铜基氮碳微球对废水中盐酸四环素的吸附性能

Adsorption of tetracycline in wastewater by copper-based nitrogen-carbon microspheres

摘要:

以水溶性低分子量壳聚糖（0.1 g）为碳源和氮源，Cu(NO3)2·3H2O（0.1802、0.2899、0.6522 g）为铜源，采用一步水热法制备三种铜基氮碳微球Cu-x/NC（x=1、2、3），通过SEM、FTIR、XRD、Raman和BET等表征了Cu-x/NC的形貌、组成和结构，通过静态吸附实验考察Cu-x/NC对盐酸四环素（TC）的吸附性能，并测定了吸附动力学、吸附等温线和吸附热力学参数，测试Cu-x/NC抗离子干扰、pH稳定性和循环吸附性能。结果表明，Cu-x/NC呈现规整的球形结构，表面有含氧和含氮基团，并均匀分布着Cu元素；在25 ℃吸附温度和24 h吸附时间的条件下，Cu-2/NC表现出吸附TC的最大平衡吸附容量（1993.42 mg/g）；Cu-2/NC吸附TC符合Langmuir等温线模型和准二级动力学模型，吸附过程是自发、吸热过程；TC溶液中存在NaCl不会降低Cu-2/NC吸附TC的平衡吸附容量，TC溶液的pH=5.5对吸附最有利；8次循环吸附测试中，Cu-2/NC对TC表现出较为稳定的去除率（95.84%~86.67%）；Cu-2/NC吸附TC依靠的主要作用力有氢键、Cu阳离子桥、电子供体-受体相互作用以及静电作用。

Abstract:

Three copper-based nitrogen-carbon microspheres Cu-x/NC (x=1, 2, 3) were successfully synthesized by a one-step hydrothermal method using water-soluble low-molecular-weight chitosan (0.1 g) as carbon and nitrogen sources, and copper nitrate trihydrate (0.1802, 0.2899, 0.6522 g) served as copper sources. The morphology, composition and structure of Cu-x/NC were characterized by SEM, FTIR, XRD, Raman and BET. The adsorption performance of Cu-x/NC to tetracycline hydrochloride (TC) was investigated by static adsorption experiments. The parameters of adsorption kinetics, adsorption isotherms and adsorption thermodynamics were also determined. Cu-x/NC against ionic interference, pH stability, and cyclic adsorption properties of Cu-x/NC were detected. The results showed that Cu-x/NC exhibited a regular spherical structure with oxygen-containing and nitrogen-containing groups on its surface, and Cu elements were uniformly distributed. Cu-2/NC exhibited the maximum adsorption capacity for TC adsorption (1993.42 mg/g) at 25 °C of adsorption temperature and 24 h of adsorption time. The adsorption of TC by Cu-2/NC was in accordance with the Langmuir isotherm model and pseudo-second-order kinetic model, and the adsorption process was spontaneous and endothermic. The presence of NaCl in TC solution didn’t reduce the equilibrium adsorption capacity of Cu-2/NC toward TC, and TC solution pH=5.5 was most favorable for adsorption. In the 8-cycle adsorption tests, Cu-2/NC showed a relatively stable removal rate to TC (95.84%~86.67%). The main driving force for TC adsorption by Cu-2/NC depended on hydrogen bond, Cu cation bonding bridge, electron donor-acceptor interaction and electrostatic interactions.