物理化学学报2025，Vol.41Issue(3)：67-76,10.DOI:10.3866/PKU.WHXB202311032
荷叶衍生多孔碳的零电荷电位调节实现废水中电化学捕集镉离子
Potential of Zero Charge-Mediated Electrochemical Capture of Cadmium lons from Wastewater by Lotus Leaf-Derived Porous Carbons
摘要
Abstract
With the growth of batteries,electroplating,and mining industries,heavy metal ions such as cadmium(Cd2+)are being discharged on a massive scale,thus posing a severe threat to the environment.Conventional techniques for removing Cd2+from wastewater with low concentrations still suffer from slow kinetics and secondary pollution.A carbon-based capacitive deionization(CDI)system is highly desired but encounters a severe co-ion expulsion effect.Herein,we developed CDI systems based on surface charge-modulated porous carbon and an asymmetric configuration.This was achieved by first preparing porous carbons through facile microwave pyrolysis of lotus leaf followed by KOH activation.The morphology,pore structure,heteroatom content,surface charge,and electrochemical behavior of porous carbons were investigated by adjusting the mass ratio of KOH to carbon.The lotus leaf-derived carbons show a morphology of nanosheet-like thin carbon(NSTC),with their specific surface areas increasing with the amount of KOH used for activation.In contrast,the heteroatom(i.e.,nitrogen and oxygen)contents decrease with the increase in the mass ratio of KOH to carbon,resulting in a more positive surface charge.Notably,the NSTC with a mass ratio of 3 for KOH/carbon(NSTC-3)displays an ultrahigh specific surface area of 3705.0 m2∙g-1,and a specific capacitance of 92.5 F∙g-1 at a current density of 0.5 A∙g-1 when coupled with a commercial activated carbon in an asymmetric YP-50F//NSTC-3 supercapacitor.Consequently,the CDI cell equipped with a YP-50F as the anode and a NSTC-3 as the cathode exhibits a high specific adsorption capacity of 88.6 mgCd·gcathode-1 at 1.2 V in a 100 mg∙L-1 Cd2+solution,which is about 36.3%higher than that of the symmetrical configuration NSTC-3//NSTC-3.Furthermore,71%of the initial removal capacity of the YP-50F//NSTC-3 system is retained after 7 cycles of charging and discharging.Characterizations of the cathode after the adsorption process indicate that the Cd2+is captured by both electrical-double-layer and pseudocapacitive mechanisms.Additionally,CdCO3 precipitate is also responsible for Cd2+removal,which might be ascribed to the reaction of dissolved CO2 in aqueous media with Cd2+under the electrified action.The high removal performance and excellent cycling stability are attributed to the tunability of the surface charge properties and the asymmetric configuration,which minimizes the co-ion expulsion and modulates potential distribution.This study provides a novel avenue to design biochar-based configurations for electrified water treatment.关键词
电容去离子/镉/荷叶衍生碳/不对称构型/零电荷电势Key words
Capacitive deionization/Cadmium/Lotus leaf-derived carbon/Asymmetric configuration/Potential of zero charge分类
化学引用本文复制引用
叶萍,覃玲霜,贺萌瑶,巫方方,陈增烨,梁明星,邓立波..荷叶衍生多孔碳的零电荷电位调节实现废水中电化学捕集镉离子[J].物理化学学报,2025,41(3):67-76,10.基金项目
The project was supported by the Shenzhen Science and Technology Program(JCYJ20220818095806013,JCYJ20230808105111022),Natural Science Foundation of Guangdong Province(2023A1515012267),National Natural Science Foundation of China(22178223),and National Sponsored Postdoctoral Researcher Program of China(GZC20231721). 深圳市科技计划(JCYJ20220818095806013,JCYJ20230808105111022),广东省自然科学基金(2023A1515012267),国家自然科学基金(22178223)及国家资助博士后研究人员计划(GZC20231721)资助项目 （JCYJ20220818095806013,JCYJ20230808105111022）
