Characterization of encapsulated ginger essential oils and its antimicrobial properties / Tengku Shafazila Tengku Saharuddin... [et al.]

Ginger essential oils (GEO) are natural products with antibacteria properties consisting of many different volatile compounds have high potential to be used in many applications. In this study, the ginger GEO was successfully encapsulated in chitosan as a carrier agent using a spray drying technique. The extraction of Zingiber officinale (ginger) essential oil is performed by steam distillation method. The GEO was encapsulated in chitosan as a carrier agents at 1:3, GEO:chitosan ratio by using spray drying technique. GEO together with encapsulated GEO were further assayed for antimicrobial activity by disc-diffusion method. For characterization of encapsulated GEO, Fourier transform infrared spectroscopy (FTIR) and Field emission scanning electron microscopy (FESEM) were used. FTIR analysis revealed that there was no existence of a new functional group in the encapsulated GEO showing that there is only physical interaction between GEO and chitosan. Besides, FESEM analysis showed the encapsulated GEO were in micro in sizes and possessed spherical shape with smooth and porous surface. Furthermore, Both GEO and encapsulated GEO showed in vitro antimicrobial activity against Escheriachia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella typhi with encapsulated GEO possessed higher in the activities for all studied bacteria compared to GEO. The encapsulated GEO demonstrated a superior performance against Salmonella typhi with the inhibition zone of 22.5 mm compared to GEO only 13.5 mm. The results obtained indicated that due to the volatility and instability of the GEO when exposed to environmental factors, its encapsulation considerably improve and enhanced its performance

Comparative adsorption isotherm for Beryllium oxide/Iron (III) Oxide toward CO2 adsorption and desorption studies

Surface modification of Fe2O3 by adding BeO was synthesized and calcined at different temperatures of 200-600 °C. The adsorbents were characterized by using XRD, N2 adsorption-desorption isotherm prior to performing CO2 adsorption and desorption studies. The CO2 adsorption data were analyzed using adsorption isotherm models such as Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich. BeO/Fe2O3-300 that calcined at 300 °C showed the most efficient adsorbent with physisorption and chemisorption were measured at 5.85 and 45.88 mg/g respectively. The CO2 adsorption notably best fitted with Freundlich isotherm with R2 = 0.9897 and calculated adsorption capacity closest to experimental data. This implies the CO2 adsorption process was governed by multilayer adsorption on the heterogeneous surface of the adsorbent. The mean free energy of adsorption (E=3.536 kJ/mol) from Dubinin-Radushkevich and heat of adsorption (bT=3.219 kJ/mol) from the Temkin model support that the adsorption process is physical phenomena

Chemical Reduction Behavior of Zirconia Doped to Nickel at Different Temperature in Carbon Monoxide Atmosphere

The reduction behavior of nickel oxide (NiO) and zirconia (Zr) doped NiO (Zr/NiO) was investigated using temperature programmed reduction (TPR) using carbon monoxide (CO) as a reductant and then characterized using X-ray diffraction (XRD), nitrogen absorption isotherm using BET technique and FESEM-EDX. The reduction characteristics of NiO to Ni were examined up to temperature 700 °C and continued with isothermal reduction by 40 vol. % CO in nitrogen. The studies show that the TPR profile of doped NiO slightly shifts to a higher temperature as compared to the undoped NiO which begins at 387 °C and maximum at 461 °C. The interaction between ZrO2 with Ni leads to this slightly increase by 21 to 56 °C of the reduction temperature. Analysis using XRD confirmed, the increasing percentage of Zr from 5 to 15% speed up the reducibility of NiO to Ni at temperature 550 °C. At this temperature, undoped NiO and 5% Zr/NiO still show some crystallinity present of NiO, but 15% Zr/NiO shows no NiO in crystalline form. Based on the results of physical properties, the surface area for 5% Zr/NiO and 15% Zr/NiO was slightly increased from 6.6 to 16.7 m2/g compared to undoped NiO and for FESEM-EDX, the particles size also increased after doped with Zr on to NiO where 5% Zr/NiO particles were 110 ± 5 nm and 15% Zr/NiO 140 ± 2 nm. This confirmed that the addition of Zr to NiO has a remarkable chemical effect on complete reduction NiO to Ni at low reduction temperature (550 °C). This might be due to the formation of intermetallic between Zr/NiO which have new chemical and physical properties

Effect of cobalt on nickel oxide toward reduction behaviour in hydrogen and carbon monoxide atmosphere

The reduction behaviour of cobalt doped with nickel oxide and undoped nickel oxide (NiO) by hydrogen (H2) in nitrogen (20%, v/v) and carbon monoxide (CO) in nitrogen (40%, v/v) atmospheres have been investigated by temperature programmed reduction (TPR). The phases formed of partially and completely reduced samples were characterized by X-ray diffraction spectroscopy (XRD). TPR results indicate that the reduction of Co doped and undoped nickel oxide in both reductants proceed in one step reduction (NiO → Ni) without intermediate. TPR results also suggested that by adding Co metal into NiO, the reduction to metallic Ni by both reductant gaseous give different intensity of the peak. The reduction process of Co and undoped NiO become faster when H2 was used as a reductant. Furthermore, in H2 atmosphere, Co-NiO give complete reduction to metallic Ni at 700 °C. Meanwhile, XRD analysis indicated that NiO without Co composed better crystallite phases of NiO with higher intensity