A chemically bonded adsorbent for separation of antimony, copper and lead

The new chemically bonded adsorbent designated as ICAA-PPG was synthesized by covalent attachment of pyrogallol to a silica gel ceramic support. The feasibility of this absorbent to separate antimony(III), copper and lead from aqueous solutions has been examined. Results of absorbent syntheses, absorbent characterization, breakthrough curve, regeneration and metal ion separation studies are presented here. The silica surface was functionalized with aromatic amine groups, which were further diazotized to attach the pyrogallol moiety. A pyrogallol surface coverage density of 0.255 mmol/g of functionalized support was achieved. ICAA-PPG showed high antimony(III) removal efficiency over a pH range of 1-10. ICAA-PPG was regenerated by desorbing antimony(III) with 4 M hydrochloric acid and 0.05 M potassium hydrogen tartrate. Stripping solutions with low acidity and high chloride concentration showed high regeneration efficiency. The desorbed antimony can easily be recovered from stripping solutions by precipita-tion as antimony hydroxide and the stripping solution can be recycled. Concentration factors of 25-30 were achieved. The initial capacity of 21.6 mg/g was achieved at breakthrough volume and the capacity of 19.6 mg/g after 10 adsorption/stripping cycles shows that ICAA-PPG is stable. Antimony(III), copper and lead were separated by selective stripping from the bed saturated with these metal ions. These results indicate that ICAA-PPG has the potential for removal and separation of antimony from dilute aqueous solutions. An ICAA-PPG adsorption process can be employed for the removal of antimony impurity from copper and zinc electrolytes.