| 不同类型LDHs负载改性麦饭石对Cr(Ⅵ)吸附性能 |
| 摘要点击 2415 全文点击 798 投稿时间：2018-04-24 修订日期：2018-06-22 |
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| 中文关键词 麦饭石 负载改性 层状双金属氢氧化物(LDHs) Cr(Ⅵ) 吸附 |
| 英文关键词 maifanite coating-loaded layered double hydroxides (LDHs) Cr(Ⅵ) adsorption |
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| 中文摘要 |
| 在碱性条件下采用水热-共沉淀法，将ZnCl2、MgCl2和AlCl3、FeCl3等不同2价和3价金属化合物两两组合，生成4种层状双金属氢氧化物（LDHs），并负载于天然麦饭石填料表面；分别通过等温吸附试验、解吸附试验、吸附动力学试验、竞争性吸附试验、不同温度及pH值吸附试验，研究LDHs涂层负载改性麦饭石对Cr（Ⅵ）吸附效果的提升作用.结果表明，改性后的各种麦饭石填料对Cr（Ⅵ）的最大理论吸附量均大于天然麦饭石，其中ZnAl-LDHs改性麦饭石对Cr（Ⅵ）的吸附效果最佳，在最适温度15℃时最大理论吸附量接近天然麦饭石的10倍；同时，解吸附试验发现LDHs的负载可以加强填料的重复利用率.所有填料对Cr（Ⅵ）的吸附热力学参数均为△Gθ < 0、△Hθ < 0、△Sθ > 0，表明填料吸附Cr（Ⅵ）过程为可自发进行的放热过程；LDHs负载改性麦饭石对Cr（Ⅵ）的吸附过程均符合准二级反应过程，以化学吸附为主.通过选用合适的金属离子组合方式制备不同的LDHs负载改性麦饭石，可达到有效提高麦饭石吸附水体中Cr（Ⅵ）性能的目的. |
| 英文摘要 |
| Under alkaline conditions, the hydrothermal coprecipitation method was used to form different layered double hydroxides (LDHs) by combining different bivalent and trivalent metal compounds, such as ZnCl2, MgCl2, AlCl3, and FeCl3, and then LDHs were coated on the surface of the original maifanite. The effect of LDHs coating-modified maifanite on the improvement of Cr(Ⅵ) adsorption in water was studied using isothermal adsorption, desorption, non-isothermal adsorption, adsorption kinetics, pH, and competitive adsorption tests, respectively. The results show that the maximum theoretical adsorption capacity of modified maifanite for Cr(Ⅵ) is close to ten times that of original maifanite at 15℃. The adsorption effect of ZnAl-LDHs coating-loaded modified maifanite is better than that of other LDHs-coating modified maifanites. In contrast, the results of the desorption experiments show that maifanite coated with LDHs enhances the reuse of substrates. The thermodynamic parameters of the substrate for Cr(Ⅵ) adsorption in the experiment were △Gθ < 0, △Hθ < 0, △Sθ > 0, indicating that the substrate adsorption process of Cr(Ⅵ) is spontaneous and exothermic. Based on the adsorption kinetics study, the adsorption process of Cr(Ⅵ) by maifanite could be fitted using a pseudo-secondary reaction process. The adsorption type was mainly chemisorption. By selecting the suitable metal ion combination method to prepare different LDHs-coating modified maifanites, the Cr(Ⅵ) performance can effectively be improved. |
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