柠檬酸改性大豆秸秆材料对铜离子的吸附性能

 为考察农业废弃物大豆秸秆对重金属的吸附性能，以大豆秸秆为原料、柠檬酸为改性剂，制备出一种柠檬酸改性大豆秸秆吸附剂（CA-SS），对其进行扫描电镜测试和红外吸收光谱分析。对比研究了大豆秸秆改性前后对铜离子（Cu²⁺）的吸附性能，分析了Cu²⁺初始浓度、吸附时间和镍离子（Ni²⁺）对Cu²⁺吸附的影响，探讨了其吸附动力学和吸附等温线。结果表明：改性过程保留了大豆秸秆的多孔结构，并为其添加了羧基功能团；吸附过程符合Langmuir 模型和准二级动力学模型，大豆秸秆经过改性对Cu²⁺的吸附能力由10.44 mg/g 提高到了19.14 mg/g，主要是因为柠檬酸为大豆秸秆提供了起离子交换作用的羧基功能团；Ni²⁺未能影响CA-SS 对Cu²⁺的吸附，而Cu²⁺抑制了CA-SS 对Ni²⁺的吸附。CA-SS 是一种对Cu²⁺有较好吸附性能的廉价吸附材料。

Adsorption Behavior of Citric Acid Modified Soybean Straw for Cu2+

Soybean straw (SS) was modified with citric acid (CA) to prepare a new adsorbent (CA-SS) to study the heavy metal adsorption efficiency of SS. The morphological and chemical characteristics of the adsorbent were evaluated through SEM and FTIR analysis. The copper ion (Cu²⁺) adsorption capability of SS and CA-SS were compared, the effects of initial Cu²⁺ concentration, contact time and competitive ions were studied, and the adsorption dynamics and thermodynamicswereanalyzed. The results show that the porous structure of SS was preserved after modification, but the carboxyl groups were introduced onto SS. The pseudo-second-order model and Langmuir equation were suited to describe the dynamics and thermodynamics data. The maximum adsorption capacity increased from 10.44 mg/g to 19.14 mg/g according to the Langmuir model. The reason for the increase was that the introduced carboxyl groups increase the net negative charge on the SS, thereby increasing its binding potential for metal ions. Furthermore, Cu²⁺ exhibits better competiveness than Ni²⁺; the competitive adsorption in the binary system is related to the chemical properties of each element. CA-SS may be used as a lowcost alternative adsorbent for the decontamination of metal-containing effluent.