[Enhanced Sorption of Cetirizine to Loessial Soil Amended with Biochar]

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.