Quantum dot- β-Cyclodextrin nanofiller decorated thin film nanocomposite membrane for removal of cationic and anionic dyes from aqueous solution

Abstract

Graphene oxide quantum dots (GOQDs) are finding tremendous attention as nanofillers in separation processes owing to their excellent chemical and mechanical robustness. GOQDs-functionalized thin film nanocomposite (TFN) membranes were fabricated via low pressure mediated interfacial polymerization (IP) over a polysulfone support, where β-Cyclodextrin (β-CD) was taken as an aqueous monomer with a fractional amount of GOQDs and tetraethylenepentamine (TEPA) as the organic monomer. The resultant TFN membranes showed improved hydrophilicity over its pristine polymeric analogue. The best performing membrane was obtained for MPG2, which had a mass loading of 3 % of β-CD, 0.3 % of TEPA and 0.4 % of GOQD during the interfacial polymerization. The membrane showed pure water flux that was two fold higher than that of the pristine polymeric membrane, with a dye rejection of 99.6 % for congo red and 96 % for methyl blue. This excellent rejection for the anionic dye can be attributed to the Donnan exclusion imparted by the negative charges on the membrane surface. The salt rejection properties of the membranes were also analyzed and the MPG2 membrane exhibited a high rejection rate of 96 % and 99.1 % for the salt containing Cl− and NO3− ions, respectively.