Biochar has considerable sorption efficiency for organic pollutants; however, the effect of physicochemical characteristics and their alteration by environmental conditions on the sorption mechanism is still unknown. We investigated the pH-dependent sorption of simazine on Miscanthus biochar produced at two pyrolysis temperatures (400 and 700 °C; hereafter B-400 and B-700) under two different electrolytes and interpreted the sorption mechanism. The surface charge density (SCD) decreased more in B-400 than in B-700 at higher pH due to more deprotonation of acidic functional groups (AFGs), but greater decreases were observed in B-700 than in B-400 from pH 2 to pH 3 as a result of alkali salts deposition. The decrease in KF with increasing pH showed that simazine sorption decreased as van der Waals forces because the surface of biochar carried a greater negative SCD, which repulses simazine molecules due to the enhanced deprotonation of AFGs. At a given pH, KF was lower in CaCl2 than in NaCl due to the formation of larger metal-biochar complexes, resulting in enhanced blocking of pores available for simazine sorption. We believe that knowledge of the pH-dependence of SCD and accessibility of biochar pores could help better interpret the behavior of simazine-like pollutants in soil and aquatic environments.

中文翻译：

---

背景电解质溶液中 pH 值和阳离子价态对两种不同热解温度下产生的芒草生物炭吸附西玛津的交互作用

生物炭对有机污染物有相当大的吸附效率；然而，物理化学特性的影响及其受环境条件的改变对吸附机制的影响仍然未知。我们研究了西玛津在两种不同电解质下在两种热解温度（400 和 700 °C；以下简称 B-400 和 B-700）上产生的芒草生物炭上的 pH 依赖性吸附，并解释了吸附机制。由于酸性官能团 (AFG) 的更多去质子化，B-400 的表面电荷密度 (SCD) 在较高的 pH 值下比 B-700 降低得更多，但从 pH 2 开始，B-700 的降低幅度大于 B-400由于碱盐沉积，pH 值达到 3。KF 随着 pH 值的增加而降低，表明西玛津的吸附随着范德华力而降低，因为生物炭表面带有更大的负 SCD，由于 AFG 的去质子化增强，这排斥西玛津分子。在给定的 pH 值下，由于形成较大的金属-生物炭复合物，CaCl2 中的 KF 低于 NaCl，导致可用于西玛津吸附的孔的阻塞增强。我们相信，了解 SCD 的 pH 依赖性和生物炭孔隙的可及性有助于更好地解释土壤和水生环境中类似西玛津的污染物的行为。导致可用于西玛津吸附的孔的阻塞增强。我们相信，了解 SCD 的 pH 依赖性和生物炭孔隙的可及性有助于更好地解释土壤和水生环境中类似西玛津的污染物的行为。导致可用于西玛津吸附的孔的阻塞增强。我们相信，了解 SCD 的 pH 依赖性和生物炭孔隙的可及性有助于更好地解释土壤和水生环境中类似西玛津的污染物的行为。