A green hydrothermal route to GaOOH nanorods

GaOOH nanorods were synthesized by a green hydrothermal method at 200 °C using nanocrystalline Ga₂O₃ powders and distilled water as the starting materials, and characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and thermogravimetric and differential scanning calorimetry (TG-DSC) analysis.     

A green hydrothermal route to nanocrystalline CuCl

CuCl, a wide bandgap (E_g = 3.395 eV at 4 K) I-VII semiconductor with excitonic binding energies of about 190 meV, can be used in the manufacture of electrooptic modulators, optical filters, solid-state batteries, catalyst, adsorbent, air purifying agents, blue-UV light-emitting devices, etc. Although many methods have already been developed for synthesizing CuCl powders with different characteristics so far, all of them either need complicated equipment and high reaction temperatures, or utilize toxic reactants and organic solvent, or produce much pollutive byproducts. In this paper, we report a green hydrothermal way to prepare nanocrystalline CuCl powders, simply by using the reaction of CuCl₂ and alpha-d-glucose in distilled water in an autoclave at 120 °C for 24 h. The obtained CuCl nanocrystals were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS), and their possible formation mechanism was also proposed.     

A facile and green route to silver nanoparticles in water

Stable water-dispersible silver nanoparticles with a narrow size distribution are obtained by light-assisted spontaneous reduction of silver nitrate with gelatin, which acts as both the reducing and the stabilizing agents, in water. The formation mechanism of the silver nanoparticles involves an in-situ conversion of Ag(+)-gelatin aggregates to gelatin-stabilized silver nanoparticles via a Ag(+)-mediated oxidation of primary amine groups of the gelatin to carboxylic acid groups. The resultant silver nanoparticles are well within the quantum size domain (10 nm). In addition, the nanoparticles are stable in aqueous solutions and can be separated easily by simple pH adjustment.     

A green and facile route to synthesize calcium silicate nanowires

Large-scale single crystalline calcium silicate nanowires have been synthesized via a simple and facile hydrothermal route using nanoscale SiO₂ and CaO powders as the starting materials. Xonotlite [Ca₆(Si₆O₁₇)(OH)₂] nanowires were first achieved after hydrothermal treatment at 220 °C for 12 h. After being calcinated at 800 °C for 1 h, the Ca₆(Si₆O₁₇)(OH)₂ nanowires are completely transformed into β-CaSiO₃ nanowires. The β-CaSiO₃ nanowires have a diameter of 30–150 nm and a length of tens of micrometers. The hydrothermal conditions and the size of the raw materials play important roles on the size of the nanowires. A possible growth mechanism of the nanowires is also proposed.     

两相电解电渗技术浓缩回收乙酸的研究

在两相电泳的基础上,针对含乙酸稀溶液的处理提出了两相电解电渗的技术．利用饱和水的正丁醇为有机相,以AM203阴离子交换膜为介质,开展普通电解电渗和两相电解电渗的研究工作,考察了浓度、电流密度等因素对电流效率、浓缩比以及水的电渗量的影响、结果发现较普通的电解电渗技术和两相电解电渗技术在浓缩比、水的电渗量的控制方面具有明显的优势,在本实验范围内,在两相电解电渗过程中基本没有发现水的电渗现象的发生,同样乙酸的回收率也可以达到100％．由此可以说明新的两相电解电渗技术对于环境稀溶液的处理是一种较为理想的方法．     

A green route to synthesize novel Ag/C antibacterial agent

A facile approach is reported for the synthesis of novel Ag/C antibacterial agent. The corn crispy is selected as the carbon substrate for supporting the Ag particles that fabricates the Ag/C composites via the high temperature carbonization process. The composites have been characterized by TEM, XRD, XPS, and IR measurements. The results reveal that about 20 nm Ag nanoparticles are uniformly dispersed within the composites. The carbonization temperature could increase the size of Ag nanoparticles. The antibacterial activity of Ag/C composites is investigated using the agar well diffusion method. The results show fine and stable antibacterial activity of composites against Bacillus subtilis and Escherichia coli due to small particle size, large surface area and favorable dispersibility of Ag nanoparticles.     

Ozonation of trichloroethylene in acetic acid solution with soluble and solid humic acid

The combined flushing and oxidation process using acetic acid and ozone has been used successfully to remove trichloroethylene (TCE) completely from contaminated soil. In this study, the effects of humic acid, a fraction of the organic matter in soil, over the performance of TCE decomposition was evaluated. TCE decomposition by ozone was enhanced by the presence of humic acid at concentrations lower than 8mgCL(-1) and then inhibited at higher concentrations. It is possible that the presence of the soluble humic acid fraction during the ozonation of TCE in acetic acid solutions produces hydroxyl radicals during the TCE ozonation which appears to be the reason for the enhanced TCE decomposition rate. Solid humic acid reduced TCE decomposition rate by acting as an ozone scavenger. Similarly, sorbed TCE reduced the amount of TCE available for decomposition by ozone in solution.     

Olfactory receptor-based polypeptide sensor for acetic acid VOC detection

Rapid detection of food-borne pathogens in packaged food products can prevent the spread of infectious diseases. This study investigates the application of novel sensing material that is sensitive to specific indicator volatile organic compound (VOC) related to Salmonella contamination in packaged meat. Specifically, the objective was to develop an olfactory receptor-based synthetic polypeptide sensor for the detecting acetic acid in low concentrations and at room temperature. Synthetic polypeptide was deposited on a quartz crystal microbalance (QCM) electrode and was evaluated for detecting acetic acid at 10–100 ppm. Developed sensor exhibited repeatable response to a particular concentration of acetic acid and displayed reproducibility among multiple sensors during acetic acid detection. Mean estimated lower detection limits of these sensors were about 1–3 ppm and linear calibration models showed linear relationships. Thus, the QCM sensors exhibited a great potential for detecting low concentrations of acetic acid at room temperature and can be used in the sensor array for packaged meat spoilage and contamination detection.     

New processes for recovery of acetic acid from waste water

This paper addresses an industrially important problem of acetic acid recovery from a waste water stream via reactive distillation. The presence of a three-phase regime on the column stages due to a liquid–liquid phase split between aqueous and organic phases is a typical characteristic of this process. A modern modeling approach is presented to detect the existence of potential phase splitting in this column. A good agreement of a phase splitting model with the literature data has been shown. A theoretical study for the recovery of acetic acid from its 30 wt% aqueous solution by esterification with n-butanol is presented. Alternate column structures were investigated and two structures rendering theoretically close to 100% conversion of acetic acid were identified. The dynamic simulations were performed on proposed structures to see transient responses wrt. to common process disturbances. The work was originally presented at the PRES-2006 (27–31 August) conference in Prague, Czech Republic.     

A continuous flow reaction system for producing acetic acid by wet oxidation of biomass waste

A continuous flow reaction system designed for producing acetic acid by wet oxidation (WO) of biomass with the maximum treatment capacity of 1 kg/h of dry biomass was developed. Experimental runs with rice hulls and starch were conducted at reaction temperatures between 300–320°C, for time of 2 and 3 min, with oxygen supplies between 70 and 100%, and at pressures between 10 and 30 MPa. The influence of each of these parameters was evaluated.     

Thermal decomposition of acetic anhydride-nitric acid mixtures

The adoption of Ac2O/HNO3 mixtures for the nitration of organics or the preparation of nitric esters is not free from some risks of explosion. The behaviour of these mixtures at varying Ac2O/HNO3 molar ratios is studied by means of adiabatic and scanning calorimetry. A simplified kinetic model, based on two lumped reactions (one of which leads to the formation of tetranitromethane) is developed to simulate the thermal decomposition of the investigated system under adiabatic conditions. The use of this model allows satisfactory prediction of the temperature profiles in the reactor whereas calculated pressures are generally overestimated due to some model inadequacies to account for the absorption of gaseous decomposition products into the reacting solution.     

Hydrothermal conversion of biomass into acetic acid

Hydrothermal process is one of the most promising processes for the conversion of biomass waste into resources among the several biomass conversion processes, because water of high temperature and high pressure has remarkable properties as a reaction medium. This paper described advances in our research involving overall reaction pathways for acetic acid production from biomass, mainly including (1) acetic acid production by controlling pathways of hydrothermal reaction, (2) acid-base behavior of water in the subcritical region and (3) effect of lignin on the acetic acid production in WO of lignocellulosic biomass.     

PDMS-AMEO膜用于渗透汽化分离乙酸/水体系的性能研究

采用原位聚合法制备了氨丙基三甲氧基硅氧烷交联聚二甲基硅氧烷( PDMS- AMEO)/有机蒙脱土(OM-MT)/聚醚砜(PES)复合膜,采用SEM和TGA对PDMS-AMEO/OMMT/PES的形貌、热学性能进行了研究.考察了复合膜在乙酸-水溶液中的溶胀性,以及OMMT含量、料液温度和浓度对膜渗透汽化性能的影响.     

Organic aerogels from the polycondensation of resorcinol with formaldehyde

The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer clusters. The covalent crosslinking of these clusters produces gels which are processed under supercritical conditions to obtain low density, organic aerogels ( 0.1 g cm^–3). The aerogels are transparent, dark red in colour, and consist of interconnected colloidal-like particles with diameters of approximately 10 nm. The polymerization mechanism, structure and properties of the resorcinol-formaldehyde aerogels are similar to the sol-gel processing of silica.     

Surface functionalisation of bacterial cellulose as the route to produce green polylactide nanocomposites with improved properties

The effect of surface functionalisation of bacterial cellulose nanofibrils (BC) and their use as reinforcement for polylactide (PLLA) nanocomposites was investigated. BC was functionalised with various organic acids via an esterification reaction. This rendered the otherwise hydrophilic BC hydrophobic and resulted in better compatibility (interfacial adhesion) between PLLA and BC. A direct wetting method, allowing the determination of the contact angle of polymer droplets on a single BC nanofibre, was developed to quantify the interfacial adhesion between PLLA and functionalised BC. It was found that the contact angle between PLLA droplets and functionalised BC decreased with increasing chain lengths of the organic acids used to hydrophobise BC. A novel method to compound BC with PLLA based on thermally induced phase separation (TIPS) to yield a dry form of pre-extrusion composite was also developed. The mechanical properties of the surface functionalised BC reinforced PLLA nanocomposites showed significant improvements when compared to neat PLLA and BC reinforced PLLA. The thermal degradation and viscoelastic behaviour of the nanocomposites were also improved over neat PLLA.     

Biomolecule-assisted green route to Sb2S3 crystals with three-dimensional dandelionlike patterns

This paper describes a simple biomolecule-assisted solvothermal approach to fabricate the three-dimensional (3D) Sb2S3 microsphere with a wealth of novel morphologies in the presence of L-cysteine, which served as both the sulfur source and the directing molecule in the formation of antimony sulfide nanostructures. The effects of different solvents, and polyvinylpyrrolidone (PVP) on the morphology, structure, and phase composition of the as-prepared Sb2S3 products were discussed. The formation of 3D dandelionlike Sb2S3 microsphere was probably via the mechanism of the orientated aggregation growth of the Sb2S3 particles under the complexing action of L-cysteine, and co-action of the surfactant PVP. The absorption spectra of as-prepared 3D dandelionlike Sb2S3 structures show an optical shoulder band gap of 1.81 eV, which is near to the optimum for photovoltaic conversion.     

2-噻吩乙酸的HPLC分析测定

建立了一种2-噻吩乙酸的反相高效液相色谱-紫外检测法.研究了流动相的组成、流速及色谱柱温度等因素对测定的影响.采用色谱柱为VARIAN C18(250 mm×4.6 mm,5μm)反相色谱柱,流动相为甲醇-水(V∶V=70∶30),流速1.0 mL/min,柱温为室温,紫外检测波长235 nm,在6 min内可完成分析.该方法的回收率为98.4%~99.8%,RSD<1%.其优点为2-噻吩乙酸与其同分异构体3-噻吩乙酸得到较好的分离,明显不重叠,且操作简单、快速和准确可靠,用于2-噻吩乙酸产品的纯度测定,结果令人满意.     

醋酸分子印迹电化学传感器的制备

基于循环伏安电化学聚合方法,以30mmol/L醋酸作为模板分子,5mmol/L苯酚作为功能单体,0.1mol/L氯化钾和0.05mol/L磷酸盐缓冲溶液(pH=5.4)作为聚合底液,聚合电位为-0.8~1.2V,扫描圈数为20,以0.1mol/L碳酸氢钠溶液作为洗脱液进行洗脱20min,最终制得性能较佳的醋酸分子印迹电化学传感器。对该传感器进行循环伏安(CV)表征、阻抗表征、扫描电镜的形貌表征、差分脉冲表征,探索了不同pH磷酸盐缓冲溶液作为聚合底液、不同浓度洗脱液和不同洗脱时间对该传感器性能的影响。发现在以0.05mol/L磷酸盐缓冲溶液(pH=5.4)作为最佳底液条件下,醋酸分子印迹电化学传感器与0~45×10^-9 mol/L浓度范围内醋酸分子二者呈现出良好的线性关系,其检出限为2.85×10^-9 mol/L,同时研究了该传感器的重现性和稳定性。     

A green route to water soluble carbon nanotubes and in situ loading of silver nanoparticles

A green approach has been developed to synthesize water soluble multi-walled carbon nanotubes (MWNTs). Ag nanoparticles have been loaded on the as-synthesized MWNTs via the in situ solution method. The strategy is based on the introduction of hydroxyl and carboxyl groups through a mild modification of MWNTs via polycondensation of citric acid and D-sorbitol, improving the water solubility of MWNTs, giving rise to preferred sites of Ag nucleation, and providing mild in situ reducing agents. The modification of MWNTs and loading of Ag nanoparticles on MWNTs were demonstrated by Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, and scanning electron microscopy.