Presented paper

IMWA2019 Students work

Synthesis Of MoS2-Based Nanohybrid For Effective Removal Of Mercury From Aqueous Solution

Fosso-Kankeu, Elvis (1); Kumar, Neeraj (2); Pandey, Sadanand (1); Ray, Suprakas (2,3)
1: North-West University, South Africa; 2: DST-CSIR, South Africa; 3: University of Johannesburg, South Africa

Artisanal and small-scale mining is livelihood activity of considerable economic importance in developing countries, supporting the lives of millions of people across Africa, South America and Asia. One of the most recorded ASM activity is goldmining, which takes place through soil excavation and gold extraction from the soil. Mercury is used for the extraction of gold from the soil in a process called amalgamation which is considered as a cheap and reliable way of gold recovery from low-grade ore. It is however reported that the rudimentary practice of mineral extraction during artisanal and small-scale gold mining contributes to the emission of 1000 tonnes of mercury into the environment every year. Mercury is known as a very toxic element that can pose a serious threat to the life of humans, animals and other ecological entities. River pollution by mercury from ASM activities generally occurred in remote, poor and rural areas where access to safe and clean water is a challenge, compelling the community to rely on untreated water sources for their various needs. Such communities require a facile and affordable technology such as adsorption to treat their water; few adsorbents have been tested for the removal of mercury from water, ranging from grafted polymer cellulosic materials to surfactant impregnated clayish materials which all suffer a number of disadvantages including lower adsorption capacities, instability and lower affinity for mercury.

Carbon nanotubes have shown remarkable performance as adsorbent because of their intraparticle porosity, large surface area and sufficient stability during regeneration; while on the other hand Sulphur has been demonstrated to have high affinity for mercury. In the context of this study, mercapto propyl trimetoxysilane (3-MPTES) was grafted to multi-wall carbon nanotubes to form the composite SH-MWCNTs which was then used to synthesize SH-MWCNTs/MoS2 nanohybrid through hydrothermal method. The complex nanohybrid was then characterized using SEM in conjunction with EDS and FTIR spectroscopy. The adsorption behavior and capacity of the synthesized SH-MWCNTs/MoS2 nanohybrid during the removal of mercury from aqueous solution was then investigated through isotherm and kinetic models study; to the best of our knowledge, this the first time such composite has been tested for the removal of mercury from water.

The results showed high potential of the SH-MWCNTs/MoS2 nanohybrid for the removal of mercury which mainly occurred through a chemisorption mechanism.

The newly synthezised nanohybrid adsorbent could therefore be considered for the treatment of river water contaminated with mercury.