Study on the removal of Cr(Ⅵ) by acid-modified distillers’ grains biochar

doi:10.19965/j.cnki.iwt.2024-0107

Abstract

Abstract:

The acid modified biochar (H-BC) was prepared with distillers’ grains, which was activated by KHCO₃ and modified by dipping in acid solution. By optimizing the preparation parameters of H-BC (pyrolysis temperature, activator ratio, type and concentration of modified acid), it was found that H-BC prepared at a pyrolysis temperature of 700 ℃ and a mass ratio of distillers’ grains biochar to activator (KHCO₃) of 1∶1.5, and modified with 0.5 mol/L nitric acid had the best adsorption performance for Cr(Ⅵ). The effects of initial pH (2.0-6.0), initial Cr(Ⅵ) mass concentration (100-600 mg/L), adsorption time (0-27 h), adsorption temperature (20-60 ℃), background ions on the adsorption efficiency of H-BC for Cr(Ⅵ) were investigated. The results showed that the best adsorption performance was achieved at pH 2.0, with the adsorption capacity of 171.05 mg/g and the removal rate of 86%. When the initial mass concentration of Cr(Ⅵ) was 100-400 mg/L and the dosage of biochar was 2.5 g/L, the adsorption capacity of H-BC could reach 151.36 mg/g, with removal rate of 94.54%, demonstrating good adsorption performance within this concentration range. The adsorption process could be divided into rapid adsorption stage (0-1 h), slow adsorption stage (1-20 h), and equilibrium stage (20-27 h). The adsorption of Cr(Ⅵ) by H-BC was an endothermic process, and the adsorption amount increased with the increase of adsorption temperature. The concentration of background electrolytes(NaCl, KCl) had a significant impact on the adsorption of Cr(Ⅵ). The adsorption process was more in line with the Langmuir isotherm model and quasi second order kinetic model. The adsorption mechanism of H-BC for Cr(Ⅵ) involved electrostatic attraction and redox reactions.

Key words: distillers’ grains biochar, modified, adsorption, Cr(Ⅵ)

摘要：

利用白酒酒糟制备生物炭，采用KHCO₃活化后，再利用酸溶液浸渍进行改性，制备了酸改性酒糟生物炭（H-BC）。对H-BC的制备参数（热解温度、活化剂比例、改性酸种类及浓度）进行优化，得到热解温度为700 ℃，酒糟生物炭与活化剂（KHCO₃）为1∶1.5，采用0.5 mol/L硝酸改性制备的H-BC对Cr（Ⅵ）的吸附性能最优。探讨了初始pH（2.0~6.0）、初始Cr（Ⅵ）质量浓度（100~600 mg/L）、吸附时间（0~27 h）、吸附温度（20~60 ℃）、背景离子等因素对H-BC吸附Cr（Ⅵ）效果的影响，结果表明，在pH=2.0时吸附性能最好，其吸附量为171.05 mg/g，去除率为86%；生物炭投加量为2.5 g/L时，Cr（Ⅵ）初始质量浓度为100~400 mg/L范围内酒糟生物炭表现出较好的吸附性能，H-BC的吸附量为151.36 mg/g，去除率为94.54%；吸附过程可分为快速吸附阶段（0~1 h）、缓慢吸附阶段（1~20 h）、平衡阶段（20~27 h）；H-BC对Cr（Ⅵ）的吸附是一个吸热过程，吸附温度升高，吸附量随之增加；背景电解质（NaCl、KCl）浓度对Cr（Ⅵ）的吸附具有较大影响；吸附过程更符合Langmuir等温模型与准二级吸附动力学模型。H-BC对Cr（Ⅵ）的吸附机理涉及静电引力与氧化还原作用。

关键词: 酒糟生物炭, 改性, 吸附, Cr（Ⅵ）

CLC Number:

X703

Hengjun TANG, Biao QIU, Weiping SIMA, Jian TANG. Study on the removal of Cr(Ⅵ) by acid-modified distillers’ grains biochar[J]. Industrial Water Treatment, 2025, 45(3): 144-151.

唐恒军, 邱彪, 司马卫平, 唐建. 酸改性酒糟生物炭对Cr（Ⅵ）的去除性能研究[J]. 工业水处理, 2025, 45(3): 144-151.

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URL: https://gyscl.magtechjournal.com/EN/10.19965/j.cnki.iwt.2024-0107

https://gyscl.magtechjournal.com/EN/Y2025/V45/I3/144

Figures/Tables 10

References 30

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吸附剂	比表面积/（m²·g^-1）	孔容积/（cm³·g^-1）	平均孔径/nm
BC	217.23	0.151 4	2.79
KH-BC	919.42	0.668 9	2.91
H-BC	1 286.79	0.872 7	2.71

吸附剂	比表面积/（m²·g^-1）	孔容积/（cm³·g^-1）	平均孔径/nm
BC	217.23	0.151 4	2.79
KH-BC	919.42	0.668 9	2.91
H-BC	1 286.79	0.872 7	2.71

生物炭	准一级反应动力学模型			准二级反应动力学模型			内扩散模型									Elovich模型
生物炭	Q _e/（mg·g^-1）	k ₁	R ²	Q _e/（mg·g^-1）	k ₂	R ²	K _d，1	C ₁	R ²	K _d，2	C ₂	R ²	K _d，3	C ₃	R ²	α	β	R ²
H-BC	60.16	0.004	0.919 8	178.89	0.000 2	0.9996	2.385	121.85	0.986 4	0.975	141.60	0.982 5	0.352	163.14	0.505 1	6.86×10⁴	0.090	0.935 6
KH-BC	36.16	0.003	0.934 7	157.98	0.000 3	0.999 7	2.263	122.67	0.941 5	0.828	128.04	0.983 8	0.185	149.09	0.298 7	1.49×10⁶	0.124	0.993 7
BC	1.61	0.002	0.908 6	9.94	0.065	0.999 5	0.194	6.72	0.683 5	0.048	8.45	0.995 3	0.056	7.71	0.855 1	9.82×10⁴	1.957	0.935 6

生物炭	准一级反应动力学模型			准二级反应动力学模型			内扩散模型									Elovich模型
生物炭	Q _e/（mg·g^-1）	k ₁	R ²	Q _e/（mg·g^-1）	k ₂	R ²	K _d，1	C ₁	R ²	K _d，2	C ₂	R ²	K _d，3	C ₃	R ²	α	β	R ²
H-BC	60.16	0.004	0.919 8	178.89	0.000 2	0.9996	2.385	121.85	0.986 4	0.975	141.60	0.982 5	0.352	163.14	0.505 1	6.86×10⁴	0.090	0.935 6
KH-BC	36.16	0.003	0.934 7	157.98	0.000 3	0.999 7	2.263	122.67	0.941 5	0.828	128.04	0.983 8	0.185	149.09	0.298 7	1.49×10⁶	0.124	0.993 7
BC	1.61	0.002	0.908 6	9.94	0.065	0.999 5	0.194	6.72	0.683 5	0.048	8.45	0.995 3	0.056	7.71	0.855 1	9.82×10⁴	1.957	0.935 6

吸附剂	Langmuir			Freundlich
吸附剂	Q _m/（mg·g^-1）	K _L/（L·mg^-1）	R²	1/n	K _F/（mg^1-1/ ⁿ ·L^1/ ⁿ ·g^-1）	R²
H-BC	181.25	0.332	0.976 8	0.204	71.53	0.937 1
KH-BC	156.60	3.08	0.987 4	0.125	89.95	0.925 3
BC	16.10	0.029	0.899 2	0.325	2.57	0.949 0

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