Carbon nanotubes used in polymer membranes for wastewater purification: an ab-initio theoretical study

In this chapter, ab initio modeling will be illustrated in order to investigate particular properties of some promising nanostructures, such as CNTs with the aim of proposing novel mixed-matrix polymer membranes. Indeed, nanostructures such as CNTs or graphene could confer an increase in membrane efficiency in terms of both selectivity and permeability. Specifically, the rejection by multi-walled CNTs (MWNTs) of low molecular weight organic solutes coming from industrial wastewater, such as cosmetics and textiles, and olive oils is investigated in depth, together with their water permeability. To start with, two key properties of a nano-enhanced membrane are investigated: firstly, the rejection of low molecular weight compounds by non-functionalized NTs, in order to predict the optimal nanotube sizes able to reject the target solutes; secondly, the permselective properties of a CNT composite membrane were studied in order to predict the permeability enhancement as a function of the density and inlet diameters of vertically aligned nanotubes. Finally, effective functionalization models are analyzed in order to maximize solute selectivity while retaining higher permeability.