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以红、白和灰3种不同颜色的砒砂岩作为吸附剂,通过研究不同吸附剂用量、pH和离子强度(IS)等外界条件对砒砂岩吸附Pb(Ⅱ)的影响,以及吸附动力学和等温吸附特征,应用动力学与热力学吸附模型,结合红外光谱(FTIR)分析,探讨砒砂岩吸附Pb(Ⅱ)的机理.结果表明,砒砂岩具有较强的吸附性,能够有效吸附Pb(Ⅱ),其吸附效果受铅浓度、吸附剂用量及pH、离子强度(IS)的影响强烈,即:随pH的增大,吸附量提高,但随离子强度的增大,吸附量却降低.3种颜色的砒砂岩对Pb(Ⅱ)的吸附均在30 min内达到平衡,吸附速率大小表现为灰色>白色>红色,其吸附过程符合准二级动力学模型.在试验浓度范围内,Freundlich和D-R模型能够较好地模拟砒砂岩对Pb(Ⅱ)的等温吸附特性,3种砒砂岩均是以非均匀孔隙或表面为主要吸附位.结合吸附模型和FTIR表征,吸附机理以静电吸附、离子交换为主,辅以部分化学吸附和一部分化学沉淀综合起作用.
The effects of external conditions such as different adsorbent dosage, pH and ionic strength (IS) on the adsorption of Pb (Ⅱ) on sandstone were studied using three different colors of red, white and gray as the adsorbent. The adsorption kinetics and The adsorption mechanism of Pb (Ⅱ) on the 砒 sandstone was studied by means of kinetic and thermodynamic adsorption models and FTIR analysis. The results show that the 砒 sandstone has strong adsorption ability and can effectively adsorb Pb (Ⅱ) , The adsorption effect is strongly influenced by lead concentration, adsorbent dosage and pH, ionic strength (IS), ie, the adsorption capacity increases with the increase of pH, but decreases with the increase of ionic strength. The adsorption of Pb (Ⅱ) by colored 砒 sandstone reached the equilibrium within 30 min, and the adsorption rate was in the order of gray> white> red, and its adsorption process accorded with the pseudo second-order kinetic model. Within the experimental concentration range, Freundlich and DR The model can well simulate the adsorption isotherm of Pb (Ⅱ) on palynological sandstone, and the three kinds of palygorsites are all characterized by heterogeneous pores or surface as the main adsorption sites.According to the adsorption model and FTIR characterization, the adsorption mechanism is characterized by electrostatic adsorption, ion exchange Mainly supplemented by some chemical absorption Part of the chemical precipitation together play a role.