Failure mechanism and thermal regeneration of activated carbon for free chlorine removal

doi:10.11949/0438-1157.20190924

Abstract

Abstract:

The effects of initial free chlorine concentration, activated carbon particle size and dosage on free chlorine removal by activated carbon were studied. The activated carbon before and after the reaction was analyzed by means of Boehm titration, Fourier transform infrared spectrometer, specific surface area analyzer, scanning electron microscope, and photoelectron spectroscopy. It is found that the failure of the activated carbon was mainly due to the consumption of reductive functional groups on the surface and the oxidative destruction of the surface structure, causing the loss of pore structure and specific surface. The thermal regeneration of the spent activated carbon under different atmospheres (nitrogen, hydrogen and ammonia) can recover the removal ability on free chlorine; and the ammonia gas regeneration is the best, which is mainly due to the improvement of pore structure and the regeneration of the reductive functional groups. The performance of regenerated activated carbon in continuous flow column test was evaluated, and it was confirmed that the regenerated one can achieve an effective and long-time operation.

Key words: free chlorine, activated carbon, failure, regeneration, removal

摘要：

研究了初始游离氯浓度以及活性炭粒径和投加量等对游离氯去除的影响，并通过Boehm滴定、傅里叶转换红外光谱仪、比表面积分析仪、扫描电子显微镜、光电子能谱等手段分析了反应前后的活性炭，发现活性炭的失效主要是由于其表面还原性官能团的消耗及表面结构的氧化破坏所带来的孔结构和比表面积变化。将失效活性炭在不同气氛(氮气、氢气、氨气)条件下进行热再生，均可使其游离氯去除能力得到恢复，且氨气条件最好，这主要得益于孔结构的提升及还原性官能团的再生。将再生后活性炭进行连续流柱实验，证实其能够长时间有效运行。

关键词: 游离氯, 活性炭, 失活, 再生, 去除

CLC Number:

TU 991.2

Xiaoyan LIU, Wanxin CAI, Likun ZHAO, Xiang ZENG, Xuhui MAO. Failure mechanism and thermal regeneration of activated carbon for free chlorine removal[J]. CIESC Journal, 2020, 71(4): 1781-1790.

刘小艳, 蔡万欣, 赵立坤, 曾香, 毛旭辉. 活性炭去除游离氯的失效机制及热再生研究[J]. 化工学报, 2020, 71(4): 1781-1790.

Figures/Tables 12

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样品	比表面积/ (m²?g^-1)	孔容/(cm³?g^-1)	微孔/(cm³?g^-1)	中孔/(cm³?g^-1)	平均粒径/nm	元素分析/%
样品	比表面积/ (m²?g^-1)	孔容/(cm³?g^-1)	微孔/(cm³?g^-1)	中孔/(cm³?g^-1)	平均粒径/nm	C	H	N
B-AC	1512.2	0.7128	0.665	0.0478	1.8855	73.45	1.67	0.09
A-AC	999.1	0.4845	0.447	0.0375	1.9399	63.60	2.11	0.05
N_2-AC	1289.8	0.616	0.588	0.028	1.9102	66.76	2.66	0.10
H₂-AC	645.93	0.3168	0.3014	0.0154	1.9617	76.70	1.45	0.07
NH₃-AC	1186.9	0.5608	0.5355	0.0253	1.8899	67.88	1.98	1.35

样品	比表面积/ (m²?g^-1)	孔容/(cm³?g^-1)	微孔/(cm³?g^-1)	中孔/(cm³?g^-1)	平均粒径/nm	元素分析/%
样品	比表面积/ (m²?g^-1)	孔容/(cm³?g^-1)	微孔/(cm³?g^-1)	中孔/(cm³?g^-1)	平均粒径/nm	C	H	N
B-AC	1512.2	0.7128	0.665	0.0478	1.8855	73.45	1.67	0.09
A-AC	999.1	0.4845	0.447	0.0375	1.9399	63.60	2.11	0.05
N_2-AC	1289.8	0.616	0.588	0.028	1.9102	66.76	2.66	0.10
H₂-AC	645.93	0.3168	0.3014	0.0154	1.9617	76.70	1.45	0.07
NH₃-AC	1186.9	0.5608	0.5355	0.0253	1.8899	67.88	1.98	1.35

样品	表面官能团/(mmol?g^-1)
样品	—OH	—COOR	—COOH	酸性官能团	碱性官能团
B-AC	0.07	0.22	0.07	0.36	0.55
A-AC	1.12	1.17	2.17	4.49	0.35
N₂-AC	0.37	0.07	—	0.44	0.45
H₂-AC	0.12	0.05	0.04	0.22	0.50
NH₃-AC	0.16	0.17	—	0.34	0.71

样品	表面官能团/(mmol?g^-1)
样品	—OH	—COOR	—COOH	酸性官能团	碱性官能团
B-AC	0.07	0.22	0.07	0.36	0.55
A-AC	1.12	1.17	2.17	4.49	0.35
N₂-AC	0.37	0.07	—	0.44	0.45
H₂-AC	0.12	0.05	0.04	0.22	0.50
NH₃-AC	0.16	0.17	—	0.34	0.71

		结合能/eV	B-AC	A-AC	N₂-AC	H₂-AC	NH₃-AC
C 1s	C—C	284.8	71.03	56.33	60.23	61.04	57.71
	C—O	286.0	16.23	14.42	17.60	8.89	11.23
	CO	287.4	0.22	1.31	0.07	3.21	6.89
	—O—CO	288.8	2.39	7.42	3.85	2.90	2.12
	总原子C/%		89.87	79.47	87.79	81.53	79.82
O 1s	CO	531.0~531.9	4.81	10.92	8.16	5.65	5.8
	C—O	533.0~533.4	4.89	7.42	7.26	4.34	6.33
	H₂O	535.2~535.4	0	1.51	2.50	1.73	2.18
	总原子O/%		9.70	19.86	17.92	11.73	14.31
O/C比			0.11	0.25	0.13	0.22	0.18