Abstract:

An adsorbent with the advantages such as high utilization of amino group, stable structure and easy-to-handle operation was prepared to efficiently capture aquatic Cr(Ⅵ) by using the polyethyleneimine (PEI) as the modification reagent and the juncus (JC), a natural biomass with sponge-like structure, as the structure support. The PEI solution containing epichlorohydrin was firstly introduced into the JC and then the PEI was in-situ attached to JC fibers by the grafting reaction, resulting in a porous adsorbent (PEI-JC). The elemental analysis, SEM, FT-IR and XPS were employed to characterize the composition and structure of PEI-JC, as well as the adsorption mechanism of Cr(Ⅵ). The effects of PEI concentration, solution pH, initial concentration of Cr(Ⅵ) and coexisting compounds on the adsorption were studied. The results show that the maximum adsorption capacity of the Langmuir model of PEI_10.0-JC prepared from PEI with concentration of 10.0%(mass) is 474.6 mg·g^-1 at 30℃ and a pH of 2.0; PEI_10.0-JC could decrease the Cr(Ⅵ) in the solutions with different coexisting compounds from 10.0 mg·L^-1 to the value that is less than the emission standard of industrial wastewater of China (0.5 mg·L^-1); PEI_10.0-JC can be reused, and its structure has not changed significantly during the adsorption process; adsorption and reduction are the main mechanisms for PEI-JC to remove Cr (Ⅵ) from aqueous solutions.

Key words: juncus, polyethyleneimine, in-situ modification, waste water, hexavalent chromium, adsorption

摘要：

为了制备具有胺基利用率高、结构稳定、使用方便的Cr（Ⅵ）吸附材料，以聚乙烯亚胺（PEI）为胺基改性剂，具有类海绵多孔结构的灯芯草（JC）为支撑基材，将吸入JC的PEI通过环氧氯丙烷原位接枝于其纤维表面，获得可整块使用的多孔吸附材料（PEI-JC）。采用元素分析、SEM、FT-IR、XPS表征PEI-JC的组成与结构，分析PEI-JC对Cr（Ⅵ）的吸附机理。考察PEI浓度、溶液的pH、Cr（Ⅵ）浓度与共存化合物等因素对吸附的影响。结果表明，质量分数为10.0%的PEI所制备的PEI_10.0-JC，在30℃与pH为2.0的条件下，其Langmuir模型的最大吸附量为474.6 mg·g^-1；PEI_10.0-JC可将含各种共存化合物溶液中的Cr（Ⅵ）从10 mg·L^-1降至排放标准（0.5 mg·L^-1）以下；PEI_10.0-JC可重复使用，其结构在吸附过程中未发生明显变化；吸附与还原作用是PEI-JC去除水溶液中Cr（Ⅵ）的主要机制。

关键词: 灯芯草, 聚乙烯亚胺, 原位改性, 废水, Cr（Ⅵ）, 吸附作用