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91.
The surface area was determined for various papermaking woodpulps: bleached eucalyptus globulus sulphate pulp; bleached eucalyptus grandis sulphate pulp; bleached betula verrucosa sulphate pulp; bleached pine/spruce sulphate pulp; bleached pine/spruce sulphate pulp fines. The method of negative adsorption was used which gives an effective wet surface area. By looking at negative adsorption data more closely, some inference can be made about the morphology of the substrate.Glossary of symbols
B
(e2/2kT)1/2
-
¯C
concentration of fibre per unit volume of pulp
-
1 - ¯¯c
-
h
angle between pore and the axis of the bed in a permeable material
-
K
permeability coefficient
-
k
Boltzmann constant
-
k
0
shape factor for pores in a permeable material
-
n
i
concentration of co-ion in the bulk solution
-
n
i
experimentally observed increase in concentration of co-ion in the bulk solution
-
S
surface area
-
S
t
wS
-
S
0
surface area per unit volume of permeable material
-
V
t
total volume of solution
-
V
excluded volume
- V
s
excluded volume accessible to water but not to ions
- V
obs
experimentally observed excluded volume
-
w
weight of dry fibre
-
¯
effective volume of fibres in a permeable pad
-
surface potential at outer Helmholtz plane 相似文献
92.
93.
《Arabian Journal of Chemistry》2020,13(9):7115-7131
The impregnation of magnetite (Mt) nanoparticle (NPs) onto Musa acuminata peel (MApe), to form a novel magnetic combo (MApe-Mt) for the adsorption of anionic bromophenol blue (BPB) was studied. The SEM, EDX, BET, XRD, FTIR and TGA were used to characterize the adsorbents. The FTIR showed that the OH and CO groups were the major sites for BPB uptake onto the adsorbent materials. The average Mt crystalline size on MApe-Mt was 21.13 nm. SEM analysis revealed that Mt NPs were agglomerated on the surface of the MApe biosorbent, with an average Mt diameter of 25.97 nm. After Mt impregnation, a decrease in BET surface area (14.89 to 3.80 m2/g) and an increase in pore diameter (2.25–3.11 nm), pore volume (0.0052–0.01418 cm3/g) and pH point of zero charge (6.4–7.2) was obtained. The presence of Pb(II) ions in solution significantly decreased the uptake of BPB onto both MApe (66.1–43.8%) and MApe-Mt (80.3–59.1%), compared to other competing ions (Zn(II), Cd(II), Ni(II)) in the solution. Isotherm modeling showed that the Freundlich model best fitted the adsorption data (R2 > 0.994 and SSE < 0.0013). In addition, maximum monolayer uptake was enhanced from 6.04 to 8.12 mg/g after Mt impregnation. Kinetics were well described by the pseudo-first order and liquid film diffusion models. Thermodynamics revealed a physical, endothermic adsorption of BPB onto the adsorbents, with ΔHo values of 15.87–16.49 kJ/mol, corroborated by high desorption (over 90%) of BPB from the loaded materials. The viability of the prepared adsorbents was also revealed in its reusability for BPB uptake. 相似文献
94.
《Journal of separation science》2003,26(17):1491-1498
Concurrent Solvent Recondensation Large Sample Volume (CRS‐LV) splitless injection overcomes the limitation of the maximum sample volume to 1–2 μL valid for classical splitless injection. It is based on control of the evaporation rate in the vaporizing chamber, utilization of a strong pressure increase in the injector resulting from solvent evaporation, and greatly accelerated transfer of the sample vapors from the injector into the inlet of an uncoated precolumn by recondensation of the solvent. The sample vapors are transferred into the column as rapidly as they are formed in the injector (concurrent transfer). 20–50 μL of liquid sample is injected with liquid band formation. The sample liquid is received by a small packing of deactivated glass wool positioned slightly above the column entrance at the bottom of the vaporizing chamber. Solvent evaporation strongly increases the pressure in the injector (auto pressure surge), provided the septum purge outlet is closed and the accessible volumes around the vaporizing chamber are small, driving the first vapors into the precolumn. Transfer continues to be fast because of recondensation of the solvent, obtained by keeping the oven temperature below the pressure‐corrected solvent boiling point. The uncoated precolumn must have sufficient capacity to retain most of the sample as a liquid. The experimental data show virtually complete absence of discrimination of volatile or high boiling components as well as high reproducibility. 相似文献
95.
96.
Amperometric glucose sensors have been fabricated with glucose oxidase (GOx) immobilized on ZnO nanotubes (ZnONTs) by physical adsorption. The ZnONTs were formed through selective dissolution of ZnO nanorods (ZnONRs) which were hydrothermally synthesized on Au cylindrical spiral (AuCS) electrodes. With the etching temperature regulated, the surface morphologies of the ZnONT arrays were tailored and their effects on the performance of the corresponding glucose sensors were investigated. It is found that at 65 °C the as-prepared ZnONT arrays show a Gaussian rough surface with larger surface area and better hydrophilicity, and have an effective solid–liquid interface with GOx solution, which further results in desirable GOx immobilization. Therefore favorable performance of the ZnONT-based glucose sensor was obtained, such as the sensitivity 2.63 μA/(mM cm2), linear range 0–6.5 mM, low detection limit 8 μM (S/N=3) and Michaelis-Menten constant 5.24 mM, which are superior to that of the ZnONR-based one. Moreover, the ZnONT-based glucose sensor exhibits good long-term stability, and excellent anti-interference ability to uric acid and ascorbic acid. The results can also be used for the performance optimization and the process standardization of other ZnONT-based amperometric biosensors. 相似文献
97.
Meena Kumari Upendra Kumar Singh Abbul Bashar Khan Maqsood Ahmad Malik 《Journal of Dispersion Science and Technology》2018,39(10):1462-1468
The effect of bovine serum albumin on the surface properties of IL-type gemini surfactant ([C10-4-C10im]Br2), have been investigated by surface tension method. The critical micelle concentration (CMC) as a function of BSA concentrations at various temperatures was investigated. The CMC of [C10-4-C10im]Br2 increases with increasing the concentration of BSA as well as the temperature of the system. The interfacial parameters viz; maximum surface excess concentration (Γmax), the minimum area per molecule (Amin), and surface pressure at CMC (Πcmc) were calculated. In addition, thermodynamic parameters of adsorption and micellization were evaluated by using surface tension data. The results indicated that the binding of [C10-4-C10im]Br2 to BSA is spontaneous and exothermic in nature. The process is entropy driven and hydrophobic interactions are the major driving forces. 相似文献
98.
We make some remarks about deriving the large deviations estimates for the Ventsel-Freidlin perturbed system and adapt these methods to derive similar results for singular perturbations of degenerate one-dimensional diffusions where β and ω are independent Brownian motions. This corresponds to a singular perturbation of the degenerate second-order operator 相似文献
99.
100.
In our previous work (Hu et al., 2014), a method has been proposed to detect gas compositions by locating the acoustic spectral peaks, which can be detected only by two-frequency acoustic measurements in practice. However, as a ‘Detection Calibration’, the effective relaxation area (ERA) constructed by existing theoretical model cannot match the two-frequency measurements when there are more than one strong relaxational components in gas mixtures. This paper proposes a method to construct the ERA by coupling the decoupled single relaxation times together to a whole relaxation time. For gas mixtures with only one single relaxation process, the predicted ERA results match with the experimental data better than those predicted by the existing model. Moreover, for gas mixtures in which more than one relaxation process are significant, the ERA results predicted by the proposed method also match with the detection results of two-frequency measurements better than the existing model. This relaxation time coupling based ERA constructing method is validated by the application in low-quality natural gas detection. 相似文献