壳聚糖(CTS)具有活性基团氨基和羟基, 可用作吸附剂。 在酸性介质中其氨基容易质子化形成氨基正离子, 具有吸附阴离子的能力, 同时也导致吸附剂的溶解流失； 进行交联处理可提高吸附剂的酸稳定性, 但也导致吸附性能的下降。 因此可进行氨基保护后进行交联以改善其酸溶液稳定性, 再脱去氨基保护剂进行质子化处理以获得较好的对阴离子的吸附性能。 以甲醛为氨基保护剂, 戊二醛为交联剂, 通过反相悬浮法制得交联壳聚糖(CCTS), 对其进行质子化制得质子化改性壳聚糖吸附剂(P-CCTS), 并首次将该吸附剂用于处理水溶液中的硫酸根离子。 通过静态吸附实验, 考察了质子化改性壳聚糖对硫酸根的吸附性能； 利用X射线能谱元素分析(EDS)和红外光谱分析(FTIR)对该吸附剂的制备以及对硫酸根离子的吸附过程进行了表征, 探索了交联反应和吸附反应的发生机理。 实验结果表明: 质子化改性壳聚糖吸附剂与交联壳聚糖相比, 其对硫酸根离子的吸附性能提高了约10倍； 甲醛、 戊二醛的醛基与壳聚糖的交联反应主要发生在的氨基(—NH2)和部分一级羟基(C6—OH)上； 质子化过程中交联壳聚糖的氨基与质子化剂形成了氯化壳聚糖氨盐； 对硫酸根离子的吸附则主要是质子化氨基上氯离子与硫酸根离子的交换作用。

In order to improve adsorbing performance and stability of chitosan in acid simultaneously, cross-linking was employed after the protection of amino groups for improving its stability, then the protection of amino groups was removed and protonated to obtain high adsorption performance. With formaldehyde as amino-group protective agent and glutaraldehyde as cross-linking reagent, cross-linked chitosan(CCTS) was prepared by reversed phase suspension method in this paper, then it was protonated to make protonation modified chitosan adsorbent(P-CCTS). The adsorption performance of sulfate ion onto P-CCTS was firstly studied and investigated by static adsorption test. Elemental analysis by energy dispersive spectrometer of X-rays (EDS) and identifying of functional groups by Fourier transform infrared spectroscopy (FTIR) were used to analyze the preparation and adsorption of the adsorbent, and the reaction mechanism of cross-linking and adsorption was investigated. The results show that the adsorption performance of P-CCTS towards sulfate ion is 10 times higher than that of unmodified chitosan, and formaldehyde and glutaraldehyde mainly react with amino (—NH2) and part of hydroxy (C6—OH) of chitosn. A salt of chitosan protonated amino chlorine was formed through the process of the protonation of amino, the adsorption of sulfate ion mainly occurs on the protonated amino on which ion exchange happened between chlorine ion and sulfate ion.