椰壳生物碳和海藻酸钙/生物碳复合材料的制备及其对Cu(II)的吸附性能和机制

Preparation and Characterization of Coconut Shell Derived Biochar and Calcium Alginate/Biochar Microsphere and their Adsorption Characteristics and Mechanism for Cu(II)

摘要:

利用海藻酸钙（CA）包覆生物碳（BC7）制备了一种新型复合材料（CA/BC7），用以吸附水溶液中的Cu(II)。系统的研究了Cu(NO3)2溶液初始浓度、pH、时间对Cu(II)吸附的影响。BC7、CA/BC7吸附Cu(II)等温热力学数据符合Langmuir模型，在pH=5的条件下对Cu(II)的最大吸附量分别为20.28 mg?g-1，35.46 mg?g-1。BC7、CA/BC7吸附Cu(II)动力学数据符合准一动力学模型，扩散是速率控制步骤。研究表明：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。

Abstract:

A microspheres (CA/BC7) was prepared using calcium alginate (CA) encapsulated biochar (BC7) as the green adsorbent for Cu(II) removal from aqueous solution. The effects of the initial Cu(II) concentration, initial pH value of Cu(II) solution and equilibrium contact time were investigated. The isothermal thermodynamic datas of the BC7 and CA/BC7 conformed to the Langmuir model. The maximum adsorption capacity of the BC7 and CA/BC7 from the Langmuir equation were 20.28 mg?g-1 and 35.46 mg?g-1 at pH=5. The adsorptions of Cu(II) by the BC7 and CA/BC7 were in good agreement with pseudo-first-order model, which suggested that the rate limiting step was governed by diffusion. Mechanism studies for Cu(II) removal by BC7 showed that the nature of Cu(II) abstraction took place through the formation of Cu(II)-O-Si and Cu(II)-Complex. The Cu(II) removal by the CA/BC7 were mainly through the ion exchange between Ca (II) and Cu(II) as well as the formation of coordination complex.