School of Chemical and Environmental Engineering, China University of Mining and Technology-Beijing, Beijing, 100083, PR China.
School of Chemical and Environmental Engineering, China University of Mining and Technology-Beijing, Beijing, 100083, PR China.
Environ Res. 2022 Nov;214(Pt 4):114103. doi: 10.1016/j.envres.2022.114103. Epub 2022 Aug 18.
Activated carbon (AC) is negatively charged in aqueous solution, which seriously restricts its application range. Quaternary ammonium salt as a common cationic surfactant was utilized to modify the surface charge distribution of materials. The evolution of the surface charge distribution of AC modified by benzalkonium chloride (BAC), diallyl dimethyl ammonium chloride (DDA) and 3-chloro-2-hydroxypropyl tri-methyl ammonium chloride (CTA) was investigated. Results showed that the surface charge of AC modified by CTA does not change significantly. BAC has a high molecular weight, low surface electrostatic potential and large steric hindrance due to its hydrophobic long-chain alkyl. The diffusion of BAC molecules from solution to AC changed its charge distribution. But these molecules were difficult to combine with AC surface, and most of them were adsorbed into the pores of AC to form aggregates, resulting in a significant reduction in the surface area. BAC modified AC could enhance the adsorption capacity of F in aqueous solution through electrostatic attraction, but the improvement effect was limited due to the reduction of surface area, and the maximum adsorption capacity was only increased from 1.18 to 3.31 mg/g. DDA has a small molecular weight and high surface electrostatic potential and easily binds to the surface of AC. Some CC bonds in DDA combined with the ionized hydrogen ions derived from phenolic hydroxyl groups in AC to form carbonium-ions. Then, they could react with AC to form ether bonds, causing DDA to be closely bonded with the surface of AC. DDA realizes the targeted regulation of the surface charge distribution of AC, it has little effect on the porous structure of AC. The modified AC still maintained strong adsorption capacity, and the maximum adsorption capacity for F was 54.98 mg/g. Meanwhile, a large number of zeolites were loaded on the modified AC and formed coating structures.
活性炭（AC）在水溶液中带负电荷，这严重限制了它的应用范围。季铵盐作为一种常见的阳离子表面活性剂，被用于改变材料的表面电荷分布。本文研究了氯化苄基铵（BAC）、二烯丙基二甲基氯化铵（DDA）和 3-氯-2-羟丙基三甲基氯化铵（CTA）改性 AC 表面电荷分布的演变。结果表明，CTA 改性 AC 的表面电荷没有明显变化。BAC 分子量较大，表面静电位低，由于其疏水性长链烷基，空间位阻大。BAC 分子从溶液扩散到 AC 时会改变其电荷分布。但这些分子很难与 AC 表面结合，大部分被吸附到 AC 的孔隙中形成聚集体，导致比表面积显著降低。BAC 改性 AC 可以通过静电吸引增强其在水溶液中对 F 的吸附能力，但由于比表面积的减少，其改善效果有限，最大吸附容量仅从 1.18 增加到 3.31mg/g。DDA 分子量较小，表面静电位高，容易与 AC 表面结合。DDA 中的一些 CC 键与 AC 中酚羟基电离出的氢离子结合形成碳正离子，然后与 AC 反应形成醚键，使 DDA 与 AC 表面紧密结合。DDA 实现了对 AC 表面电荷分布的靶向调控，对 AC 的多孔结构影响很小。改性后的 AC 仍保持较强的吸附能力，对 F 的最大吸附容量为 54.98mg/g。同时，大量沸石负载在改性 AC 上形成了涂层结构。
