氢氧化铌对水溶液中磷酸根的吸附特性研究

以氢氟酸法制备的氢氧化铌作为磷酸根的吸附剂,考察了氢氧化铌用量及焙烧温度对吸附效果的影响。在25℃,磷酸根初始浓度为50mg/L、体积200mL的条件下,确定吸附剂的最佳用量为0.1g,此时氢氧化铌原样对磷酸根的最大吸附量为48.2mg/g。上述条件下,经200、300、400、500℃焙烧后的氢氧化铌对磷酸根的最大吸附量依次为25.9、15.6、11.6、7.5mg/g。分析表明,随着焙烧温度的升高,表面羟基逐渐减少,氢氧化铌对磷酸根的吸附能力逐渐降低。在吸附过程中,焙烧前后的氢氧化铌对磷酸根吸附速率均较快(20min达到吸附平衡)。

Characteristic of Phosphate Adsorption in Aqueous Solution by Niobium Hydroxide

Niobium hydroxide prepared by the hydrofluoric acid method was used as the adsorbent of phosphate.The effect of the dosage of niobium hydroxide and the calcination temperature on the adsorption was investigated.The optimum dosage of adsorbent was determined to be 0.1 g when the initial concentration of phosphate was 50 mg/L and the volume of solution was 200 mL at 25 ℃,meanwhile,the largest capacity of phosphate adsorption by the original niobium hydroxide was 48.2 mg/g.In the same conditions,the largest capacity of phosphate adsorption was 25.9、15.6、11.6、7.5 mg/g.when the calcination temperature was 200、300、400、500 ℃,respectively.The analysis showed that the capacity of phosphate adsorption decreased gradually with the increase of calcination temperature,due to the decrease of surface hydroxyl groups of niobium hydroxide.The niobium hydroxide before and after calcination still had the rapid adsorption rate of phosphate(the adsorption process reached equilibrium in 20 min) in the adsorption process.