A closed-loop system to recycle rare earth elements from industrial sludge using green leaching agents and porous β-cyclodextrin polymer composite
Journal
Resources, Conservation and Recycling
Journal Volume
180
Date Issued
2022
Author(s)
Abstract
Industrial sludge is classified as hazardous waste as well as a resource of valuable metals and needs to be adequately treated for the sake of the environment and economy. This study reports a green approach for extracting and purifying rare earth elements (REEs) from industrial sludge using environmentally friendly washing solutions ((NH4)2SO4, N, N-Bis(carboxymethyl) glutamic acid (GLDA), tetrabutylammonium bromide ionic liquid (TBAB), and water) and a porous β-cyclodextrin polymer composite (PCDP-M-SHM) respectively. The results showed that there is no significant difference between used extracting solutions. However, the speciation study indicated that most REEs in the sludge sample were bounded to a water-soluble fraction. Therefore, for economic reasons, water was used for further studies. Furthermore, the recycling efficiencies after the purification of leached REEs with PCDP-M-SHM were in the range of 76.0 % (Gd) to 87.3% (Pr), except for Ce (8.29%). Moreover, cost evaluation and sensitivity analysis studies were performed to investigate the applicability of the reported method at the industrial level. The cost evaluation results estimated $3676 as the cost of processing 1 ton of sludge with revenue of $710/ton of sludge. Finally, the sensitivity analysis test affirmed the profitability to depend on the cost of PCDP-M-SHM. Based on the future market price of REEs, the proposed closed-loop recycling approach could be a promising green solution for environmental problems related to mining, processing, and conservation of REEs resources as well as industrial sludge disposal. ? 2022 Elsevier B.V.
Subjects
closed-loop recycling
cost evaluation
green solutions
Industrial sludge
Rare earth elements (REEs)
Amino acids
Chlorine compounds
Closed loop systems
Composite materials
Cost benefit analysis
Economics
Ionic liquids
Leaching
Rare earths
Recycling
Sensitivity analysis
Closed-loop
Closed-loop recycling
Closed-loop system
Cost evaluations
Green solution
Leaching agents
Polymer composite
Rare earth element
β-Cyclodextrin polymers
Rare earth elements
beta cyclodextrin
cerium
gadolinium
glutamic acid
ionic liquid
lanthanide
n,n bis(carboxymethyl) glutamic acid
polymer
praseodymium
tetrabutylammonium
unclassified drug
water
hazardous waste
industrial waste
ionic composition
leaching
rare earth element
recycling
sludge
Article
economic aspect
environmental impact
extraction
financial management
green chemistry
industrial sludge
mining
purification
sensitivity analysis
sludge disposal
water solubility
SDGs
Type
journal article