QSPR modeling of adsorption of pollutants by carbon nanotubes (CNTs)

Abstract

Harmful effects produced by hazardous chemicals/pollutants toward the environment have been a serious issue of concern since the past. Therefore, a cherished goal of chemists lies in applying novel methods to control the harmful effects of hazardous chemicals/pollutants toward the environment. There are several traditional techniques which are widely used to make the environment free from all types of toxic/hazardous contaminants. Among these processes, adsorption is widely used as an efficient technique to remove various toxic contaminants from the environment due to its low-cost process and because it is easy to perform. Nanotechnology has introduced a new generation of adsorbents like carbon nanotubes (CNTs), which have drawn a widespread interest due to their outstanding ability for the removal of various inorganic and organic pollutants from the environment. CNTs have been widely investigated as alternative adsorbents for the pollution management due to their high surface area and high adsorption affinity toward the organic contaminants, and that they can be modified (functionalized) in different ways to enhance their selectivity toward specific target pollutants. Estimation of adsorption property of environmental pollutants like organic materials, heavy metal ions, radioactive elements, etc. is necessary for both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). However, considering a sufficient number of such chemicals synthesized in factories and industries, it will be very impracticable to carry out an exhaustive testing of chemical hazard. To investigate the toxic property of hazardous chemicals using nanoparticles like CNTs is time-consuming, and it needs animal experimentation. According to REACH (Registration, Evaluation, and Authorization and Restriction of Chemicals), use of laboratory animals is causing ethical, scientific, and logistical problems that would be incompatible with the time-schedule envisaged for testing. In this perspective, the non-animal methods like quantitative structure-activity relationships (QSARs) could be used in a tiered approach to provide a rapid and scientifically justified basis to evaluate the adsorption property of different hazardous organic chemicals onto the CNTs. The QSAR modeling investigates the chemical features or structural properties of organic chemicals which are essential for adsorption of hazardous chemicals onto CNTs. The present chapter reviews the information regarding source of hazardous chemicals which are toxic to the environment, risk assessment and management of toxic chemicals, basic information of CNTs, and mechanism of adsorption of organic chemicals into the CNTs. Finally, an overview about the necessity of in silico methods like QSPR modeling for prediction of adsorption property of toxic chemicals as well as successfully reported QSPR models regarding adsorption of hazardous chemicals onto both SWCNTs and MWCNTs are discussed.