- Equilibrium, kinetics and thermodynamic studies on the adsorption of
direct dye onto a novel green adsorbent Uncaria gambir
A. Achmad, J. Kassim, T. K. Suan, R. C Amat and T. L Seey
Abstract:
Uncaria gambir was chemically modified with a view to develop a novel green adsorbent. The modified gambir adsorbent was characterized by FTIR, SEM-EDX and pHzpc and its potential for the removal of direct red 23 from aqueous solution was investigated. The results showed that equilibrium data was well described by Langmuir isotherm with maximum adsorption capacity of 26.67 mg/g. The kinetic of adsorption direct red 23 was followed by pseudo-second-order kinetic model. Thermodynamic parameters such as enthalpy change (ΔH°), free energy change (ΔG°) and entropy change (ΔS°) were studied and the adsorption process of direct red 23 was endothermic and spontaneous.
- Analysis of etching of tooth-coloured restoratives by different acidulating
systems in topical fluoride gels
K. Mokhtar and J.McIntyre
Abstract:
The aims of this study were to determine the etching effects of acidulated fluoride gels on high glass content restorations and to compare with different acidulating systems. Samples of KetacFil, Fuji IX, Z100 and porcelain were each submerged into test solutions of 1.23 % APF and its individual acidic components (HF and H3PO4) together with fluoride ion for 1–20 mins at 37°C. Subsequently, Fuji IX samples were exposed to the potential alternative acidulating solutions (polyacrylic, malic, maleic and tartaric acids) for similar time periods and assessed for roughness using profilometer and/or Scanning Electron Microscopy. The results showed that the GICs were most rapidly and extensively etched by APF solutions. However, porcelain less rapidly and Z100 showed no etching. Of the acidulated fluoride solutions tested, malic and maleic acids showed the greatest etching effect on Fuji IX, followed by APF, HFF, tartaric, PAA and HPF. In conclusion, the acidulating system containing ortho-phosphoric acid showed the least rapid etching effects, though these were still of concern with long term exposure.
- Secondary metabolites from Jatropha podagrica Hook.
N. N. Rumzhum, M. H. Sohrab, M. A. Al-Mansur, M. S. Rahman,
C. M. Hasan and M. A. Rashid
Abstract:
The stem bark of Jatropha podagrica Hook. (Family - Euphorbiaceae) was subjected to a thorough phytochemical investigation. Repeated chromatographic separation and purification of the crude methanol extract of this bark provided six compounds, fraxidin (1), fraxetin (2), scoparone (3), 3-acetylaleuritolic acid (4), β-sitosterol (5) and sitosterone (6). The structures of the isolated compounds were determined by spectroscopic analysis, notably 2D NMR techniques as well as comparison of their spectral data with previously reported values.
- Electrical and Optical properties of Magnasium Filled Polystyrene (PS-Mg)
Composites
I. R. Agool
Abstract:
In this paper, the effect of filler content on electrical and optical properties of polystyrene filled with Mg powders has been investigated. For that purpose, the PS samples with Mg additive prepared with different percentages and different thickness. The experimental results showed that the conductivity of such composites increased suddenly by several orders of magnitude at a critical weight concentration. The electrical conductivity changed with increasing of temperature. Also, the activation energy change with increasing filler concentration. The dielectric constant, dielectric loss and electrical conductivity are changed with the change of the concentration of the filler and frequency of applied electrical field. The absorption coefficient, extinction coefficient, energy gap of the indirect allowed and forbidden transition, real and imaginary dielectric constants and optical conductivity have been determined.
- Preliminary studies on 222Rn concentration in ground water from Zaria metropolis
N. N. Garba, N. Rabi’u and B. B. M. Dewu
Abstract:
Preliminary studies on groundwater samples from selected wells and boreholes in Zaria metropolis was carried out to determine the concentration of 222Rn. The analysis was carried out during dry season when the weather was fairly stable and the community depends solely on groundwater sources for domestic use during the period. Measurements were carried out using liquid scintillation counter at the Center for Energy Research and Training, Ahmadu Bello University, Zaria-Nigeria. The average concentration obtained was 7.18 ± 1.11 Bq/l for wells and 7.41 ± 2.04 Bq/l for borehole waters respectively. The result is within the maximum concentration limit of 11.1Bq/L and world average value of 10Bq/L for drinking water.
- Optimization and kinetic studies on the extraction process of essential oil
from Zingiber cassumunar
Y. P. Teoh, M. Mat Don and T. Muhammad Azhar
Abstract:
Three operating parameters of hydrodistillation have been optimised by a response surface method using central composite design to obtain high yields of essential oil from rhizome of the Zingiberaceae species, Zingiber cassumunar. The optimum conditions for the maximum essential oil produced (6.64 g) were found to be at extraction time 4 hr, solid to solvent ratio of 3:150 and hydrodistillation rate 78 mL/hr, respectively. The study was then further continued with the three proposed models of the extraction process. Kinetic models proposed by Milojevi et al. and Hervas et al. were suitable for the process under low (20 mL/hr) and high distillation rate (70 mL/hr), respectively, whereas the model by Ana et al. was valid for all range of rates studied (20-70 mL/hr). It can be concluded that hydrodistillation rate was one of the important parameter for determining the extraction kinetic.
- Secondary metabolites from seed extracts of Syzygium cumini (L.)
M. A. A. Sikder, M. A. Kaisar, M. S. Rahman, C. M. Hasan, A. J. Al-Rehaily
and M. A. Rashid
Abstract:
Four compounds were isolated from the pet-ether and carbon tetrachloride soluble partitionates of a methanol extract of seeds of Syzygium cumini. The structures of the isolated compounds were elucidated as 7-hydroxycalamenene (1), methyl-β-orsellinate (2), β-sitosterol (3) and oleanolic acid (4) by extensive spectroscopic studies, including high field NMR analyses. 7-hydroxycalamenene (1) appeared to be first report of its occurrence from S. cumini as well as from the Myrtaceae family although it was reported in cultured cells of the liverwort, Heteroscyphus planus. This is also the first report of isolation of compounds 2-4 from this plant species.
- An Analysis Study for Absorption spectrum of Styrene-Butadiene in Toluene
(Short Communication)
M. F. H. Al-Kadhemy, R. Hussein and A. A. D. Al- Zuky
Abstract:
The absorption spectrum of styrene- butadiene in toluene at different concentration (0.1–0.6) wt% were studied experimentally, and estimate theoretical model for these spectra. There is a blue shifting toward a short wavelength ~ 31.64 nm with increasing concentration. An estimated theoretical model for the effect of concentration on the absorption spectrum of styrene - butadiene in toluene was achieved by using "Table Curve 2D, version 5.01" program. This estimated model was applied on test concentration of styrene – butadiene in toluene 0.45 wt% that is not taken experimentally. We get good matching between experimental and theoretical spectrum in the value of wavelength and the behaviour of spectrum.
