Yit Thai Ong

A review on carbon nanotubes in an environmental protection and green engineering perspective

Recent developments in nanotechnologies have helped to benchmark carbon nanotubes (CNTs) as one of the most studied nanomaterials. By taking advantages of CNTs extraordinary physical, chemical and electronic properties, a wide variety of applications has been proposed in various engineering fields. In this short review, the contribution of CNTs is addressed in terms of sustainable environment and green technologies perspective, such as waste water treatment, air pollution monitoring, biotechnologies, renewable energy technologies, supercapacitors and green nanocomposites. Consideration of CNTs for large scale application from the aspect of cost and potential hazards are also discussed. Based on the literature studied, CNTs pose a great potential as a promising material for application in various environmental fields.

Carbon Nanotubes Applications: Solar and Fuel Cells, Hydrogen Storage, Lithium Batteries, Supercapacitors, Nanocomposites, Gas, Pathogens, Dyes, Heavy Metals and Pesticides

Energy and environment are major global issues inducing environmental pollution. Energy generation from conventional fossil fuels has been identified as the main culprit of environmental degradation from global warming effects, in addition to environmental pollution which arises from rapid industrialization and agricultural development. In order to address these issues, nanotechnology plays an essential role in revolutionizing the applications for energy conversion and storage, environmental monitoring, as well as green engineering of environmental friendly materials. Carbon nanotubes and their hybrid nanocomposites have received immense research attention for their potential applications in various fields due to their unique structural, electronic, and mechanical properties. Here, we review the applications of carbon nanotubes (i) in energy conversion and storage as in solar cells, fuel cells, hydrogen storage, lithium ion batteries, and electrochemical supercapacitors, (ii) in environmental monitoring and wastewater treatment as in the detection and removal of gas pollutants, pathogens, dyes, heavy metals, and pesticides, and (iii) in green nanocomposite design. Integration of carbon nanotubes in solar cells and fuel cells has increased the energy conversion efficiency of these energy conversion applications, which serve as the future sustainable energy sources. Carbon nanotubes doped with metal hydrides show high hydrogen storage capacity of around 6 wt% as a potential hydrogen storage medium. Carbon nanotubes nanocomposites have exhibited high energy capacity in lithium ion batteries and high specific capacitance in electrochemical supercapacitors, in addition to excellent cycle stability. High sensitivity and selectivity towards the detection of environmental pollutants is demonstrated by carbon nanotubes based sensors, as well as the anticipated potentials of carbon nanotubes as adsorbent to remove environmental pollutants, which show high adsorption capacity and good regeneration capability. Carbon nanotubes are employed as reinforcement material in green nanocomposites, which is advantageous in supplying the desired properties, in addition to the biodegradability. This paper presents an overview of the advantages imparted by carbon nanotubes in electrochemical devices of energy applications and green nanocomposites, as well as nanosensor and adsorbent for environmental protection.

A Review on the Use and Stability of Supported Liquid Membranes in the Pervaporation Process

In recent decades, pervaporation has been one of the most studied membrane separation processes and has undergone substantial progress and exciting breakthroughs due to its effectiveness in separating azeotropic mixtures and its low energy consumption. Often, pervaporation processes are operated using a solid membrane. However, the inherent limitations of solid membranes prompted the use of supported liquid membranes (SLMs), which are formed by immobilizing the liquid membrane with a porous supporting membrane. The idea of using a SLM in pervaporation is attractive because the rate of molecular diffusion in liquid is much higher than that in a solid membrane. This short article reviews the role of SLMs as a pervaporation membrane. The effects of operating parameters on the pervaporation performance of SLMs as well as concerns on the stability of SLMs and methods to improve its stability are discussed. At the end of this article, we propose the use of carbon nanotubes (CNTs) in SLMs and perform an evaluation of the commercial value of SLMs.