Novel Graphene-Like Electrodes for Capacitive Deionization
Novel Graphene-Like Electrodes for Capacitive Deionization
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DOI：
10.1021/es101888j
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发表时间：
2010-11-15
影响因子：
11.4
通讯作者：
Sun, Zhuo
中科院分区：
文献类型：
--
作者：
Li, Haibo;Zou, Linda;Sun, Zhuo
电容去离子（CDI）是一种新的技术，已开发用于从盐水中去除带电离子物种，如作为盐离子。CDI以及电吸附的基本概念是通过施加直接电场以形成强双电层并保持离子来迫使带电离子朝向相反极化的电极。一旦电场消失，离子立即释放回本体溶液。CDI是一种可替代的低能耗海水淡化技术。制备了具有较高比表面积的石墨烯纳米片，并将其用作电容去离子电极。通过改进的Hummers法使用肼还原来合成GNF。通过原子力显微镜、77 K下的N2吸附和电化学工作站对其进行了表征。结果发现，硝酸和硫酸的比例在确定GNF的比表面积中起着至关重要的作用。其电吸附性能远优于商品活性炭，在电容去离子方面具有很大的应用潜力。进一步研究了不同偏压、流速和离子强度下GNF电极的电吸附性能，并研究了GNF电极的电吸附等温线和动力学。结果表明，该工艺制备的石墨纳米纤维的比表面积为222.01 m（2）/g。当初始浓度为25 mg/L时，GNF对钠离子（Na+）的比电吸附容量为23.18 μ mol/g，高于先前报道的在相同实验条件下使用石墨烯和AC的数据。此外，平衡的电吸附容量确定为73.47 μ mol/g，在2.0 V，通过拟合数据通过Langmuir等温线，和速率常数被发现是1.01分钟（-1），通过拟合数据通过伪一级吸附。结果表明，化学合成的石墨纳米纤维可以作为有效的电极材料，在CDI过程中的苦咸水淡化。
Capacitive deionization (CDI) is a novel technology that has been developed for removal of charged ionic species from salty water, such as salt ions. The basic concept of CDI, as well as electrosorption, is to force charged ions toward oppositely polarized electrodes through imposing a direct electric field to form a strong electrical double layer and hold the ions. Once the electric field disappears, the ions are instantly released back to the bulk solution. CDI is an alternative low-energy consumption desalination technology. Graphene-like nanoflakes (GNFs) with relatively high specific surface area have been prepared and used as electrodes for capacitive deionization. The GNFs were synthesized by a modified Hummers' method using hydrazine for reduction. They were characterized by atomic force microscopy, N-2 adsorption at 77 K and electrochemical workstation. It was found that the ratio of nitric acid and sulfuric acid plays a vital role in determining the specific surface area of GNFs. Its electrosorption performance was much better than commercial activated carbon (AC), suggesting a great potential in capacitive deionisation application. Further, the electrosorptive performance of GNFs electrodes with different bias potentials, flow rates and ionic strengths were measured and the electrosorption isotherm and kinetics were investigated. The results showed that GNFs prepared by this process had the specific surface area of 222.01 m(2)/g. The specific electrosorptive capacity of the GNFs was 23.18 mu mol/g for sodium ions (Na+) when the initial concentration was at 25 mg/L, which was higher than that of previously reported data using graphene and AC under the same experimental condition. In addition, the equilibrium electrosorption capacity was determined as 73.47 mu mol/g at 2.0 V by fitting data through the Langmuir isotherm, and the rate constant was found to be 1.01 min(-1) by fitting data through pseudofirst-order adsorption. The results suggested that the chemically synthesized GNFs can be used as effective electrode materials in CDI process for brackish water desalination.