دانلود رایگان مقاله انگلیسی روند اخیر در سنتز گرافن و اکسید گرافین بر اساس نانومواد برای حذف فلزات سنگین - الزویر 2018

Abstract

The advanced synthesis and development of raw graphene based on various significant functionalization has been outstanding in the wastewater treatment compared to the other alternatives such as carbon nanotubes and other carbon nanomaterials. Nano size graphene is known to possess large surface area and some promising properties in terms of mechanical, electrical, chemical and magnetism. Besides, the graphene can be generated via both Top-down and Bottom-up methods such as chemical exfoliation, chemical vapor deposition and other techniques so that it can be further functionalized to form graphene oxide-based nanomaterials. Hence, graphene oxide-based nanomaterials are discovered to be useful in the application of heavy metal removal from wastewater. In short, this paper critically reviewed on the synthesis method of graphene and application of graphene oxidebased nanomaterials in the term of heavy metal removal. The advantages, drawbacks, comparison of the data efficiencies, and research requirements are further highlighted, elaborated and discussed detailly. Lastly, the future challenges of graphene are elaborated. Therefore, it can be guaranteed that the wastewater discharged should be detected with the minimum or none of the heavy metals so that minimum effects on the ecosystem is discovered.

6. Conclusion

In short, for the synthesis of graphene, Top-down method such as chemical exfoliation is more recommended to be used since Top-down methods can produce the least layers and smaller size of graphene compared to Bottom-up methods. For instance, production of graphene by using chemical exfoliation method such as improved Hummers method could result in Nano-sized graphene which fulfil the requirement of producing graphene oxide-based nanomaterials for heavy metal removal from wastewater.

Furthermore, by referring to the Tables 5-8, some nanomaterials are capable to remove few types of heavy metals. For instance, PAMAMs/GO can remove Cd(II), Pb(II) and Cu(II) ions while L-Trp/GO and EDTA/mGO can eliminate both Pb(II) and Cu(II)ions. Besides, chitosan/SH/GO are used to remove Cd(II) and Cu(II) ions but graphene nanosheets can be used to adsorb both Cd(II) and Pb(II) ions. Lastly, chitosan/GO can be act as the adsorbent to remove Pb(II), Cu(II) and Cr(VI) ions. In short, Pb(II) ions are the most favourable heavy metal to be adsorbed among the nanomaterials mentioned previously.