Characterizations of TiO2@Mn-Zn ferrite powders for magnetic photocatalyst prepared from used alkaline batteries and waste steel pickling liquor

•We successfully prepared the TiO2@Mn-Zn ferrite for magnetic photocatalyst.•The shell TiO2 nanocrystal was prepared by sol–gel hydrolysis precipitation.•Mn-Zn ferrite as a magnetic core prepared from industry and commercial wastes.•The magnetic photocatalyst can be applied to treat dye waste waters.

We successfully prepared the TiO2@Mn-Zn ferrite composite powder for magnetic photocatalyst. The core Mn-Zn ferrite powder was synthesized by using steel pickling liquor and used alkaline batteries as the starting materials. The shell TiO2 nanocrystal was prepared by sol–gel hydrolysis precipitation of titanium isopropoxide (Ti(OC3H7)4) on the Mn-Zn ferrite powder. The thickness of the titania shell was found to be approximately 2 nm. The core of Mn-Zn ferrite is of spherical or elliptical shape and the particle size of the core is in the range of 20–40 nm. The magnetic Mn-Zn ferrite nanopowder is uniformly encapsulated in a titania layer forming the core–shell structure of TiO2@Mn-Zn ferrite powder. The magnetic photocatalyst can be successfully used to treat dye waste waters.

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