Modeling of removal of an organophosphorus pesticide from aqueous solution by amagnetic metal–organic framework composite

Today,a variety of pesticides are used to fight plant pests in the world.The entry of these resistant pollutants into water resources can have devastating effects on human health and the environment,hence their removal from the environment is a vital task.In the present work,the magnetic iron-based metalorganic framework(Fe_(3) O_(4)/MIL-101(Fe)) was synthesized by a simple and feasible method and characterized by FT-IR,XRD,BET,FESEM,TEM,TGA,and VSM techniques.The synthesized nanocom posite was successfully applied for the removal of fenitrothion(FEN) pesticide from the aqueous solutions.The isothermal and kinetic models were also investigated.The Langmuir isotherm model(type I) and pseudo-second-order kinetic model were more consistent in the adsorption process.The thermodynamic parameters of fenitrothion sorption were also calculated.The results revealed that the adsorption of fenitrothion onto Fe_(3) O_(4)/MIL-101(Fe) was spontaneous and endothermic under optimized conditions.Moreover,the removal efficiency of FEN was predicted using the developed fuzzy logic model.Four input variables including the initial concentration of FEN(mg·L^(-1)),pH of the solution,adsorbent dosage(mg).and contact time(min) versus removal efficiency as output were fuzzified by the usage of an artificial intelligence-based method.The fuzzy subsets consisted of Triangular and Trapezoidal membership functions(MFs) with six levels and a total of 23 rules in IF-THEN format which was applied on a Mamdani inference system.The obtained coefficient of determination value(R_(pred)^(2)=0.98205) proved the excellent accuracy of the fuzzy logic model as a powerful tool for the prediction of FEN removal efficiency.

A rapid synthesis of high surface area PdRu nanosponges:Composition-dependent electrocatalytic activity for formic acid oxidation

Here, Pd Ru nanoparticle networks（NPNs） with various compositions were synthesized through an inexpensive method in water as a green solvent, at different ratios of the H;PdCl;and RuCl;precursors. This is a fast, room temperature and surfactant free strategy which is able to form high surface area metal nanosponges with a three-dimensional（3D） porous structure. The structure of as-prepared nanosponges was characterized using the techniques of field emission scanning electron microscopy（FESEM）, energy dispersive spectroscopy（EDS） and cyclic voltammetry（CV）. Then, the electrocatalytic activities of Pd Ru NPNs towards formic acid oxidation were examined by electrochemical measurements including CV,chronoamperometry, and electrochemical impedance spectroscopy（EIS）. Based on studies, it was found that the current density of formic acid oxidation（FAO） is strongly dependent on the composition of Pd Ru NPNs. The best performance was realized for Pd;Ru;NPNs compared to monometallic Pd counterpart and other bimetallic NPNs which might be ascribed to the role of Ru in the decrease of CO adsorption strength on the catalyst and consequently the priority of formic acid oxidation through the direct pathway. The Pd;Ru;NPNs also showed the maximum current density and stability in chronoamperometric measurements. In addition, comparative studies were performed between as-prepared NPNs and CNTs-supported Pd nanoparticles（Pd NPs/CNTs）. The present results demonstrated the unique structural advantages of NPNs compared to individual Pd NPs supported on the CNT which leads to the promising performance of NPNs as supportless catalysts for the oxidation of formic acid.

An efficient and mild protocol for the synthesis of unsymmetrical ureas in the absence of catalyst and additives

A new practical method for the synthesis of unsymmetrical ureas was achieved by reaction of phenylurea with primary and secondary amines under neutral and mild condition in very good yields. The reaction took place in refluxing dioxane and does not require any catalyst or additives.

Synthesis,characterization and application of BiVO_4 photoanode for photoelectrochemical oxidation of chlorate

A high‐quality polycrystalline bismuth vanadate(BiVO4)film was prepared on a fluorine‐doped tinoxide substrate via a facile two‐step strategy involving electrodeposition and annealing processes.The morphology and structural characterization of the resulting film were investigated by differentmethods including scanning electron microscopy,transmission electron microscopy,X‐ray diffraction(XRD),and Fourier transform infrared,ultraviolet‐visible(UV‐vis)absorption,and Ramanspectroscopies.XRD patterns as well as optical measurements revealed that BiVO4film crystallizedwith a pure monoclinic scheelite structure.The prepared BiVO4film was used for heterogeneousoxidation of chlorate ions in aqueous solution via electrochemical(EC),photochemical(PC),andphotoelectrochemical(PEC)processes.The decrease in concentration of chlorate was monitoredusing UV‐vis absorption spectroscopy.The results revealed that BiVO4could effectively performchlorate oxidation under light irradiation through a PEC method.The kinetics of chlorate oxidationwas consistent with a first‐order reaction,and the rate constant for the PEC process was found to bemuch higher than those of EC and PC.Furthermore,a possible photocatalytic oxidation mechanismfor chlorate mainly based on the formation of perchlorate ions is proposed.

Electrocatalytic oxidation of thiosulfate at 2,7-bis(ferrocenylethyl)-fluoren-9-one-modified carbon paste electrode(2,7-BFEFMCPE):Application to the catalytic determination of thiosulfate in real sample

Electrocatalytic oxidation of thiosulfate at the 2,7-BFEFMCPE occurs at a potential about 460 mV less positive than that unmodified carbon paste electrode.The diffusion coefficient（=5.6×10^-5）cm^2 s^-1）,the kinetic parameters such as electron transfer coefficient,（=0.5） and kh（=1.21×10^-3 cm s^-1） of thiosulfate oxidation at the surface of,2,7-BFEFMCPE were determined.The electrocatalytic oxidation peak current of thiosulfate showed two linear dynamic ranges（0.0006-0.009 mmol/L and 0.009- 0.900 mmol/L） and a detection limit of 0.00015 mmol/L.This method was also examined as a new electrochemical sensor for the determination of thiosulfate in real sample.

Synthesis and Characterization of Sol-Gel Derived MgO/CNTs Nanocomposite

In this research, synthesis of magnesium oxide-multi walled carbon nanotube （MgO/MWCNTs） nanocomposite is reported using sol-gel method in which magnesium nitrate is added to aqueous solution. The structure of MWCNTs and MgO/MWCNTs composite has been characterized by analyzing the X-ray diffraction pattern （XRD）, Fourier Transform Infrared （FT-IR） spectra and Scanning Electron Microscopy （SEM） images. Experimental results indicate that the surface of purified MWCNTs sample is covered homogenously by a layered of MgO nanoparticles.

Extraordinary adsorption of acidic fuchsine and malachite green onto cheap nano-adsorbent derived from eggshell

Removal of dyestuffs such as Acidic Fuchsine(AF)and Malachite Green(MG)being present in many forms in industries is vital to protect water reservoirs from their catastrophic effects on the ecosystem.This study attempts to effectively eliminate these dyes using a low-cost and eco-friendly material.Eggshell,as a biocompatible by-product,was initially characterized,then some modifications were conducted,and its morphology and chemical structure were then examined through(Atomic force microscopy)AFM,(Fourier-Transform Infrared Spectroscopy)FTIR,(Energy-Dispersive X-ray Spectroscopy)EDS and(Brunauer–Emmett–Teller)BET analyses.They revealed that the modifications on raw material gave rise to a natural nano-adsorbent presenting porous medium appropriate for targeted adsorbate molecules with the average particle size and average pore diameter of 54 and^2 nm,respectively.Functional groups on the adsorbent surface were also of importance to assist the adsorption of AF and MG.The effect of contact time,adsorbent dose,solution p H and initial concentration was evaluated.Pseudo-second order model accurately correlated the experimental kinetic data for both dyes.Moreover,the participation of intra-particle diffusion along with film diffusion in controlling the process was suggested.Langmuir isotherm model fitted very well to the equilibrium data for both dyes and maximum monolayer adsorption capacity of AF and MG was accordingly calculated to be 5000 and 3333.33 mg·g-1 respectively.The inherent characteristics of eggshell make it a potential material to remove contaminants from wastewater in future applications.

二氧化钛纳米粒子催化合成Hantzsch酯和多氢喹啉衍生物(英文)

1,4-Dihydropyridine and polyhydroquinoline derivatives have been prepared efficiently in a one-pot synthesis via Hantzsch condensation using nanosized titanium dioxide as a heterogeneous catalyst.The present methodology offers several advantages such as excellent yields,short reaction times (30-120 min),environmentally benign,and mild reaction conditions.The catalyst can be readily separated from the reaction products and recovered in excellent purity for direct reuse.

以有序介孔二氧化硅纳米粒子为可再生催化剂多组分一锅法合成4H-氧萘衍生物(英文)

A simple,efficient and environmentally benign protocol for the synthesis of 4H-chromene derivatives was developed using bio-compatible,neutral,and recoverable mesoporous silica nanoparticles as a catalyst.The 4H-chromene derivatives were obtained in excellent yields by three component reaction of an aldehyde or isatin,malononitrile,and cyclic 1,3-diketones in ethanol at 60℃.

用聚(L-蛋氨酸)/纳米金修饰玻碳电极同时灵敏检测多巴胺和尿酸(英文)

A novel electrochemical sensor was fabricated by electrodeposition of gold nanoparticles on a poly(L-methionine)(PMT)-modified glassy carbon electrode(GCE) to form a nano-Au/PMT composite-modified GCE(nano-Au/PMT/GCE).Scanning electron microscopy and electrochemical techniques were used to characterize the composite electrode.The modified electrode exhibited considerable electrocatalytic activity towards the oxidation of dopamine(DA) and uric acid(UA) in phosphate buffer solution(pH = 7.00).Differential pulse voltammetry revealed that the electrocatalytic oxidation currents of DA and UA were linearly related to concentration over the range of 5.0 ×10–8 to 10–6 mol/L for DA and 7.0 × 10–8 to 10–6 mol/L for UA.The detection limits were 3.7 × 10–8mol/L for DA and 4.5 × 10–8 mol/L for UA at a signal-to-noise ratio of 3.According to our experimental results,nano-Au/PMT/GCE can be used as a sensitive and selective sensor for simultaneous determination of DA and UA.

Effect of Functionalized Magnetite Nanoparticles and Diaminoxanthone on the Curing, Thermal Degradation Kinetic and Corrosion Property of Diglycidyl Ether of Bisphenol A-Based Epoxy Resin

To prepare a high-performance epoxy resin with excellent thermal, chemical and corrosion stability, diaminoxanthone（DAX） was used to cure diglycidylether of bisphenol-A（DGEBA）-based epoxy resin and blend of DGEBA with functionalized Fe3O4 nanoparticles. Kinetic parameters of curing and thermal degradation of epoxy resin systems were estimated by differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA）, respectively. The 10% weight loss temperature has been increased from 340 °C to 366 °C and there was an increase in the char yield from 32.6% to 45.3% for the above systems. The corrosion performance of epoxy coated carbon steel was examined by potentiodynamic polarization, along with immersion test in 1.0 mol/L HCl solution. The results showed that epoxy resins cured with DAX had low tendency to corrosion. In addition, the cured epoxy resin containing 10% Fe3O4 had higher anticorrosion activity than bare DGEBA system. The results showed that functionalized Fe3O4 nanoparticles enhanced char formation and improved the thermal stability as well as anticorrosion activity of the resin.

Electrocatalytic determination of L-cysteine using a modified carbon nanotube paste electrode:Application to the analysis of some real samples

The electrooxidation of L-cysteine（L-Cys） was studied using a benzoylferrocene（BF） modified multi-wall carbon nanotube paste electrode（BFCNPE） using cyclic voltammetry（CV）,square wave voltammetry（SWV） and chronoamperometry（CHA）.Under optimum pH in CV the oxidation of L-Cys occurs at a potential about 215 mV less positive than that at the surface of unmodified carbon paste electrode.The catalytic oxidation peak currents were dependent on the L-Cys concentration and a linear calibration curve was obtained in the range 0.7-350.0 mmol/L of L-Cys with SWV method.The detection limit（3s） was determined as 0.1 mmol/L.This method was also used for the determination of L-Cys in some real samples.

EFFECT OF NANOSILICA ON THE KINETICS OF CURE REACTION AND THERMAL DEGRADATION OF EPOXY RESIN

Nanocomposites from nanoscale silica particles（NS）,diglycidylether of bisphenol-A based epoxy（DGEBA）,and 3,5-diamino-N-（4-（quinolin-8-yloxy） phenyl） benzamide（DQPB） as curing agent were obtained from direct blending of these materials.The effect of nanosilica（NS） particles as catalyst on the cure reaction of DGEBA/DQPB system was studied by using non-isothermal DSC technique.The activation energy（E_a） was obtained by using Kissinger and Ozawa equations. The E_a value of curing of DGEBA/DQPB/10%NS system showed a decrease of about 10 kJ/mol indicating the catalytic effect of NS particles on the cure reaction.The E_a values of thermal degradation of the cured samples of both systems were 148 kJ/mol and 160 kJ/mol,respectively.The addition of 10%of NS to the curing mixture did not have much effect on the initial decomposition temperature（T_i） but increased the char residues from 20%to 28%at 650℃.

A highly efficient procedure for the synthesis of quinoxaline derivatives using polyvinylpolypyrrolidone supported triflic acid catalyst(PVPP.OTf)

A polyvinylpolypyrrolidone supported triflic acid was shown to be useful as a recyclable heterogeneous catalyst for the rapid and efficient synthesis of quinoxaline derivatives in good-to-excellent yields. The catalyst is easily prepared, air-stable, reusable, and easily removed from the reaction mixtures.

以方沸石负载Ni(Ⅱ)催化剂修饰的电极电氧化甲醇(英文)

There is a high overvoltage in the oxidation of methanol in fuel cells,and so modified electrodes are used to decrease it.A modified electrode that used Ni(II) loaded analcime zeolite to catalyze the electrooxidation of methanol in alkaline solution was proposed.Analcime zeolite was synthesized by hydrothermal synthesis,and Ni(II) ions were incorporated into the analcime structure,which was then mixed with carbon paste to prepare modified electrode.The electrocatalytic oxidation of methanol on the surface of the modified electrode in alkaline solution was investigated by cyclic voltammetry and chronoamperometry.The effects of the scan rate of the potential,concentration of methanol,and amount of zeolite were investigated.The rate constant for the catalytic reaction of methanol was 6 × 103 cm3 mol-1 s-1 from measurements using chronoamperometry.The proposed electrode significantly improved the electron transfer rate and decreased the overpotential for methanol oxidation.

Pt/十六烷基三甲基溴化铵纳米聚集体修饰玻碳电极促进析氢(英文)

A novel, cost-effective, and simple electrocatalyst based on a Pt-modified glassy carbon electrode(GCE), using cetyltrimethylammonium bromide(CTAB) as a cationic surfactant, is reported. Amphiphilic CTAB molecules were adsorbed on GCE by immersion in a CTAB solution. The positively charged hydrophilic layer, which consisted of small aggregates of average size less than 100 nm,was used for accumulation and complexation of [PtCl2. anions by immersing the electrode in Ksolution. The modified electrode was characterized using scanning electron microscopy,energy-dispersive X-ray spectroscopy, impedance spectroscopy, and electrochemical methods. The electrocatalytic activity of the Pt particles in the hydrogen evolution reaction(HER) was investigated.The results show that the CTAB surfactant enhances the electrocatalytic activity of the Pt particles in the HER in acidic solution.

银纳米颗粒的合成及用于抗癌药氟他胺的电化学检测（英文）

Ag nanoparticles were synthesized on the surface of a glassy carbon electrode modified with p‐tert‐butylcalix[4]arene and p‐tert‐butylcalix[6]arene by the deposition of Ag+ at an open circuit potential followed by the electrochemical reduction of the Ag+.The presence of the calixarene layer on the electrode surface controlled the particle size and prevented agglomeration.Cyclic voltam‐metry showed that the Ag nanoparticles on the modified glassy carbon electrode had good catalytic ability for the reduction of flutamide.The effects of calixarene concentration,potential applied for the reduction of Ag+,number of calixarene layers,and p H value on the electrocatalytic activity of the Ag nanoparticles were investigated.The modified electrode had a linear range in differential pulse voltammetry of 10-1000 μmol/L with a detection limit of 9.33 μmol/L for flutamide at an S/N = 3.The method was applied to the detection of flutamide in practical samples.

银掺杂聚(2-氨基二苯胺)修饰碳糊电极作为一种简单有效的电催化剂用于甲醛氧化（英文）

This work describes the promising activity of silver nanoparticles on the surface of a poly(2‐amino diphenylamine) modified carbon paste electrode(CPE) towards formaldehyde oxidation. Electro‐deposition of the conducting polymer film on the CPE was carried out using consecutive cyclic voltammetry in an aqueous solution of 2‐aminodiphenylamine and HCl. Nitrogen groups in the polymer backbone had a Ag ion accumulating effect, allowing Ag nanoparticles to be electrochemi‐cally deposited on the surface of the electrode. The electrochemical and morphological characteris‐tics of the modified electrode were investigated. The electro‐oxidation of formaldehyde on the sur‐face of electrode was studied using cyclic voltammetry and chronoamperometry in aqueous solu‐tion of 0.1 mol/L Na OH. The electro‐oxidation onset potential was found to be around-0.4 V, which is unique in the literature. The effect of different concentrations of formaldehyde on the electrocat‐alytic activity of the modified electrode was investigated. Finally, the diffusion coefficient of formal‐dehyde in alkaline media was calculated to be 0.47 × 10–6 cm2/s using chronoamperometry.

Estimation of photolysis half-lives of dyes in a continuous-flow system with the aid of quantitative structure-property relationship

In this paper the photolysis half-lives of the model dyes in water solutions and under ultraviolet （UV） radiation were determined by using a continuous-flow spectrophotometric method. A quantitative structure- property relationship （QSPR） study was carried out using 21 descriptors based on different chemometric tools including stepwise multiple linear regression （MLR） and partial least squares （PLS） for the prediction of the photolysis half-life （t1/2） of dyes. For the selection of test set compounds, a K-means clustering technique was used to classify the entire data set, so that all clusters were properly represented in both training and test sets. The QSPR results obtained with these models show that in MLR-derived model, photolysis half-lives of dyes depended strongly on energy of the highest occupied molecular orbital （EHoMO）, largest electron density of an atom in the molecule （ED^＋） and lipophilicity （logP）. While in the model derived from PLS, besides aforementioned EHOMO and ED^＋ descriptors, the molecular surface area （Sm）, molecular weight （M-W）, electronegativity （X）, energy of the second highest occupied molecular orbital （EHoMO- 1） and dipole moment （μ） had dominant effects on logt1/2 values of dyes. These were applicable for all classes of studied dyes （including monoazo, disazo, oxazine, sulfo- nephthaleins and derivatives of fluorescein）. The results were also assessed for their consistency with findings from other similar studies.

Novel Conductive PANI/Hydrophilic Thiacalix[4]arene Nanocomposites: Synthesis, Characterization and Investigation of Properties

Nanocomposites of polyaniline （PANI） and the macrocycle thiacalix[4]arene tetra sulfonate （TCAS） were successfully synthesized in feed ratios of 1：0.25, 1：0.50 and 1：0.75 by three prevail synthetic methods, i.e. in situ polymerization, emulsion polymerization and solution casting technique. The structures of the nanocomposites were confirmed by FTIR, UV-Vis, XRD, SEM, and TEM techniques. The conductivity was measured by a four probe method. The conductivity was recorded to be as high as 105 x 10-2 S.cm-~ for the nanocomposite with a nanometer size structure and homogeneously distributed morphology. The electroactivity of the nanocomposites was approved by cyclic voltammetry （CV） and impedance spectroscopy technique （EIS）. The antioxidant ability and thermal property of the composites were further studied. Preliminary studies have evidenced the production of conductive nanocomposites with good thermal property and relatively good solubility in N-methyl 2-pyrrolidone （NMP）, with the antioxidant activity reaching up to 80%.