腐殖酸定向修饰Ce-Co铁基生物焦汞吸附机理

使用腐殖酸对铁基改性生物焦进行定向修饰，并借助固定床吸附装置考察改性后生物焦汞吸附性能，探究了不同腐殖酸负载量下的铁基改性生物焦的汞吸附能力.采用BET、XPS、FTIR表征手段，考察了定向修饰后生物焦的孔隙结构、表面元素价态及表面功能基团的组成，通过SEM扫描电镜探究生物焦微观形貌，并利用EDS能谱分析生物焦表面活性金属成分分布.结果表明，使用腐殖酸对铁基改性生物焦定向修饰后的生物焦汞脱除性能大幅提高，使用5%质量分数包裹后的生物焦汞脱除性能最高，3h单位累积汞吸附量为18025ng/g，相较于未被修饰的铁基改性生物焦汞吸附性能提高65%；负载腐殖酸后的生物焦以介孔为主，表面活性金属种类丰富，有利于单质汞的氧化；样品表面羧基、醇羟基等含氧官能团数量增加，定向修饰后生物焦表面出现大量氨基等利于重金属吸附的含氮官能团；定向修饰后的生物焦表面出现团聚现象，包裹量过高会将生物焦表面活性位点完全包裹，阻碍了氧化还原反应的进行，不利于汞的进一步氧化；汞在生物焦表面的吸附过程同时存在化学吸附与物理吸附.

The adsorption mechanism of humic acid directional modification Ce-Co modified iron-based biochar mercury

Iron-based modified biochar was directionally modified with humic acid (HA), and a fixed-bed adsorption device was used to investigate its mercury removal performance. The mercury removal performance of iron-based modified biochar under different loadings of HA was explored. The pore structure, valence state of surface elements and composition of surface functional groups of the biochar after directional modification were investigated by BET, XPS and FTIR. The microscopic morphology of the biochar was explored by scanning electron microscopy, and the distribution of active metal components on the surface of the biochar was analyzed by energy dispersive spectroscopy (EDS). The experimental results showed that the mercury removal performance of biochar after the directional modification of iron-based modified biochar with HA was greatly improved. The biochar coated with 5% HA by mass had the highest mercury removal performance, and the cumulative mercury adsorption is 18025ng/g every 3h, which is 65% higher than that of the iron-based modified biochar without HA. The biochar loaded with humic acid is mainly mesoporous, and the types of surface active metals are abundant, which is conducive to the oxidation of elemental mercury. The biochar loaded with HA has an increased number of oxygen-containing functional groups, such as carboxyl and alcoholic hydroxyl groups. After directional modification, a large number of amino groups and other nitrogen-containing functional groups that were beneficial to the adsorption of heavy metals appear on the surface of the biochar. The surface of the biochar exhibited agglomeration after directional modification. When the HA was overloaded, it completely covered the active sites on the biochar surface. It hinderd the redox reaction and was not conducive to the further oxidation of mercury. The process of removing mercury on the surface of biochar involves both chemical adsorption and physical adsorption.