Authors:Y.-P. Huang, Y. Liu, P. Shen, and S.-S. Qu
The application of a microcalorimetric method to the study of extremophiles is described briefly. Using the LKB 2277 Bioactivity
Monitor, the growth thermogenic curves of three strains of Halobacterium halobium were determined at 37C, and compared with the spectrophotometric curves. Then the suitable growth thermokinetic equation
was established based on the characteristics of growth thermogenic curves. By using cycle-flow method, all of the growth thermogenic
curves of H. halobium strains displayed a brief lag phase before the onset of exponential growth when they were cultured in Halo-2 medium.
Authors:W. Huang, Y. Xu, X. Chen, X. Gao, and Y. Fu
The radiation effect of γ-ray on polyether-urethane foam was studied. The gas products from irradiated samples were analyzed
quantitatively and qualitatively by gas chromatography, the thermal property and radical intensity were determined by differential
thermal gravimetry and electron spin resonance. The dynamic mechanical property, compression and tensile properties were analyzed.
Positron annihilation lifetime of irradiated samples was also measured at room temperature in vacuum. The results show that
the general mechanical properties of ETPU sample irradiated by γ-rays at a dose of 8.0·105 Gy is excellent, but there are considerable gas products and a great deal of radicals created, which indicates that the sample
has been damaged by radiation. Relatively, the thermal stability of the sample remained fine.
The characteristic properties of the chelating resin-3926(II) and the advantage of using it in the preconcentration procedure was described. The chemical recoveries determined by the trace technique were presented. The preconcentration procedure put forward in this paper may be used satisfactorily in neutron activation analysis.
Multiwall carbon nanotubes (MWCNTs) oxidized by nitric acid solution were used to investigate the adsorption behavior of strontium
from aqueous solutions similar to the nuclear waste media. The physical properties of both as produced and oxidized MWCNTs
were studied by Boehm’s titration method and nitrogen adsorption/desorption. The results showed that the surface properties
of MWCNTs such as specific surface area, functional groups and the total number of acid sites were improved after oxidation.
Furthermore, the effect of solution conditions such as initial concentration of strontium(II), pH, ionic strength, MWCNT concentration
and contact time were studied at room temperature. The results of this study showed that the adsorption of strontium(II) was
significantly influenced by the pH value and the solution ionic strength. According to the Langmuir model, the maximum adsorption
capacities of strontium(II) onto the as produced and oxidized MWCNTs were obtained as 1.62 and 6.62 mg g−1, respectively. The contact time to reach equilibrium was 100 min. The good adsorption of strontium(II) on oxidized MWCNTs
at the lower ionic strength, the relatively high pH and the short equilibrium time indicate that the oxidized MWCNTs have
great potential applications in the field of the environmental protection.
Multiwall carbon nanotubes (MWCNTs) were modified by nitric acid solution and then used to study the adsorption of cesium
from aqueous solution using a batch technique under ambient conditions. As produced and oxidized MWCNTs were characterized
by nitrogen adsorption/desorption, Boehm’s titration method and Fourier transform infrared spectroscopy. The physical properties
of MWCNTs such as functional groups, total number of acid sites and specific surface area were greatly improved after oxidation,
and these were responsible for more sorption of cesium from aqueous solution and made them more dispersible in water. The
adsorption of cesium ions as a function of contact time, initial concentration of cesium, pH, ionic strength and oxidized MWCNT concentrations was also investigated. The results showed that cesium adsorption percentage
strongly depended on the pH value, oxidized MWCNT content and on the solution ionic strength. Kinetic data indicated that
the adsorption process achieved equilibrium within 80 min. Equilibrium data for as produced and oxidized MWCNTs was well described
by both Freundlich and Langmuir isotherms. The dominant mechanism of cesium adsorption on oxidized MWCNTs may be mainly attributed
to ion exchange. This study suggests that oxidized MWCNTs can be a promising candidate for the removal of cesium from nuclear
Authors:C. Zeng, J.-C. Zhu, Y. Liu, Y. Yang, J.-Y. Zhu, Y.-P. Huang, and P. Shen
was used to study the influence of NaCl concentration on Halobacterium
salinarum growth. From the thermogenic curves and thermokinetic
parameters of H. salinarum growth in different
concentrations of NaCl, it was found that the optimum NaCl concentration for H. salinarum growth was not a wide range from 3.5
mol L–1 to NaCl saturation (about 5.2 mol
L–1), as is generally acknowledged, but just
around 230 g L–1 (approximately 3.9 mol L–1).
And when external NaCl concentration was above 230 g L–1,
the growth metabolism of H. salinarum decreased
constantly with the increasing of NaCl concentration. These have never been
described before. Further investigation by transmission electron microscopy
revealed that H. salinarum growing in approaching
NaCl saturation underwent plasmolysis, which interpreted the novel finding
of microcalorimetry perfectly. Our work shows that microcalorimetry may reveal
more and newer details about microbial growth than the existing methods do.
These details are significant to understand biological processes.
Authors:Sheri L. Shamblin, Eva Y. Huang, and G. Zografi
The purpose of this study was to measure the effect of co-lyophilized polymers on the crystallization of amorphous sucrose, and to test for a possible relationship between the ability of an additive to raise theTg of a sucrose-additive mixture, relative to theTg of pure sucrose, and its ability to inhibit crystallization. Differential scanning calorimetry was used to measure the glass transition temperature,Tg, the non-isothermal crystallization temperature,Tc, and the induction time for crystallization,Q, of sucrose in the presence of co-lyophilized Ficoll or poly(vinylpyrrolidone) (PVP). The effect of these polymers on the crystallization of sucrose was significant as demonstrated by a marked increase inTc, and in the induction time (Q) in the presence of relatively small amounts (1–10%) of additive. Surprisingly, small amounts of polymeric additive had no effect on theTg of sucrose, although at higher concentrations, theTg increased proportionally. Thus, it appears that the inhibition of sucrose crystallization by the additition of small amounts of a higher-Tg component cannot be attributed solely to changes in molecular mobility associated with an increase inTg.
A separation procedure of trace platinum from large amounts of mercury and other interfering elements is described. After irradiation, the HgO target was dissolved in concentrated HCl solution. The thallium fraction was removed by solvent extraction with ether. In the aqueous phase after extraction the radioisotope of platinum produced by irradiation was precipitated as (NH4)2PtCl6 by adding a saturated solution of NH4Cl in the presence of H2PtCl6·6H2O as stable carrier. The decontamination factor of mercury, gold and thallium and the recovery of platinum in the process of separation are satisfactory.
Authors:R. Yavari, Y. Huang, S. Ahmadi, and G. Bagheri
This study investigates uptake of cesium and strontium from aqueous solution similar to nuclear waste on three samples of
titanium molybdophosphate (TMP) synthesized under various conditions. Effects of concentration of sodium nitrate, pH and contact
time on the uptake of cesium and strontium have been studied by bath method. The results showed that TMP has high affinity
toward cesium and strontium at pH > 2 and relatively low concentration of sodium nitrate. Kinetic data indicated that cesium
uptake process to achieve equilibrium was faster than strontium. Cesium and strontium breakthrough curves were examined at
25 °C using column packed with H3O+ form of TMP and breakthrough curves showed symmetrical S-shaped profiles. At the same time, the calculated breakthrough capacity
for cesium was higher than strontium. The results of desorption studies showed that over 99% of cesium and strontium was washed
out of column by using 4 M NH4Cl solution. This study suggests that TMP can have great potential applications for the removal of strontium and specially
cesium from nuclear waste solution.
Authors:Y. Chou, J. Huang, J. Tseng, S. Cheng, and C. Shu
Organic peroxides have caused many serious explosions and fires that were promoted by thermal instability, chemical pollutants,
and even mechanical shock. Cumene hydroperoxide (CHP) has been employed in polymerization and for producing phenol and dicumyl
peroxide (DCPO). Differential scanning calorimetry (DSC) has been used to assess the thermal hazards associated with CHP contacting
sodium hydroxide (NaOH). Thermokinetic parameters, such as exothermic onset temperature (T0), peak temperature (Tmax), and enthalpy (ΔH) were obtained. Experimental data were obtained using DSC and curve fitting using thermal safety software (TSS) was employed
to obtain the kinetic parameters. Isothermal microcalorimetry (thermal activity monitor, TAM) was used to investigate the
thermal hazards associated with storing of CHP and CHP mixed with NaOH under isothermal conditions.
TAM showed that in the temperature range from 70 to 90°C an autocatalytic reaction occurs. This was apparent in the thermal
curves. Depending on the operating conditions, NaOH may be one of the chemicals or catalysts incompatible with CHP. When CHP
was mixed with NaOH, the T0 is lower and reactions become more complex than those associated with assessment of the decomposition of the pure peroxide.
The data by curve fitting indicated that the activation energy (Ea) for the induced decomposition is smaller than that for decomposition of CHP in the absence of hydroxide.