不同温度条件下制备的生物炭对水相Cu2+的吸附性能

    Adsorption of Cu2+ From Aqueous Solution on Biochar Produced From Rice Husk and Sawdust Under Different Temperatures

    • 摘要: 以稻壳和木屑为原料,分别制备不同温度(200~700 ℃)条件下稻壳生物炭(DBC200~DBC700)和木屑生物炭(MBC200~MBC700),对其性质进行表征,研究其对Cu2+的吸附效果,筛选出吸附效果最好的生物炭,进而探究其对Cu2+的吸附等温线、吸附动力学及动态淋洗吸附效果。结果表明,高温制备的生物炭有利于对Cu2+的吸附,木屑生物炭对Cu2+的吸附效果优于相同温度条件下制备的稻壳生物炭,其中DBC700和MBC700对Cu2+的吸附量最高。稻壳生物炭对Cu2+的吸附量与其pH、比表面积和羧基含量之间呈显著相关关系,与孔体积之间呈极显著相关关系;木屑生物炭对Cu2+的吸附量与总酸性官能团含量之间呈显著相关关系,与pH和羧基含量之间呈极显著相关关系。DBC700和MBC700对Cu2+的吸附等温线更符合Freundlich模型。准一级和准二级动力学模型都能较好地描述DBC700和MBC700对Cu2+的吸附动力学特性。此外,DBC700和MBC700对Cu2+的动态平均淋洗吸附量分别为7.58和16.12 mg·g-1。可见,稻壳和木屑生物炭可以用作去除废水中Cu2+的吸附剂。

       

      Abstract: Twelve types of biochars were prepared by pyrolyzing rice husk and sawdust at different temperatures (200-700 ℃), which were referred as DBC200-DBC700 and MBC200-MBC700, respectively. The characteristics of these biochars and their Cu2+ adsorption performance were investigated, including the adsorption isotherms, kinetics and dynamic leaching. Results indicate that biochars derived from higher temperature showed better performance for Cu2+ adsorption, and those produced at 700 ℃ showed the highest sorption capability. The sawdust biochar had higher adsorption capacity than rice husk biochar derived under the same pyrolysis temperature. There was significant correlation between Cu2+ adsorption and each of the parameters, such as pH, specific surface area, carboxyl group content, and pore volume for rice husk biochars. For sawdust biochar, there was significant correlation between Cu2+ adsorption and the total acid groups, and obviously significant correlation between Cu2+ adsorption and pH as well as the carboxyl group content. Adsorption isotherms of Cu2+ by DBC700 and MBC700 were well fitting with Freundlich model, and the adsorption kinetics were greatly fitting to both pseudo-first-order model and pseudo-second-order model. The average amount of Cu2+ adsorption by DBC700 and MBC700 from dynamic adsorption experiment reached 7.58 and 16.12 mg·g-1, respectively. The results indicate that rice husk and sawdust biochars could be used as efficient adsorbents to remove Cu2+ from wastewater.

       

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