[Show abstract][Hide abstract] ABSTRACT: Adsorption is one of the most widely applied techniques for environmental remediation. Its kinetics are of great significance
to evaluate the performance of a given adsorbent and gain insight into the underlying mechanisms. There are lots of references
available concerning adsorption kinetics, and several mathematic models have been developed to describe adsorption reaction
and diffusion processes. However, these models were frequently employed to fit the kinetic data in an unsuitable or improper
manner. This is mainly because the boundary conditions of the associated models were, to a considerable extent, ignored for
data modeling. Here we reviewed several widely-used adsorption kinetic models and paid more attention to their boundary conditions.
We believe that the review is of certain significance and improvement for adsorption kinetic modeling.
Journal of Zhejiang University - Science A: Applied Physics & Engineering 01/2009; 10(5):716-724. · 0.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Herkogamy may act as a mechanism to reduce interference between the reproductive functions of female and male organs, but too great a distance between stigmas and anthers may also decrease the outcross pollen transfer and male and female fitness. Our goal was to quantify the effect of movement herkogamy in Kosteletzkya virginica on reproductive success and its contribution to pollen receipt and reproductive assurance. Field investigations and hand-pollination experiments were performed to test: (1) the relationship between herkogamy before curvature of un-pollinated lobes and reproductive success under pollinator exclusion; (2) the contribution of movement herkogamy to pollen receipt; and (3) the relationship between pollen load and seed set. We noted that variation in herkogamy before curvature of un-pollinated lobes did not affect the outcome of autogamous self-pollination measured by fruit set and mean number of seeds per fruit. Under natural conditions, 39% of pollen grains deposited per flower were from autogamous self-pollination via movement herkogamy resulting in contact between anthers and stigmas. The relationship between the amount of pollen grains and the number of seeds per capsule was highly significant. Flowers producing four or five seeds received more pollen grains than those producing only one seed. Our data provides experimental evidence that movement herkogamy, which decreases the separation between anthers and stigmas and results in delayed self-pollination, contributes to pollen receipt and further enhances seed set when pollinators are scarce or absent.
[Show abstract][Hide abstract] ABSTRACT: A series of spherical activated carbons (SACs) with different pore structures were prepared from chloromethylated polydivinylbenzene by ZnCl 2 activation. The effects of activation temperature and retention time on the yield and textural properties of the resulting SACs were studied. All the SACs are generated with high yield of above 65% and exhibit relatively high mesopore fraction (me%) of 35.7%−43.6% compared with conventional activated carbons. The sample zlc28 prepared at 800°C for 2 h has the largest BET surface area of 891 m 2 g −1 and pore volume of 0.489 cm 3 g −1 . SEM and XRD analyses of zlc28 verify the presence of developed porous structure composed of disordered micrographite stacking with large amounts of interspaces in the order of nanometers.
Chinese Journal of Polymer Science 01/2008; 26. · 1.27 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The adsorption behavior of p-aminobenzoic acid and o-aminobenzoic acid onto the different polymeric adsorbents was systematically investigated as a function of the solution concentration and temperature. Experimental results indicated that the equilibrium adsorption data of the four polymeric adsorbents fitted well in the Freundlich isotherm. The adsorption capacity of multi-functional polymeric adsorbent NJ-99 was the highest, which might be attributed to the strong hydrogen-bonding interaction between the amino groups on the resin and the carboxyl group of aminobenzoic acid. The adsorption capacity of o-aminobenzoic acid onto any adsorbent was higher than p-aminobenzoic acid. Thermodynamic studies suggested the exothermic, spontaneous physical adsorption process. Adsorption kinetics results showed that the adsorption followed the pseudo-second-order kinetics model and the intraparticle mass transfer process was the rate-controlling step.
Journal of Environmental Sciences 02/2007; 19(11):1298-304. · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cooperative simultaneous adsorptions of 1-naphthol and 1-naphthylamine from aqueous solutions on hyper-cross-linked polymeric adsorbents (NDA103 and NDA100) were investigated. The results indicate that at the higher equilibrium concentrations, the total uptake amounts of 1-naphthol and 1-naphthylamine in binary systems (1-naphthol: 1-naphthylamine = 3:1, 1:1, 1:3) are obvious larger than the pure uptake amounts in single systems, and a large excess was noted on the particle surface at saturation, which is presumably due to the cooperative effect primarily arisen from the hydrogen bonding or weak acid-base interaction between 1-naphthol and 1-naphthylamine. The adsorption isotherms for them in both single and binary systems can be well fitted by Langmuir equation. The increasing temperature from 293 K to 313 K puts much more effect on the cooperative coefficient of simultaneous adsorption of 1-naphthylamine and 1-naphthol on NDA103 than on NDA100. The amino groups on NDA103 enhance the adsorption affinity as well as the cooperative coefficient of 1-naphthol.
Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.] 05/2006; 27(4):727-31.
[Show abstract][Hide abstract] ABSTRACT: Thermal regeneration of hypercrosslinked polymeric adsorbent (HPA) was performed at 67 degrees C. Experiments were carried out using a multimode microwave oven operating at 2450 MHz and a thermostatic water bath so as to compare the effect of the different heating mechanisms on the regeneration efficiency of the HPA saturated with nitrophenols. The temperature rise action of the heterogeneous regeneration system under microwave irradiation was described. Additionally, a complete structure and chemical characterization of the regenerated HPA was also carried out in order to study the influence of the subsequent regeneration cycles on the structure and the adsorption capacities of the adsorbents. Structure characterization of the regenerated HPA was accomplished by means of the analysis of FTIR spectra.
Journal of Environmental Sciences 02/2006; 18(4):765-70. · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The adsorption behaviors of 1-naphthol, 1-naphthylamine and 1-naphthol/1-naphthylamine mixtures in water over two macroreticular adsorbents were investigated in single or binary batch systems at 293 K, 303 K and 313 K respectively. All the adsorption isotherms in the studied systems can be adequately fitted by Langmuir model. In the case of aminated macroreticular adsorbent NDA103, 1-naphthol is adsorbed to a larger extent than 1-naphthylamine; while, the opposite trend is found for nonpolar macroreticular adsorbent NDA100. It is noteworthy that at higher temperature (303 K and 313 K), the total uptake amounts of 1-naphthol and 1-naphthylamine in all binary-component systems are obvious larger than the pure uptake amounts in single-component systems, which is presumably due to the cooperative effect primarily arisen from the hydrogen-bonding interaction between the loaded 1-naphthol and 1-naphthylamine molecules. The simultaneous adsorption systems were confirmed to be helpful to the selective adsorption towards 1-naphthol according to the larger selective index.
Journal of Environmental Sciences 02/2005; 17(5):782-5. · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The adsorption behaviors of phenol and aniline on nonpolar macroreticular adsorbents (NDA100 and Amberlite XAD4) were investigated in single or binary batch system at 293K and 313K respectively in this study. The results indicated that the adsorption isotherms of phenol and aniline on both adsorbents in both systems fitted well Langmuir equation, which indicated a favourable and exothermic process. At the lower equilibrium concentrations, the individual amount adsorbed of phenol or aniline on macroreticular adsorbents in single-component systems was higher than those in binary-component systems because of the competition between phenol and aniline towards the adsorption sites. It is noteworthy, on the contrast, that at higher concentrations, the total uptake amounts of phenol and aniline in binary-component systems were obviously larger than that in single-component systems, and a large excess was noted on the adsorbent surface at saturation, which is presumably due to the cooperative effect primarily arisen from the hydrogen bonding or weak acid-base interaction between phenol and aniline.
Journal of Environmental Sciences 02/2005; 17(4):529-34. · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adsorption of catechol from aqueous solution with the hypercrosslinked polymeric adsorbent NDA-100 and its derivatives AH-1, AH-2 and AH-3 aminated by dimethylamine, the commercial resin Amberlite XAD-4 and weakly basic anion exchanger resin D301 was compared. It was found that the aminated hypercrosslinked resins had the highest adsorption capacities among the tested polymers. The empirical Freundlich equation was successfully employed to describe the adsorption process. Specific surface area and micropore structure of the adsorbent, in company with tertiary amino groups on matrix affected the adsorption performance towards catechol. In addition, thermodynamic study was carried out to interpret the adsorption mechanism. Kinetic study testified that the tertiary amino groups on the polymer matrix could decrease the adsorption rate and increase the adsorption apparent activation energy.
Journal of Environmental Sciences 02/2005; 17(4):584-8. · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An aminated hypercrosslinked macroporous polymeric adsorbent was synthesized and characterized. Adsorption isotherms for 1-amino-2-naphthol-4-sulfonic acid (1,2,4-acid) and 2-naphthol obtained from various binary adsorption environments can be well fitted by Freundlich equation, which indicated a favorable adsorption process in the studied range. Adsorption for 1,2,4-acid was an endothermic process in comparison with that for 2-naphthol of an exothermic process. 2-naphthol molecules put a little influence on the adsorption capacity for 1,2,4-acid. However, the adsorption to 1,2,4-acid depressed that to 2-naphthol in a large extent for the stronger electrostatic interaction between 1,2,4-acid and adsorbent. The predominant mechanism can be contributed to the competition for adsorption sites. And the simultaneous environment was confirmed to be helpful to the selective adsorption towards 1,2,4-acid based on the larger selectivity index.
Journal of Environmental Sciences 02/2004; 16(3):471-5. · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adsorption equilibrium isotherms of phenolic compounds, phenol, p-cresol, p-chlorophenol and p-nitrophenol, from aqueous solutions by Amberlite XAD-4 polymeric adsorbent and its acetylized derivative MX-4 within temperature range of 283-323K were obtained and fitted to the Freundlich isotherms. The capacities of equilibrium adsorption for all four phenolic compounds from their aqueous solutions increased around 20% on the acetylized resin, which may be contributed to the specific surface area and the partial polarity on the network. Estimations of the isosteric enthalpy, free energy, and entropy for the adsorption process were reported.
Journal of Environmental Sciences 11/2002; 14(4):457-63. · 1.77 Impact Factor