Institute for Environment and Energy, Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea.
Graduate School of Carbon Neutrality, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan, 44919, Republic of Korea.
Sci Rep. 2023 Mar 30;13(1):5170. doi: 10.1038/s41598-023-32108-3.
Santa Barbara Amorphous-15 (SBA) is a stable and mesoporous silica material. Quaternized SBA-15 with alkyl chains (Q) exhibits electrostatic attraction for anionic molecules via the N moiety of the ammonium group, whereas its alkyl chain length determines its hydrophobic interactions. In this study, Q with different alkyl chain lengths were synthesized using the trimethyl, dimethyloctyl, and dimethyoctadecyl groups (C1Q, C8Q, and C18Q, respectively). Carbamazepine (CBZ) is a widely prescribed pharmaceutical compound, but is difficult to remove using conventional water treatments. The CBZ adsorption characteristics of Q were examined to determine its adsorption mechanism by changing the alkyl chain length and solution conditions (pH and ionic strength). A longer alkyl chain resulted in slower adsorption (up to 120 min), while the amount of CBZ adsorbed was higher for longer alkyl chains per unit mass of Q at equilibrium. The maximum adsorption capacities of C1Q, C8Q, and C18Q, were 3.14, 6.56, and 24.5 mg/g, respectively, as obtained using the Langmuir model. For the tested initial CBZ concentrations (2-100 mg/L), the adsorption capacity increased with increasing alkyl chain length. Because CBZ does not dissociate readily (pK = 13.9), stable hydrophobic adsorption was observed despite the changes in pH (0.41-0.92, 1.70-2.24, and 7.56-9.10 mg/g for C1Q, C8Q, and C18Q, respectively); the exception was pH 2. Increasing the ionic strength from 0.1 to 100 mM enhanced the adsorption capacity of C18Q from 9.27 ± 0.42 to 14.94 ± 0.17 mg/g because the hydrophobic interactions were increased while the electrostatic attraction of the N was reduced. Thus, the ionic strength was a stronger control factor determining hydrophobic adsorption of CBZ than the solution pH. Based on the changes in hydrophobicity, which depends on the alkyl chain length, it was possible to enhance CBZ adsorption and investigate the adsorption mechanism in detail. Thus, this study aids the development of adsorbents suitable for pharmaceuticals with controlling molecular structure of QSBA and solution conditions.
圣巴巴拉无定形-15（SBA）是一种稳定的中孔硅材料。季铵化的 SBA-15 带有烷基链（Q），通过铵基的 N 部分对阴离子分子表现出静电吸引，而其烷基链长度决定了其疏水相互作用。在这项研究中，使用三甲基、二甲基辛基和二甲基十八烷基（C1Q、C8Q 和 C18Q）合成了不同烷基链长的 Q。卡马西平（CBZ）是一种广泛应用的药物化合物，但使用传统的水处理方法难以去除。通过改变烷基链长度和溶液条件（pH 值和离子强度），研究了 Q 对 CBZ 的吸附特性，以确定其吸附机制。较长的烷基链导致吸附较慢（长达 120 分钟），而在平衡时，单位质量 Q 上吸附的 CBZ 量对于较长的烷基链更高。使用 Langmuir 模型，C1Q、C8Q 和 C18Q 的最大吸附容量分别为 3.14、6.56 和 24.5mg/g。对于测试的初始 CBZ 浓度（2-100mg/L），吸附容量随烷基链长度的增加而增加。由于 CBZ 不易解离（pK=13.9），尽管 pH 值发生变化（C1Q、C8Q 和 C18Q 的 pH 值分别为 0.41-0.92、1.70-2.24 和 7.56-9.10mg/g），仍观察到稳定的疏水性吸附；例外是 pH 值为 2。从 0.1 到 100mM 增加离子强度会将 C18Q 的吸附容量从 9.27±0.42mg/g 提高到 14.94±0.17mg/g，因为疏水性相互作用增加，而 N 的静电吸引减少。因此，离子强度是比溶液 pH 值更强的控制因素，决定了 CBZ 的疏水性吸附。基于取决于烷基链长度的疏水性变化，可以增强 CBZ 的吸附并详细研究吸附机制。因此，这项研究有助于开发适合具有控制 QSBA 分子结构和溶液条件的药物的吸附剂。
