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过程工程学报 ›› 2020, Vol. 20 ›› Issue (6): 646-654.DOI: 10.12034/j.issn.1009-606X.219299

• 反应与分离 • 上一篇    下一篇

pH对壳聚糖螯合铜(II)的螯合机理及稳定常数的影响

冯 颖1*, 张庆瑾1, 王珏程2, 张建伟1   

  1. 1. 沈阳化工大学能源与动力工程学院,辽宁 沈阳 110142 2. 中国石油天然气股份有限公司辽河油田,辽宁 盘锦 124000
  • 收稿日期:2019-09-24 修回日期:2019-12-09 出版日期:2020-06-22 发布日期:2020-06-19
  • 通讯作者: 冯颖
  • 基金资助:
    壳聚糖絮凝-螯合法去除中药液中重金属离子及胶体杂质的研究;螯合沉淀法去除中药液中重金属离子的研究;兴辽英才计划;沈阳化工大学科学研究项目

Effect of pH on the chelating mechanism and stability constant of chitosan-Cu(II) chelate complex

Ying FENG1*, Qingjin ZHANG1, Juecheng WANG2, Jianwei ZHANG1   

  1. 1. School of Energy and Power Engineering, Shenyang University of Chemical Technology, Shenyang, Liaoning 110142, China 2. Liao He Oilfield, China National Petroleum Corporation, Panjin, Liaoning 124000, China
  • Received:2019-09-24 Revised:2019-12-09 Online:2020-06-22 Published:2020-06-19

摘要: 用紫外分光光度法研究了pH值对壳聚糖螯合Cu(II)的影响。通过显微图像、X衍射图谱及红外光谱对沉淀物进行分析。结果表明,随体系pH值增加,壳聚糖碳链上的活性基团与铜离子的螯合能力增强。溶液体系pH=5~6时,螯合物的稳定常数最大值为1.1×108;当pH接近7时,部分螯合产物析出导致稳定常数降低。酸性条件下pH值的变化对螯合物的配位比(n)无明显影响,壳聚糖–铜螯合物的配位比n=2。通过调节pH值可使溶液中壳聚糖铜螯合物析出,随pH增加,Cu2+浓度降低,当pH约为9时,Cu2+浓度达最小值1.5 mg/L。壳聚糖的主要活性基团–NH2与铜离子发生螯合,反应生成壳聚糖-铜。

关键词: 壳聚糖, 铜离子, 螯合机理, 稳定常数, 沉淀

Abstract: Heavy metal ions in water or soil are serious pollution, and human health is seriously endangered by pollution. The removal of heavy metal ions quickly and efficiently has become an important research field. Chitosan is a natural high molecular polymer with excellent flocculation and metal chelation. The effect of pH values on the stability constant and chelation properties of chitosan chelated Cu2+ was studied by ultraviolet spectrophotometry in this work. The chelation performances of chitosan to copper ions were investigated with the pH value increasing from 1 to 9. The experimental results showed that the chelating ability of active groups on chitosan carbon chain with copper ion was enhanced with the increase of the pH value. When the pH values of the solution system ranged from 5 to 6, the stability constant of the chelate was the maximum value of 1.1×108, when the pH was close to 7, some chelate products precipitated and the stability constant decreased. The change of pH value had no obvious effect on the coordination ratio (n) of the chelate under acidic conditions and the ratio (n) was 2. The chitosan-Cu(II) chelate could be separated out by adjusting the pH value of the solution. With the increase of pH value, some floccules precipitated from the solution and the concentration of Cu2+ decreased. When the pH value was about 9, the Cu2+ concentration reached a minimum value of 1.5 mg/L. The precipitate of chitosan reacted with copper ions was analyzed by microscopic image, X-ray diffraction pattern and Fourier transform infrared spectroscopy (FT-IR), the results showed that the main component of the precipitate was chitosan-Cu(II) formed by chelation of –NH2 with Cu2+. This study could provide a theoretical basis for the removal of metal ions by chitosan.

Key words: chitosan, copper ions, chelating mechanism, stability constant, precipitation