Surface modification of activated carbon by corona treatment

Surface modification may lead activated carbon (AC) to take on different properties. This study aimed to promote surface modification of activated carbons using corona treatment (electrical discharge). In this study, powdered commercial activated carbon was used. Activated carbons were subjected to corona treatment at different exposure times (2, 5, 8 and 10 min) at 4.5 cm height from the source. To observe differences promoted by treatment, activated carbons were analyzed by acidity, surface functional groups, Fourier Transform Infrared Spectroscopy (FTIR), elemental analysis (CHN), proximate analysis and thermogravimetry. Corona treatment impacted surface chemistry of activated carbons. There was a trend of increasing surface acidity according to exposure time. There were changes in functional groups, increasing carboxyl acid and decreasing lactone and phenol groups. FTIR analysis showed peaks in the bands at 3500, 1650 and 1300 cm-1. Increase of oxygen content and decrease of carbon content were also found. Immediate analysis followed similar tendency for volatile and fixed carbon content. There were also differences in thermogravimetry analysis. Treated activated carbons were different compared to virgin activated carbon. This difference was performed by surface oxidation. Thus, this study showed that corona treatment caused surface modifications and might impact adsorption process.

表面改性可赋予活性炭（Activated Carbon, AC）各异的理化特性。本研究旨在采用电晕处理（电放电处理）手段开展活性炭的表面改性研究。本研究采用商用粉状活性炭作为实验原料，将其置于距电晕源4.5厘米的高度处，分别以2、5、8、10分钟的暴露时长进行电晕处理。为探究电晕处理带来的性能差异，本研究通过表面酸度、表面官能团表征、傅里叶变换红外光谱（Fourier Transform Infrared Spectroscopy, FTIR）、元素分析（CHN）、工业分析以及热重分析对活性炭样品进行了系统测试。结果表明，电晕处理可显著改变活性炭的表面化学性质：随着暴露时长增加，活性炭的表面酸度呈现逐渐升高的趋势；表面官能团也发生了显著变化，羧酸基团含量上升，而内酯与酚羟基基团含量下降。傅里叶变换红外光谱分析结果显示，样品在3500、1650及1300 cm⁻¹波数处出现特征吸收峰。同时检测到样品的氧元素含量上升、碳元素含量下降。工业分析结果显示，挥发分与固定碳含量同样呈现出相似的变化趋势。热重分析结果同样显示出显著差异。经电晕处理的活性炭与未处理的原始活性炭存在明显差异，该差异源于活性炭表面发生的氧化反应。综上，本研究证实电晕处理可有效实现活性炭的表面改性，且该工艺可能对其吸附性能产生影响。