废弃绿茶对水溶液中Co^(2+)的吸附研究

Adsorption of Co^(2+) from aqueous solutions by waste green tea

利用废弃绿茶叶粉末(简称茶叶末)作为吸附剂,考察了pH、温度、时间等对水溶液中Co2+的影响。结果表明:(1)茶叶末对Co2+的吸附量随着pH的上升而上升,其中pH=5.50为最佳。茶叶末对Co2+的吸附量均随时间延长呈现上升趋势,吸附速度先快后慢,吸附最佳时间为90min。(2)不同温度下,茶叶末对Co2+的吸附较好地符合Langmuir模型。该吸附过程是化学离子交换过程,主要发生在重金属离子与羟基、氨基的氢原子之间。(3)茶叶末对Co2+的吸附是自发、放热过程,降温有利于吸附,反应时吸附界面上的混乱度增加。(4)盐酸是很好的解吸介质,解吸率为92.65%。通过灼烧(或燃烧)可以回收水溶液中绝大部分的Co2+,不仅减小了对环境的污染,而且节约了资源。

Waste green tea powder was used as adsorbent to remove the Co2＋ from aqueous solutions.The effect of pH,contact time,Co2＋ concentration and reaction temperature on adsorption efficiency was investigated.Experimental results showed that the Co2＋ adsorption quantity was increased with increasing the pH and contacting time,the optimal pH and contacting time was 5.50 and 90 min respectively.The adsorption rate appeared first quick back slow trend.The Co2＋ adsorption process under different temperature could be well fitted by Langmuir model.The mechanism of adsorption was chemical ion-exchange,mainly happened between heavy metal ions and hydroxyl,amino and hydrogen atoms.The adsorption processes was spontaneous and exothermic;decreasing the temperature was benefit for Co2＋ adsorption,the chaos of adsorption interface was increased during the adsorption process.Hydrochloric acid was a perfect desorption medium,the desorption rate of Co2＋ in hydrochloric acid was 92.65%.It was feasible to recover Co2＋ from solution by incineration method,which could eliminate the Co2＋ pollution to environment and save resources.