Comparative analysis of adsorption and release properties of β-phenylethanol on two kinds of activated carbon

In order to understand the adsorption and release properties of β-phenylethanol on activated carbon produced from different carbon sources, coconut shell activated carbon (CAC) and petroleum coke activated carbon (PAC) were selected for the immobilization β-phenylethanol. The structure and morphology of CAC and PAC were characterized by SEM, BET and TGA analysis. And then the effect of carbon sources and pore structure on β-phenylethanol adsorption and release properties were investigated by kinetic model. The results showed that the microporosity ratios for CAC and PAC were 89.13% and 77.12%, respectively, and both types of activated carbon were dominated by micropore structure. The adsorption behavior of β-phenylethanol on the CAC and PAC was both controlled by the physical adsorption, and the equilibrium adsorption capacity of CAC (391.2 mg/g) was 45.50% of that of PAC (859.8mg/g). Quasi primary equation can be used to describe the adsorption of β-phenylethanol on both types of activated carbon, i.e., the external transport resistance plays a major role in the adsorption process. The results of thermogravimetric analysis showed that the thermal stability of β-phenylethanol was obviously improved after the immobilization into activated carbon, accompanied with a higher temperature intervals for the release process and a decreased release rate. And the thermal stability of CAC loaded with β-phenylethanol was higher than that of PAC. Furthermore, the sustained release of β-phenylethanol from CAC and PAC was more consistent with the Korsmeyer-Peppas model and was dominated by Fick diffusion. The release rates of β-phenylethanol were 27.34% and 57.57% for CAC and PAC, respectively, under 35 days of storage at room temperature. The higher micropore ratio and lower mean pore width of CAC were responsible for the good stability and sustained release properties of immobilized β-phenylethanol.