Functionally reduced graphene oxide supported iron oxides composites as an adsorbent for the immobilization of uranium ions from aqueous solutions

Dual Effect of Acetic Acid Efficiently Enhances Sludge-Based Biochar to Recover Uranium From Aqueous Solution

Excess sludge (ES) treatment and that related to the uranium recovery from uranium-containing wastewater (UCW) are two hot topics in the field of environmental engineering. Sludge-based biochar (SBB) prepared from ES was used to recover uranium from UCW. Excellent effects were achieved when SBB was modified by acetic acid. Compared with SBB, acetic acid-modified SBB (ASBB) has shown three characteristics deserving interest: 1) high sorption efficiency, in which the sorption ratio of U(VI) was increased by as high as 35.0%; 2) fast sorption rate, as the equilibrium could be achieved within 5.0 min; 3) satisfied sorption/desorption behavior; as a matter of fact, the sorption rate of U(VI) could still be maintained at 93.0% during the test cycles. In addition, based on the test conditions and various characterization results, it emerged as a dual effect of acetic acid on the surface of SBB, i.e., to increase the porosity and add (−COOH) groups. It was revealed that U(VI) and −COO− combined in the surface aperture of ASBB via single-dentate coordination. Altogether, a new utilization mode for SBB is here proposed, as a means of efficient uranium sorption from UCW.

Iron oxides/graphene hybrid structures - Preparation, modification, and application as fillers of polymer composites

The current status of knowledge regarding magnetic hybrid structures based on graphene or carbon nanotubes with various forms of iron oxides is reviewed. The paper starts with a summary of the preparation and properties of iron oxide nanoparticles, both untreated and coated with silica or polymer layers. In the next section, organic-inorganic hybrid materials obtained as a result of a combination of graphene or carbon nanotubes and iron chemical compounds are characterized and discussed. These hybrids constitute an increasing percentage of all consumable high performance biomedical, electronic, and energy materials due to their valuable properties and low production costs. The potential of their application as components of materials used in corrosion protection, catalysis, spintronics, biomedicine, photoelectrochemical water splitting and groundwater remediation, as well as magnetic nanoparticles in polymer matrices, are also presented. The last part of this review article is focused on reporting the most recent developments in design and the understanding of the properties of polymer composites reinforced with nanometer-sized iron oxide/graphene and iron oxide/carbon nanotubes hybrid fillers. The discussion presents comparative analysis of the magnetic, electromagnetic shielding, electrical, thermal, and mechanical properties of polymer composites with various iron oxide/graphene structures. It is shown that the introduction of hybrid filler nanoparticles into polymer matrices enhances both the macro- and microproperties of final composites as a result of synergistic effects of individual components and the simultaneous formation of an oriented filler network in the polymer. The reinforcing effect is related to the structure and geometry of hybrid nanoparticles applied as a filler, the interactions between the filler particles, their concentration in a composite, and the method of composite processing.