改性腐殖酸去除水中氟化物性能研究

On the increased efficiency of fluorine removal from water with the modified humic acid

以腐殖酸（HA）为原材料,通过络合铝离子改性处理,制备了新型除氟吸附剂（HAAl）。通过扫描电子显微镜（SEM）、傅里叶红外光谱（FTIR）、X射线衍射（XRD）及X射线能谱（EDS）对该吸附剂进行了表征,并系统研究了该吸附剂对水中F^-的吸附性能。结果表明：在p H值为4~10时HAAl均对水中F-表现出较高的吸附能力,其饱和吸附量为60.606 mg/g,吸附等温线符合Langmuir方程;吸附动力学可用准二级速率方程描述,表现为化学吸附;共存阴离子Cl^-、HCO3^-和NO3^-对氟的吸附影响较小,HAAl吸附剂除氟率可达85.99%,出水氟质量浓度低于国家饮用水标准;此外,HAAl铝不易脱落,具有优良的稳定性。

In this paper, we would like to introduce our study of a novel method for preparing a modified adsorbent with strong affinity towards the fluoride humic acid. To develop the modified adsorbent, we have chosen humic acid as a kind of raw material with a modified aluminum sulfate. And, in so doing, it has been made possible to obtain the novel adsorbent （HAA1） for the fluoride removal. To achieve the purpose, we have investigated the effects of the reaction time, the pH value and the initial concentration of the sodium fluoride on the adsorption behavior of the adsorbent. In addition, we have made an exploration of the mechanism of the modification and adsorp- tion by using the sodium fluoride infrared spectroscopy （IR） and the equilibrium pH （after adsorption） as the adsorption subjects. The re- suits of our experimental study have shown that the number of pores of the modified humic acid has been greatly increased, with the modified products still holding the amorphous state. When we studied the ad- sorption behavior of HAA1 in the aqueous solution of fluoride ions, we have found the adsorptive capacity of HAA1 toward the fluoride has been improved in the pH range of 4- 10, with the maximum adsorp- tive capacity being 60.606 mg/g. And, consequently, the adsorbed amount of the modified humic acid tends to be greater than that of the unmodified one （9.234 mg/g）. Besides, the adsorption process of HAM on the fluorine has been found much closer to the Langmuir isotherm model than with that of Freundlich isotherm. The absorption isotherm results of the modified humic acid demonstrate that the ad- sorption of fluoride is by nature the monomolecular adsorption on the surface of the modified humic acid. Moreover, the ion exchange tends to take place in the HAAI＇ s adsorption process, which may help to increase the pH value of the solution as the result of the hydroxide ion release. Theoretically speaking, the above mentioned adsorption kinetics process tends to occur as the chemi-sorption which can be shown via the Second-Order rate equation. With the presence of anions, such as Cl- , HCO3- and NO3- , the HAAI process can be expected to reach a high fluoride removal rate of 85.99%. The amount of fluoride in the HAA1 processed water has been made lower than the permission in the Chinese national drinking water standard. Furthermore, the aluminum content in the water can be made stabilized by HA efficiently, which helps to ensure the reusability of HAAl. Therefore, the HAAl adsorbent can be expected to enjoy a great potential application prospect in removing fluoride in water.