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The aim of this article is to present a nonconventional method for the efficient removal of lead ions from industrial wastewater. For this purpose, magnetite nanomaterial was used, which was very easily separated from the wastewater at the end of the treatment due to its magnetic properties. Currently, nanotechnology is an efficient and inexpensive manner that is being researched for wastewater treatment. Additionally, iron oxide nanoparticles are widely used to remove heavy metal ions from water due to their special properties. The experimental results detailed in this article show the influence of pH and contact time on the process of adsorption of lead ions from wastewater. The magnetite nanomaterial had its maximum efficiency of speed when the wastewater had pH 6. At a lower pH, the highest treatment efficiency was over 85%, and the required contact time has doubled. When the pH increases above 6, the precipitation process occurs. Langmuir and Freundlich models were used to describe the adsorption process.

Halloysite is a clay mineral that it is found in nature being a non-toxic material. Halloysites are used in different industrial fields having an important potential. In this paper we reviewed the properties and structural characteristics of halloysites and their applications in wastewater treatment. Halloysites showed good results for heavy metals removal process from wastewater. Researches has been carried out on removing from wastewater heavy metals, such as: Cu(II), Fe(III), Cr(VI), Pd(II), Pb(II), Ag(I), Co(II), Zn(II).

Electrospinning is a unique technique that can be used to synthesize polymer and metal oxide nanofibers. In materials science, a very active field is represented by research on electrospun nanofibers. Fibrous membranes present fascinating features, such as a large surface area to volume ratio, excellent mechanical behavior, and a large surface area, which have many applications. Numerous techniques are available for the nanofiber’s synthesis, but electrospinning is presented as a simple process that allows one to obtain porous membranes containing smooth non-woven nanofibers. Titanium dioxide (TiO2) is the most widely used catalyst in photocatalytic degradation processes, it has advantages such as good photocatalytic activity, excellent chemical stability, low cost and non-toxicity. Thus, titanium dioxide (TiO2) is used in the synthesis of nanofibrous membranes that benefit experimental research by easy recyclability, excellent photocatalytic activity, high specific surface areas, and exhibiting stable hierarchical nanostructures. This article presents the synthesis of fiber membranes through the processes of electrospinning, coaxial electrospinning, electrospinning and electrospraying or electrospinning and precipitation. In addition to the synthesis of membranes, the recent progress of researchers emphasizing the efficiency of nanofiber photocatalytic membranes in removing pollutants from wastewater is also presented.

In the past years, nanotechnology has been studied and it proved that is one of the advanced ways for toxic compounds removal from wastewater. In this paper we focus on nanomaterials used for treatment of wastewater containing heavy metals. Nanoparticles have very high and specific adsorption capacity being applied in water depollution, remediation and treatment process. The depollution methods based on nanomaterials could be more cost-effective, less time and energy consuming, generating no or less waste in comparison with conventional methods. The aim of this review is to summarize the applications of nanoadsorbants within heavy metals depollution methods.