Department of Civil and Environmental Engineering, Sejong University, Gunja-Dong 98, Gwangjin-Gu, Seoul, Republic of Korea.
J Hazard Mater. 2011 Oct 30;194:385-92. doi: 10.1016/j.jhazmat.2011.08.001. Epub 2011 Aug 7.
A combined reaction, consisting of granular activated carbon (GAC) adsorption and catalytic oxidation, has been proposed to improve the removal efficiencies of formaldehyde, one of the major indoor air pollutants. In this study, silver nano-particles attached onto the surface of GAC (Ag-GAC) using the sputtering method were evaluated for the simultaneous catalytic oxidation and adsorption of formaldehyde. The evolution of CO(2) from the silver nano-particles indicated that formaldehyde was catalytically oxidized to its final product, with the oxidation kinetics expressed as pseudo-first order. In addition, a packed column test showed that the mass of formaldehyde removed by the Ag-GAC was 2.4 times higher than that by the virgin GAC at a gas retention time of 0.5s. However, a BET analysis showed that the available surface area and micro-pore volume of the Ag-GAC were substantially decreased due to the deposition of the silver nano-particles. To simulate the performance of the Ag-GAC, the homogeneous surface diffusion model (HSDM), developed for the prediction of the GAC column adsorption, was modified to incorporate the catalytic oxidation taking place on the Ag-GAC surface. The modified HSDM demonstrated that numerical simulations were consistent with the experimental data collected from the Ag-GAC column tests. The model predictions implied that the silver nano-particles deposited on the GAC reduced the adsorptive capacity due to decreasing the available surface for the diffusion of formaldehyde into the GAC, but the overall mass of formaldehyde removed by the Ag-GAC was increased due to catalytic oxidation as a function of the ratio of the surface coverage by the nano-particles.
一种联合反应，包括颗粒活性炭（GAC）吸附和催化氧化，已被提议用于提高甲醛的去除效率，甲醛是主要的室内空气污染物之一。在这项研究中，使用溅射法将银纳米颗粒附着在 GAC 表面上（Ag-GAC），用于同时催化氧化和吸附甲醛。从银纳米颗粒中释放出的 CO(2)表明甲醛被催化氧化为最终产物，其氧化动力学表示为拟一级反应。此外，填充柱测试表明，在气体保留时间为 0.5s 时，Ag-GAC 去除的甲醛质量是原始 GAC 的 2.4 倍。然而，BET 分析表明，由于银纳米颗粒的沉积，Ag-GAC 的可用表面积和微孔体积大大减少。为了模拟 Ag-GAC 的性能，开发用于预测 GAC 柱吸附的均相表面扩散模型（HSDM）进行了修改，以纳入在 Ag-GAC 表面发生的催化氧化。修改后的 HSDM 表明，数值模拟与从 Ag-GAC 柱测试收集的实验数据一致。模型预测表明，沉积在 GAC 上的银纳米颗粒由于减少了甲醛扩散到 GAC 中的可用表面而降低了吸附能力，但由于催化氧化，Ag-GAC 去除的甲醛总量增加，这与纳米颗粒的表面覆盖率成比例。
