Cd(II) Adsorption Capability of the Biochar Derived from Co-pyrolysis of Lignin and Polyethylene

doi:10.16258/j.cnki.1674-5906.2022.02.015

Ecology and Environment ›› 2022, Vol. 31 ›› Issue (2): 344-353.DOI: 10.16258/j.cnki.1674-5906.2022.02.015

• Research Articles • Previous Articles Next Articles

Cd(II) Adsorption Capability of the Biochar Derived from Co-pyrolysis of Lignin and Polyethylene

QIN Kun¹^,²^,³(), WANG Zhikang¹^,², WANG Zhanghong¹^,²^,³^,⁴^,^*(), YANG Cheng²^,³, LIU Jiegang²^,³, SHEN Dekui⁴

1. Colledge of Eco-Environmental Engineering, Guizhou Minzu University, Guiyang, 550025, P. R. China
2. Guizhou Provincial Engineering Geological Disaster Prevention and Control Engineering Research Center of Guizhou Minzu University, Guizhou Minzu University, Guiyang, 550025, P. R. China
3. Research Centre for Solid Waste Pollution Control and Recycling Technology, Guizhou Minzu University, Guiyang 550025, P. R. China
4. Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education/Southeast University, Nanjing 210096, P. R. China;

Received:2021-06-22 Online:2022-02-18 Published:2022-04-14
Contact: WANG Zhanghong

木质素-聚乙烯共热解生物炭对Cd(II)的吸附性能

秦坤¹^,²^,³(), 王志康¹^,², 王章鸿¹^,²^,³^,⁴^,^*(), 杨成²^,³, 刘杰刚²^,³, 沈德魁⁴

1.贵州民族大学生态环境工程学院,贵州贵阳 550025
2.贵州省工程地质灾害防治工程研究中心（贵州民族大学）,贵州贵阳 550025
3.贵州民族大学固废污染控制与资源化技术研究中心,贵州贵阳 550025
4.东南大学/能源热转换及其过程测控教育部重点实验室,江苏南京 210000

通讯作者: 王章鸿
作者简介:秦坤（1996年生）,男,硕士研究生,主要从事喀斯特地区典型固体废弃物的资源化利用。E-mail: 2435004756@qq.com
基金资助:
贵州省高新技术产业化示范工程项目(黔发改高技[2020]896号)

Abstract

Abstract:

In order to explore a way to utilize lignin and develop low-cost and highly-efficient adsorbents for the removal of heavy metals, this study prepared biochar by lignin and pyrolysis of lignin（LG-600C） and polyethylene mixture（LG/PE-600C）, respectively, under the same condition at 600 ℃. The physicochemical properties involving surface morphology, textural characteristics, surface functional groups, and composition of LG-600C and LG/PE-600C were determined by scanning electron microscope (SEM), N₂ adsorption/desorption, fourier transform infrared spectroscopy (FT-IR), and ultimate analysis. The biochar adsorption capability of LG-600C ad LG/PE-600C for Cd(II) were investigated as well. Compared to LG-600C, LG/PE-600C presented a rougher surface and a more developed pore structure with specific surface area reaching 213.87 m²∙g^-1, which was about 2.5 times that of LG-600C. The introduction of polyethylene led to the decrease of O content and O-containing surface functional groups of LG/PE-600C. The adsorption test results confirmed that the adsorption capability of LG/PE-600C for Cd(II) was apparently superior to that of LG-600C. The adsorption capability of LG/PE-600C for Cd(II) can be promoted with the increase of Cd (II) initial concentration, ambient temperature, adsorption time, and solution pH within a certain range. Langmuir isotherm model and pseudo-second-order kinetic model can be employed to well simulate the adsorption of LG/PE-600C for Cd (II), indicating that the adsorption process belongs to a monolayer adsorption and is dominated by chemical actions. The theoretical maximum adsorption capacity of LG/PE-600C for Cd (II) calculated by Langmuir model was 40.82 mg∙g^-1. Thermodynamic analysis showed that the adsorption of LG/PE-600C for Cd (II) was a spontaneous and endothermic reaction. According to mechanism analysis, the introduction of polyethylene could intensify the degradation of lignin and promote the growth of pore structure of LG/PE-600C. As a result, abundant adsorption sites, such as -OH, C=C, and C-O-C, for Cd(II) were exposed, leading to a higher adsorption capability of LG/PR-600C via complexation, precipitation, and ion exchange. Results confirmed that the conversion of lignin into biochar with the addition of polyethylene could be considered as an alternative way to use lignin.

Key words: lignin, polyethylene, biochar, co-pyrolysis, Cd(II), adsorption

摘要：

为了寻求木质素的资源化利用途径和开发低廉、高效的重金属吸附材料,该研究将木质素和聚乙烯混合物在600 ℃下热解制备生物炭（LG/PE-600C）,以单独木质素在相同条件下所制备的生物炭作对比（LG-600C）,利用扫描电镜（SEM）、N₂吸附/脱附、傅里叶红外光谱（FT-IR）和元素分析等对比分析LG-600C和LG/PE-600C在表观形貌、孔隙特性、表面官能团、物质组成等的差异,并进一步考察两种生物炭对Cd(II)的吸附性能。相对于LG-600,LG/PE-600C表面较粗糙,孔隙结构较发达。LG/PE-600C的比表面积达213.87 m²∙g^-1,约为LG-600的2.5倍。聚乙烯的介入,导致LG/PE-600C的O元素含量和表面含氧官能团较LG-600C有所降低。吸附结果显示,LG/PE-600C对Cd(II)的吸附性能明显优于LG-600。在一定范围内,Cd(II)初始浓度、环境温度、吸附时间、溶液pH的增加均能够促进LG/PE-600C对Cd(II)的吸附。Langmuir模型和准二级动力学模型能够很好地拟合Cd(II)的吸附过程,表明LG/PE-600C对Cd(II)的吸附为化学作用主导的单分子层吸附。基于Langmuir模型所得到的理论最大吸附量达到40.82 mg∙g^-1。热力学分析证实,LG/PE-600C对Cd(II)的吸附为自发的吸热反应。机理分析表明,LG/PE-600C具有优于LG-600C的吸附性能,其主要原因在于聚乙烯介入能够强化木质素的分解,促进LG/PE-600C孔隙的发育,使得LG/PE-600C表面暴露大量Cd(II)的吸附位点,如-OH、C=C、-C-O-C等。这些吸附位点能够通过配位、沉淀、离子交换等作用对Cd(II)进行吸附。由此证实,添加聚乙烯与木质素进行共热解制备生物炭用于Cd(II)的吸附可作为木质素重要的资源化利用方式。

关键词: 木质素, 聚乙烯, 生物炭, 共热解, Cd(II), 吸附

CLC Number:

QIN Kun, WANG Zhikang, WANG Zhanghong, YANG Cheng, LIU Jiegang, SHEN Dekui. Cd(II) Adsorption Capability of the Biochar Derived from Co-pyrolysis of Lignin and Polyethylene[J]. Ecology and Environment, 2022, 31(2): 344-353.

秦坤, 王志康, 王章鸿, 杨成, 刘杰刚, 沈德魁. 木质素-聚乙烯共热解生物炭对Cd(II)的吸附性能[J]. 生态环境学报, 2022, 31(2): 344-353.

Figures/Tables 13

References 31

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样品 Sample	比表面积 Specific surface area/ (m²∙g^-1)	孔比表面积 Pore specific surface area/ (m²∙g^-1)	总孔容 Total pore volume/ (m³∙g^-1)	微孔孔容 Micropore volume/ (m³∙g^-1)	平均孔隙直径 Average pore diameter/ nm
LG-600C	89.12	44.84	0.15	0.09	40.12
LG/PE-600C	213.87	108.74	0.75	0.29	23.85

样品 Sample	比表面积 Specific surface area/ (m²∙g^-1)	孔比表面积 Pore specific surface area/ (m²∙g^-1)	总孔容 Total pore volume/ (m³∙g^-1)	微孔孔容 Micropore volume/ (m³∙g^-1)	平均孔隙直径 Average pore diameter/ nm
LG-600C	89.12	44.84	0.15	0.09	40.12
LG/PE-600C	213.87	108.74	0.75	0.29	23.85

样品 Sample	w_(C)/%	w_(H)/%	w_(O)/%	w_(S)/%	pH	灰分 Ash/%
LG-600C	80.15	4.12	14.23	0.32	7.48	3.54
LG/PE-600C	90.14	3.48	4.94	0.51	7.66	3.87

样品 Sample	w_(C)/%	w_(H)/%	w_(O)/%	w_(S)/%	pH	灰分 Ash/%
LG-600C	80.15	4.12	14.23	0.32	7.48	3.54
LG/PE-600C	90.14	3.48	4.94	0.51	7.66	3.87

样品 Sample	Langmuir模型 Langmuir model			Freundlich模型 Freundlich model
样品 Sample	q_m/ (mg∙g^-1)	k₁/ (L∙mg^-1)	R²	k_f/ [mg^(1-ⁿ⁾Lⁿ∙g^-1]	n	R²
LG-600C	5.54	0.18	0.998	2.36	6.13	0.974
LG/PE-600C	40.82	0.23	0.999	7.20	2.34	0.929

Cd(II) Adsorption Capability of the Biochar Derived from Co-pyrolysis of Lignin and Polyethylene

木质素-聚乙烯共热解生物炭对Cd(II)的吸附性能

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Figures/Tables 13

References 31

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样品 Sample	实验平衡吸附量q_e,exp/(mg∙g^-1)	准一级动力学模型 Pseudo-first-order model			准二级动力学模型 Pseudo-second-order model
样品 Sample	实验平衡吸附量q_e,exp/(mg∙g^-1)	k₁/(h^-1)	q_e/(mg∙g^-1)	R²	k₂/(g∙mgh^-1)	q_e/(mg∙g^-1)	R²
LG-600C	3.14	0.042	3.14	0.459	0.35	3.60	0.936
LG/PE-600C	36.58	0.037	36.58	0.230	0.050	40.16	0.928

样品 Sample	吉布斯自由能 ΔG⁰/(kJ·mol^-1)				焓 ΔH⁰/ (kJ∙mol^-1)	熵 ΔS⁰/ [J∙(mol∙K)^-1]
样品 Sample	288 K	298 K	308 K	318 K	焓 ΔH⁰/ (kJ∙mol^-1)	熵 ΔS⁰/ [J∙(mol∙K)^-1]
LG-600C	-6.05	-9.83	-10.47	-11.58	43.84	175.97
LG/PE-600C	-9.47	-12.25	-14.54	-16.20	55.44	226.26

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