FET-based sensor devices.

Recent developments and consideration issues in solid adsorbents for CO2 capture from flue gas

The increase in energy demand caused by industrialization leads to abundant CO 2 emissions into atmosphere and induces abrupt rise in earth temperature. It is vital to acquire relatively simple and cost-effective technologies to separate CO 2 from the flue gas and reduce its environmental impact. Solid adsorption is now considered an economic and least interfering way to capture CO 2 , in that it can accomplish the goal of small energy penalty and few modifications to power plants. In this regard, we attempt to review the CO 2 adsorption performances of several types of solid adsorbents, including zeolites, clays, activated carbons, alkali metal oxides and carbonates, silica materials, metal–organic frameworks, covalent organic frameworks, and polymerized high internal phase emulsions. These solid adsorbents have been assessed in their CO 2 adsorption capacities along with other important parameters including adsorption kinetics, effect of water, recycling stability and regenerability. In particular, the superior properties of adsorbents enhanced by impregnating or grafting amine groups have been discussed for developing applicable candidates for industrial CO 2 capture.

Novel route for amine grafting to chitosan electrospun nanofibers membrane for the removal of copper and lead ions from aqueous medium

A novel step wise synthetic route was developed to prepare amine grafted nanofibers (AGNFs) affinity membrane. The chemical structure of the nanofibers (NFs) after grafting was studied by acquiring Fourier Transform Infrared (FT-IR) spectra and Carbon, Hydrogen and Nitrogen (CHN) data. The morphology of the NFs before and after grafting was studied by Field Emission Scanning Electron Microscope (FE-SEM). FT-IR and CHN data confirmed the introduction of new functional groups into the primary structure of chitosan (CH). FE-SEM showed denser membrane with no deterioration of the NFs morphology after grafting. The aqueous stability of the membranes was studied in distilled water. The AGNFs membranes showed good aqueous stabilities (with only ∼ 6% loss in weight until 24 h and remained stable thereafter) which was less than the weight loss by glutaraldehyde treated nanofibers (GNFs) (∼44% loss in weight until 24 h) and pristine NFs (100% loss in weight as soon as the NFs were immersed in distilled water). The maximum adsorption (qm) capacity of AGNFs for Cu (II) and Pb (II) was observed to be 166.67 mg.g−1 and 94.34 mg.g−1. The adsorption capacity of the present systems was much higher for Cu (II) when compared to the already existing conventional and chitosan adsorbents. This increased might be related not just to the size, but more potentially to the increase in the number of nitrogen binding sites (chelating sites). Nitrogen donates lone-pair of electrons for chelation. The combination of processing into nano size and amine grafting (AG) has significantly increased the adsorption capacity of CH NFs membrane.

Elimination and Substitution Compete During Amination of Poly(vinyl chloride) with Ehtylenediamine: XPS Analysis and Approach of Active Site Index

Various chemical modification methods have been tried on PVC polymer materials for recycling and functionalization purpose. These methods employ substitution, elimination (dehydrochlorination) and grafting polymerization processes. PVC is treated with ethylenediamine (EDA) for amine grafting since it is a reactive amine for substitution and efficient removal of chlorides. Nevertheless, optimum conditions for substitution (amination) and significance of its competition with elimination have not been reported in detail so far. In this study, PVC resin has been treated with 99% EDA and 80% EDA (aqueous), and also 9.1% THF solution of PVC has been treated with 99% EDA at varying temperatures (RT to 85 °C or RT to 65 °C). Additionally, PVC membranes have been treated with 99% EDA and 80% EDA (aqueous) at three different temperatures (RT, 50 °C, 75 °C). Effects of temperature and solvent on the degrees of amination and dehydrochlorination have been elaborated. Up to 99% dechlorination and 34% amination is possible with the use of EDA. Direct amination of membranes facilitates production of ready-cast aminated PVC membranes. FTIR Spectroscopy was used to study chemical structures. Morphology was observed via scanning electron microscopy (SEM) and atomic contents were analyzed via X-ray photoelectron spectroscopy (XPS) in order to survey the degree of amination etc. UV-Visible Spectroscopy was used to characterize the length of conjugation.

Polyfunctional cotton fabrics with catalytic activity and antibacterial capacity

A novel, eco-friendly and cost-effective method involving cotton fabric (CF) coating with copper oxide and grafting of 3-chloropropyltriethoxisilane and diethanolamine resulted in a multifunctional material (CF@CuO-Si-N(OH)2). The latter exhibited catalytic activity in 4-nitrophenol (4-NP) reduction, Methylene Blue degradation and antibacterial activity. Scanning electron microscopy, energy dispersive X-ray-fluorescence, Fourier transform infrared and UV–visible spectroscopies, contact angle and thermogravimetric analysis revealed the key-role of amine grafting in changes in wettability, stability, morphological and thermal properties. 4-NP catalytic reduction was found to obey 1st-order kinetics, affording 98% conversion even after 7 successive reuses. CF@CuO-Si-N(OH)2 also exhibited appreciable antibacterial capacity against Staphylococcus epidermidis (S.epidermidis) and Escherichia coli (E. coli). These results open promising prospects for using textile fiber-based nanocomposites in diverse technological applications.