生物质炭对茶园土壤水溶性氟吸附特性的影响

Effects of Biochar on Adsorption Characteristics of Water-soluble Fluorine in Tea Garden Soil

采用室内培养试验法对添加生物质炭的茶园土壤水溶性氟吸附特性进行了研究。结果表明,茶园土壤随生物质炭添加量增加对水溶性氟的吸附量和吸附率均逐渐降低,应用等温吸附Langmuir方程、Freundlich方程和Temkin方程均能够较好地描述其吸附规律,其中以Freundlich方程拟合曲线最佳。随生物质炭添加量的增加土壤氟净吸附量逐渐降低。各处理土壤的氟吸附动力学过程包含吸附快反应和慢反应阶段,平衡时间小于120 min区间为吸附量快速上升期,平衡时间达到1 440 min后0.25%和0.50%生物质炭添加量处理土壤基本达到平衡状态。从双常数方程、Elovich方程和一级动力学方程拟合方程计算得到的理论吸附量与试验实测吸附量之间的符合程度较高,可准确描述添加生物质炭土壤对水溶性氟的吸附过程。添加生物质炭使土壤p H值升高与茶园土壤对水溶性氟最大吸附量、吸附强度和净吸附量的降低密切相关。

The adsorption characteristics of water-soluble fluoride with application of biochar in tea garden soil was studied by indoor culture test. The results showed that the adsorption quantity and adsorption rate of water-soluble fluorine decreased gradually with the increase of biochar amounts in tea garden soil. The isothermal adsorption of Langmuir equation, Freundlich equation and Temkin equation could be better used to describe the adsorption law of water-soluble fluorine, and the Freundlich equation had the best fitting curve. With the increase of biochar content of soil, the net amount of fluoride adsorption reduced gradually. The adsorption kinetics of fluoride in soil was characterized by fast adsorption and slow reaction stages. The equilibrium time was less than 120 min for the rapid increase of adsorption, 0.25% and 0.50%biomass carbon content treatments of the soil reached to equilibrium after 1 440 min. The results of theoretic calculation were in good agreement with experimental adsorption quantity by dual constant equation, Elovich equation and first order kinetics equation, which could accurately describe the adsorption process of water-soluble fluorine in soil with biochar. The increase of soil p H with the addition of biochar was closely related to the decrease of maximum adsorption quantity, adsorption intensity and net adsorption quantity of water-soluble fluorine in tea garden soil.