Converting Spent Cu/Fe Layered Double Hydroxide into Cr(VI) Reductant and Porous Carbon Material

Abstract

Recycling solid waste as functional materials is important for both environmental remediation and resource recycling. This study attempts to recycle spent Cu/Fe layered double hydroxide (Cu/Fe-LDH) which is generated from the adsorption of dyes by converting to Cr(VI) reductant and porous carbon material. Results showed that the obtained reductant was mainly composed of Fe0 and Cu0, and exhibited good reductive activity toward Cr(VI). The species of Fe0, Fe2+, Cu0, and Cu+ all favored the reduction of Cr(VI) according to X-ray photoelectron spectroscopy analysis. During Cr(VI) removal, solution pH could increase to neutral which caused the metal ions to precipitate near completion. On the other hand, the spent Cu/Fe-LDH could be employed to produce porous carbon materials, and the generated waste metals solution herein could be reused for LDH synthesis. Specific surface areas of the obtained carbon materials varied from 141.3–744.2 m2/g with changes in adsorbed amount of dyes on the LDH. This study illustrates that all the components of wastes can be useful resources, offering a simple recycling approach for similar organic-inorganic solid wastes. This work also enlightens us that designing a proper initial product is crucial to make waste recycling simpler.

Dynamics of Charge-Transfer Behavior in a Plasmon-Induced Quasi-Type-II p–n/n–n Dual Heterojunction in Ag@Ag3PO4/g-C3N4/NiFe LDH Nanocomposites for Photocatalytic Cr(VI) Reduction and Phenol Oxidation

“…62 Furthermore, with the increment of pH, there is a chance that the soluble metal cations (i.e., Ni 2+ , Fe 3+ , and Cr 3+ ) would be removed away from the solution by forming Ni(OH) 2 ( K sp of 5.5 × 10 –16 ) and Fe(OH) 3 ( K sp of 2.79 × 10 –39 ). 62 Alternatively, in very strong acidic or basic conditions, the dissolution of oxygen-containing functional groups of the NiFe LDH phase present in the heterostructure would be possible and decrease the adsorption process as well as the rate of reduction. Therefore, the suitable pH, that is, 5, was effective for the reduction reaction of Cr(VI) to Cr(III) in the heterostructure CNLDHAgP4.…”

Carbonaceous composite materials from calcination of azo dye-adsorbed layered double hydroxide with enhanced photocatalytic efficiency for removal of Ibuprofen in water

“…After adsorption of anions from wastewater, treatment of spent LDHs becomes a tough challenge. Normal landfilling or piling up may result in foul smell, contamination of soil and underground water by leachate [13]. According to limited research consequences, after adsorption, Laipan et al [13] fabricated carbon-LDH composites via calcination under inert gas flow.…”

Layered Double Hydroxide Protective Films Developed on Aluminum and Aluminum Alloys: Synthetic Methods and Anti-Corrosion Mechanisms

“…Due to the anion exchange capability of LDHs, various anions can be successfully incorporated inside the LDH interlayer to modify the chemistry of LDH for specific applications: for instance, supercapacitors, environmental sciences, catalysts, adsorption, etc. [31][32][33][34][35][36][37]. Recently, regarding the subject of anti-corrosion materials, layered double hydroxide (LDH)-based coating systems have also been widely explored, due to LDHs' peculiar morphology, a wide range of cationic/anions combinations, environmental friendliness, barrier properties, high surface to volume ratio and multifunctional design along with the capability to intercalate various species, such as metal ions of mixed valences, complex inorganic, organic molecules in the in LDH interlayers, and thus can be utilized as multifunctional coating systems.…”