Abstract:

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 mediumpH 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: Fe3+>Ni2+>Cu2+>Zn2+.

Key words: Salicylic acid, Chelate resin, Crosslinked polystyrene, Chelation adsorption, Entropy driving