Removal of trace pharmaceutical residues by adsorption on modified inorganic porous materials

Abstract

The objective of this research work is to study the mechanism and efficiency of mesoporous silica materials in removal of trace pharmaceutical residues by adsorption. HMS, SBA-15, and MCM-41 and PMO were synthesized via surfactant template method. A-HMS and M-HMS were synthesized by surface modification of virgin HMS with amino- and mercapto-organosilanes via co-condensation method. Functionalized PMOs were synthesized by surface modification of PMO with three different types of amino-organosilane. The physicochemical properties of the synthesized materials were investigated by XRD, SEM, TEM, N2 adsorption-desorption isotherm, TGA, DTA, elemental analysis, FTIR, acid/base titration, water contact angle and zeta potential analysis. XRD patterns showed that the synthesized materials had well ordered hexagonal structure. N2 adsorption-desorption isotherm showed that the pore sizes of synthesized materials were in the mesoscale. The removal of 5 selected pharmaceuticals (DCF, CBZ, NAP, CFA and ACT) were examined by batch adsorption experiment onto the synthesized materials. The adsorption capacity of HMS for CBZ, DCF and NAP increased after modification with mercapto functional group, whereas its adsorption for CFA and ACT increased after modification with amino functional group. The adsorption capacity of PMO for CFA increased after surface modification with mono-, di- and tri-organosilane. The adsorption capacity of PMO derivatives varied with the type and density of amine functional groups on their surface. In competitive (selective) adsorption study the adsorption capacity of HMS and M-HMS for DCF, CBZ and NAP varied with the molecular sizes of the adsorbates. But the adsorption of A-HMS for acidic pharmaceuticals (DCF, NAP and CFA) varied with the pKa of the adsorbates.