Leonardite (LND) and its biochar have gained much attention as it can improve soil quality and immobilize herbicides in the subsurface. Our objective was to quantify the herbicide adsorption characteristics of carbonized LND (cLND). The physiochemical properties were compared side by side between LND and cLND at different pyrolysis temperatures (450–850 °C). Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy spectral analysis confirmed the loss of oxygen-containing functional groups such as H-bonded OH, carbonyl, or C=O and the presence of the aromatic C=C group up to 650 °C. Both of which were later used to establish the governing adsorption mechanism. At >450 °C, the Si content decreased slightly and the calcium content increased, indicating proper use of cLND for Si-deficit soil and acidified soil. By conducting multiple linear regression analyses, the atrazine adsorption kinetic fitted well with pseudo-second-order models while both alachlor and atrazine sorption behavior were well described using a monolayer isotherm (Langmuir and Jovanovich, respectively). The herbicide hydrophilicity slightly affected the sorption mechanism which indirectly resulted from the existence of graphitic carbon on the LND carbonized at a higher temperature. Increased cLND in the soil resulted in much better improvement in the water holding capacity than from LND due to the presence of sufficient mesopores and adequate surface porosity. Our results showed that LND can be readily transformed into better adsorbing biochar at 550 °C compared to higher temperatures. Overall, the study provided a better understanding of the application of leonardite derived-biochar as an effective alternative soil amendment and herbicide-immobilizing adsorbent.

伦纳石（LND）及其生物炭已获得广泛关注，因为它可以改善土壤质量并在地下固定除草剂。我们的目标是量化碳化LND（cLND）的除草剂吸附特性。比较了在不同热解温度（450–850°C）下LND和cLND的理化特性。傅里叶变换红外光谱和X射线光电子能谱分析证实，高达650°C的含氧官能团（如H键合的OH，羰基或C = O）的丢失以及芳族C = C基团的存在。两者后来都用于建立控制吸附机理。在> 450°C时，Si含量略有降低，而钙含量则有所增加，这表明cLND可在缺硅土壤和酸化土壤中适当使用。通过进行多个线性回归分析，at去津吸附动力学与拟二级模型非常吻合，而丙草胺和at去津吸附行为均使用单层等温线（分别为Langmuir和Jovanovich）进行了描述。除草剂的亲水性稍微影响了吸附机理，这间接是由于在较高温度下碳化的LND上存在石墨碳而引起的。由于存在足够的中孔和足够的表面孔隙度，土壤中cLND的增加比LND导致的持水量大大改善。我们的结果表明，与更高的温度相比，LND在550°C时可以很容易地转化为更好的生物炭。总体，