posted on 2022-12-29, 18:09authored byJikang Wang, Xianggui Kong, Mufei Yang, Wenbo Xiong, Zixian Li, Hua Zhou, Geoffrey I. N. Waterhouse, Si-Min Xu, Hong Yan, Yu-Fei Song, Haohong Duan, Yufei Zhao
The
efficient removal of heavy metals from wastewater and contaminated
soil is vital for the environmental remediation and sustainable recycling
of metals. Here, we demonstrate that ultrathin MgFe-LDH nanosheets
(LDH-S) offer excellent mineralization of Cu2+ ions in
aqueous solutions and soils (ultrahigh uptake capacity of 662 mg/g).
The LDH-S can purify real electroplating wastewater (Cu2+ concentration >5000 mg/L) and trace heavy-metal-containing wastewater
(∼10 mg/L) to drinkable levels (below 1 ppb). In the process
of Cu2+ removal, MgFe-LDH is transformed into Cu(Mg)Fe-LDH
through surface adsorption and isomorphous substitution. The Cu(Mg)Fe-LDH
product could be used directly to remove azo dyes and phosphate anions
by adsorption or be processed into metallic copper via a leaching–electroreduction
process. The release of Mg2+ ions by LDH-S during Cu2+ removal was shown to promote crop growth by acting as magnesium
fertilizer, even in acidic soils. This work simultaneously addresses
several bottlenecks in heavy metal sequestration, including removal
capacity, stability, reusability, and metal recovery.