交联羧甲基木薯淀粉对Pb^2＋的吸附特性研究

Adsorption characteristics of cross-linked carboxymethyl cassawa starch for Pb^(2+) from the aqueous solution

通过实验室模拟Pb2+废水,研究了Pb2+初始质量浓度、吸附剂取代度、吸附剂用量、温度、pH值和吸附时间对交联羧甲基木薯淀粉吸附Pb2+的影响。结果表明,淀粉羧甲基取代度越高,交联羧甲基木薯淀粉对Pb2+的吸附能力越强。当Pb2+初始质量浓度为80 mg/L、淀粉用量为4 g/L、取代度为0.526、pH=6、温度为40℃、吸附时间为30 min时,交联羧甲基木薯淀粉对Pb2+的吸附率为78.4%,吸附量为19.6 mg/g,吸附符合朗缪尔的等温吸附线;同时,淀粉解吸附能力良好。研究表明,交联羧甲基木薯淀粉对废水中Pb2+具有良好的吸附能力。

This paper is concerned about the study of the absorption features of Pb^2＋ by using cross-linked earboxymethyl cassawa starch as an agent in aqueous solution. For the research purpose, a series of influential factors on the Pb^2＋ absorption process were thoroughly researched, such as the initial mass concentration of Pb^2＋ , the starch substitution degree, starch dosage, temperature, pH value and adsorption time. The results of our research show that, at the low Pb^2＋ mass concentration （ 〈 80 mg/L）, the adsorption efficiency tends to increase with the initial Pb^2＋ mass concentration. When Pb^2＋ mass concentration exceeds 80 mg/L, the adsorption efficiency tends to remain unchanged in spite of the increase of its mass concentration. But, when the starch dosage reaches 4 g/L, the maximum adsorption efficiency would crop up. At the same time, the effects of pH value on the adsorption efficiency reveal the same tendency with the rise of Pb^2＋ mass concentration, while the maximum adsorption efficiency is pH = 6. In addition, the adsorption reaction would come to a state of balance in 30 min. Actually, the maximum adsorbing capacity of Pb^2 is expected to be 19.6 mg/g under the optimal condition, that is to say, when the initial Pb^2＋ mass concentration was 80 mg/L, the starch dosage would be 4 g/L on the condition of the pH value being 6 at the adsorption temperature of 40 ℃ , in an adsorption time of 30 min, which can be thought of as the best desorption capability of the starch in accordance with Langmuir adsorption isothenns.