Session: 03-15-01: Multifunctional Materials, Structures and Devices: Modeling, Design, Manufacturing, and Characterization

Paper Number: 69156

Start Time: Thursday, 12:40 PM

69156 - Comparison of the Multilayer Effects on Water Desalination Using Graphene and Mos2 

COMPARISON OF THE MULTILAYER EFFECTS ON WATER DESALINATION USING GRAPHENE AND MoS₂

Peter Ozaveshe Oviroh, Sunday Temitope Oyinbo, and Tien-Chien Jen

Mechanical Engineering Science Department

University of Johannesburg, Johannesburg, Gauteng, South Africa

 

 

Climate change and its related effects are imposing severe stress on the current freshwater supplies.  This has been exacerbated due to the growth in population, rapid industrialization, and increased energy demand. Increased water requirement is a global challenge. Although more than 70% of the Earth is covered by water, much of it is unusable for human use. Freshwater reservoirs, ponds, and subterranean aquifers account for just 2.5% of the world's overall freshwater availability. Unfortunately, these water supplies are not very unevenly spread. Therefore, the need to augment these supplies through the desalination of seawater or brackish water.

Reverse osmosis (RO) is currently the most widespread method of desalination. However, the unit cost of water is still high partly due to the thin-film composite (TFC) polymer membranes used in the current desalination system. Thus the need for low-cost nanomaterials for Water Desalination and Purification.  A promising way to meet this demand is to use two-dimensional (2D) nanoporous materials such as graphene and MoS₂ to minimize energy consumption during the desalination process. New nanotechnology methodologies that apply reverse osmosis have been developed. Among some of these technologies is using 2D materials such as graphene and MoS_2, which have been studied extensively for water desalination.

Single-layer nanoporous 2D materials such as graphene and MoS₂ promises better filtrations in the water channel. Although the single-layer graphene (SL_G) and single-layer MoS₂ (SL_MoS₂) membrane have much promise in the RO desalination membrane, multilayer MoS₂ and multilayer graphene membranes are simpler to make and more cost-efficient. Building on the SL_G and SL_MoS₂ membrane knowledge, we have used the molecular dynamics method (MD) to explore the effects of multilayer graphene and multilayer MoS₂ in water desalination. This comparison is made as a function of the pore size, applied pressure, salt rejection, and water flux. In addition, we also looked at the effect of the increased gap between layers of the nanoporous 2D membrane and then made the comparison.

From results obtained, averaging over all three membrane types studied for both graphene and MoS₂, the ions rejection follows the trend trilayer > bilayer > monolayer. We find that the thin, narrow layer separation plays a vital role in the successful rejection of salt ions in bilayers and trilayers membranes. These findings will help build and proliferate tunable nanodevices for filtration and other applications.

 

Keywords: Desalination, graphene, membrane, MoS₂, multilayers

Presenting Author: Peter Oviroh University of Johannesburg

Authors:

Tien-Chien Jen University of Johannesburg
Sunday Oyinbo University of Johannesburg
Peter Oviroh University of Johannesburg
Sina Karimzadeh University of Johannesburg