Environmental Research ( IF 8.3 ) Pub Date : 2021-09-09 , DOI: 10.1016/j.envres.2021.112035 Ming-Xiu Zhan 1 , Yu-Wei Liu 2 , Wen-Wen Ye 3 , Tong Chen 4 , Wen-Tao Jiao 5
Activated carbon is commonly used to remove dioxins from flue gas via adsorption. Improving the targeted adsorption capacity of activated carbon for dioxins can reduce the consumption of adsorbents and help achieve emission standards for target pollutants. Here, commercial coal-based activated carbon was used as a raw material and modified by urea impregnation along with treatment at high temperature under a nitrogen atmosphere. It was found that modification with urea effectively improved the pore structure of activated carbon while incorporating a certain amount of nitrogen. The best modification effect was achieved at a modification temperature of 600 °C, an impregnation ratio of urea to activated carbon of 1:1, and with high-temperature treatment for 2 h. The mesopore volume of the modified activated carbon (AC600) reached 0.38 cm3/g, accounting for 57.58% of the total pore volume. With an impregnation ratio of urea to activated carbon of 1:1, high-temperature treatment for 2 h, and a modification temperature of 800 °C, a certain amount of nitrogen was introduced into the carbon rings to form a modified activated carbon (AC800) rich in pyridine and pyrrole groups (atomic percentage = 4.84%). The activated carbon modified by urea and the unmodified activated carbon were subsequently selected for dioxin adsorption experiments using a dioxin generation and adsorption system. AC600 showed the highest adsorption efficiency for dioxins, reaching 97.65%, based on toxicity equivalents. Although AC800 has poor pore properties, it has more pyridine and pyrrole groups than AC600. Consequently, the efficiency of AC800 at adsorbing low-concentration dioxins reached 85.24% based on toxicity equivalents. Overall, this study describes two mechanisms for effectively modifying activated carbon with urea based on (1) optimizing the pore structure of activated carbon and (2) incorporating nitrogen.
中文翻译:
用尿素改性活性炭以增强对二恶英的吸附
活性炭通常用于通过吸附去除烟气中的二恶英。提高活性炭对二恶英的目标吸附能力,可以减少吸附剂的消耗,有助于目标污染物达标排放。在这里,以商业煤基活性炭为原料,通过尿素浸渍和氮气氛下的高温处理进行改性。发现用尿素改性有效改善了活性炭的孔结构,同时掺入了一定量的氮。改性温度为600 ℃、尿素与活性炭的浸渍比为1:1、高温处理2 h时改性效果最佳。改性活性炭(AC600)的中孔体积达到0.38 cm3/g,占总孔容的 57.58%。尿素与活性炭的浸渍比为1:1,高温处理2 h,改性温度800 ℃,在碳环中通入一定量的氮,形成改性活性炭(AC800 ) 富含吡啶和吡咯基团(原子百分比 = 4.84%)。随后使用二恶英生成和吸附系统选择尿素改性活性炭和未改性活性炭进行二恶英吸附实验。基于毒性当量,AC600 对二恶英的吸附效率最高,达到 97.65%。AC800虽然孔隙性能较差,但比AC600具有更多的吡啶和吡咯基团。因此,AC800 对低浓度二恶英的吸附效率达到 85。24% 基于毒性当量。总体而言,本研究描述了两种用尿素有效改性活性炭的机制,基于(1)优化活性炭的孔结构和(2)掺入氮。