Removal of fluoride from water by modified polypyrrole

doi:10.16085/j.issn.1000-6613.2020-1551

Abstract

Abstract:

Modified polypyrrole (PPy) nanofibers with different diameters were synthesized by controlling the synthesis conditions and adding ARG, MO and α-CD+MO in the polymerization process, respectively. The physicochemical properties of the as-prepared PPy were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy(FTIR), nitrogen adsorption desorption analysis (BET) and zeta potential analysis. The results showed that the specific surface area of PPy with special morphology was 7—10 times higher than that of traditional granular PPy. Compared with traditional granular PPy, the modified PPy with special morphology can reach the adsorption equilibrium within 10 min at room temperature and pH=5 when the initial concentration of F^- was 3—5mg/L and the dosage was 2g/L. The concentration of F^- can be reduced to less than 1mg/L in the Integrated Wastewater Discharge Standard (GB 5749—2006). The results indicated that the control of special morphology had a great influence on the adsorption of F^- by PPy. In addition, the adsorption behavior was a spontaneous exothermic process, which can be well fitted by Langmuir model. The removal of F^- by PPy was mainly the result of ion exchange.

Key words: polypyrrole (PPy), fluorine ion, adsorption, special morphology, mechanism

摘要：

通过控制合成条件和在聚合过程中分别引入酸性红G（ARG）、甲基橙（MO）、α-环糊精（α-CD）和甲基橙等掺杂剂合成了表面带有毛刺的纤维、不同直径纳米纤维编织成的微米片状特殊微形貌的改性聚吡咯（PPy）材料。通过场发射扫描电子显微镜（SEM）、透射电子显微镜（TEM）、傅里叶变换红外光谱分析（FTIR）、氮气吸脱附分析（BET）、zeta电位分析等方法对其物理化学性能进行了表征，并将其应用于水体低浓度氟离子的吸附去除，比较了改性聚吡咯材料与传统方法合成的颗粒状聚吡咯对氟离子吸附的性能。结果表明：改性的特殊微形貌PPy的比表面积比传统颗粒状PPy提高了7~10倍；在常温和pH=5的条件下，F^-初始浓度在3~5mg/L，投加量为2g/L时，改性的特殊微形貌PPy可在10min之内达到吸附平衡，并将F^-的浓度降低到国家《生活引用水卫生标准》（GB 5749—2006）规定的1mg/L以下，说明特殊微形貌的控制对PPy吸附F^-具有很大影响。另外，该吸附行为是自发的放热过程，Langmiur模型可以很好地拟合该吸附过程，PPy对F^-的去除主要涉及离子交换作用。

关键词: 聚吡咯, 氟离子, 吸附, 特殊微形貌

CLC Number:

X 523

FENG Jiangtao, WANG Xi, ZHAO Xuyang, GONG Xianghong, YAN Wei. Removal of fluoride from water by modified polypyrrole[J]. Chemical Industry and Engineering Progress, 2021, 40(7): 4036-4046.

冯江涛, 王睎, 赵旭阳, 龚向红, 延卫. 改性聚吡咯材料去除水中氟离子的性能[J]. 化工进展, 2021, 40(7): 4036-4046.

Figures/Tables 17

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样品名称	碳原子 /%	氮原子 /%	氧原子 /%	氯原子 /%
纯PPy	50.55	46.44	—	3.01
ARG/PPy	57.50	28.40	10.79	3.31
MO/PPy	50.44	31.23	14.68	3.65
α-CD/MO/PPy	55.33	30.56	10.16	3.95

样品名称	碳原子 /%	氮原子 /%	氧原子 /%	氯原子 /%
纯PPy	50.55	46.44	—	3.01
ARG/PPy	57.50	28.40	10.79	3.31
MO/PPy	50.44	31.23	14.68	3.65
α-CD/MO/PPy	55.33	30.56	10.16	3.95

样品名称	S_BET/m²·g^-1	总孔容V/cm³·g^-1	平均孔径R/nm
纯PPy	6.35	0.140	9.49
ARG/PPy	45.36	0.333	11.87
MO/PPy	62.10	0.481	10.75
α-CD/MO/PPy	65.10	0.403	12.75

样品名称	S_BET/m²·g^-1	总孔容V/cm³·g^-1	平均孔径R/nm
纯PPy	6.35	0.140	9.49
ARG/PPy	45.36	0.333	11.87
MO/PPy	62.10	0.481	10.75
α-CD/MO/PPy	65.10	0.403	12.75

样品	C₀	q_e，e	准一级动力学模型参数			准二级动力学模型参数
样品	C₀	q_e，e	k₁	q_e，c	R²	q_e，c	k₂	R²
纯PPy	3	1.125	0.121	1.126	0.9964	1.126	0.063	0.9993
	5	2.107	0.153	2.109	0.9946	2.109	0.056	0.9971
	10	3.852	0.113	3.865	0.9909	3.865	0.037	0.9978
ARG/PPy	3	1.205	0.769	1.205	0.9846	1.205	0.702	0.9999
	5	2.128	0.526	2.129	0.9994	2.129	0.646	0.9998
	10	4.089	0.514	4.092	0.9792	4.092	0.578	0.9996
MO/PPy	3	1.227	0.727	1.223	0.9918	1.223	0.891	0.9980
	5	2.205	0.726	2.206	0.9927	2.206	0.797	0.9991
	10	4.124	0.710	4.854	0.9941	4.854	0.675	0.9999
α-CD/MO/PPy	3	1.275	0.753	1.275	0.9922	1.275	0.941	0.9999
	5	2.268	0.704	2.258	0.9940	2.258	0.890	0.9984
	10	4.357	0.675	4.354	0.9948	4.354	0.722	0.9993