학술논문
高温烟气活化生物炭制备活性炭及其Cu2+吸附性能 / Preparation of activated carbon from high-temperature flue gas activated biochar and their Cu2+ adsorption performance
Document Type
Academic Journal
Source
低碳化学与化工 / Low-Carbon Chemistry and Chemical Engineering. 48(6):98-106
Subject
Language
Chinese
ISSN
2097-2547
Abstract
开发农林废弃生物质高效清洁制备活性炭技术,对于中国实现双碳战略具有重大意义.农林废弃生物质快速热解生成大量生物炭,如何低成本、规模化地将生物炭转化为活性炭是当前的研究热点.以马尾松生物炭为原料,采用N2/CO2混合气体模拟循环流化床高温烟气,并通入水蒸气作为活化剂,对生物炭进行活化,制备活性炭.通过单因素实验,探究了水蒸气流量、活化温度、活化时间对活性炭碘吸附值和产率的影响规律,确定了最佳制备条件.采用全自动物理化学吸附仪、扫描电镜和傅里叶变换红外光谱仪,对活性炭物化性质和结构进行了表征;考察了pH、吸附时间、活性炭投加量、Cu2+初始浓度(质量浓度)对活性炭Cu2+吸附性能的影响;采用动力学模型及等温线模型研究了活性炭吸附Cu2+的机制.研究表明,最佳制备条件下(高温烟气为100 mL/min、水蒸气流量为0.9 mL/min、活化温度为850 ℃、活化时间为2.5 h),活性炭产率为7.32%、碘吸附值为1914 mg/g、比表面积为1556 m2/g,表面官能团含有O—H、C—O、C==C和C==O键等化学键.最佳吸附工艺下(pH为5.5、吸附时间为30 min、活性炭投加量为1.5 g/L、Cu2+初始浓度为10 mg/L),Cu2+最大去除率为99.97%,剩余Cu2+浓度为0.003 mg/L,符合我国生活饮用水标准(<1 mg/L).准二级动力学模型和Langmuir模型能更好地拟合吸附过程,吸附为单分子层化学吸附,颗粒内扩散不是唯一的控速步骤.
Developing efficient and clean technology for the preparation of activated carbon from agricultural and forestry waste biomass is of great significance for China's dual carbon strategy.The rapid pyrolysis of agricultural and forestry waste biomass generates a large amount of biochar.The current research focus is on cost-effective and large-scale conversion of biochar into activated carbon.Using Masson pine biochar as the raw material,N2/CO2 mixed gas was used to simulate the circulating fluidized bed high-temperature flue gas,and water vapor was introduced as an activating agent to prepare activated carbon through activation of the biochar.Through single-factor experiments,the influence of water vapor flow rate,activation temperature,and activation time on the iodine adsorption value and yield of activated carbon were explored to determine the optimal preparation conditions.The physicochemical properties and structure of the activated carbon were characterized using an automatic physical and chemical adsorption instrument,scanning electron microscope,and Fourier transform infrared spectroscopy.The effects of pH,adsorption time,activated carbon dosage and initial Cu2+ concentration(mass concentration)on the adsorption performance of activated carbon for Cu2+ were investigated.The adsorption mechanism of Cu2+ on activated carbon was studied using kinetic and isotherm models.The research shows that under the optimal preparation conditions(high-temperature flue gas flow rate of 100 mL/min,water vapor flow rate of 0.9 mL/min,activation temperature of 850 ℃ and activation time of 2.5 h),the activated carbon yield is 7.32%,the iodine adsorption value is 1914 mg/g,and the specific surface area is 1556 m2/g.The functional groups on the surface contain various chemical bonds such as O—H,C—O,C==C and C==O bond.Under the optimal adsorption process conditions(pH of 5.5,adsorption time of 30 minutes,activated carbon dosage of 1.5 g/L and initial Cu2+ concentration of 10 mg/L),the maximum removal rate of Cu2+ is 99.97%,and the residual Cu2+ concentration is 0.003 mg/L,which complies with China's drinking water standards(＜1 mg/L).The pseudo-second-order kinetic model and Langmuir model can better fit the adsorption process,indicating that the adsorption is a monolayer chemical adsorption,and the intraparticle diffusion is not the only rate-controlling step.
Developing efficient and clean technology for the preparation of activated carbon from agricultural and forestry waste biomass is of great significance for China's dual carbon strategy.The rapid pyrolysis of agricultural and forestry waste biomass generates a large amount of biochar.The current research focus is on cost-effective and large-scale conversion of biochar into activated carbon.Using Masson pine biochar as the raw material,N2/CO2 mixed gas was used to simulate the circulating fluidized bed high-temperature flue gas,and water vapor was introduced as an activating agent to prepare activated carbon through activation of the biochar.Through single-factor experiments,the influence of water vapor flow rate,activation temperature,and activation time on the iodine adsorption value and yield of activated carbon were explored to determine the optimal preparation conditions.The physicochemical properties and structure of the activated carbon were characterized using an automatic physical and chemical adsorption instrument,scanning electron microscope,and Fourier transform infrared spectroscopy.The effects of pH,adsorption time,activated carbon dosage and initial Cu2+ concentration(mass concentration)on the adsorption performance of activated carbon for Cu2+ were investigated.The adsorption mechanism of Cu2+ on activated carbon was studied using kinetic and isotherm models.The research shows that under the optimal preparation conditions(high-temperature flue gas flow rate of 100 mL/min,water vapor flow rate of 0.9 mL/min,activation temperature of 850 ℃ and activation time of 2.5 h),the activated carbon yield is 7.32%,the iodine adsorption value is 1914 mg/g,and the specific surface area is 1556 m2/g.The functional groups on the surface contain various chemical bonds such as O—H,C—O,C==C and C==O bond.Under the optimal adsorption process conditions(pH of 5.5,adsorption time of 30 minutes,activated carbon dosage of 1.5 g/L and initial Cu2+ concentration of 10 mg/L),the maximum removal rate of Cu2+ is 99.97%,and the residual Cu2+ concentration is 0.003 mg/L,which complies with China's drinking water standards(＜1 mg/L).The pseudo-second-order kinetic model and Langmuir model can better fit the adsorption process,indicating that the adsorption is a monolayer chemical adsorption,and the intraparticle diffusion is not the only rate-controlling step.