ABSTRACT

Adsorption and desorption rates play an important role in the availability and mobility of Lead (Pb²⁺) in soils treated with biochar. However, information is still limited about the effects of pyrolysis temperature, presence of Zn and incubation times on these processes. This study was performed to investigate the effects of 1% (w/w) walnut leaves biochars produced at different temperatures (200 °C (B200), 400 °C (B400) and 600 °C (B600)) on adsorption and desorption kinetics of Pb²⁺ in the presence of Zn²⁺ at two incubation times (30 and 90 d). Results explained that the adsorption rate of Pb²⁺ was decreased with increasing the pyrolysis temperature, whereas the desorption rate of Pb²⁺ was increased. In the presence of Zn²⁺, there was a decrease in the adsorption sites for Pb²⁺, while there was an increase in the available desorption sites for Pb²⁺. The rate of Pb²⁺ adsorption in 90 d of incubation was higher than 30 d of incubation, whereas the rate of Pb²⁺ desorption in 90 d of incubation was slower than 30 d of incubation. It can be concluded that 1% (w/w) walnut leaves biochar could not immobilize Pb²⁺ in the soil because more than 74% adsorbed Pb²⁺ desorbed in DTPA-TEA solution.

摘要

吸附和解吸速率对使用生物炭处理的土壤中铅 (Pb ²⁺ )的可用性和迁移率起着重要作用。然而，关于热解温度、Zn 的存在和孵育时间对这些过程的影响的信息仍然有限。本研究旨在研究在不同温度（200 °C (B200)、400 °C (B400) 和 600 °C (B600)）下生产的 1% (w/w) 核桃叶生物炭对吸附和解吸动力学的影响在两个孵育时间（30 天和 90 天）存在 Zn ²⁺的情况下，Pb ²⁺的浓度。结果表明，随着热解温度的升高，Pb ²⁺的吸附率降低，而Pb ²⁺的解吸率降低增加了。在锌的存在下²⁺，有在吸附位点对Pb的降低²⁺，虽然有增加的可用解吸位点的Pb ²⁺。90 d Pb ²⁺吸附速率高于30 d，而90 d Pb ²⁺解吸速率低于30 d。可以得出结论，1% (w/w) 核桃叶生物炭不能将 Pb ²⁺固定在土壤中，因为超过 74% 的吸附 Pb ²⁺在 DTPA-TEA 溶液中解吸。