Functionalization of acidified multi-walled carbon nanotubes for removal of heavy metals in aqueous solutions

Water pollution is a worldwide issue for the ecoenvironment and human society. removal of various pollutants including heavy metals from the environment is a big challenge. techniques of adsorption are usually simple and work effectively. in the current study, mwcnts were prepared by chemical vapor deposition (cvd) of acetylene at 600 °c. fe–co/caco3 catalyst/support was prepared by wet impregnation method. the crystal size of the catalyst was identified using xrd. acidified functionalized multiwalled carbon nanotubes (mwcnt) were produced from oxidation of multi-walled carbon nanotubes by mixture of h2o2 + hno3 in a ratio of 1:3 (v/v) at 25 °c. the structure and purity of synthesized functionalized cnts were examined by tem, n2-bet method and thermogravimetric analysis. the functional groups produced at cnts surface were investigated using ftir spectroscopy. acidified functionalized mwcnts with a high surface area of 194 m^2g^-1 and porous structure (17.19 nm) were used for water treatment from harmful cations (pb^2+, cu^2+, ni^2+ and cd^2+), single cation solutions and quaternary solution at different ph values and different times. the results were interesting because in single solutions the catalyst removed pb^2+, ni^2+, cu^2+ and cd^2+ with percentages of 93, 83, 78 and 15%, respectively, in 6 h. while in quaternary solution, adsorption was more complex and the order of the adsorbed metals was as following: pb^2+ (aq)>cu^2+(- aq)>cd^2+ (aq)>ni^2+ (aq).