论文总字数：20109字

摘 要

水体中的氟离子对生态环境和人体健康都会产生危害。本论文通过对小麦秸秆颗粒进行化学改性，制备成阴离子吸附剂用于水体中低浓度氟离子的去除。通过改变温度、初始浓度、pH、竞争离子、时间等条件考察改性秸秆对于水体中氟离子的去除效果，并结合脱附再生实验和动态柱吸附实验探究其在实际应用中的价值。研究结果如下：改性前后秸秆颗粒由黄色变为褐色，红外光谱分析显示改性后秸秆中引入了季铵基团；随着温度的升高，改性秸秆对氟离子的吸附效果变强，其对氟离子的吸附符合Freundlich等温方程；在其他条件不变的情况下，中性偏酸的pH值有利于改性秸秆对氟离子的吸附；改性秸秆对水溶液中氟离子的吸附过程主要符合二级动力学方程；在竞争阴离子共存的情况下，硫酸根对改性秸秆吸附氟离子的干扰最强，氯离子其次，硝酸根离子最弱，且都随着作为干扰的阴离子摩尔量的增大，干扰效果越来越强；当氟离子溶液浓度为4 mg·L^-1，以氟浓度1.5 mg·L^-1作为穿透点时，改性秸秆阴离子吸附剂对氟离子的有效处理量可达到140BV；改性小麦秸秆的再生效果好，可以在应用中循环利用。

关键词：小麦秸秆 改性 氟离子 吸附

Preparation of anionic adsorbent by wheat straw and its application for fluoride removal

Abstract

Fluoride ions in water can cause harm to the ecological environment and human health.In this paper, the wheat straw particles were chemically modified to prepare an anionic adsorbent for the removal of low concentration fluoride ions in water.By changing the temperature, initial concentration, pH, competitive ion, time and other conditions, the removal effect of modified straw on fluorine ion in water was investigated, and its value in practical application was explored in combination with desorption regeneration experiment and dynamic column adsorption experiment.The research results are as follows:The straw particles changed from yellow to brown before and after modification, and infrared spectrum analysis showed that quaternary ammonium groups were introduced into the modified straw；With the increase of temperature, the adsorption effect of modified straw on fluoride ion becomes stronger, and its adsorption on fluoride ion accords with Freundlich isotherm equation；When other conditions remain unchanged, the pH value of neutral acid is conducive to the adsorption of fluorine ion by modified straw；The adsorption process of modified straw to fluorine ion in aqueous solution conforms to the second order kinetic equation；In the case of competitive anion coexistence, sulfate has the strongest interference on adsorption of fluorine ion by modified straw, followed by chloride ion, and nitrate ion has the weakest. The interference effect becomes stronger and stronger with the increase of the number of anion as the interference；When fluorine ion solution concentration of 4 mg·L^-1, fluorine concentration of 1.5 mg·L^-1 as the breakthrough point, the modified straw anion adsorbent of fluorine ion capacity can reach 140 BV；The modified wheat straw has good regeneration effect and can be recycled in the application.

Key Words: wheat straw；modified； fluoride ion；adsorption

目录

摘要 I

Abstract Ⅱ

第一章 绪论 1

1.1研究背景 1

1.2氟化物的去除方法 1

1.2.1沉淀法 1

1.2.2离子交换法 2

1.2.3电化学法 2

1.2.4反渗透法 2

1.2.5吸附法 3

1.3农业秸秆的吸附剂 3

1.3.1秸秆吸附剂处理有机污染物 3

1.3.2秸秆吸附剂吸附无机污染物 4

1.3.3秸秆的改性方法 4

1.4本课题的提出及研究内容 5

1.4.1本课题的提出及意义 5

1.4.2研究内容 6

第二章 实验材料及方法 7

2.1实验材料 7

2.1.1小麦秸秆材料 7

2.1.2实验药品 7

2.1.3仪器和设备 8

2.2实验方法 8

2.2.1 小麦秸秆阴离子吸附剂的制备 8

2.2.2产物表征实验 9

2.2.3吸附实验方法 9

第三章 结果与分析 13

3.1材料表征 13

3.2 吸附热力学实验 14

3.2.1 吸附等温线拟合 14

3.2.2 热力学分析 15

3.3 pH对吸附效果的影响 17

3.4吸附动力学实验 18

3.5竞争吸附实验 20

3.6柱吸附 22

3.7解吸再生实验 22

第四章 结论与展望 24

参考文献 25

致谢 28

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