• 关键词：浓碱-冻融法  粗多糖  Pb²⁺  吸附

• 基金项目：海洋公益性行业科研专项（No.201305022）；广东省自然科学基金-博士启动基金（No.2014A030310326）

• 陈利华
• 北京大学深圳研究生院环境与能源学院, 深圳 518055

• 王欣
• 北京大学深圳研究生院环境与能源学院, 深圳 518055

• 成家杨
• 北京大学深圳研究生院环境与能源学院, 深圳 518055

• 摘要：采用浓碱法（40 mg·mL^-1 NaOH）辅助冻融、加热方法提取混合海洋硅藻粗多糖，通过比较粗多糖得率、总糖、蛋白质及硫酸基含量筛选提取方法，并利用最佳方法提取的粗多糖作为生物吸附剂对Pb²⁺进行吸附.提取实验结果表明，最优的提取方法为浓碱（40 mg·mL^-1 NaOH）-冻融法，其粗多糖得率为33.14%，总糖含量为31.65%（480 nm）和27.27%（490 nm），蛋白质含量为6.44%、硫酸基含量为3.23%.吸附结果表明，该粗多糖对Pb²⁺的吸附在2 h左右达到平衡，在180 r·min^-1、25℃、pH=4~6时吸附效果最佳；在初始浓度为600 mg·L^-1混合重金属溶液条件下，粗多糖对Cd²⁺、Pb²⁺、Cu²⁺和Ni²⁺的吸附容量大小顺序为：Ni²⁺ > Cu²⁺ > Cd²⁺ > Pb²⁺（以物质的量浓度为单位进行评价）；粗多糖中含有的小分子糖类杂质对Pb²⁺吸附的贡献远远大于蛋白质杂质.吸附动力学拟合结果表明，此硅藻粗多糖对Pb²⁺的吸附过程更符合伪二级动力学模型，且Langmuir方程拟合的可决系数R²大于0.9，说明粗多糖对Pb²⁺的吸附为单层吸附.

• Abstract：Crude polysaccharide was extracted from mixed marine diatom by concentrated alkali (40 mg·mL^-1 NaOH) method assisted by heating, freeze-thawing method. The method was optimized by comparing extraction rates, total sugar contents, protein contents and sulfate contents of the extracted crude polysaccharide. The crude polysaccharide extracted by the optimal method was then used to adsorb Pb²⁺ from aqueous solution. The results of extraction experiments show that the extraction rate of crude polysaccharide was 33.14%, The total sugar, protein and sulfate contents of crude polysaccharide were 31.65% (480 nm) and 27.27% (490 nm), 6.44%, and 3.23%, respectively. The results of adsorption experiments show that the adsorption reached equilibrium at about 2 h and the adsorption capacity of Pb²⁺ by the crude polysaccharide was the highest under conditions of 180 r·min^-1, 25℃, and pH=4~6. The adsorption capacity of Cd²⁺, Pb²⁺, Cu²⁺ and Ni²⁺ in mixed solution with initial concentration by crude polysaccharide follows the trend as:Ni²⁺ > Cu²⁺ > Cd²⁺ > Pb²⁺ (the adsorption rate was evaluated by molar concentration). Small molecular sugars impurities in the crude polysaccharide contribute to Pb²⁺ adsorption far more than protein impurities. The adsorption kinetics and fitting results suggested that adsorption process of Pb²⁺ by the crude polysaccharide fit the Pseudo-two dynamic model well and the value of R² for Langmuir equation simulation was higher than 0.9, which indicates Pb²⁺ adsorption on the crude polysaccharide was monolayer adsorption.

• Key words：concentrated alkali-freeze-thawing method  polysaccharide  Pb²⁺  adsorption

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