The Influence Of Pd Nanoparticle Size On Pd/TiO2 Catalysts For Cinnamaldehyde Hydrogenation Reaction

Palladium nanoparticles (PdNP) supported onto the anatase phase of TiO2 were successfully synthesised using a colloidal method. This synthesis method involved the reduction of K2PdCl4 solution by NaBH4 at different temperatures (1, 25, 50, 75oC) and stabilised with PVA ligand. Transmission electron microscope (TEM) was used to determine the particle size of PdNP on the TiO2. Colloidal synthesis at 1oC and 25oC produced PdNP with less than a 3 nm diameter, whereas when the synthesis temperatures were higher than 25oC, PdNP were produced with a size larger than 4 nm. The catalytic activity of Pd/TiO2 was significantly improved when palladium (Pd) was produced at 1oC with high selectivity towards the hydrogenation of cinnamaldehyde to hydrocinnamaldehyde. The conversion and selectivity trends from the cinnamaldehyde hydrogenation reaction demonstrated the influence of Pd nanoparticle size to provide active sites for the reduction of C=C and C=O bonds. Pd with a diameter of 2.58 nm favoured hydrogenation of C=C bond to produce high selectivity towards hydrocinnamaldehyde, meanwhile a large Pd diameter > 4 nm allowed simultaneaous reduction of C=C and C=O bonds to give comparable selectivity between hydrocinnamaldehyde and hydrocinnamylalcohol

Adsorption of carbon dioxide by reusing drinking water treatment plant sludge

Cost effective, easy to use and regenerate could be the desired properties of an adsorbent. Reusing of waste material as CO2 adsorbent can be a good alternative for solving the problem of waste disposal as well. Thus, in this study, aluminium-based drinking water treatment plant sludge as carbon dioxide adsorbent was reused. The sludge collected from a local drinking water treatment plant. It was dried and characterized using scanning electron microscope-energy disperse X-ray (SEM-EDX), Fourier transform infrared spectrometer (FTIR) and thermogravimetric analysis (TGA). Investigations of the effects of temperature, flow rate, concentration of CO2 and adsorbent dosage on CO2 adsorption capacity were performed using a fixed bed column at a pressure of 1 bar. The maximum capacity of 32.56 mg/g was found which was higher than that of some reported adsorbents

Dielectric Properties of Ceramic, CaCu3Ti4O12, Substituted with Sr or Ba

There has been a considerable interest in non-ferroelectric perovskite oxide CaCu3Ti4O12 (CCTO). This material was discovered to possess one of the largest static dielectric constants, reaching nearly ε ~ 80, 000 for single-crystal samples at room temperature. This compound has centrosymmetric structure at room temperature with cubic space group Im3. Because of such incredibly high dielectric constant, the structure, dielectric and electrical properties of CaCu3Ti4O12 substituted at Ca-site with other alkaline earth metals i.e. Ba and Sr as substitution elements were studied. An extensive studies were carried out on the dielectric properties of the Ca1-xBaxCu3Ti4O12 and Ca1-xSrxCu3Ti4O12 where x = 0.5, 0.52, 0.56 and 0.6 at various temperatures. The substitutions were based on ionic radius (rCa < rSr < rBa) and the dielectric studies of Ca1-xMxCu3Ti4O12 (where M = Sr, Ba) have not been reported so far. There are two categories in the experimental investigation. First, is the X-ray diffraction that is vital to provide evidence to the proposed model of dielectric behavior. Secondly, the main experiment consists of alternating current conductivity measurement where the ability to store charge (capacitance) and conductance can be investigated. The XRD measurements reveals that the lattice parameter of CaCu3Ti4O12 after substitution of Sr2+ and Ba2+ changes while the pattern can be assigned to all the lines on the basis of a cubic symmetry. Single–phase for Ca1-xSrxCu3Ti4O12 was observed while for Ca1-xBaxCu3Ti4O12 it was found as multi-phase with some impurity element in the compound. The electrical measurement was performed using High Dielectric Resolution Analyzer, measured as a function of frequency from 10-2 Hz to 106 Hz. The data collected were plotted in log-log scale of frequency against real and imaginary of permittivity and conductivity respectively. The graphs were then fitted using the universal law to obtain the properties and mechanism that took part, with parameters involved such as m, n and p. Most of the fitted graphs showed that Ca1-xBaxCu3Ti4O12 and Ca1-xSrxCu3Ti4O12 consisted of quasi-dc, dipolar mechanism, conductance G, and some Rs effect. The substitution of Sr2+ and Ba2+ into Ca-site of CaCu3Ti4O12 reveals the specific behavior of this material when it is doped with a higher radius of the element. However, substitution of Sr2+ has apparently given the highest value of dielectric constant i.e. ~ 2.6 x 102 when substituted by 50 mole % of Sr2+ at Ca-site of CaCu3Ti4O12

Wpływ wstępnej obróbki na strukturę celulozy bakteryjnej z Nata de Coco (Acetobacter xylinum)

This paper presents a structural analysis of various methods to produce bacterial cellulose (BC) from Nata de Coco (Acetobacter xylinum). BC sheet, BC chem and BC mech powders were successfully prepared using oven drying, chemical and mechanical treatment. The X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and field emission scanning electron microscopy (FESEM) were used to analyze the structure of prepared BC. The structure of bacterial cellulose was compared with the structure of commercial microcrystalline cellulose (MCC) and cotton fabric. The XRD results showed that the BC sheet sample had the highest degree of crystallinity (81.76%) compared to cotton cellulose (75.73%). The crystallite size of cotton was larger than the BC sheet, with the value of 6.83 ηm and 4.55 ηm, respectively. The peaks in the FTIR spectra of all BC were comparable to the commercial MCC and cotton fabrics. FESEM images showed that the prepared BC sheet, BC mech, and BC chem had an almost similar structure like commercial MCC and cotton fabric. It was concluded that simple preparation of BC could be implemented and used for further BC preparation as reinforcement in polymer composites, especially in food packaging.Niniejszy artykuł zawiera analizę struktury celulozy bakteryjnej (BC) wytworzonej z Nata de Coco (Acetobacter xylinum) różnymi metodami. Folia BC i proszki BC chem oraz BC mech zo -stały wytworzone poprzez suszenie w piecu, obróbkę chemiczną i mechaniczną. Do oceny struktury celulozy bakteryjnej stosowano dyfrakcję rentgenowską (XRD), spektroskopię Fouriera w podczerwieni (FTIR) i skaningową mikroskopię elektronową z emisją polową (FESEM). Strukturę celulozy bakteryjnej porównano ze strukturą handlowej celulozy mikrokrystalicznej (MCC) i tkaniny bawełnianej. Wyniki XRD wykazały, że najwyższy stopień krystaliczności miała próbka arkusza BC (81,76%) w porównaniu z celulozą bawełnianą (75,73%). Wielkość krystalitów bawełny była większa niż folii BC i wynosiła, odpowiednio, 6,83 ηm oraz 4,55 ηm. Piki widm FTIR wszystkich otrzymanych form celulozy bakteryjnej były porównywalne z komercyjnymi tkaninami bawełnianymi i z celulozy mikrokrystalicznej. Zdjęcia FESEM folii BC oraz proszków BC mech i BC chem również były podobne do komercyjnej MCC i tkaniny bawełnianej. Stwierdzono, że z wykorzystaniem prostych technik można otrzymać BC, która może być stosowana jako wzmocnienie w kompozytach polimerowych, w szczególności w opakowaniach do żywności

Factorial design analysis of Zn(II) ions adsorption on thermally treated rice husk

Adsorption of Zn(II) ions from aqueous solutions by thermally treated rice husk was investigated using factorial experimental design to study effects of heating temperature and period of rice husk, pH, initial Zn(II) ion concentration, adsorption temperature and contact time, and adsorbent dosage. Main and interaction effects of these factors were analyzed using statistical techniques and the results were analyzed statistically using the Student’s t-analysis and analysis of variance which were used to determine significant factors that affect the percentage removal of Zn(II). These significant factors were heating temperature of rice husk, pH, initial metal concentration, contact time, and adsorbent dosage. The interaction between two different effects also affects the percentage removal of Zn(II) ions. These include the interactions between heating temperature of rice husk and initial metal concentration, pH and initial metal concentration, and pH and the adsorbent dosage