Synthesis of sulphonic acid functionalized magnetic mesoporous silica for Cu(II) and Co(II) adsorption

Abstract

Sulphonic acid functionalized core-shell magnetic mesoporous silica nanoparticles have been synthesized and used for preconcentration and enrichment of Cu(II) and Co(II). Mercapto groups were introduced via co-condensation which were then oxidized by H2O2 to incorporate the sulphonic acid functionality on the silica shell. The higher surface area of the sorbent and magnetic core simplified the extraction process. The adsorption of Cu(II) and Co(II) was achieved in less than 30 min at pH 7. The data showed that the adsorption mechanism followed pseudo-second order rate. The experimental data fits well in Langmuir, Freundlich and Temkin adsorption models. The maximum adsorption capacities for Cu(II) and Co(II) were 132 mg/g and 99.1 mg/g respectively. The newly synthesized material was successfully employed to develop an efficient preconcentarion method prior to the analysis of Cu(II) and Co(II) by graphite furnace atomic absorption spectrometer (GFAAS). The factors affecting the analysis were optimized and interferences from co-existing ions were also investigated. The detection limits for Cu(II) and Co(II) were 20 ng/L and 27 ng/L respectively. The results indicate that the new sorbent can be used for efficient preconcentration of Cu(II) and Co(II) from complex environmental samples.