生物炭增强黄绵土对西替利嗪的吸附作用

Enhanced Sorption of Cetirizine to Loessial Soil Amended with Biochar

生物炭可以作为稳定剂控制污染物在土壤中的迁移转化,削减其环境风险.以西替利嗪(cetirizine,CTZ)为目标污染物,黄绵土为供试土壤,采用吸附批实验法,研究添加了不同质量比、不同碳化温度核桃壳生物炭的土壤对CTZ的吸附作用.结果表明,生物炭对CTZ的吸附能力均强于土壤.添加400~700℃制备的生物炭可显著增强黄绵土对CTZ的吸附能力,这主要与添加生物炭后比表面积(SA)和含碳量相比土壤增大有关.土壤-生物炭混合体系(除添加300℃制备的生物炭)对CTZ吸附分配系数的实验值相比理论值偏小.这是由于土壤和生物炭组分之间发生了一定的相互作用,土壤中有机质及其它组分会与生物炭吸附位点相互堵塞或相互竞争.添加400~700℃制备的核桃壳生物炭有利于稳定土壤中的CTZ,但溶液中CTZ浓度相对较低、添加生物炭的量相对较高时,忽略土壤与生物炭组分之间的相互作用,会高估混合体系对CTZ的吸附能力.

Biochar could be used as a stabilizer to control the migration and transformation of pollutants in soil and reduce their environmental risks. Cetirizine（CTZ） was selected as a target pollutant to investigate the effect of biochar on sorption characteristics of loessial soil by batch experiments. Biochars were produced from walnut shell at different temperatures and added to soil at different mass ratios. The results indicated that all biochars showed obviously higher sorption capacity than loessial soil. The sorption capacity for CTZ was obviously enhanced by soils amended with biochars produced at 400-700℃,which could be attributed to the increased bulk carbon content and specific surface area（SA）. Sorption of CTZ to mixtures,excluding the soils amended with biochar produced at 300℃,was lower than the theoretical value. This could be due to the cross-effect between soil components and biochar. At the same time,the organic matter and native sorbates in soil may block or compete for adsorption sites on biochar surface. Biochars would be helpful to stabilize the loessial soil contaminated with CTZ. However,for relatively low concentration of CTZ in aqueous solution and soils amended with relatively high biochar mass ratio,the sorption capacity of the mixtures could be overestimated theoretically without considering the cross-effect between soil and biochar.