TY - JOUR
T1 - An investigation of gold adsorption from a binary mixture with selective mesoporous silica adsorbents
AU - Lam, Koon Fung
AU - Yeung, King Lun
AU - McKay, Gordon
PY - 2006/2/9
Y1 - 2006/2/9
N2 - Gold-selective adsorbents were prepared from mesoporous MCM-41 silica by grafting organic amine groups (i.e., RNH2, R2NH, and R3N; R = propyl). NH2-MCM-41, NRH-MCM-41, and NR 2-MCM-41 displayed strong affinity for gold and at 1 mmol/g loading adsorbed 0.40, 0.33, and 0.20 mmol/g of gold. Copper and nickel were not adsorbed on these adsorbents. Grafting surface chemical moieties introduces heterogeneity on an otherwise uniform MCM-41 pore surface and metal adsorption is best described by the Freundlich adsorption model. A series of binary adsorption equilibrium studies with NH2-MCM-41 containing 2.2 mmol RNH2/g shows that NH2-MCM-41 adsorbs only gold from solutions containing copper and nickel with an adsorption capacity of 0.6 mol of Au/mol of RNH2 (1.1 mmol of Au/g of NH2-MCM-41). Copper and nickel were not adsorbed by NH2-MCM-41 regardless of the solution concentration, composition, and pH (i.e., 2 to 4) in the presence of gold. The Le Van and Vermeulen adsorption model based on a single component Freundlich isotherm and corrected for the anion effect accurately predicted the binary adsorptions. The adsorbed gold was completely recovered by a simple acid wash and the recovered gold solution is 99% pure. The regenerated NH 2-MCM-41 remained 100% selective for gold removal and exhibited the same adsorption capacity even after several uses.
AB - Gold-selective adsorbents were prepared from mesoporous MCM-41 silica by grafting organic amine groups (i.e., RNH2, R2NH, and R3N; R = propyl). NH2-MCM-41, NRH-MCM-41, and NR 2-MCM-41 displayed strong affinity for gold and at 1 mmol/g loading adsorbed 0.40, 0.33, and 0.20 mmol/g of gold. Copper and nickel were not adsorbed on these adsorbents. Grafting surface chemical moieties introduces heterogeneity on an otherwise uniform MCM-41 pore surface and metal adsorption is best described by the Freundlich adsorption model. A series of binary adsorption equilibrium studies with NH2-MCM-41 containing 2.2 mmol RNH2/g shows that NH2-MCM-41 adsorbs only gold from solutions containing copper and nickel with an adsorption capacity of 0.6 mol of Au/mol of RNH2 (1.1 mmol of Au/g of NH2-MCM-41). Copper and nickel were not adsorbed by NH2-MCM-41 regardless of the solution concentration, composition, and pH (i.e., 2 to 4) in the presence of gold. The Le Van and Vermeulen adsorption model based on a single component Freundlich isotherm and corrected for the anion effect accurately predicted the binary adsorptions. The adsorbed gold was completely recovered by a simple acid wash and the recovered gold solution is 99% pure. The regenerated NH 2-MCM-41 remained 100% selective for gold removal and exhibited the same adsorption capacity even after several uses.
UR - http://www.scopus.com/inward/record.url?scp=33644745548&partnerID=8YFLogxK
U2 - 10.1021/jp055577n
DO - 10.1021/jp055577n
M3 - Article
AN - SCOPUS:33644745548
SN - 1520-6106
VL - 110
SP - 2187
EP - 2194
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 5
ER -