TITLE:
Efficiency of Crude α-Cyclodextrin in Gold Recovery from Electronic Waste and Soil
AUTHORS:
Ibrahim Karume, Simon Tewolde, Emmanuel Tebandeke, Is’harq Z. T. Mukasa, Ruth Mbabazi
KEYWORDS:
Starch, α-Cyclodextrin, Electronic Waste, Soil, Gold
JOURNAL NAME:
Green and Sustainable Chemistry,
Vol.12 No.3,
August
19,
2022
ABSTRACT: In this study, the metal coordination ability of
alpha-cyclodextrin (α-CD) was
employed to complex gold and thus isolate and extract it from different matrices
of acid-digests of electronic waste and soil. The crude α-CD used was extracted
from cassava and yam starch of the non-edible plant species using E. coli α-cyclodextrin
glucanotransferase (α-CGTase), with yields ≥ 62%. The reaction was
monitored progressively by ultraviolet-visible spectroscopy and checked with
infrared spectroscopy (IR) for the presence of α-CD. The crude α-CD
extract without need for purification was refluxed with gold containing-electronic
waste and soil predigested in a mixture of NaBr/HNO3 for 4 - 7 days.
Recoveries of up to 22.9% and 70.8% gold were achieved from electronic waste
and soil, respectively using 0.1 M α-CD.
This approach is cheap, effective, and environmentally benign.