جستجوی مقالات مرتبط با کلیدواژه "functionalization" در نشریات گروه "شیمی"

Adsorption properties of sulfamethoxazole drug on the pristine (C60) and functionalized (C60HNH2) fullerenes in different situations were calculated by density functional theory calculations using the ωB97XD method and 6-31G(d) standard basis set in gas and solution phase. Based on the adsorption and Gibbs free energies, the adsorption of sulfamethoxazole on the pristine C60, in all situations, was unfavorable, but its adsorption on the functionalized fullerene was spontaneous and favorable, in two situations. Also, in agreement with the Gibbs free energy data, functionalized fullerene have the negative solvation energy in two situations, therefore, it can be suitable as a nano-carrier in the drug delivery systems. In addition, the nature of interaction between sulfamethoxazole and functionalized fullerene in the most favorable situation, was analyzed by the independent gradient model based on Hirshfeld partition (IGMH). The [4+2] cycloaddition reactions of SMX with the fullerenes were also studied and the results ruled out the possibility of chemical adsorption via such reactions.

Organochlorine pesticides (OCPs) have been extensively used in agriculture to boost crop yields, creating a significant and enduring global contaminant with adverse effects on the environment and human well-being. These pesticides are characterized by their bioaccumulative and persistent nature, capable of long-distance dispersion. To address this challenge, efforts are ongoing to develop advanced technologies for effectively removing OCPs from the environment, thereby mitigating their impact through appropriate treatment methods in soil and other environmental matrices. Specifically, extensive research has been conducted on the utilization of nanomaterials, including TiO2, Fe2O3, graphene, and graphene oxide, as sorbents in sample preparation and degradation techniques. Graphene (G) and graphene oxide (GO) exhibit unique combination of outstanding characteristics derived from carbon materials (such as exceptional physical, chemical properties, mechanical, and electronic features), deep eutectic solvents (DES) (acting as a functionalization agent), and nanomaterials (including an ultrahigh surface area, abundant functional groups, and a nanometer-scale structure). This review focuses on the adsorption and degradation of OCPS and their metabolites using the remarkable attributes of a mixed graphene-based sorbent, deep eutectic solvents (DES) and MNPs. The combination of these materials, with features such as an expansive surface area (2630 m² g-¹), hydrophilicity, inherent adsorption sites on both sides for molecules, hydrophobicity, double-sided polyaromatic scaffold, adaptable surface modification, hydrogen-bonding, and extensive π-electron structure, positions them as excellent advanced adsorbents and efficient photocatalysts for Magnetic Solid Phase Extraction (MSPE) and Solid Phase Extraction (SPE). These characteristics make them suitable for extracting OCPs from different environmental matrices such as food, environment water, medicine, and biological samples.

Graphene Oxide has been synthesized using Hummer’s method by the oxidation of graphite powder using reagents like potassium permanganate, Sulphuric acid, hydrogen peroxide, and distilled water at low temperatures. The filtered suspension of graphene oxide was changed to a dry powder at room temperature. Synthesized Graphene oxide was further modified by functionalizing using diamine 2,6-bis(4-aminophenoxy)benzonitrile (BAAP) by ultrasonication and reflux methodology, air-cooled mixture was washed with the equimolar ratio of ethanol and water which was dried at room temperature and followed by drying in the oven at 80 oC. The sample was characterized by Fourier Transform InfraRed (FT-IR) spectroscopy which confirmed all required functional groups and proved the functionalization and modification of Graphene Oxide. Further, UV-Visible spectroscopy confirmed the slight reduction of graphene oxide by the redshift which is due to the chromophoric effect of diamine. X-ray diffraction also confirmed the expected d-spacing due to the covalent reduction of graphene oxide by shifting the peak position towards higher 2θ values. The cyclic voltammetry results are in a quasi-rectangular shape, due to the pseudocapacitance behaviour of diamine functionalized graphene oxide; successfully synthesised and functionalized graphene oxide showed electrochemical stability and an increase in capacitance with an increase in scan rates which is the promising property for supercapacitance to ensure energy storage and conservation.

A chemically modified glassy carbon electrode was developed using multi-walled carbon nanotubes covalently immobilized with 2,6-dichlorophenolindophenol. The immobilization of 2,6-dichlorophenolindophenol with multi-walled carbon nanotubes was characterized by UV–visible absorption spectroscopy and Fourier transform infrared spectroscopy, and was determined using cyclic voltammetry. The cyclic voltammetric response of 2,6-dichlorophenolindophenol grafted onto multi-walled carbon nanotubes indicated that it promoted the electrocatalytic, sensitive and stable determination of sulfide ions. Meanwhile, the dependence of response currents on the concentration of sulfide was also examined and was linear in the range of 1.8 µM – 2.5 mM. The detection limit of sulfide was 1.1 µM, and RSD for 10 and 1000 µM sulfide was 1.8 and 1.3 %, respectively. Many interfering species had little or no effect on the determination of sulfide. This procedure was applied for determination of sulfide in water samples.

Facile hydrothermal synthetic technique was employed for the fabrication of SALEN grafted multifunctional nanocomposite biochar with the main aim of efficient and effective removal of cadmium (Cd). The elemental composition and structure of the composite and the cadmium loaded sorbent were characterized using EDX, FTIR and SEM. Variables affecting cadmium removal such as initial metal ion concentration, contact time and pH were investigated by batch experiment. Maximum adsorption capacity of 8220 mg/kg was obtained at optimal pH 10 with percentage removal efficiency of 99.30 % for 4480 ppm initial metal ion dosage. Data simulated into the adsorption and kinetic models fitted well the Freundlich isotherm implicating multilayer adsorption – chemisorption process and pseudo-second –order kinetics as the rate limiting step. Critical examination of the adsorption mechanism showed that inner-sphere complexation, ion exchange, co-precipitation and electrostatic attraction are the main driving force in the mechanistic interaction of the SALEN Schiff base N2O2 surface functionalized nanocomposite biochar with cadmium. The new nanocomposite is of low cost, benign, effective and efficient for the removal of cadmium in comparison with industrial sorbents and other functionalized biomaterials and highly recommended for decontamination of cadmium polluted sites.

The lack of a high-yield, renewable and low-cost synthesis method limits the potential applications of boron nitride with impressive characterizations. In this study, a facile method is developed for the preparation of chemically functionalized boron nitride nanosheets (BNNSs) by considering the quantity and quality of chemical materials involved in the synthesis process. The proposed green method is a suitable and high-efficiency method for replacing other production methods of BNNSs. Ultrathin BNNSs is produced by chemical reactions and subsequent liquid exfoliation. The possibility of chemical reaction is the highest at the defect sites especially at the upper/lower surfaces as well as the edge of bulk material. Due to hydroxyl functional groups that are coupled to the surface during the synthesis, the obtained products can well be dispersed in polar solutions such as water, ethanol, acetone and isopropyl alcohol. AFM, TEM, and SEM techniques are utilized to confirm the quality of the used method and illustrated that the produced-BNNSs have minimum thicknesses in the range of 1–5.6 nm and with lateral sizes ranging from 0.8–2.5 μm. The existence of functional groups and the structure of the BNNSs are verified by FTIR, EDX, XPS, XRD and Raman analyses. It was seen that the hexagonal structure was retained during the functionalization procedure. One can expect that the functionalization and sonication process introduces functional groups onto the surface of BNNSs. By this method, the obtained yield of BN dispersion is improved up to 17-20%.

The Fischer–Tropsch Synthesis (FTS) activities of cobalt-based catalysts supported on carbon nanotubes (CNTs) and functionalized carbon nanotubes (FCNTs) are investigated in this work. The cobalt-based catalysts are synthesized by the reverse micro-emulsion technique using a non-ionic surfactant, and characterized by the Brunauer-Emmett-Teller, X-ray diffraction, H2 chemisorption, temperature program reduction, and transmission electron microscopy techniques. The activities of the synthesized catalysts are evaluated in terms of the FTS production rate (g produced hydrocarbons /g.cat./h) and selectivity (percentage of the CO converted to hydrocarbon products). According to the TEM results, the synthesized cobalt nanoparticles have a narrow size distribution and are mostly confined inside the functionalized CNTs (FCNTs) . These nanoparticles are highly reducible as evidenced by the reduction peaks of the FCNT catalyst shifting to low temperatures. In comparison to non-functionalized CNT, FCNT increases the FTS rate and CH4 selectivity and decreases the C5+ selectivity as a catalytic support. In addition, the FCNT support preserves the high dispersion and reducibility of cobalt, which can be attributed to the hydrogen spill-over effect of the functional groups present on the CNT surface.

Bacteria can grow in different materials that are in close contact with humans, foods, etc., so, it is very important to control this matter in order to prevent risk of infections. Antimicrobial resistance (AMR) threatens the effective prevention and treatment of an ever-increasing range of infections caused by bacteria, parasites, viruses and fungi. Multiwall carbon nanotubes (MWNTs) have interesting antibacterial activities and offering a promising new treatment preventing bacteria from becoming resistant. With this aim, we report for the first time three novel modified carboxylated multiwall carbon nanotubes consisting of MWNT–CO-Metformin, MWNT–CO- [Metformin][CuCl2] and MWNT–CO-[Metformin][AgNO3]. The functionalized carboxylated multiwall nanotubes were then characterized by FT-IR, Raman, TEM, EDX and Elemental analysis. Moreover, the antibacterial activity of all of compounds has been investigated against gram-negative Escherichia coli and gram-positive Staphylococcus aureus. These results show that nano compounds exhibited significant antibacterial activity and have a potential to be used as antibacterial agent.

In this study, kinetics and mechanism of the sulfur dioxide adsorption on the single-walled carbon nanotubes (CNT) are investigated. Three single-walled carbon nanotubes, including the armchair (6,6), chiral (6,5) and zigzag (6,0) CNTs were chosen as the models and the different orientations of SO2 molecule relative to the CNT axis were considered. The B3LYP functional within the 6-31G(d) basis set was used for the theoretical calculations. For all orientations, reaction Gibbs free energies (ΔG˚) were calculated and the transition state structures were investigated for the spontaneous reactions. Chiral single-walled carbon nanotube (6,5) showed the least activation energy (11.72 kcal mol-1) while the armchair model showed the highest one (17.93 kcal mol-1). Natural bond orbital analysis showed that the electronic charge is transferred from CNT to sulfur dioxide. Topological analysis confirmed the C-S bond formation at the transition state. Density of states analysis showed that Fermi level energy is increased in armchair model. The application of the external electric field indicated that the CNTs stability and the functionalization energies are improved. Based on the obtained data, by using the electric field, it is possible to elevate the conductivity of CNT and the functionalization rate of SWCNT for industrial applications.