氨基硫脲/季铵木质素对铂的吸附

Adsorption of platinum by thiosemicarbazide/quaternary ammonium lignin

木质素及其衍生物因具有经济高效和无污染等特点,在有价金属提取和有毒金属离子去除等领域具有广阔的应用前景。本研究采用氨基硫脲/季铵木质素吸附铂,通过FTIR分析揭示了吸附过程的机制,考察了盐酸浓度、Pt(IV)初始浓度、吸附时间和吸附剂用量对吸附效果的影响。结果表明,改性木质素中含有大量的酚羟基、胺基和季铵官能团,PtCl_(6)^(2-)被氨基硫脲/季铵木质素中的酚羟基还原成PtCl_(4)^(2-)后与胺基发生配合反应和氯离子发生离子交换反应,在盐酸浓度为0.5 mol·L^(-1)、Pt(IV)初始浓度为1170 mg·L^(-1)和吸附时间为120 min的条件下,1 g·L^(-1)氨基硫脲/季铵木质素对Pt(IV)的饱和吸附容量为267.80 mg·g^(-1),7 g·L^(-1)时的最大吸附率为88.50%。吸附过程遵循Freundlich模型和准二级动力学模型,表明吸附过程为单分子层非均质的化学吸附。

Lignin and its derivatives have broad application prospects in the fields of extraction of valuable metals and removal of toxic metal ions because of the characteristics of economical, efficient and friendly. Platinum was adsorbed by thiosemicarbazide/quaternary ammonium lignin in this study. The mechanism of adsorption was revealed by FTIR and the influence factors such as initial concentration of Pt(IV), hydrochloric acid concentration, adsorption time and adsorbent dosage on adsorption were optimized. The results show that the modified lignin contains a large number of phenolic hydroxyl, amino and quaternary ammonium functional groups. PtClis reduced toby phenolic hydroxyl and then reacts with amino group by coordination reaction and chloride by ion exchange reaction. Using the optimum conditions, which include hydrochloric acid of 0.5 mol·L^(-1), Pt(IV) of 1 170 mg·L^(-1),adsorption time of 120 min and thiosemicarbazide/quaternary ammonium lignin addition of 1 g·L^(-1), the maximum adsorption capacity is 267.80 mg·g^(-1). Under the same conditions besides 7 g·L^(-1)thiosemicarbazide/quaternary ammonium lignin, the maximum adsorption ratio is 88.50%. The adsorption process can be simulated by Freundlich model and quasi-second-order kinetic model, which indicates that adsorption is chemisorptions of monolayer heterogeneous.