水溶液中磷的吸附与预测模型

用红壤和水滑石作为吸附剂,进行了水溶液中磷的等温吸附试验,目的是研究吸附剂(W)0效应和起始吸附质浓度(C)0效应对经典方程参数变异的影响,分析经典Langmuir和Freundlich方程在液/固离子吸附体系中的适用性和验证新吸附模型的预测精确度。试验结果显示,红壤和水滑石在吸附磷的过程中存在明显的吸附剂和吸附质浓度效应,单一的经典方程仅适用于给定吸附剂或吸附质浓度的体系,因此,用其参数来表征不同吸附剂的吸附能力或描述不同吸附剂或吸附质浓度水平上的吸附规律具有一定的局限性。数据分析表明,单位吸附剂的平衡吸附量qe不唯一由初始浓度C0或液相平衡浓度Ce所决定,而是C0/W0或Ce/W0的函数,新吸附预测模型能较好的反映红壤和水滑石磷吸附的总体趋势。新的预测模型用来描述红壤和水滑石的磷吸附曲线时具有较高的精确度。在实践中,新模型可用来预测给定条件下磷的吸附量和所需吸附剂的用量。

Phosphorus Adsorption in Aqueous Solution and Its Prediction Model

Experiments of phosphorus adsorption from aqueous solutions onto red soil and hydrotalcite were done to test applicability of Langmuir and Freundlich equations for describing ion adsorption at different initial phosphorus concentration and adsorbent concentration levels in liquid/solid systems.The effect of adsorbent and adsorbate concentrations on traditionally defined adsorption isotherm parameters was investigated,the application of a new prediction model was testified.Results indicated the presence of obvious adsorbent and adsorbate concentration effects on phosphorus adsorption isotherms.A single Langmuir-type equation was found to fit the experimental data well only at a given adsorbent or adsorbate concentration level,and its parameters varied significantly with adsorbent and adsorbate concentrations,showing that estimated parameters have limitation in the application.Results obtained from the analysis showed that the equilibrium ion adsorption density is not a single function of either initial phosphorus concentration or equilibrium ion concentration in liquid phase.The obtained experimental data fit well the new model at high levels of accuracy.The proposed model can thus be used to predict either adsorbed quantity or required adsorbent quantity under given conditions.