腐殖酸对针铁矿吸附磷的影响机理

通过添加HA(Humic acid,腐殖酸),研究不同环境条件下HA对针铁矿吸附磷的影响. 结果显示,加入HA能显著降低磷吸附量,pH为4.5时分别加入100和40 mg/L HA,磷的最大吸附量分别降低了26.6%和25.6%；pH为7.0时分别加入100和40 mg/L HA,磷的最大吸附量分别降低了26.8%和23.1%. 不同添加顺序试验结果表明:针铁矿对磷的吸附量大小顺序为后添加HA>同时添加HA和磷>先添加HA；无论是否添加HA,针铁矿对磷的吸附量都随着pH的升高而降低,相应的吸附等温线也都符合Langmuir吸附等温方程；总有机碳和红外光谱特征表明,HA和磷在针铁矿表面吸附点位形成竞争吸附,并且针铁矿表面的羟基在吸附磷和HA的过程中起到了一定的作用. 

Mechanism of Humic Acid Influence on the Adsorption of Phosphate on Goethite

According to adsorption experiments of phosphate on goethite and its competitive interaction with humic acid(HA),the HA influence on phosphate adsorption by goethite under different conditions was studied.The addition of HA could significantly reduce the amount of phosphate adsorbed by goethite,which was up to 26.6% and 25.6% with the addition of 100 mg/L and 40 mg/L of HA,respectively,at pH 4.5.The reductions at pH 7.0 were 26.8% and 23.1%,respectively.Different ordering of the addition of phosphate and HA resulted in different phosphate amounts being adsorbed by goethite: initial addition of phosphate > simultaneous addition > initial addition of HA.The results also showed that increasing pH could result in decreasing adsorption of phosphate by goethite.The equilibrium data of phosphate adsorption agreed well with the Langmuir adsorption isotherm in both conditions of presence and absence of HA.The results of total organic carbon and infrared spectral features indicated that HA competed with phosphate on the goethite surface,and hydroxyl on the surface of goethite played an important role in the process of adsorption of phosphate and HA.