1-Phenyl-3-Methyl-4-stearoyl-5-pyrazolone doped porous silica for solid phase extraction of metal from aqueous solution

Abstract

1-Phenyl-3-methyl-4-stearoyl-5-pyrazolone (HPMSP) doped mesoporous silica was prepared in a one-step synthesis by encapsulation of a pyrazolone ligand in surfactant templated silica. The influence of NaOH concentration used as catalyst and quantity of HPMSP on the doped mesoporous silica synthesis were investigated. When 0.1 M NaOH was used in the synthesis, the doping molecules were easily dissolved and the silica precipitation was rapidly occurred. This route of synthesis was capable of incorporating HPMSP into the doped mesoporous silica for the maximum amount of 0.09 mol, associated with complete accessibility of the ligand to the aqueous phase. The obtained materials were characterized by XRD, TGA and BET. The results showed that the crystal structure of HPMSP doped mesoporous silica was obtained from the synthesis. After removal of organic species by calcinations, the sol-gel doped silica prepared by this technique was mesoporous silica. The extraction ability of HPMSP doped mesoporous silicas with respect to Cu(∥) in 0.1 M NaNO₃ medium was investigated. It was found that these sorbents had an excellent Cu(∥) extraction capacity even at low pH values (pH 0.7). The effect of KNO₃ and Ca(NO₃)₂ on copper extraction by HPMSP doped mesoporous silica was also studied and it was shown that these ions did not interfere its sorption behavior. In addition, the excellent extraction capacity of the sorbents for Co(∥) and Ni (∥) was occurred above pH 4. The studies of extraction time revealed that the extraction was extremely rapid. Furthermore, quantitative desorption of metals from HPMSP doped mesoporous silica was accomplished using a 1 M HNO₃.