本研究考察了离子强度、重金属(Cd²⁺)和pH对200 ℃和400 ℃热解条件下制备的玉米秸秆生物炭(分别记作CS200和CS400)吸附西玛津的影响。结果表明：炭化程度较高的CS400对西玛津的吸附能力(logK_oc)高于炭化程度较低的CS200，因为CS400具有较强的疏水性、较多的芳香碳和较大的比表面积。尽管H–键作用可能会发生，但是CS400的主导吸附机制为疏水作用、电荷转移(π–π*)作用和孔填充作用，而CS200的主导吸附机制为分配作用。两种生物炭对西玛津的吸附几乎未因离子强度增大和Cd²⁺的存在而受到影响，表明西玛津和生物炭之间未发生离子交换和Cd²⁺并没有起到键桥离子的作用。低的pH有利于两种生物炭对西玛津的吸附。负载西玛津后，CS400的zeta电位显著降低证实了电荷转移(π–π*)的重要作用，而CS200的zeta电位降低不明显说明分配作用为主导。Cd²⁺的存在几乎未改变两种生物炭吸附西玛津的zeta电位表明特定位点的表面吸附并不是生物炭吸附Cd²⁺的主导机制。离子交换可能是生物炭吸附Cd²⁺的主导机制，这也很好解释了CS200比CS400吸附更多的Cd²⁺和Cd²⁺的存在对两种生物炭吸附西玛津几乎未产生影响的原因。

Simazine sorption to biochars produced by pyrolysis of corn straw at 200 ℃ (CS200) and 400 ℃ (CS400) as influenced by ionic strength, heavy metal (Cd²⁺) and pH was examined. The more carbonized biochar CS400 had higher sorption affinity (log K_oc) for simazine than CS200 because CS400 had stronger hydrophobicity, more aromatic fractions and larger surface area. Although H-bonding interaction could occur, the dominant sorption mechanisms for CS400 were hydrophobic binding, charge-transfer (π–π*) interaction and pore-filling, while for CS200 was partitioning. Increase of ionic strength and presence of Cd²⁺ had no significant effects on the sorption affinities for the both biochars, indicating no cationic exchange occurred between simazine and biochars and Cd²⁺ could not play the role of bridging ion. Lower pH facilitated for sorption of simazine to the both biochars. After loading simazine, significant decrease of zeta potentials for CS400 verified an important role of charge-transfer (π–π*) interaction between them, while only slightly decrease of zeta potentials for CS200 illustrated the partition-dominant mechanism. Nearly no change of zeta potentials for biochars sorbing simazine with and without Cd²⁺ demonstrated that specific adsorption was not dominant mechanism for Cd²⁺ sorption to biochars. Cation exchange might be the dominant mechanism for Cd²⁺ sorption to biochars, which also could well explain sorption more Cd²⁺ to CS200 than to CS400 and little effect of Cd²⁺ on sorption of simazine to biochars.

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太原科技大学博士科研启动基金项目(20122043)，山西省高校科技创新项目(20131047)，科技部项目 (2013AA062705-3)和环保部项目(201309044)资助