四氧化三铁-沸石复合材料去除水中铵和磷酸盐研究

Removal of ammonium and phosphate from aqueous solution by magnetite/zeolite composite

通过实验考察了四氧化三铁-沸石复合材料对水中铵和磷酸盐的吸附-解吸性能。结果表明,四氧化三铁-沸石复合材料对水中铵和磷酸盐的去除率随吸附剂投加量的增加而增加。当溶液pH为4～9时,四氧化三铁-沸石复合材料对水中铵的吸附能力较高;当溶液pH由9增加到11时,铵的吸附能力明显下降。四氧化三铁-沸石复合材料对水中磷酸盐的吸附能力随溶液pH的增加而降低。四氧化三铁-沸石复合材料对水中铵和磷酸盐的吸附动力学过程较好地满足准二级动力学模型。四氧化三铁-沸石复合材料对水中铵的吸附平衡数据较好地满足Langmuir等温吸附模型,对水中磷酸盐的吸附平衡数据可以采用Langmuir、Freundlich和Dubinin-Radushkevich等温吸附模型加以描述。溶液共存的Ca2+、Na+和K+会抑制四氧化三铁-沸石复合材料对水中铵的吸附。溶液共存的Cl-、SO42-和NO3-会略微促进四氧化三铁-沸石复合材料对水中磷酸盐的吸附,而共存的HCO3-则会略微抑制对水中磷酸盐的吸附。采用0.1 mol/LNaCl溶液可以使吸附到四氧化三铁-沸石复合材料上的铵全部解吸下来。采用0.1 mol/L NaOH溶液可以使大部分吸附到四氧化三铁-沸石复合材料上的磷酸盐解吸下来。

The adsorption of ammonium and phosphate from aqueous solution on magnetite/zeolite composite （MZC） as a function of adsorbent dosage, solution pH, reaction time, initial adsorbate concentration, and coexisting ions was investigated. The ammonium and phosphate removal efficiencies of MZC increased with increasing adsorbent dosage. The ammonium adsorption capacity for MZC was relatively high at pH 4-9, and decreased with increasing pH from 9 to 11. The phosphate adsorption capacity for MZC decreased with increasing pH from 4 to 11. The adsorption kinetics of ammonium and phosphate on MZC could be described by a pseudo-second-order kinetic model. The equilibrium adsorption data of ammonium on MZC could be described by the Langmuir isotherm model. The equilibrium adsorption data of phosphate on MZC could be described by the Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. Coexisting Ca2＋ , Na ＋ or K＋ in solution reduced the adsorption of ammonium on MZC. Coexisting C1- , SO42- or NO3 - in solution slightly enhanced the adsorption of phosphate on MZC, while coexisting HCO3 - slightly reduced the adsorption of phosphate on MZC. The ammonium molecules adsorbed on MZC could be completely desorbed in 0.1 moL/L NaC1 solution. Most of phosphate molecules adsorbed on MZC could be desorbed in 0.1 mol/L NaOH solution.