Effective removal of metal ions from aqueous solution by mesoporous MnO2 and TiO2 monoliths: Kinetic and equilibrium modelling

In the present study, ordered hierarchically porous silica (by sol-gel method) and metal-oxide monoliths (through nanocasting method) were synthesized. Porous silica and metal oxide monoliths (MnO2 and TiO2) exhibited excellent adsorption for heavy metal ions such as Pb(II) & Cd(II). The morphological and structural study of the synthesized silica and metal oxide monoliths were done by FESEM and XRD analysis. The adsorption studies were conducted in different batches. The maximum adsorption of Pb(II) on SiO2, MnO2 and TiO2 varied from 91 to 125, 166-200 and 769-857 mg/g respectively depending upon the choice of PEG, which is used as a structure directing/controlling agent. Similarly the maximum adsorption of Cd(II) on SiO2, MnO2 and TiO2 varied from 90 to 100, 100-125 and 667-770 mg/g respectively. The effects of contact time (0-80 min), temperature (at 303, 313 and 323 K) and pH (3-10) on the Pb(II) & Cd(II) removal were also explored.