The adsorption and desorption static experiments were carried out as follows. A quantity (1.0 g) of pretreated HPD-300 macroporous resin and 25 mL of the sample solution with a concentration of 0.8 mg/mL for paeonol were added into conical flasks (50 mL), and the flasks were continually shaken at 120 rpm for 12 h at a constant temperature (25 °C). During this period, 100 µL of the sample solution was taken every hour, and the paeonol concentrations were determined by HPLC. The adsorption ratios were calculated, and the adsorption kinetic curve was plotted.
When adsorption equilibriums were reached, the macroporous resins were washed with deionized water. A mixture of 25 mL 50% ethanol solution and macroporous resin after adsorption equilibrium were shaken at 120 rpm at 25 °C for 12 h after adsorption equilibrium. The paeonol concentration was measured in 100 µL of the supernatant every hour. The desorption ratios of HPD-300 macroporous resin were measured, and the desorption kinetic curve was plotted. Under the same pH conditions, seven crude MC solutions with different initial paeonol concentrations (0.1, 0.2, 0.4, 0.6, 0.8, 1.0, and 1.4 mg/mL) were employed to investigate the effect of the paeonol concentration on the adsorption process. The effect of pH on static absorption was researched by adjusting the pH from 2 to 8. Static desorption tests were developed with an ethanol eluent at different concentrations in a range of 20–100% (v/v).
When adsorption equilibriums were reached, the macroporous resins were washed with deionized water. A mixture of 25 mL 50% ethanol solution and macroporous resin after adsorption equilibrium were shaken at 120 rpm at 25 °C for 12 h after adsorption equilibrium. The paeonol concentration was measured in 100 µL of the supernatant every hour. The desorption ratios of HPD-300 macroporous resin were measured, and the desorption kinetic curve was plotted. Under the same pH conditions, seven crude MC solutions with different initial paeonol concentrations (0.1, 0.2, 0.4, 0.6, 0.8, 1.0, and 1.4 mg/mL) were employed to investigate the effect of the paeonol concentration on the adsorption process. The effect of pH on static absorption was researched by adjusting the pH from 2 to 8. Static desorption tests were developed with an ethanol eluent at different concentrations in a range of 20–100% (v/v).
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