부산대학교 도서관

Geopolymers are inorganic, chemically resistant aluminosilicate-based binding agents, which remove hazardous metal ions from exposed aqueous media. However, the removal efficiency of a given metal ion and the potential ion remobilization have to be assessed for individual geopolymers. Therefore, copper ions (Cu[sup.2+]) were removed by a granulated, metakaolin-based geopolymer (GP) in water matrices. Subsequent ion exchange and leaching tests were used to determine the mineralogical and chemical properties as well as the resistance of the Cu[sup.2+]-bearing GPs to corrosive aquatic environments. Experimental results indicate the pH of the reacted solutions to have a significant impact on the Cu[sup.2+] uptake systematics: the removal efficiency ranged from 34–91% at pH 4.1–5.7 up to ~100% at pH 11.1–12.4. This is equivalent to Cu[sup.2+] uptake capacities of up to 193 mg/g and 560 mg/g in acidic versus alkaline media. The uptake mechanism was governed by Cu[sup.2+]-substitution for alkalis in exchangeable GP sites and by co-precipitation of gerhardtite (Cu[sub.2](NO[sub.3])(OH)[sub.3]) or tenorite (CuO) and spertiniite (Cu(OH)[sub.2]). All Cu-GPs showed excellent resistance to ion exchange (Cu[sup.2+] release: 0–2.4%) and acid leaching (Cu[sup.2+] release: 0.2–0.7%), suggesting that tailored GPs have a high potential to immobilize Cu[sup.2+] ions from aquatic media.
Author(s): Nenad Grba [1]; Cyrill Grengg [2]; Mirjana Petronijević [3]; Martin Dietzel [2]; Andre Baldermann (corresponding author) [2,*] 1. Introduction Heavy metals, such as lead (Pb), copper (Cu), cadmium (Cd) [...]