Surface area and pore size tailoring of mesoporous silica materials by different hydrothermal treatments and adsorption of heavy metal ions

This paper reports the synthesis, characterization and adsorption behavior of mesoporous materials obtained by hydrothermal method using nonyltrimethyl ammoniumbromide (NTMAB) template without any functionalization. The template of the as synthesized materials was removed by calcination. The effective elimination of template was confirmed by FT-IR spectra. It is observed that temperature, time, calcination, filtration and pH were the different parameters that affect the surface of the mesoporous materials. Increase in temperature, time and calcination affected significantly the distribution of pore size and surface area. Relatively high surface area (779.83 m2/g) and large pore size (2.28 nm) were obtained at optimum synthesis conditions. Dialysis membrane filtration was found to be successful for first time. Langmuir adsorption of metal ions, such as Pb2+, Cu2+ and Ni2+ was discussed and the experimental results reveal that the adsorption is physical phenomenon and maximum adsorption was obtained in optimized experimental conditions. Under the same experimental conditions, Pb2+ (9.85 mg/g) showed enhanced adsorption when compared to Cu2+ (3.85 mg/g) and Ni2+ (2.58 mg/g) due to larger ionic radius and higher electro-negativity. A comparative study of adsorption capacity of as synthesized mesoporous materials with commercially available adsorbents showed that the order of adsorption is as follows; ZC-9 > PAC > zeolite-Y > beta zeolite. Hence, herein reported mesoporous materials hold great potential to remove heavy metal ions from aqueous solutions.