柠檬酸修饰沙漠砂对Cd （Ⅱ） 吸附行为的研究

Study on Adsorption Behavior of Desert Sands Modified with Citric Acid for Cd(Ⅱ)

摘要

文章利用柠檬酸对沙漠砂 (Desert Sand，DS) 进行湿法修饰，将修饰沙漠砂 (Modified Desert Sand，MDS) 作为吸附剂，基于原子吸收光谱 (AAS) 研究MDS对Cd(Ⅱ) 的静态吸附行为并优化吸附条件。利用扫描电镜 (SEM)、傅里叶变换红外光谱 (FT-IR) 对沙漠砂修饰前后的表面形貌和官能团进行观察和表征。结果表明，柠檬酸修饰使沙漠砂表面形貌发生变化的同时增加了其官能团数量，MDS对Cd(Ⅱ) 的吸附性稍优于原沙漠砂。通过Langmuir和Freundlich等温式进行拟合发现，Langmuir吸附模型更符合MDS对Cd(Ⅱ) 的吸附行为。在室温下，溶液pH为6，吸附时间为120 min时吸附率可达到83%，修饰前后沙漠砂对Cd(Ⅱ) 的饱和吸附量分别可达到13.0 mg/g和15.6 mg/g。

Abstract

Natural desert sand (DS) was wet modified with citric acid and used as adsorbent. The static adsorption behavior of the modified desert sand (MDS) for Cd(Ⅱ) was studied and the adsorption conditions were optimized based on atomic absorption spectroscopy (AAS). Scanning electron microscopy (SEM) and infrared spectroscopy (FT-IR) were used to characterize the surface morphology and functional groups of desert sand before and after modification. The experimental results showed that the adsorption behavior of MDS for cadmium ions was slightly better than that of the original desert sand. By fitting the Langmuir and Freundlich isothermal formulas, and the adsorption behavior of MDS for Cd(Ⅱ) was more suitable for the Langmuir adsorption model. At room temperature, the pH of the solution was 6, the adsorption time was 120 min, the adsorption rate could reach 83%, and the saturated adsorption capacity of Cd(Ⅱ) ion on the desert sand before and after modification could reach 13.0 and 15.6 mg/g, respectively.

Graphical abstract

关键词

沙漠砂 / 柠檬酸 / 湿法修饰 / 吸附行为

Key words

Desert sand / Citric acid / Wet modification / Adsorption behavior

基金资助

国家自然科学基金项目(基金号52163030)

新疆维吾尔自治区大学生创新训练计划项目(基金号S202210755032)