In this paper, four modified chitosan compounds were prepared by reaction between chitosan (CS) and carbonyl groups such as salicylaldehyde (SA), benzaldehyde (BA), para-chloro benzaldehyde (PCBA) and acetanilide (A) as an amide compound. The corresponding Schiff-bases were characterized by FTIR, EDX, FESEM, BET and TGA-DTA techniques. The BET analysis on the prepared Schiff bases shows that the total volume of the pores and their specific surface area is different. The synthesized compounds have got less than 10 nm in diameter. The adsorption of copper and nickel ions in the aqua medium by prepared Schiff bases was studied. A comparison of the adsorption percentage of prepared compounds indicates that Schiff-base CS-A has slightly better adsorption than CS-SA. The calculation of boundary orbital energy (HOMO–LUMO) shows that the chitosan molecule has the highest chemical hardness (η) and the minimum reactivity to synthesized Schiff-Base compounds. The HOMO–LUMO energy gap of all the adsorbed molecules diminished after the adsorption of metal cations. The adsorption efficiency of Cu²⁺ per molar unit changes as: CS-A (92.5%) > CS-SA (80.4%) > CS-BA (43.2%) > CS-PCBA (42.2%) > CS (30.5%). The adsorption efficiency of Ni²⁺ per molar unit changes as: CS-A (81.8%) > CS-SA (59.9%) > CS-BA (56.1%) > CS-PCBA (46.6%) > CS (40.25%). Thus, the modified chitosan compounds by imine bonds are well compounds to adsorption of metal ions.

本文通过壳聚糖（CS）与羰基反应制备了四种改性壳聚糖化合物，例如水杨醛（SA），苯甲醛（BA），对氯苯甲醛（PCBA）和对乙酰苯胺（A）作为酰胺化合物。通过FTIR，EDX，FESEM，BET和TGA-DTA技术对相应的席夫碱进行了表征。对制备的席夫碱的BET分析表明，孔的总体积及其比表面积是不同的。合成的化合物的直径小于10 nm。研究了席夫碱对水介质中铜和镍离子的吸附作用。所制备化合物的吸附百分比的比较表明，席夫碱CS-A的吸附性比CS-SA略好。边界轨道能量（HOMO-LUMO）的计算表明，壳聚糖分子具有最高的化学硬度（η）和对合成的席夫碱化合物的最低反应性。吸附金属阳离子后，所有吸附分子的HOMO-LUMO能隙减小。铜的吸附效率每摩尔单位^2+的变化为：CS-A（92.5％）> CS-SA（80.4％）> CS-BA（43.2％）> CS-PCBA（42.2％）> CS（30.5％）。每摩尔单位Ni ²⁺的吸附效率变化为：CS-A（81.8％）> CS-SA（59.9％）> CS-BA（56.1％）> CS-PCBA（46.6％）> CS（40.25％） 。因此，通过亚胺键改性的壳聚糖化合物是吸附金属离子的良好化合物。