Synergism of Zinc Oxide/Organoclay-Loaded Poly(lactic acid) Hybrid Nanocomposite Plasticized by Triacetin for Sustainable Active Food Packaging

The synergistic effect of organoclay(OC)and zinc oxide(ZnO)nanoparticles on the crucial properties of poly(lactic acid)(PLA)nanocompositefilms was systematically investigated herein.After their incorporation into PLA via the solvent casting technique,the water vapor barrier property of the PLA/OC/ZnOfilm improved by a maximum of 86%compared to the neat PLAfilm without the deterioration of Young’s modulus or the tensile strength.Moreover,thefilm’s self-antibacterial activity against foodborne pathogens,including gram-negative(Escherichia coli,E.coli)and gram-positive(Staphylococcus aureus,S.aureus)bacteria,was enhanced by a max-imum of approximately 98–99%compared to the neat PLAfilm.Furthermore,SEM images revealed the homo-geneous dispersion of both nano-fillers in the PLA matrix.However,the thermal stability of thefilm decreased slightly after the addition of the OC and ZnO.Thefilm exhibited notable light barrier properties in the UV-Vis range.Moreover,the incorporation of a suitable biodegradable plasticizer significantly decreased the Tg and notably enhanced theflexibility of the nanocompositefilm by increasing the elongation at break approxi-mately 1.5-fold compared to that of the neat PLAfilm.This contributes to its feasibility as an active food packa-ging material.

Photocatalytic degradation of Acid Blue 62 over CuO-SnO_2 nanocomposite photocatalyst under simulated sunlight

The novel CuO-SnO2 nanocomposite oxide photocatalysts were prepared by simple co-precipitation method, and characterized by X- ray diffraction, transmission electron microscopy, N2 adsorption-desorption measurement and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activities of CuO-SnO2, evaluated using the photodegradation of Acid Blue 62 as a probe reaction under the irradiation of Xenon light, were also found to be related to the calcination temperature and the molar ratio of Cu to Sn. The maximum photocatalytic activity of the CuO-SnO2 photocatalyst was observed to be calcined at 500~C for 3 h （the molar ratio of Cu to Sn was 1：1） due to the sample with good crystallization and high surface area. It also showed much higher photocatalytic activity in treatment dye wastewater under simulated sunlight irradiation compared to Degussa P25 TiO2.

Photocatalytic Degradation of Acid Blue 62 over La/I/TiO2 Nanocomposite Photocatalyst under Simulated Sunlight

In order to explore the photocatalytic activity of the lanthanum and iodine co-doped TiO2,the degradation of acid blue 62 as a probe reaction under simulated sunlight irradiattion was investigated.A novel visible-light-activated La/I/TiO2 nanocomposition photocatalyst was prepared using precipitation-diping method,and characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）and UV-Vis diffuse reflectance spectroscopy（UV-Vis-DRS）.The photocatalytic efficiency of La/I/TiO2 was evaluated by the photodegradation of reactive acid blue 62 as a probe reaction under simulated sunlight irradiationt.Photocatalytic experiment results shows that the La/I co-doped TiO2 catalyst has higher photocatalytic activity than the standard Degussa P25,La-doped TiO2 and I-doped TiO2 photocatalysts under simulated sunlight irradiation,and the way of La/I co-doping extends the absorption spectra of TiO2 and shifts the absorption edge remarkably toward longer wavelength.

Pt-Containing Ag_2S-Noble Metal Nanocomposites as Highly Active Electrocatalysts for the Oxidation of Formic Acid

Nanocomposites with synergistic effect are of great interest for their enhanced properties in a given application. Herein, we reported the high catalytic activity of Pt-containing Ag2S-noble metal nanocomposites in formic acid oxidation, which is a key reaction in direct formic acid fuel cell. The electrochemical measurements including voltammograms and chronoamperograms are used to characterize the catalytic property of Pt-containing nanocomposites for the oxidation of formic acid. In view of the limited literatures on using nanocomposites consisting of semiconductor and noble metals for catalyzing the reactions of polymer electrolyte membrane-based fuel cells, this study provides a helpful exploration for expanding the application of semiconductor-noble metal nanocomposites.

Green Modification of Cellulose Nanocrystals and Their Reinforcement in Nanocomposites of Polylactic Acid

Cellulose nanocrystals （CNCs） of rod-like shape were prepared from degreased cotton using sulfuric acid hydrolysis. The obtained CNC suspension was neutralized using a sodium hydroxide solution to remove the residual sulfuric acid and improve the thermal stability of the CNC particles. Then, poly（ethylene oxide） （PEO） was employed to modify the nanocrystals through entanglement and physical adsorption. The goal was to further improve the thermal stability and weaken the hydrophilicity of CNCs. Original and modifed CNCs were dosed into a polylactic acid （PLA） matrix to prepare nanocomposites using a hot compression process. Results of the thermogravimetric analysis showed that the initial thermal decomposition temperature of the modifed CNCs showed a 120℃ improvement compared to the original CNCs. That is, the thermal stability of the modified CNCs improved because of their shielding and wrapping by a PEO layer on their surface. Results from scanning electron microscopy and ultraviolet-visible spectrophotometry showed that the compatibility of the modifed CNCs with organic PLA improved, which was attributed to the compatibility of the PEO chains adsorbed on the surface of the CNCs. Finally, the results of tensile tests indicated a significant improvement in terms of breaking strength and elongation at the break point.

Enhanced photocatalytic activity of methylene blue using heterojunction Ag@TiO_(2)nanocomposite:Mechanistic and optimization study

The objective in this study is to investigate the adsorption-degradation of the methylene blue(MB)dye using a fabricated heterojunction Ag@TiO_(2)nanocomposite.The batch factors used in photo catalytic reactions were pH,UV-irradiation time,temperature,catalytic dosage,and concentration of MB.The results showed that 0.2×10^(3) g·ml^(-1))of the catalytic dose caused the Ag@TiO_(2)adsorption to degrade by 96.67%with darks and UV exposure.Using the Langmuir-Hinshelwood model to determine the kinetic,the Ag@TiO_(2)displays a greater kinetic rate than TiO_(2)and silver nanoparticle(AgNPs).The photocatalytic degradation of MB,which is an endothermic reaction involving all catalysts,is shown by the thermodynamic parameter to have the positive value of enthalpy(ΔH°).The enthalpies observed were Ag@TiO_(2)(126.80 kJ·mol^(-1))<AgNPs(354.47 kJ·mol^(-1))<TiO_(2)(430.04 kJ·mol^(-1)).Ascorbic acid(·OH scavenger),2-propanol(·O_(2)scavenger),and ammonium oxalate(AO)(hole h+scavenger)were employed to conduct the scavenger effects.The Ag@TiO_(2)demonstrated a reduction in MB degradation when combined with 2-propanol,and this clearly demonstrated that,in contrast to hydroxyl radicals(·OH)and holeh scavengers,superoxide radical anion(O_(2)scavenger)plays a significant role in MB degradation.Utilizing density functional theory(DFT)to elucidate the mechanism and B3LYP/6-311+G(d,p)level optimization,the degradation-adsorption process was explained.When the N-N,C-N or C-C bonds were severed,the Fukui faction was demonstrated for nucleophilic,electrophilic,and radical attack.

The Application of Cellulose Nanocrystals Modified with Succinic Anhydride under the Microwave Irradiation for Preparation of Polylactic Acid Nanocomposites

The aim of this work was to use cellulose nanocrystals that were obtained by hydrolysis in phosphoric acid solution and further modified with succinic anhydride in the microwave field for PLA reinforcement.A series of allbionanocomposites containing unmodified and surface modified cellulose nanocrystals with CNC content in the range of 1–3%_(w.t.) were obtained by melt blending and tested by XRD,SEM,DSC and DMA to investigate the effect of surface esterification of CNCs on the structure,morphology,dynamic mechanical properties of bionanocomposites,as well as phase transitions of PLA in the presence of cellulosic nanofiller.DMA investigations showed the highest increase of storage modulus by ca.7%(335 MPa at 25℃)in the glassy state of PLA for 2%_(w.t.)of unmodified CNC.Though,addition of 2%_(w.t.)of succinylated CNCs caused the highest increase of the onset of glass transition temperature(by 6.2℃)thus widening the temperature range of biocomposite application.The increase of glass transition temperature indicates the strongest interfacial interactions due to improved miscibility of surface modified nanocrystals and thus good dispersion of additive in PLA matrix providing high interface.

Synthesis and Characterization of Poly Anthranilic Acid Metal Nanocomposites

Intrinsically conducting polymer metal nanocomposites were synthesized by polymerising anthranilic acid (PANA) with metal salts like ferric chloride, Zinc oxide and Magnesium oxide by chemical oxidation method. Polyanthranilic acidiron nano composite (PANA-Fe), Polyanthranilic acid-Zinc nano composite(PANA-Zn) and Polyanthranilic acid-magnesium nano composite (PANA-Mg) synthesized were characterised by UV-Visible and FTIR studies. FTIR spectra of polymer-metal nano composites showed peaks in the region between 1690 cm-1 and 1490 cm-1 which corresponds to the deformation in different types of N-H bond. The participation of the -NH group in polymerization was confirmed by the appearance of a peak around 3431 cm-1. Cyclic voltammetric studies revealed the presence of an adherent polymer film on the glassy carbon electrode and showed redox behavior of the polymer metal nanocomposites. The XRD (XRay Diffraction) studies showed a rather more crystalline behaviour of the nano composites and the grain size was calculated using Scherrer’s formula and it was found to be in nano range. SEM (Scanning Electron Microscope) analysis showed a rather mixed crystalline and amorphous behavior. EDAX (Energy Dispersive X Ray Spectroscopy) confirms the incorporation of the metals iron, Zinc and Magnesium in the polymermetal nano composites. The inhibition efficiency of the polymermetal nano composites were calculated for stainless steel in acidic environment using elec-trochemical impedance spectroscopy (EIS) and polarization (Tafel) studies and the prepared PANA-Fe and PANA-Zn nano composites showed effective anti-corrosive behavior on stainless steel in acid medium.

影响光催化超滤膜反应器降解Acid Blue 7的因素研究

设计研制了一种光催化超滤膜反应器,并选用一种颗粒状纳米级TiO2作光催化剂,对染料AcidBlue7光氧化降解进行了研究。影响染料降解的因素包括:错流速度、催化剂浓度、染料初始浓度、溶液的pH值以及曝气条件。研究结果发现,光催化超滤反应器对染料废水处理具有较高的处理效果,且颗粒状光催化剂能够实现良好分离。

Cu(Ⅱ),Ni(Ⅱ)Complexation with Acid Alizarine Blue B in the Presence of Cetyltrimethylammonium Bromide

The coordination reactions of Cu（Ⅱ） and Ni（Ⅱ） with acid alizarine blue B （AABB） in the presence of cetyltrimethylammonium bromide （CTAB） micelle were investigated using the microsurface adsorptionspectral correction technique （MSASC）. The aggregation of AABB on CTAB followed the Langmuir isothermal adsorption law. The enrichment of AABB on CTAB sensitized the complexation between Cu（Ⅱ） or Ni（Ⅱ）and AABB. The binding ratio of AABB to CTAB was 1：2.5, and monomeric aggregate, AABB2CTAB5, was formed with an adsorption constant of 5.95×10^5 at 20 ℃ or 2.48×10^5 at 40 ℃. In the ternary complexation, the ratio of AABB：Cu and AABB：Ni were 1：1 and 1：2.5, respectively. Two types of aggregates, Cu2.AABB2·CTAB80 and Ni5.AABB2.CTAB80, were formed.

In vitro bioactivity and corrosion of PLGA/hardystonite composite-coated magnesium-based nanocomposite for implant applications

A type of polymer/ceramic coating was introduced on a magnesium-based nanocomposite, and the nanocomposite was evaluated for implant applications.The microstructure, corrosion, and bioactivity of the coated and uncoated samples were assessed.Mechanical alloying followed by sintering was applied to fabricate the Mg–3Zn–0.5Ag–15NiTi nanocomposite substrate.Moreover, different contents of poly(lactic-co-glycolic acid)(PLGA) coatings were studied, and 10 wt% of PLGA content was selected.The scanning electron microscopy(SEM) images of the bulk nanocomposite showed an acceptable homogenous dispersion of the Ni Ti nanoparticles(NPs) in the Mg-based matrix.In the in vitro bioactivity evaluation, following the immersion of the uncoated and coated samples in a simulated body fluid(SBF) solution, the Ca/P atomic ratio demonstrated that the apatite formation amount on the coated sample was greater than that on the uncoated nanocomposite.Furthermore, assessing the corrosion resistance indicated that the coatings on the Mg-based substrate led to a corrosion current density(icorr) that was considerably lower than that of the substrate.Such a condition revealed that the coating would provide an obstacle for the corrosion.Based on this study, the PLGA/hardystonite(HT) composite-coated Mg–3Zn–0.5Ag–15NiTi nanocomposite may be suitably applied as an orthopedic implant biomaterial.

Flow-injection Spectrophotometric Determination of Uric Acid in Urine via Prussian Blue Reaction

A simple and sensitive flow injection（FI） spectrophotometric method was reported for the determination of uric acid based on the reduction of Fe（III）/ferricyanide in the presence of uric acid. The in situ reduced ions reacted with unreduced portion of ferricyanide/Fe（III） to form soluble Prussian blue, which was monitored at an absorption wavelength of 735 nm. The optimized conditions allow a linear calibration graph in a concentration range of 1―100 μmol/L. The relative standard deviation was in a range of 0.5%―2.5%, with a detection limit（3σ blank） of 0.3 μmol/L and a sampling frequency of 60 injection/h was obtained. The effect of common substances present in human physiological fluids on the determination of uric acid was examined. The method was applied to determining uric acid in human urine samples with the recoveries in a range of 96%―105%. The results agree well with those by spectrophotometric reference method at a confidence level of 95%. Spectrophotometric procedures for uric acid determination in clinical samples were reviewed briefly.

Kinetic Spectrophotometric Determination of Trace Titanium(Ⅳ) Based on Oxidation Discoloration of Acid Chrome Blue K with Hydrogen Peroxide

A simple and sensitive kinetic spectrophotometric method for the determination of trace amounts of titanium(IV),based upon the catalytic effect of Ti(IV) on the oxidation of acid chrome blue K (ACBK) by hydrogen peroxide in 0.002 mol/L sulfuric acid,is described. The reaction rate is monitored spectrophotometrically by measuring the decrease in absorbance of ACBK at 524 nm. The detection limit of the method is 1.01×10?9 g/mL,and the linear range is 0-0.048 mg/L. The influence of acidity,concentration of reactants,reaction time,reaction temperature and for-eign ions is also discussed. The optimum reaction conditions were established and some kinetic parameters determined. The apparent activation energy of the catalytic reaction is 5.32 kJ/mol. The relative standard deviation for the determi-nation of titanium(IV) at the concentration of 0.048 mg/L is calculated to be 1.31% (n = 11). In combination with sol-vent extraction separation,the method has been successfully applied to the determination of trace titanium(IV) in human hair,plant matter,tea and rock samples. The results are in good agreement with the certified values with the relative standard deviations (RSD) of 1.4%-3.5%.

Catalytic-kinetic spectrophotometric determination of vanadium (V) based on the Celestine blue-bromate-vanadium (V)-citric acid reaction

A novel sensitive and relatively selective kinetic method is presented for the determination of V（V） based on its catalytic effect on the oxidation reaction of Celestine blue by potassium bromate in the presence of citric acid as an activator. The reaction was monitored spectropho- tometrically by measuring the decrease in absorbance of Celestine blue at a maximum absorption wavelength of 540 nm between 0.5 and 9 min （the fixed-time method） in an H3PO4 medium at 45℃. The effect of various parameters such as concentrations of H3PO4, citric acid, potassium bromate and Celestine blue, ionic strength, reaction temperature and time on the rate of V（V） catalyzed reaction was studied. The method is free from the most interferences, especially from large amounts of V（IV）. The decrease in absorbance is proportional to the concentration of V（V） over the entire concentration range tested （0.025-1.25 lag.mL^-1） with a detection limit of 6.80 tag.L^-1 （according to statistical 3Sblank/k criterion） and a coefficient of variation （CV） of 1.78% （for ten replicate measurements at 95% confidence level）. The proposed method suffers from a few interferences such as Cr（VI） and Hg（Ⅱ） ions. The method was successfully applied to the determination of V（V） in river water, lake water, tap water, natural drinking water samples and a certified standard reference material such as SRM-1640 with satis- factory results. The vanadium contents of natural water samples were detected by using both linear calibration curve and standard addition curve methods. The recoveries of spiked vanadium （V） into the certified standard water sample were found to be quantitative, and the reproducibility was satisfactory. It was observed that the results of the SRM 1640 were in good agreement with the certified value.

Resonance Rayleigh Scattering and Resonance Nonlinear Scattering Methods for Determination of Methylene Blue with 12-Tungstophosphoric Acid

In a pH=0.65―1.5 NaAc-HCl medium, methylene blue（MB） reacts with 12-tungstophosphoric acid （TPA） by virtue of electrostatic attraction and hydrophobic force to form a 3：2 ion-association complex. As a result, the intensities of resonance Rayleigh scattering（RRS）, second-order scattering（SOS） and frequency doubling scatte- ring（FDS） are enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS are located at 316, 647 and 311 nm. The increments of scattering intensity（△I） are directly proportional to the concentration of MB in a certain range. The methods exhibited high sensitivity, and the detection limits（3s） for MB are 2.3 ng/mL（RRS method）, 5.6 ng/mL（SOS method） and 6.4 ng/mL（FDS method）, respectively. The effects of coexisting substances have been examined, and the results indicate that the methods have good selectivity. Based on the above researches, a new spectral method for the determination of trace amounts of MB has been developed. It can be applied to the determination of MB in human serum, and the recoveries are 97.5%―105.0%. The results are in good agreement with those obtained by the pharmacopoeia method. In this work, the optimum conditions of the reaction and the influencing factors were investigated. In addition, the reaction mechanism and the reasons of the enhancement of resonance light scattering were discussed.

Novel EPS/TiO2 Nanocomposite Prepared from Recycled Polystyrene

The synthesis and characterization of a new nanocomposite material that was prepared from recycled expanded polystyrene (EPS) and titanium dioxide (TiO2) is reported here. The EPS was obtained from chemical reagent box insulation. To obtain the nanocomposite, these materials were dispersed in a solvent, mixed with TiCl4 and heated. The resulting new material was characterized with SEM, TEM, TGA, BET, Raman and IR techniques. The Raman and IR spectra provided complementary information regarding the structure of the nanocomposite. The Raman spectra were used to identify the crystalline structure of TiO2 in the nanocomposite. In contrast, the IR spectra were used to identify the organic portion of the nanocomposite. The TEM images indicated that the nanocomposites had an average particle size of 6 - 12 nm. In addition, the adsorption and photocatalytic properties of the new material were evaluated. The EPS/TiO2 nanocomposite was efficient at degrading methylene blue (MB) dye solutions under UV irradiation. Furthermore, according to thermal analysis, this material had greater polymer stability due to the incorporation of TiO2.

High Efficient Photocatalytic Degradation of 3,7-Bis(Dimethylamino)-Phenothiazin-5-Ium Chloride Dye and Kinetics of H2 Evolution of N2H4H2O by Synthesized CdS/NiS Nanocomposite by Electrochemical Method

CdS/NiS nanocomposites were synthesized by electrochemical method. Ni and Cd is one of the important II-VI semiconducting materials with a direct band gap of 3.26 eV which finds applications in electrical conductivity and photo-catalysis. The synthesized nanocomposites were characterized by BET, UV-VIS, XRD, FE-SEM (EDAX) techniques. X-Ray diffraction (XRD) reveals crystallite size to be 23.22 nm which was calculated using Williamson-Hall (W-H) plot method. The energy of the band gap for CdS/NiS could be thus estimated to be 3.26 eV. The photocatalytic activity of the sample was evaluated by the degradation of textile dye methylene Blue (MB) in aqueous solutions under UV radiation. Hydrogen energy is regarded as a promising alternative in terms of energy conversion and storage. Hydrogen Evolution Reaction (HER) was carried out in both visible light and UV light by using Hydrazine (N2H4H2O) in the presence of CdS/NiS nanocomposite. The synthesized photocatalyst shows applicable performance for kinetics of Hydrogen Evolution Reaction (HER) in Visible light and UV light. The decomposition of hydrazine (N2H4H2O) proceeded rapidly to generate free hydrogen rich gas through OH radical contact with CdS/NiS nanocomposite at room temperature. The rate of HER is limited by either proton adsorption onto an active site or evolution of formed hydrogen from the surface. A high Tafel slope is indicative of proton adsorption as the rate limiting step, while a lower Tafel slope (20 - 45 mV) indicates that the evolution of molecules hydrogen from the catalyst is rate limiting. In the present case the Tafel slopes for visible light 23.5 mV and 42.5 mV for UV light. Blank experiments show poor activity for HER i.e. 10.1 - 13.5 mV.

Nanocomposites Based on Natural Biodegradable Materials: Effect of Post-Preparative γ-Irradiation on the Swelling Properties

Nanocomposites were prepared by in situ intercalative polymerization of acrylamide/acrylic acid in presence of fuller’s earth. Agro- and food industry wastes, sugarcane bagasse and chitin, respectively were used as reinforcing/ adsorbent materials. Effect of γ-radiation on adsorption characteristics of nanocomposites was evaluated by the comparison of swelling and erosion measurements of the exposed and unexposed samples. Low doses of γ-radiation improved the characteristics as adsorbents. Better results were obtained for the nanocomposites with polyacrylic acid matrix.

Kinetic analysis of experiment data for the formation of C.I.Acid Blue 9 leuco compound

A systematic study of the synthesis of C.I.Acid Blue 9 leuco compound in water is reported.The kinetic analysis of experimental data for the condensation reaction between 2-formylbenzenesulfonic acid sodium and N-ethyl-N-(3'-sulfonic acid benzyl) aniline obtained at four different temperatures ranging between 85 and 100°C is discussed.It is shown that the reaction followed second-order rate kinetics.The overall rate constant(k) increased with the increase of temperature.On the basis of the value of k,activation energy(E_a) of the reaction was evaluated.Importantly,it is found that reactant concentration has great effect on the formation of C.I.Acid Blue 9 leuco compound,implying that it is not enough to improve the conversion of N-ethyl-N-(3'-sulfonic acid benzyl) aniline by only prolonging reaction time in the late period of the reaction.