Abstract:

In this study, magnetic particle adsorbent Fe₃O₄@SiO₂@PDA-PAT was prepared by using polydopamine (PDA) assisted loading polyaminothiazole (PAT) method. The adsorbent was characterized by XRD, VSM, TG, SEM, XPS, EDS, and Zeta potential analysis, and the adsorption performance of the adsorbent for mercury was investigated. The results showed that Fe₃O₄@SiO₂@PDA-PAT exhibited super paramagnetic behavior, and its Zeta potential was positive at pH<2 and negative at pH>2. At 303 K and a mercury ion concentration of 50 mg/L in simulated wastewater, the equilibrium adsorption capacities of Fe₃O₄@SiO₂@PDA-PAT were 121.9 mg/g and 153.1 mg/g at pH 1.3 and pH 5.0, respectively. The adsorption process of mercury ions by Fe₃O₄@SiO₂@PDA-PAT was a spontaneous process and followed the second-order kinetic model and Langmuir isotherm model at 303 K, as well as in strong acid (pH 1.3) and weak acid (pH 5.0) environments. The adsorption of mercury ions by Fe₃O₄@SiO₂@PDA-PAT in strong acid environment (pH 1.3) was an exothermic process driven by enthalpy, while in weak acid environment (pH 5.0) it was an endothermic process driven by entropy. The use of 2 mol/L mixed acid (hydrochloric acid and nitric acid in a molar ratio of 1∶1) as the desorption solution could achieve a mercury desorption rate of more than 91%. Under the conditions of 303 K, pH 1.3, and Hg²⁺ concentration 20 mg/L, when the mass concentration of Na⁺, K⁺, Mg²⁺, Ca²⁺, Cu²⁺, Zn²⁺, and Ni²⁺ were 20 times that of Hg²⁺, the Hg²⁺ equilibrium adsorption capacities of Fe₃O₄@SiO₂@PDA-PAT for mercury ions decreased by 33.2%, 32.1%, 20.6%, 26.7%, 21.2%, 29.6%, and 17.8%, respectively. In simulated seawater, the mercury adsorption capacity decreased by 40.9%. Fe₃O₄@SiO₂@PDA-PAT exhibited good mercury adsorption selectivity and had the potential to be used for purifying seawater and removing heavy metals.

Key words: polyaminothiazole, magnetic adsorbent, ferric oxide, wastewater containing Hg²⁺

摘要：

聚多巴胺（PDA）辅助负载聚氨基噻唑（PAT）法制备了磁性颗粒吸附剂Fe₃O₄@SiO₂@PDA-PAT。对吸附剂进行了XRD、VSM、TG、SEM、XPS、EDS和Zeta电位等表征分析，考察了吸附剂对Hg²⁺的吸附性能。结果表明，Fe₃O₄@SiO₂@PDA-PAT具有超顺磁性，在pH小于2时Zeta电位为正，pH大于2时Zeta电位为负。在303 K和Hg²⁺浓度为50 mg/L模拟废水中，当pH为1.3和5.0时，Hg²⁺的平衡吸附量分别为121.9 mg/g和153.1 mg/g。在强酸（如pH 1.3）和弱酸（如pH 5.0）环境下Fe₃O₄@SiO₂@PDA-PAT吸附Hg²⁺的过程均是自发过程，且符合二级动力学模型和Langmuir等温吸附模型。强酸环境下（如pH 1.3）Fe₃O₄@SiO₂@PDA-PAT吸附Hg²⁺是焓驱动的放热过程，弱酸（如pH 5.0）环境下是熵驱动的吸热过程。用2 mol/L混酸（盐酸和硝酸摩尔比为1∶1）作为解吸液可使Hg²⁺解吸率达91%以上。在303 K、pH 1.3、Hg²⁺浓度20 mg/L条件下，当Na⁺、K⁺、Mg²⁺、Ca²⁺、Cu²⁺、Zn²⁺、Ni²⁺质量浓度为Hg²⁺的20倍时，Fe₃O₄@SiO₂@PDA-PAT的Hg²⁺平衡吸附量分别下降了33.2%、32.1%、20.6%、26.7%、21.2%、29.6%、17.8%。在模拟海水下，Hg²⁺吸附量下降40.9%。Fe₃O₄@SiO₂@PDA-PAT具有较好的Hg²⁺选择性，具有净化海水脱除重金属的应用潜力。

关键词: 聚氨基噻唑, 磁性吸附剂, 四氧化三铁, 含Hg²⁺废水