共存阴离子对氢氧化铌吸附磷酸根的影响

The influence of co-existing anions on adsorption of phosphate by niobium hydroxide

以氢氟酸法制备的氢氧化铌为吸附剂,以水溶液中磷酸根为吸附对象,考察了Cl-、SO42-、NO3-3种阴离子对吸附效果影响。结果表明,在温度为25℃,磷酸根质量浓度50mg/L、体积200mL,吸附剂用量0.1g,pH=2条件下,氢氧化铌对磷酸根的最大吸附量可达43.31mg/g。当3种共存阴离子质量浓度分别为50、100、150mg/L时,氢氧化铌对各阴离子吸附顺序依次如下:PO43->>SO42->NO3->Cl-;PO43->>SO24->NO3->Cl-;PO43->>Cl-≈SO42->NO3-。共存阴离子Cl-、SO42-、NO3-存在与PO34-形成吸附竞争,均使氢氧化铌对PO34-吸附量减少。采用质量分数为25%的氨水(10mL)洗去氢氧化铌表面吸附的PO43-,并用蒸馏水进行冲洗,将所得滤液用蒸馏水稀释定容到50mL,其解吸率为53.1%。吸附前后及解吸后的氢氧化铌红外光谱分析结果表明,氢氧化铌表面吸附的磷酸根并没有被完全解吸下来。

Abstract： Niobium hydroxide prepared by the hydrofluoric acid method was used as the adsorbent of phosphate. The effect of co-existing anions such as C1-, SOl- and NOg on adsorption was investigated by using phosphate in the solution as adsorbate. The results showed that the largest adsorption capaci- ty of phosphate by the niobium hydroxide was 43.31 mg/g when 200 mL of phosphate（50 mg/L,PH= 2）was added at 25 °C. When the concentration of three anions was 50,100,150 mg/L respectively, the adsorption capacity of different anions was in the following order： POa- 〉〉SO24-〉NO3-〉 Cl-, PO4a- 〉〉SO42- 〉NO3- 〉C1- and PO4a- 〉〉C1- mSO24- 〉NO3-, respectively. However, the adsorption ca- pacity of PO4a- was reduced in the presence of the co-existing anions（C1- ,SO24- ,NO3-）, and tiae com- petition was formed among these anions. The phosphate adsorbed by the niobium hydroxide could be desorbed under certain conditions. 25% Concentrated ammonia solution（10 mL）was added to wash a- way the phosphate on the surface of niobium hydroxide,washing with distilled water, the filtrate was added water to 50 mL, the desorption ratio was about 53. 1%. The results of FT-IR spectra showed that the phosphate on the surface was not completely desorbed.