Use of MMC for Treatment of Pharmaceutical Residues in Wastewater

Sammanfattning: Environmentally hazardous pharmaceutical residues in wastewater cannot successfully be removed by standard treatment procedures used in Swedish wastewater plants. There is a need for cheap, efficient techniques for removing pharmaceutical residues from wastewater. Mesoporous magnesium carbonate (MMC) and modified MMC were investigated for the application of adsorbing pharmaceuticals from wastewater. The removal of venlafaxine hydrochloride (VEN), sulfamethoxazole (SMX), carbamazepine (CBZ) and diclofenac sodium salt (DFC) was investigated. Studies were performed through small batch studies, where concentrations before and after shaking with material were analysed using UV-vis spectroscopy. Comparative studies were performed with activated carbon. Larger batch studies were also performed and the solid precipitate after adsorption was characterised to investigate surface interactions. Small batch studies showed that MMC was only efficient in removing pharmaceuticals at higher concentrations (> 200 mg L-1). Only the poorly water soluble pharmaceuticals, CBZ and SMX, were adsorbed at lower concentrations. The adsorption capacity at lower concentrations could be increased by modifying the MMC with a hydrophobic modifying agent. However, the adsorption capacity was manifold higher for activated carbon. Stability studies indicated that the material was not stable in water. XRD confirmed tendencies to crystallise and SEM confirmed changes in the surface morphology. This affected the porosity of the material, indicated by the significant decrease in specific surface area. The material needs further improvements in terms of water stability and surface chemistry before it could be useful for the application of adsorbing pharmaceuticals from wastewater.