| 氢氧化镧-天然沸石复合材料对水中低浓度磷酸盐的吸附作用 |
| 摘要点击 2792 全文点击 1265 投稿时间：2015-03-07 修订日期：2015-09-01 |
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| 中文关键词 镧-沸石复合材料 磷酸盐 吸附 低浓度 影响因素 |
| 英文关键词 lanthanum hydroxide/natural zeolite composite phosphate adsorption low concentration influencing factor |
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| 中文摘要 |
| 采用液相沉淀法将氢氧化镧和天然沸石进行复合,制备得到镧-沸石复合材料,并通过批量吸附实验考察了该复合材料对水中磷酸盐的吸附作用,特别是考察了该复合材料去除水中低浓度磷酸盐的影响因素. 结果表明,当制备复合材料时沉淀pH值为5~7或13时,复合材料对水中磷酸盐的吸附能力较差; 当沉淀pH值控制为9~12,复合材料对水中磷酸盐的吸附能力较好,且当沉淀pH值由9增加到11时,复合材料的吸磷能力明显增加,继续增加pH值由11~12时,复合材料的吸磷能力基本不变. 沉淀pH值为11时制备的镧-沸石复合材料对水中磷酸盐的吸附平衡数据可以较好地采用Langmuir模型加以描述,根据Langmuir模型预测的最大磷酸盐吸附量为44 mg ·g-1(磷酸盐溶液pH 7和反应温度30℃); 该复合材料对水中低浓度磷酸盐的吸附动力学可以较好地采用准二级动力学模型加以描述. 当磷酸盐溶液pH值由3增加到8时,沉淀pH值为11条件下制备得到的镧-沸石复合材料对低浓度磷酸盐的吸附能力增加,继续增加磷酸盐溶液pH值时,该复合材料对磷酸盐的吸附能力下降; 与磷酸盐溶液共存的氯离子和硫酸根离子不会抑制该复合材料对低浓度磷酸盐的吸附,而碳酸氢根离子则会略微抑制该复合材料对磷酸盐的吸附; 与磷酸盐溶液共存的腐殖酸会抑制该复合材料对水中低浓度磷酸盐的吸附. 当磷酸盐溶液pH值为7时,沉淀pH值为11时镧-沸石复合材料吸附磷酸盐的机制主要为配位体交换作用. 因此,沉淀pH值为11时制备得到的镧-沸石复合材料适合作为吸附剂去除水和废水中低浓度磷酸盐. |
| 英文摘要 |
| A series of composites of lanthanum hydroxide/natural zeolite (La(OH)3/NZ composites) were prepared by co-precipitation method, and these composites were used as adsorbents to remove phosphate from aqueous solution. The phosphate adsorption capacities of different composites prepared with different precipitated pH values were compared in batch mode. The adsorption characteristics of phosphate from aqueous solution on the La(OH)3/NZ composite prepared with the precipitated pH value of 11 was investigated using batch experiments. The results showed that the La(OH)3/NZ composite prepared with the precipitated pH values of 5-7 and 13 had a low adsorption capacity for phosphate in aqueous solution, while the La(OH)3/NZ composites prepared with the precipitated pH values of 9-12 exhibited much higher phosphate adsorption capacity. The phosphate adsorption capacity of the La(OH)3/NZ composite increased with the increase of the precipitated pH value from 9 to 11, but remained basically unchanged with the increase of the precipitated pH value from 11 to 12. The equilibrium adsorption data of phosphate from aqueous solution on the La(OH)3/NZ composite prepared with the precipitated pH value of 11 could be described by the Langmuir isotherm model with the predicted maximum phosphate adsorption of 44 mg ·g-1 (phosphate solution pH 7 and 30℃). The kinetic data of phosphate adsorption from low concentration phosphate solution on the La(OH)3/NZ composite prepared with the precipitated pH value of 11 well followed a pseudo-second-order model. The presence of Cl- and SO42- in low concentration phosphate solution had no negative effect on phosphate adsorption onto the La(OH)3/NZ composite prepared with the precipitated pH value of 11, while the presence of HCO3- slightly inhibited the adsorption of phosphate. Coexisting humic acid had a negative effect on the adsorption of phosphate at low concentration on the La(OH)3/NZ composite prepared with the precipitated pH value of 11. The mechanism for phosphate adsorption onto the La(OH)3/NZ composite prepared with the precipitated pH value of 11 was explained by the ligand exchange process. Results of this work indicate that the La(OH)3/NZ composite prepared with the precipitated pH value of 11 is a promising adsorbent material for the removal of low concentration phosphate from water/wastewater. |
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