水杨酸型螯合树脂对Fe(Ⅲ)离子的螯合吸附行为

Chelation Adsorption Behavior of a Salicylic Acid-Type Chelate Resin for Fe(Ⅲ) Ions

以5-氨基水杨酸(ASA)为胺化试剂,使氯甲基化的交联聚苯乙烯(CMCPS)微球表面的苄氯基团发生亲核取代反应,制得了水杨酸型螯合树脂ASA-CPS.研究了该螯合树脂对金属离子的螯合吸附行为,探讨了其吸附热力学与吸附机理,考察了介质pH值对树脂螯合吸附性能的影响以及树脂对不同金属离子的螯合吸附能力.实验结果表明,水杨酸型螯合树脂ASA-CPS对重金属离子具有强螯合吸附性能,尤其对Fe3+离子表现出很强的螯合吸附能力,常温下吸附容量可达21 g/100 g.吸附过程属熵驱动的化学吸附过程,升高温度,吸附容量增高;在可抑制金属离子水解的pH范围内,介质的pH值越高,螯合吸附能力越强;对于性质不同的金属离子,ASA-CPS的吸附性能是有差别的,吸附容量的顺序为Fe3+>Ni2+>Cu2+>Zn2+.

The nucleophilic substitution reaction of phenyl chloride groups on chloromethylated cross-linked polystyrene （CMCPS） microspheres was conducted using 5-amino salicylic acid （ASA） as an amination reagent. The resultant product was a salicylic acid-type chelate resin （ASA-CPS）. Chelation adsorption behavior of the ASA-CPS resin for metal ions was studied and adsorption thermodynamics as well as the adsorption mechanism was also investigated. The effect of medium pH on adsorption of the ASA-CPS resin was examined and the chelation adsorption abilities of ASA-CPS for different metal ions were tested. Experimental results show that the salicylic acid-type chelate resin, ASA-CPS, possesses strong chelation adsorption ability for heavy metal ions. The resin is especially good at adsorbing Fe （Ⅲ） ions and the adsorption capacity can reach 21 g/100 g at room temperature. Adsorption is a process driven by entropy and higher temperatures facilitate the adsorption process and thus increase the adsorption capacity. In the pH range where the hydrolysis of metal ions is inhibited, an increase in the pH value of the medium will strengthen the chelation adsorption ability of the ASA-CPS resin for heavy metal ions. For different metal ions, ASA- CPS exhibits different adsorption abilities with the following order of adsorption capacity： Fe^3＋〉Ni^2＋〉Cu^2＋〉Zn^2＋.