Chromium removal from chromium gypsum through microwave hydrothermal crystal phase regulation.

Chromium gypsum (CG) is a common hazardous waste formed in chromium salt or electroplating industries. The trapped or lattice-doped CrO in gypsum crystals are difficult to be reduced or removed by traditional methods, which will be re-oxidized or slowly released during long-term hypaethral storage. In this study, microwave hydrothermal treatment was applied to remove chromium in CG.

Construction of heterostructured NiFeO-C nanorods by transition metal recycling from simulated electroplating sludge leaching solution for high performance lithium ion batteries.

NiFe2O4 has been regarded as one of the promising candidates for lithium-ion battery (LIB) anode materials due to its high theoretical specific capacity. However, the large volume expansion and pulverization of NiFe2O4 during the charge/discharge process result in severe capacity fading. Herein, heterostructured NiFe2O4-C nanorods have been successfully fabricated by recovering transition metals from simulated electroplating sludge leaching solution.

Targeted conversion of Ni in electroplating sludge to nickel ferrite nanomaterial with stable lithium storage performance.

The recovery of heavy metals from industrial solid waste is of great significance for simultaneously alleviating heavy metal pollution and recycling valuable metal resources. However, the complex compositions of the multiple metallic electroplating waste severely limit the selective recovery of metal resources such as nickel. In this study, a kind of nickel-laden electroplating sludge was taken as an example and the Ni in it was targetedly converted into highly valuable NiFeO (nickel ferrite) nanomaterials via a regulator assisted hydrothermal acid-washing strategy, eventually leading to selective extraction of Ni and Ca from the sludge.