棉秆和油页岩共热解生物炭的氨氮吸附性能研究

Investigation of the Ammonia Nitrogen Adsorption Properties of co-Pyrolysis Biochar Derived from Cotton Stalk and Oil Shale

使用棉秆(CS)和油页岩(OS)为原料,采用共热解的方式制备了共热解生物炭,探究了对氨氮的吸附性能。考察了不同热解时间、CS和OS比例、热解温度、CS的粒径对共热解生物炭的氨氮吸附量的影响规律,确定了最佳制备条件,并研究了吸附动力学和吸附等温线模型。研究表明,棉秆和油页岩共热解后生物炭的结构特性和表面形貌有较大改善,对氨氮的吸附能力有明显的提高。最佳的制备条件是热解温度为500℃、m(棉秆)∶m(油页岩)=3∶1、热解时间为30 min和CS的粒径为0.20~0.30 mm。在投加量为10.0 g/L、pH 9.0时,最佳条件所制备炭的吸附量为4.89 mg/g,是棉秆生物炭的2.2倍。吸附过程以准二级动力学和Langmuir等温吸附模型描述。吸附机制主要包括为离子交换、静电吸附和配位作用。

By utilizing cotton stalk(CS)and oil shale(OS)as raw materials,co-pyrolysis biochar was prepared by co-pyrolysis,followed by an investigation into its ammonia nitrogen.Various factors such as pyrolysis time,CS and OS ratio,pyrolysis temperature,and CS particle size were examined to optimize the adsorption capacity of the co-pyrolysis biochar for ammonia nitrogen.Additionally,the adsorption kinetics and adsorption isotherm models were also analyzed.The results revealed a significant enhancement in the structural and surface morphology of co-pyrolysis biochar derived from cotton stalks and oil shale,thereby increasing its adsorption capacity for ammonia nitrogen.The optimal preparation conditions included a pyrolysis temperature of 500℃,a mass ratio of cotton stalk to oil shale of 3∶1,pyrolysis time of 30 min,and a CS particle size of 0.20~0.30 mm.Under the conditions of 10.0 g/L adsorbent dosage and pH 9.0,the adsorption capacity of the biochar prepared under the optimal conditions reached 4.89 mg/g,which was 2.2 times higher than that of cotton stalk biochar.The adsorption process followed pseudo-second-order kinetics and Langmuir isotherm adsorption model.The primary mechanism involved in the adsorption process were ion exchange,electrostatic adsorption,and complexation.