Dr. Abdel-Wahab's primary focus is on chemical and physical processes associated with treatment of water and wastewater and solar-powered photoelectrochemical processes for carobon doixide reduction and contaminants degradation. This work includes discovery and development of new classes of treatment processes. It includes utilization of solar energy for photo-electrochemical conversion of CO2 into useful fuel, inland desalination with zero liquid discharge, reactive adsorption of heavey metas onto iron sulfide nanoparticles, development of innovative extensions of lime softening for removal of a wide range of contaminants from recirculating cooling water and brine concentrate in zero liquid discharge systems, advanced oxidation processes, advanced reduction processes, electrocoagulation; and some of the only research conducted on applying solid solution theory to water and wastewater treatment. He is also involved in developing reactive transport computational tools for environmental impact assessment and for prediction of chemical behavior in aquatic systems.