Water Disinfection by Photosensitizers Immobilized in Polymers

Yamit Mualem, Chemical Engineering, Biotechnology and Materials, Ariel University, Ariel, Israel
Marina Nisnevitch, Chemical Engineering, Biotechnology And Materials, Ariel University, Ariel, Israel  

As the demand for environmentally friendly processes increases, the use of alternative technologies for water disinfection becomes increasingly attractive. This research proposes to immobilize photosensitizers (PS) onto a polymeric solid support in order to examine their antibacterial properties. For this purpose, a hot melting extrusion was performed with the help of a single screw extruder, which was used as a device for dissolution and homogenous distribution of PS in a melted polymer. This single-stage solvent-free approach to PS immobilization has a number of advantages over solvent-based processes due to its simplicity and lack of need for additional chemicals. Since immobilized PS is located in a solid phase there is no separation problem between the PS and the aqueous phase after the treatment. Hematoporphyrin (HP) was immobilized in polyethylene and tested for the ability to disinfect contaminated water. Immobilized HP was found to be active against Gram-positive and Gram-negative bacteria in batch experiments under white lamplight illumination. A model photodynamic reactor was designed for eradication of bacteria in a circulation mode under white lamplight and sunlight illumination. The experiments showed good disinfection activity of PS in a solid phase. The use of immobilized PS opens prospects for continuous wastewater disinfection.