坡缕石黏土负载铁锰复合氧化物吸附磷的性能

以氧化还原共沉淀的方法将铁锰复合氧化物负载于坡缕石黏土表面,制备负载型吸附剂,由静态吸附实验研究了吸附剂对磷的吸附性能,探讨了吸附的动力学特征、热力学参数和吸附机理。结果显示,吸附剂对磷的吸附受溶液初始pH值、吸附时间及温度的影响,在中性条件下吸附平衡时间为90 min,pseudo-second-order吸附动力学方程能较好描述吸附过程,吸附表观活化能为11.76 k J/mol;吸附等温线与Freundlich方程的拟合结果略优于Langmuir方程,由Langmuir方程得到最大吸附量为26~31 mg/g。吸附焓变为9.29 k J/mol,吸附熵变为正值,自由能变为-4.3~-5.8 k J/mol,吸附作用有多层不均匀吸附的性质,同时包含物理作用和化学作用,但不属强的化学键作用。

Adsorption performance of Fe-Mn binary oxide loaded on palygorskite clay for phosphate

The supported adsorbent was prepared by loading Fe-Mn binary oxide onto the surface of palygorskite clay with the oxidation reduction coprecipitation techniques. The adsorption properties and mechanism of adsorbing phosphate were investigated by static adsorption experiments with a discussion on the adsorption kinetics and thermodynamic characteristics. The results demonstrate that the initial pH value, adsorption time and temperature of the solution can influence adsorption capability, and adsorption equilibrium can be reached after about 90 min under neutral conditions. It is found that the adsorption processes follow pseudo-second-order equation most effectively, with the adsorption apparent activation energy being 11.76 kJ/mol. The fitting of the adsorption isotherms with Freundlich equation is slightly better than that with Langmuir equation, and the maximum adsorption capacity is 26~31mg/g. Adsorption enthalpy is 9.29 kJ/mol, adsorption entropy is positive and adsorption Gibbs free energy changes are in the range of -4.3~-5.8 kJ/mol. The adsorption is multilayered and heterogeneous, with the coexistence of physical and chemical effects, without strong chemical bond function.