Abstract
This manuscript reports the synthesis and characterization of caprylpyrazolone tailored silica nanospheres, synthesized through sol-gel procedure by activating the silica nanospheres with organosilane precursor and grafting with caprylpyrazolone. Its successful attachment to the silica is confirmed by FTIR, TGA and elemental techniques. The feasibility of the synthesized nanospheres as adsorbent was systematically checked by elimination of trace level of Cr(III) from aqueous medium, using radiotracer technique. A number of factors such as effect of pH, agitation time, adsorbent and adsorbate dosage were optimized to guarantee the use of the adsorbent for practical use. Various counter ions were added to the matrix solution to check the selectivity of the synthesized sorbent. Various rate equations and adsorption isotherms such as Freundlich, D-R and Langmuir were employed to suggest the mechanistic pathway of the adsorption process. The Cr(III) extraction was monitored at room and elevated temperatures and thermodynamic parameters such as change in enthalpy, entropy, and Gibbs free energy of the metal ion uptake were computed. The removal of Cr(III) is endothermic (Delta H = 30.00 J mol(-1) K-1) and spontaneous (Delta S = 105.43 J mol(-1) K-1) in nature. Application of the adsorbent to real water samples demonstrated the practical utility of the adsorbent. The sorbent displayed good stability. Its cleaning efficiency is not significantly affected after various adsorption-desorption cycles and so it can be used repeatedly.