海藻酸钙/椰壳生物碳对Cu(Ⅱ)的吸附性能和机制

Characteristics and Mechanism of Cu(Ⅱ) Adsorption by Calcium Alginate/Coconut Shell Derived Biochar Microsphere

利用海藻酸钙（CA）包覆生物碳（BC7）制备了一种复合材料（CA/BC7）,用以吸附水溶液中的Cu（Ⅱ）。对BC7和CA/BC7进行了FTIR、SEM、XRD、XPS及元素分析测试,并对其吸附Cu（Ⅱ）的机理进行了考察。结果表明：BC7、CA/BC7吸附Cu（Ⅱ）等温热力学数据符合Langmuir模型,在pH=5时对Cu（Ⅱ）的最大吸附量分别为20.28,35.46 mg/g。BC7、CA/BC7吸附Cu（Ⅱ）动力学数据符合准一级动力学模型,扩散是速率控制步骤。BC7吸附Cu（Ⅱ）的机制包括形成Cu（Ⅱ）—O—Si以及形成Cu（Ⅱ）-Complex配合物;CA/BC7吸附Cu（Ⅱ）的机制主要包括形成配合物,以及Ca（Ⅱ）与Cu（Ⅱ）发生离子交换。

A microsphere（CA/BC7） was prepared using calcium alginate（CA） encapsulated biochar（BC7） and then used as a green adsorbent for Cu（Ⅱ） removal from aqueous solution. The mechanisms of Cu（Ⅱ） adsorption on BC7 and CA/BC7 were discussed based on characterization of the materials by means of FTIR,SEM,XRD,XPS and elemental analysis. The isothermal thermodynamic datas of BC7 and CA/BC7 for Cu（Ⅱ） conformed to the Langmuir model. The maximum adsorption capacities of BC7 and CA/BC7 calculated by Langmuir equation were 20.28 mg/g and 35.46 mg/g at pH=5. The adsorption kinetics of Cu（Ⅱ） by BC7 and CA/BC7 were in good agreement with the pseudo-first-order model,which suggested diffusion was the rate-limiting step. The mechanism of Cu（Ⅱ） adsorption by BC7 was attributed to formation of Cu（Ⅱ）—O—Si and formation of Cu（Ⅱ）-complex complex,while that of Cu（Ⅱ） adsorption by CA/BC7 was mainly due to formation of complex and ion exchange between Ca（Ⅱ） and Cu（Ⅱ）.