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第 6 期 常柄权，等: 变叶海棠叶总黄酮的分离纯化及体外抗炎活性 ·1153·

the contact time in the first 15 min and subsequently 1.247 g/L (Fig.2B). Thus, the initial concentration of
slowly increased. The adsorption equilibrium for FMTs in the sample solution for adsorption was
FMTs was observed at approximately 3 h. Hence, 3 h selected as 1.247 g/L.
is sufficient to establish the adsorption equilibrium for Additionally, for interpretation of the adsorption’s
FMTs. experimental data, the Langmuir and Freundlich
3.3 Adsorption isotherms models were used. Table 2 lists the two isotherm
In order to investigate the adsorption capacity and equations at different temperatures and two critical
characterize the adsorption behaviour of FMTs, parameters: the Q max value (obtained from the
sample solutions with various concentrations of FMTs Langmuir isotherm) and the 1/n value (obtained from
(0.086~2.483 g/L) were shaken with AB-8 resin at 25, the Freundlich isotherm). The correlations (0.99677~
35 and 45 ℃. The adsorption capacity increased with 0.99988) for FMTs on AB-8 indicated that the two
the initial concentration and reached the saturation models were suitable for describing the tested
plateau when the initial concentration of FMTs was adsorption system in the concentration ranges studied.

Table 2 Langmiur and Freundlich adsorption parameters of FMTs on AB-8 resin at different temperatures.
2
Temperature/℃ Langmiur equation R Q max/(mg/g) Freundlich equation R 2 1 / n
25 ρ e/Q e=0.005ρ e+0.0041 0.99988 200 Q e=138.74ρ e 0.2681 0.99859 0.2681
35 ρ e/Q e=0.007ρ e+0.0055 0.99722 142.86 Q e=112.25ρ e 0.2453 0.99792 0.2453
45 ρ e/Q e=0.011ρ e+0.0068 0.99805 90.91 Q e=88.19ρ e 0.2049 0.99677 0.2049

Generally, in the Freundlich equation, the subsequent experiments.
adsorption was easy to carry out when the 1/n value 3.5 Effect of the sample solution pH value
was between 0.1 and 0.5, and it was difficult to take The initial pH value of the sample solution has an
place if the 1/n value was above 1 [20] . In Table 2, all important effect on the adsorption capacity of the resin.
values of 1/n are in the range of 0.2049-0.2681, The pH value can affect the adsorption affinity by
indicating that the adsorption of FMTs on AB-8 resin determining the extent of ionization of the sample
took place easily. Thus, AB-8 resin was appropriate molecules [22] . As shown in Fig.2D, for FMTs, AB-8
for the enrichment of FMTs. resin showed higher adsorption capacities at pH 4.0
Within the range of temperatures investigated, the than at other pH values. The results suggest that
adsorption capacities decreased as the temperature hydrogen bonding may play an important role in the
increased (Fig.2B), which indicated that the adsorption adsorption process on AB-8 resin. The phenolic
process was a thermopositive process. Similar results hydroxyl groups of FMTs can dissociate to form H +
were obtained for the enrichment of other compounds and corresponding anions at higher pH values. Then,
using macroporous resins. Therefore, 25 ℃ was the ionization process decreases the hydrogen bonding
selected in the following experiments. interactions and consequently reduces the adsorption
3.4 Effect of the sample concentration interaction between FMTs and AB-8 resin. Therefore,
The initial concentration of the sample solution has the pH value of the sample solution was adjusted to
an important effect on the affinity of the flavonoids to 4.0 for all subsequent experiments.
the resins. In general, the adsorption capacity of the 3.6 Dynamic breakthrough curves of AB-8 resin
resin increases with the concentration of the sample, The breakthrough curves of AB-8 resin were
whereas the adsorption rate decreases [21] . The effect of provided based on the volume of the effluent liquid
the sample concentration on the dynamic adsorption and the concentrations of FMTs at a flow rate of
capacity of AB-8 resin was evaluated by loading 2 BV/h. In general, it is defined that the adsorption
different concentrations of Malus toringoides leaf process reaches the leakage point when the
extracts onto five resin columns. As shown in Fig.2C, concentration of elute is 10% (mass fraction) of the
for FMTs, the adsorption capacities rapidly increased original concentration [23] . As shown in Fig.3A, FMTs
with increasing concentration and reached the have identical leakage points because of their similar
saturation plateau when the initial concentration of structure and polarity. Below 10 BV, FMTs in the
Malus toringoides (Rehd.) Hughes leaf extracts was extract solutions were almost entirely adsorbed by
15.0 g/L (the concentration is approximately equal to AB-8 resin. Then, the concentrations of FMTs in the
1.25 g/L FMTs). In contrast, the adsorption rate effluent liquid rapidly increased until it reached a
significantly decreased at higher concentrations. Thus, steady plateau at 18 BV. A sample loading amount of
15.0 mg of extract per 1 mL of solution was selected 9 BV (144 mL) was selected for the dynamic
as the initial concentration of the sample solution for adsorption.