改性桑树叶吸附材料对废水中Cd(Ⅱ)的吸附性能研究
Study on Biosorption Performance of Cd(Ⅱ) in Waste Water by Modified Mulberry Leaves
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摘要: 桑树叶富含植物多酚和黄酮类化合物, 表面存在着大量羟基、羧基功能基团, 在一定条件下通过络合作用或静电作用能与重金属离子发生吸附作用。但由于生物质中普遍存在着可溶性单宁, 直接使用生物质吸附废水中的镉, 去除效果不够理想。本文以生物质桑树叶为原料, 经沸水蒸煮去除小分子和稀磷酸酸化改性, 提高桑树叶的吸附容量, 制备成活性吸附材料去除废水中的Cd(Ⅱ)。吸附条件实验表明:在pH=4.0时改性桑树叶对Cd(Ⅱ)的吸附效果最佳, 当Cd(Ⅱ)初始浓度为150 mg/L, 改性桑树叶的添加量为6 g/L时吸附率可达96.58%。化学改性桑树叶对Cd(Ⅱ)的吸附过程符合准二阶动力学方程, Langmuir等温吸附模型能更好地描述改性桑树叶的吸附行为, Cd(Ⅱ)最大吸附量为30.58 mg/g, 与前人报道的吸附量显著提高。本项研究的改性桑树叶吸附材料价廉易得, 为废水中镉的处理提供了一个新的方法。
Abstract: Mulberry leavesare rich in plant polyphenol and flavonoid.Amounts of hydroxyl and hydroxyl functional groups are distributed on the surface, which can be absorbed with heavy metal ions by complexation and electrostatical processes.However, there are commonly soluable tannic in organisms and it is not suitable to use organisms to remove Cd from waste water.In this study, mulberry leaves were used as the experimental materials and were boiled and modified with 1 mol/L H3PO4 to prepare an adsorbent for cadmium.Results show that the absorption effect of modified mulberry leaves to Cd(Ⅱ) is best when pH is 4.0.When the initial concentration of Cd is 150 mg/L, 6 g/L modified mulberry leaves have absorption recovery of 96.58%.The adsorption process of modified mulberry leaves to Cd(Ⅱ) adheres to the pseudo-second order equation.The isothermal adsorption process of cadmium with modified mulberry leaves fits the Langmuir model well.Maximum absorption capacity of Cd(Ⅱ) on the chemically modified mulberry leaf absorbent is 30.58 mg/g, which is higher than that of a previous study.The modified mulberry leaves are easily available, which provides a new method for Cd removal from waste water.
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