Preparation of L-ascorbic acid-stabilized nanoscale zerovalent iron and its application in Cd(Ⅱ) wastewater treatment

doi:10.16085/j.issn.1000-6613.2017-2278

Abstract

Abstract: In this study, L-ascorbic acid stabilized Nanoscale Zerovalent Iron (AAS-nZVI) was produced by liquid-phase reduction and was used for wastewater treatment containing Cd(Ⅱ). On the basis of the optimum AAS/Fe²⁺(molar ratio), the influence factors of reaction system, such as AAS-nZVI dosage, reaction time and initial pH for the effects of the Cd(Ⅱ) removal efficiency were studied. The influential order of the 3 factors and optimal combination conditions were determined by improving the L₉(3⁴) orthogonal layout. Air stability of AAS-nZVI and its kinetic characteristics in Cd(Ⅱ) wastewater treatment were also investigated. The morphology of AAS-nZVI before and after the reaction was characterized by scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results indicated that AAS-nZVI has the best removal effect on Cd(Ⅱ) removal when the molar ratio of AAS/Fe²⁺ was 1:3. The effect of AAS-nZVI dosage on Cd(Ⅱ) removal rate tended to be very significant(p < 0.01), while the effect of reaction time and initial pH were significant(p < 0.05).The important effects of the 3 factors on Cd(Ⅱ) reduction can be shown in the following descending order:AAS-nZVI dosage > reaction time > initial pH. The numerical optimization revealed that the optimum removal rate 92. 62%(the initial Cd(Ⅱ) concentration and volume was 20mg/L and 100mL, respectively)obtained at AAS-nZVI dosage of 2.0g/L, contact time of 40min and initial pH of 6. AAS-nZVI has good air stability, and the removal rate of Cd(Ⅱ) by AAS-nZVI placed 15d in the air was only 1.99% lower than that of the fresh AAS-nZVI. The removal of Cd(Ⅱ) was in accordance with the pseudo first order reduction kinetics model and could be described by the L-H kinetic model. The removal of Cd(Ⅱ)by AAS-nZVI was the common effect of adsorption and reducing action.

Key words: L-ascorbic acid, nanoscale zerovalent iron, Cd (Ⅱ) containing wastewater, reduction kinetics

摘要： 利用液相还原法制备抗坏血酸稳定纳米零价铁（AAS-nZVI）并将其应用于含Cd（Ⅱ）废水的处理。在确定最佳AAS/Fe²⁺（摩尔比）的基础上，研究了AAS-nZVI投加量、反应时间和溶液初始pH对Cd（Ⅱ）处理效果的影响，通过L₉（3⁴）正交试验优化AAS-nZVI处理含Cd（Ⅱ）废水的工艺条件；考察了AAS-nZVI的空气稳定性及其处理含Cd（Ⅱ）废水的动力学特性；通过SEM和XRD对处理Cd（Ⅱ）前后的AAS-nZVI进行形貌观测和表征分析。结果表明，AAS/Fe²⁺（摩尔比）为1∶3时，AAS-nZVI对Cd（Ⅱ）去除的去除效果最佳。AAS-nZVI投加量、反应时间和溶液初始pH对Cd（Ⅱ）去除率的影响均达到显著水平（p < 0.05），其中AAS-nZVI投加量的影响达到极显著水平（p < 0.01）；其显著性大小依次为：AAS-nZVI投加量 > 反应时间 > 溶液初始pH。在AAS-nZVI投加量为2.0g/L、反应40min、溶液初始pH=6的最佳工艺条件下，含Cd（Ⅱ）废水（初始浓度20mg/L，溶液体积100mL）的去除率可达92.62%。AAS-nZVI具有很好的空气稳定性，空气中放置15d的AAS-nZVI对Cd（Ⅱ）的去除率仅下降1.99%。AAS-nZVI对Cd（Ⅱ）的去除较好地符合准一级动力学模型，可用L-H动力学模型描述；AAS-nZVI对Cd（Ⅱ）的去除是吸附和还原共同作用的结果。

关键词: 抗坏血酸, 纳米零价铁, 含Cd (Ⅱ)废水, 动力学

CLC Number:

SONG Zhenxia, ZHANG Jimei, JU Mengdie, TANG Hai, XU Dayong. Preparation of L-ascorbic acid-stabilized nanoscale zerovalent iron and its application in Cd(Ⅱ) wastewater treatment[J]. Chemical Industry and Engineering Progress, 2018, 37(08): 3231-3237.

宋珍霞, 张继梅, 巨梦蝶, 唐海, 徐大勇. 抗坏血酸稳定纳米零价铁的制备及其在含Cd(Ⅱ)废水处理中的应用[J]. 化工进展, 2018, 37(08): 3231-3237.

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