木素胺化改性制备重金属吸附剂

Preparation of Lignin Based Heavy Metal Adsorbent by Lignin Aminating Modification

关键词:  木素  胺化  酸酐改性  Pb²⁺  吸附

Key Words:lignin  acylation  aminating modification  Pb²⁺  adsorption

摘要:以木素为原料,通过胺化改性制备木素基重金属吸附剂,吸附Pb²⁺。实验中首先将木素用琥珀酸酐进行酸酐改性,然后以对甲苯磺酰氯为催化剂与三乙烯四胺反应,得到胺化改性木素。以琥珀酸酐与木素摩尔比及反应时间为变量优化酸酐改性条件。通过测定羧基含量、红外光谱分析(FT-IR)和吸附性能分析对产物性能进行表征。结果表明,琥珀酸酐与木素摩尔比1.5∶1、反应时间1 h、温度28℃、pH值8.5～9.0时，所得酸酐改性木素中羧基含量最高，达1.98 mmol/g；FT-IR谱图分析显示木素改性成功；胺化改性木素对Pb²⁺吸附符合拟二阶动力学模型和Freundlich模型,同时随着pH值的升高,产物吸附性能随之提高,pH值>5时吸附性能降低,在pH值为5时胺化改性木素对Pb²⁺的吸附量达到152.95 mg/g。

Abstract:In this experiment, Lignin based heavy mental adsorbent used for obsorbing Pb²⁺ solution was prepared by aminating modification using lignin as raw material. The purified lignin was modified by amber anhydride firstly, then reacted with triethylene tetramine using paratoluensulfonyl chloride as catalyst the aminatd lignin was prepared. The product was characterized by carboxyl group determination, Fourier Transform Infrared spectrum (FT-IR) and adsorption performance analysis.The results showed that when the molar ratio of amber anhydride and lignin was 1.5∶1, the reaction time was 1 h, the temperature was 28℃, pH value was 8.5～9.0, the carboxyl group content of the modified lignin was 1.98 mmol/g. FT-IR spectrum analysis showed that lignin modification was successful.The adsorption of Pb²⁺ was in accordance with the pseudo two order kinetic model and Freundlich model. The adsorption capacity of the product improved with the increase of pH, and the adsorption capacity decreased when pH value>5. When pH value was 5, the adsorption capacity reached 152.95 mg/g.