Pd/TiN nanocomposite catalysts for selective hydrogenation of phenol and its derivatives

Pd/TiN nanocomposite catalysts were fabricated for one-step selective hydrogenation of phenol to cyclohexanone successfully. High conversion of phenol (99%) and selectivity of cyclohexanone (98%) were obtained at 30℃ and 0.2 MPa H₂ for 12 h in the mixed solvents of H₂O and CH₂Cl₂. The Pd nanoparticles were stable in the reaction, and no aggregation was detected after four successive runs. The catalytic activity and selectivity depended on slightly the Pd particle sizes. The generality of the catalysts for this reaction was demonstrated by the selective hydrogenation of phenol derivatives, which showed that the catalyst was selective for the formation of cyclohexanone.     

Poly(butyl methacrylate)-grafted alginate/Fe3O4 nanocomposite: Synthesis and its application for removal of dyes

This study involved the utilization of a free radical-graft copolymerization reaction for the development of a novel adsorbent, namely, poly(butyl methacrylate)-grafted alginate/Fe₃O₄ nanocomposite (PBMA-gft-Alg/Fe₃O₄). Transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction patterns analysis, and Fourier transform infrared spectroscopy (FT-IR) were carried out for the characterization of Fe₃O₄ NPs and PBMA-gft-Alg/Fe₃O₄ nanocomposites. The capability of nanocomposites and nanoparticles to adsorb dyes such as MG and MB, resulting in their removal from aqueous media, was evaluated under different conditions such as pH, temperature, contact time, and dose of adsorbent. Optimum parameters for adsorption of dyes were found to be pH of 10, 50°C, contact time of 180 min, and 0.2 g of adsorbent. Efficiency of the PBMA-gft-Alg/Fe₃O₄ nanocomposite was found to be significantly greater than that of Fe₃O₄ NPs for eliminating the desired dye. Langmuir, Freundlich, Sips, and Temkin models were used for testing the experimental data. Freundlich model was the one that best described the adsorption.     

Synthesis of EDTA-modified magnetic activated carbon nanocomposite for removal of permanganate from aqueous solutions

In this study, activated carbon particles were magnetized by different amounts of maghemite in different temperatures using co-precipitation method and the resultant nanocomposite were modified with ethylenediaminetetraacetic acid (EDTA) to increase the permanganate contaminants adsorption capacity and to prevent degradation and oxidation of maghemite nanoparticles. Various properties of nanocomposite were investigated using different techniques including, vibrating sample magnetometer, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectrometer. Different kinetics, isotherms and thermodynamic models of adsorption process were investigated. Comparing data with kinetic models showed that the adsorption process complies with the pseudo-second-order kinetic model. The study of equilibrium isotherms data at different temperatures indicated that the adsorption process is more compatible with Langmuir model. Negative values of ΔG and positive values of ΔH revealed that adsorption process is spontaneous and endothermic. Response surface methodology was used to determine optimal parameters of an adsorbent dose of 1 g L⁻¹, pH = 2 and initial permanganate concentration of 50 mg L⁻¹, according to which, the maximum capacity of permanganate adsorption obtained under optimal conditions was 93.86 mg g⁻¹.     

炭黑/聚苯胺纳米复合粒子的制备与表征

用现场原位聚合法制备了炭黑/聚苯胺纳米复合粒子,讨论了聚合反应条件对产物电导率的影响,并表征了复合粒子的形态和耐热性能.结果表明,所得的炭黑/聚苯胺纳米复合粒子粒度约为50 nm并具有核-壳结构,其电导率达30 S.cm-1,热分解温度约为600℃.     

Synthesis of iron-MFI zeolite and its photocatalytic application for hydroxylation of phenol

This work focuses on the preparation of Fe-MFI zeolites by a one-step method with different iron concentrations and their characterization by different methods such as X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), nitrogen sorption measurements at 77 K, scanning and transmission electron microscopy (SEM and TEM), and UV–Vis reflectance diffuse spectroscopy. The results show that the modification of the zeolites with high iron concentrations led to the formation of well-dispersed oxides within the framework, decreasing the specific surface area. The photocatalytic activity of the iron-modified zeolites was evaluated using hydroxylation of phenol with hydrogen peroxide at room temperature. High conversion (80%) of phenol was obtained by Fe–Al-MFI (0.5) containing lower iron concentration. Interesting selectivity towards catechol was achieved, confirming that the reaction is influenced by sites on the external surface.     

Ag-Co3O4@MWCNTs纳米复合材料的合成及其在多巴胺检测中的应用

本文使用水热法制备了Ag-Co₃O₄@MWCNTs纳米复合材料,使用扫描电镜和能谱仪对材料进行了表征。将Ag-Co₃O₄@MWCNTs纳米复合材料与壳聚糖超声混合均匀,并修饰到玻碳电极(GCE)表面,得到Ag-Co₃O₄@MWCNTs/GCE电化学传感器。电化学测定结果表明,该修饰电极对多巴胺的电化学反应具有显著的催化作用。峰电流与多巴胺浓度在0.5~377.5μmol·L^-1范围内具有良好的线性关系,检出限为0.16μmol·L^-1(S/N=3)。该传感器具有线性范围宽、检出限低、灵敏度高等优点,可用于人体血清样品中多巴胺的含量分析。     

Synthesis of polyamidoamine dendrimer (PAMAM/CuS/AA) nanocomposite and its application in the removal of Isma acid fast yellow G Dye

The adsorption of Isma acid fast yellow G dye was studied using polyamidoamine (PAMAM)/Copper sulfide (CuS)/AA nanocomposite containing different amounts of CuS by batch technique. PAMAM dendrimer/CuS/AA nanocomposites were synthesized via gamma irradiation cross‐linking method with the aid of sonication. The nanocomposites were characterized by Fourier‐transform infrared, X‐ray diffraction, transmission electron microscope, energy dispersive spectroscopy X‐ray, thermal gravimetric analysis, ultraviolet‐visible, and fluorescence spectroscopy. The size of the CuS nanoparticles was formed in the range of 12–19 nm. The adsorption capacity of the nanocomposites was evaluated as a function of initial dye concentration, pH, adsorbent dosage, and time. It was verified that the adsorption rate fits a pseudo‐second‐order kinetics for initial Isma acid fast yellow G dye concentrations. Results indicated that the adsorption of Isma acid fast yellow G dye fitted well to the Langmuir model. Our results demonstrate that the PAMAM dendrimer/CuS/AA nanocomposite is very promising for removing organic dyes from wastewater. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and characterization of styrene grafted carbon nanotube and its polystyrene nanocomposite

Effective side wall functionalization of single-walled carbon nanotube (SWCNT) with 4-vinylaniline was carried out through solvent free functionalization. The functionalized SWCNT was characterized through FT-IR and NMR. Typical peaks to identify the functionalization were observed. Thermal analysis shows around 48% weight loss in functionalized SWCNT in comparison to the pure SWCNT. The ratio of disordered to order transition (I_D/I_G) in FT-Raman, indicated the generation of some surface defects due to functionalization. Near infrared spectrum of functionalized SWCNT also confirmed the functionalization of SWCNT. The polystyrene nanocomposite materials were prepared with functionalized SWCNT as fillers by solution casting from tetrahydrofuran. The functionalized SWCNT nanocomposite showed significant improvement in mechanical properties and electrical properties. The dispersibility of the carbon nanotube in the composite was investigated by using scanning electron microscopy.     

Synthesis and characterisation of magnetic activated carbon/diopside nanocomposite for removal of reactive dyes from aqueous solutions: experimental design and optimisation

In this work, a series of magnetic activated carbon/nanodiopside (Fe₃O₄/AC/Diop) nanocomposites were synthesised and used for the removal of reactive green KE-4BD dye from the aqueous solution. After preparation of nanodiopside by sol-gel method and activated carbon from coconut husk, first, Fe₃O₄/AC composite was prepared by in situ synthesis of Fe₃O₄ nanoparticles between activated carbon pores, and then, different percentages of Fe₃O₄/AC/Diop nanocomposites were prepared by simple mixing of Fe₃O₄/AC composite and Diop in ethanol. Formation of Fe₃O₄/AC and Fe₃O₄/AC/Diop composites was characterised by FTIR, field emission scanning electron microscopy, BET, XRD and vibrating sample magnetometer analyses. Thermogravimetric analysis was used to show the adsorption capacity of the adsorbent more accurately. Effects of amount of adsorbent, initial pH, contact time and dye concentration on reactive green dye removal were also studied using central composite design. Optimal conditions for maximum reactive green KE-4BD dye adsorption (98.35%) process were as follows: pH= 4.90, adsorbent amount: 0.015 g, dye concentration: 37.17 mg/L and contact time: 10.12 min, respectively. In addition, the adsorption kinetics, thermodynamics and isotherms were examined. Adsorption isotherms (q_max: 344.827 mg/g), kinetics and thermodynamics were demonstrated that the sorption processes were better described by the pseudo-second-order equation and the Langmuir equation.     

Synthesis of a MnO2/multiwalled carbon nanotube nanocomposite and its application as a sorbent for removing Cu2+ ions from aqueous media

In this research, a manganese dioxide/multiwalled carbon nanotube (MnO₂/MWCNT) was firstly synthesized and characterized and then was applied as an effective sorbent for removing Cu²⁺ ions from aqueous solution. The effects of initial concentration, temperature, contact time, pH solution, and sorbent dosage were investigated and the optimum value of each was determined. The Langmuir isotherm model, Freundlich model, and Temkin model were used to fit our experimental results. Ultimately, using the Van't Hoff approach, the thermodynamic functions of the intended adsorption phenomenon such as ΔH°_ad, ΔS°_ad, and ΔG°_ad were estimated.     

Catalytic and peroxidase-like activity of carbon based-AuPd bimetallic nanocomposite produced using carbon dots as the reductant

In this report, carbon-based AuPd bimetallic nanocomposite (AuPd/C NC) was synthesized using carbon dots (C-dots) as the reducing agent and stabilizer by a simple green sequential reduction strategy, without adding other agents. The as synthesized AuPd/C NC showed good catalytic activity and peroxidase-like property. The structure and morphology of these nanoparticles were clearly characterized by UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The AuPd/C NC catalyst exhibits noticeably higher catalytic activity than Pd and Au nanoparticles in catalysis reduction of 4-nitrophenol (4-NP). Moreover, based on the high peroxidase-like property of AuPd/C NC, a new colorimetric detection method for hydrogen peroxide (H₂O₂) has been designed using 3,3′,5,5′-tetramethyl-benzidine (TMB) as the substrate, which provides a simple and sensitive means to detect H₂O₂ in wide linear range of 5 μM–500 μM and 500 μM–4 mM with low detection limit of 1.6 μM (S/N = 3). Therefore, the facile synthesis strategy for bimetallic nanoparticles by the mild reductant of carbon dot will provide some new thoughts for preparing of carbon-based metal nanomaterials and expand their application in catalysis and analytical chemistry areas.     

Adsorbents based on carbon microfibers and carbon nanofibers for the removal of phenol and lead from water

This paper describes the production, characteristics, and efficacy of carbon microfibers and carbon nanofibers for the removal of phenol and Pb(2+) from water by adsorption. The first adsorbent produced in the current investigation contained the ammonia (NH(3)) functionalized micron-sized activated carbon fibers (ACF). Alternatively, the second adsorbent consisted of a multiscale web of ACF/CNF, which was prepared by growing carbon nanofibers (CNFs) on activated ACFs via catalytic chemical vapor deposition (CVD) and sonication, which was conducted to remove catalytic particles from the CNF tips and open the pores of the CNFs. The two adsorbents prepared in the present study, ACF and ACF/CNF, were characterized by several analytical techniques, including SEM-EDX and FT-IR. Moreover, the chemical composition, BET surface area, and pore-size distribution of the materials were determined. The hierarchal web of carbon microfibers and nanofibers displayed a greater adsorption capacity for Pb(2+) than ACF. Interestingly, the adsorption capacity of ammonia (NH(3)) functionalized ACFs for phenol was somewhat larger than that of the multiscale ACF/CNF web. Difference in the adsorption capacity of the adsorbents was attributed to differences in the size of the solutes and their reactivity towards ACF and ACF/CNF. The results indicated that ACF-based materials were efficient adsorbents for the removal of inorganic and organic solutes from wastewater.     

Synthesis of carbon nanotube‐based nanocomposite and application for wastewater treatment by ultrasonicated adsorption process

The sorption of methylene blue (MB) and basic yellow 28 (BY28) dyes in water on Ag@ZnO/MWCNT (Ag‐doped ZnO loaded on multiwall carbon nanotubes) nanocomposite is investigated in a batch process, optimizing starting initial dye concentration, sonication time and adsorbent mass. Isotherms and kinetic behaviours of MB and BY28 adsorption onto Ag@ZnO/MWCNT were explained by extended Freundlich and pseudo‐second‐order kinetic models. Ag@ZnO/MWCNT was synthesized and characterized using X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, field emission scanning electron microscopy and Brunauer–Emmett–Teller analysis. According to the experimental data, adaptive neuro‐fuzzy inference system (ANFIS), generalized regression neural network (GRNN), backpropagation neural network (BPNN), radial basic function neural network (RBFNN) and response surface methodology (RSM) were developed, and applied to forecast the removal performance of the sorbent. The influence of process variables (i.e. sonication time, initial dye concentration, adsorbent mass) on the removal of MB and BY28 was considered by central composite rotatable design of RSM, GRNN, ANFIS, BPNN and RBFNN. The performances of the developed ANFIS, GRNN, BPNN and RBFNN models were compared with RSM mathematical models in terms of the root mean square error, coefficient of determination, absolute average deviation and mean absolute error. The coefficients of determination calculated from the validation data for ANFIS, GRNN, BPNN, RBFNN and RSM models were 0.9999, 0.9997, 0.9883, 0.9898 and 0.9608 for MB and 0.9997, 0.9990, 0.9859, 0.9895 and 0.9593 for BY28 dye, respectively. The ANFIS model was found to be more precise compared to the other models. However, the GRNN method is much easier than the ANFIS method and needs less time for analysis. So, it has potential in chemometrics and it is feasible that the GRNN algorithm could be applied to model real systems. The monolayer adsorption capacity of MB and BY28 was 292.20 and 287.02 mg g^?1, respectively.     

Synthesis and application of treated activated carbon for cationic dye removal from modelled aqueous solution

Use of activated carbon (AC) prepared from rice husk and treated with anionic surfactant is investigated to eliminate cationic dye crystal violet (CV) using modelled dye solution. AC modified with anionic surfactant sodium lauryl sulfate (ACSLS) and other two surfactant namely sodium dodecyl sulfonate and hexadecyl trimethyl ammonium bromide were used for the analysis. Optimum ACSLS was analyzed and characterized using BET, XRD, SEM accompanied with XEDS, FTIR, HR-TEM and zeta potential, which confirms the sorption of CV onto ACSLS. Influence of pH, dose of adsorbent, concentration of initial dye, contact time, additive salts as well as actual water samples were investigated. Presence of NH⁴⁺, Ca²⁺, Mg²⁺, Na²⁺, Ca²⁺ and K⁺ cations in dye solution were having negligible (less than 4 %) influence on dye removal capacity. Study of mass transfer parameters revealed intra particle diffusion and film diffusion both played their part, whereas other kinetic studies has shown that experimental data fitted best with Pseudo 2nd order rate. Isotherm studies accompanied with error analysis revealed that Langmuir isotherm controls the adsorption equilibrium with highest capacity of CV adsorption with optimum operating conditions as pH = 6, temperature = 318 K, adsorbent dose = 100 mg/L and dye concentration = 30–60 mg/L. Study of thermodynamics and temperature analysis have shown that the sorption reaction was favourable and spontaneous with rise in temperature and endothermic in nature. Column studies are reported for varying rate of flow, depth of bed and dye concentrations along with analysis of column experimental data with various models like Yoon-Nelson, Thomas, Bohart-Adam and Clark model. Reusability (no. of cycles) of used adsorbent was studied using regeneration experiments. Analysis inferred that AC modified using surfactants can be a useful technique for enhanced adsorption capacity of dyes from aqueous solution and not much work has been reported on use of anionic surfactant modified AC for dye removal process.     

Bifunctional activated carbon with dual photocatalysis and adsorption capabilities for efficient phenol removal

Bifunctional activated carbons (AC) with the abilities of both photocatalysis and adsorption were fabricated via the sol?Cgel route combined with hydrothermal treatment and N₂ reactivation method. TiO₂ was located mainly at the entrance of the surface macropores of AC. Under UV light irradiation, efficient removal of phenol was realized by combination of adsorption and photocatalytic degradation for the obtained bifunctional materials. In insufficient light or dark, phenol removal occurred mainly through adsorption. The prepared bifunctional carbon with a mass ratio of 50 TiO₂ per AC ratio exhibited high efficiency for phenol removal. The total phenol removal capacity of 50TiO₂/AC was almost 5 times of that of pure AC and 6 times of that pure TiO₂ after 10 cycles. The prepared bifunctional carbons possess the advantages of high pollutant removal capability and good recyclability, making them promising for the efficient treatment of lightly polluted aqueous solutions.     

Electrochemically deposited nanocomposite of chitosan and carbon nanotubes for biosensor application

A simple and controllable electrodeposition method for the formation of a chitosan-carbon nanotube nanocomposite film on an electrode surface was proposed and further used for the construction of an electrochemical biosensor.     

Synthesis and characterization of cadmium selenide nanoparticles loaded on activated carbon and its efficient application for removal of muroxide from aqueous solution

In the first, Cadmium selenide Nanoparticle loaded on activated carbon (CdSe-NP-AC) has been synthesized and characterized by different techniques including XRD and SEM. Then, this new adsorbent successfully has been applied for the removal of muroxide (MO) from aqueous solution in batch studies, while the effect of various experimental parameters like initial pH (pH(0)), contact time, amount of (CdSe-NP-AC) and initial MO concentration (C(0)) on its removal percentage was examined by one at a time optimization method. It was found following optimization of variable, the adsorption of MO onto (CdSe-NP-AC) followed pseudo-second-order kinetics and show Tempkin and Langmuir models for interpretation of experimental data. It was observed that by increasing the temperature the removal percentage was improved and the positive change in entropy (ΔS°) and heat of adsorption (ΔH°) show the endothermic nature of process, while the high negative value in Gibbs free energy change (ΔG°) indicates the feasible nature of adsorption process.     

Synthesis,characterization and photocatalytic properties of PDI/TiO2/activated carbon nanocomposite

Research on Chemical Intermediates - 1-Hydroxy perylene diimide-doped TiO2 loaded on the activated carbon (HO-PDI/TiO2/AC) nanocomposite was prepared by hydrothermal method. The nanocomposite was...     

负载氯的分级多孔炭制备及其脱汞性能的研究

以纳米碳酸钙为模板,水稻秸秆为碳前驱体,采用共热解法制备了负载氯的分级多孔生物质炭。在模拟烟气条件下,利用固定床实验台架研究了生物质碳材料对烟气中的单质汞（Hg⁰）的脱除性能。采用扫描电镜（SEM）、透射电镜（TEM）、N₂吸附-脱附（BET）、程序升温脱附（Hg-TPD）以及X射线光电子能谱（XPS）等方法对材料进行表征。结果表明,盐酸浸渍不仅可去除模板产物生成多孔结构,并且有效地将氯负载到材料表面。负载氯的分级多孔炭B1C1-Cl2的比表面积和总孔容分别达到398.1 m²/g和0.4923 cm³/g。在120℃,空速（GHSV）为225000 h^-1时,脱汞效率可达95%。多孔结构有利于气体扩散,高比表面积为材料提供了更多的反应位点,微孔-介孔内表面上的C-Cl共价键为脱汞的主要化学吸附活性位点。