In situ polymerization of magnetic graphene oxide-diaminopyridine composite for the effective adsorption of Pb(II) and application in battery industry wastewater treatment

A review on current progress of graphene-based ternary nanocomposites in the removal of anionic and cationic inorganic pollutants

The current review aims to summarize the ongoing advances in high-performing graphene-based ternary nanocomposites for removing cationic and anionic inorganic pollutants. Graphene derivatives are extensively utilized for the development of composites due to their high synergism with co-functional materials, rational design, flexible surface chemistry, high mobile charge carriers, improved binding properties, and many more. The past ten years have witnessed progressive research on graphene-based ternary nanocomposites in a multitude of pollution remediation applications. Therefore, the focus falls on understanding how these ternary nanocomposites are tailored to capture the inorganic cationic and anionic contaminants with particular emphasis on graphene derivatives as base matrix and filler. The review investigates the synthesis, categorization, and characterization techniques of graphene-based ternary composites. Besides, the study broadens the understanding of the binding mechanism of the pollutants onto graphene ternary composites. The review also assesses the separation and recycling efficacy of the composites in detail. The future prospects in improving the practical application of the ternary systems also have been discussed. The comprehensive review on graphene based ternary systems detailing their structural and functional aspects, as well as their performance as inorganic decontaminants can provide deep insights for researchers in improvising wastewater treatment technologies.

Preparation and characterization of polyethyleneimine functionalized magnetic graphene oxide as high uptake and fast removal for Hg (II)

Polyethyleneimine functionalized magnetic graphene oxide adsorbent (PEI-mGO) was synthesized by introducing polyethyleneimine onto Fe₃O₄/graphene oxide. The structures and morphologies of PEI-mGO was identified by using Fourier-tranform infrared (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) methods. Quantities of bar-like Fe₃O₄ nanoparticles were observed on the surfaces of PEI-mGO. The adsorption of PEI-mGO for Cu(II), Pb(II), Hg(II), Co(II) and Cd(II) was compared. The adsorption results indicated that PEI-mGO showed higher uptake for Hg(II) than the other ions. The influence of various variables for the adsorption of Hg(II) on PEI-mGO was explored. The adsorption kinetics and isotherm could be described well by the pseudo-second-order and Langmuir models. The maximal uptake of PEI-mGO for Hg(II) from Langmuir model was 857.3 mg g^-1, which was higher than that reported previously. The adsorption removal was a fast and endothermic process governed by the chemical process. The uptake increased with increasing temperature. PEI-mGO showed an excellent performance for removal of Hg(II) with 93.3% removal efficiency from simulated wastewater. Adsorption-desorption cycled experiments indicated that PEI-mGO could be recycled. PEI-mGO could be easily separated from the adsorbed solution by using a magnet. Hence, this novel adsorbent would be promising for the removal of Hg(II) from wastewater.

Three dimensional flower-like magnetic polyethyleneimine@MoS2 composites for highly efficient removal of Cr(VI) and Pb(II) ions

Magnetic Fe₃O₄ nanoparticles were coated by polyethyleneimine (PEI), and then Fe₃O₄@PEI was further modified with MoS₂ by the hydrothermal method to fabricate 3D flower-like structured magnetic polyethyleneimine@MoS₂ (MP@MoS₂) composites, and the composites were served as efficient adsorbents to capture Cr(VI) and Pb(II) from aqueous solution. The effects of temperature, pH, shaking time and environmental conditions on adsorption performance of MP@MoS₂ towards Cr(VI) and Pb(II) have been conducted by batch adsorption experiments. The prepared MP@MoS₂ exhibited high adsorption capacities (192.30 mg/g for Cr(VI) at pH 3.0 and 256.41 mg/g for Pb(II) at pH 6.0) and the adsorption equilibrium could be achieved in a short time. Moreover, MP@MoS₂ composites with high saturation magnetization could be simply separated under an external magnet. Combined experiments and spectral analysis, the underlying adsorption mechanism for Cr(VI) on MP@MoS₂ was mainly attributed to the reduction of Cr(VI) to Cr(III), and the removal of Pb(II) was due to the complexation with sulfur groups and amino-groups. Consequently, the prepared 3D flower-like structured MP@MoS₂ has a great potential for the practical application in removing Cr(VI) and Pb(II) from the aquatic environment.