Removal of organic contaminants from aqueous systems

• Main Author: Goh, Sher Leen
• Published: University of Strathclyde 2015
• Subjects: 660
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.644869

This research investigates the removal of aromatic organic contaminants (nitrobenzene (NB), aniline (AN), paracetamol (PCT) and hydroquinone (HQ)) from aqueous systems. For NB, this study focusses on removal via both iron reduction and adsorption, while removal of the other three compounds is focussed purely on adsorption. The results demonstrate NB degradation using iron powder produces AN, with the rate decreasing under basic conditions, due to corrosive effects; it is established that the iron surface is essential to the degradation process. Initial NB concentration influences degradation, and pseudo-first order kinetics are observed for all systems studied. For the adsorption studies on all four species, non-functionalised Macronet MN200, acidic functionalised hyper-cross-linked polymeric resins MN500 and S957, and Granular Activated Carbon (GAC) were tested as sorbents. The results show the kinetics of adsorption, for all contaminants, follow pseudo-second order models with rates controlled by particle diffusion. For adsorption of NB, PCT and HQ, the equilibrium uptake capacities increase with decreasing acidic functionalisation of the sorbent surface; while the opposite trend was obtained for AN removal. The adsorption rate decreased as sorbent acidic capacity increased, for all sorbents, due to the inherent surface chemistry and smaller surface area of the acidic functionalised sorbents used. For equilibria study, the Freundlich equation fits the data most appropriately and adsorption of all contaminants onto the selected sorbents is a physical process. Adsorption of NB, AN, and PCT onto the studied sorbents is favourable, while it is moderately favourable for HQ. Leaching tendencies showed < 40% of all contaminants were leached from the sorbents with the higher leaching rates for the macroporous sorbents. Overall, the results obtained suggest polymeric resins as viable candidates for the removal of targeted aromatic substances from aqueous systems.