ABSTRACT

Lead (Pb²⁺) sorption and desorption rates are the most important processes controlling the mobility and availability of this metal in soil. However, information about biochar addition on amounts and rates of Pb²⁺ sorption and desorption in calcareous soils is limited. In this study, the effect of application of 1% (w/w) walnut leaf biochar produced at 200 (B200), 400 (B400), and 600°C (B600) was investigated on the adsorption and desorption characteristics (isotherm and kinetics) of Pb²⁺ in a calcareous clay loam soil at two incubation times (30 and 90 days). Results of the isotherm study showed that the maximum adsorption capacity (qm) (2–277 mg kg⁻¹) and the strength of adsorption (K_L) (0.010–0.230 l mg⁻¹) increased significantly (P < .05) with an increase in the pyrolysis temperature. The qm and K_L decreased significantly (P < .05) in the soils incubated for 90 days compared to the soils incubated for 30 days (except B600). Moreover, rate of Pb²⁺ adsorption increased significantly (P < .05) with an increase in the pyrolysis temperature, while, available sites and rate of Pb²⁺ desorption decreased significantly (P < .05) with an increase in the pyrolysis temperature. The rate of Pb²⁺ adsorption decreased (P < .05) during incubation, while rate of Pb²⁺ desorption increased (P < .05). Significant correlations (P < .05) were found between isotherm and kinetics coefficients and surface area and P of the biochars. It can be concluded that the application of biochars produced at high temperature contain high P and surface area are suitable for improve Pb-contaminated calcareous soils.

摘要

铅 (Pb ²⁺ ) 吸附和解吸速率是控制这种金属在土壤中的流动性和可用性的最重要过程。然而，关于生物炭添加量和钙质土壤中 Pb ²⁺吸附和解吸速率的信息是有限的。在本研究中，研究了在 200 (B200)、400 (B400) 和 600°C (B600) 下生产的 1% (w/w) 核桃叶生物炭对吸附和解吸特性（等温线和动力学）的影响)在两个培养时间（30 天和 90 天）的钙质粘壤土中的 Pb ²⁺。等温线研究结果表明，最大吸附容量 (qm) (2–277 mg kg ^-1 ) 和吸附强度 (K _L ) (0.010–0.230 l mg^-1 ) 随着热解温度的增加而显着增加 ( P < .05)。与培养 30 天的土壤（B600 除外）相比，培养 90 天的土壤中的 qm 和 K _L显着降低（P < .05）。此外，随着热解温度的升高，Pb ^{2+ 的}吸附速率显着增加（P < .05），而随着热解温度的升高，Pb ^{2+ 的}可用位点和解吸速率显着降低（P < .05） . PB的速率²⁺吸附降低（P孵育期间<0.05），而铅的速率²⁺解吸增加（P < .05）。在等温线和动力学系数以及生物炭的表面积和 P 之间发现了显着的相关性 ( P < .05)。可以得出结论，高温生产的生物炭含有高P和表面积，适用于改善Pb污染的钙质土壤。