Using a strong base anion resin to remove sulphuric acid from ammonium sulphate solution through acid retardation” presented by Busisiwe Silwana from Cwenga Technologies at the 4th Young Professionals Conference
I am Busisiwe Silwana, an intern at Cwenga Technologies. I completed my research project as a pre-requisite for obtaining my BTech in chemical engineering at the University of Johannesburg with the much appreciated assistance of Jenny Hardwick and Ed Hardwick from Cwenga. This research involved investigating the use of strong base anion resins to remove sulphuric acid from ammonium sulphate by acid retardation. The removal of sulfuric acid from ammonium sulphate using strongly basic anion exchange resins by acid retardation has not been widely reported; this is therefore a novel process.
Although commercial ion exchange resins are being used, this is not an ion exchange process. It is a diffusion dependent process, where the resins preferentially sorb strong acids. Hydrogen sulphate ions move against their concentration gradient through the boundary layer then through the pore volume, this is how the acid is sorbed onto the resin. This continues to happen until equilibrium is reached; at this stage, the resin is exhausted and no further acid retardation is possible. Acid retardation is successful when the acid is sorbed and the solution is no longer acid rich. Desorption was successfully done with water. Hydrogen sulphate ions moved against their concentration gradient through the resin pore volume then the boundary layer into the bulk solution. This yields an acid rich product.
Acid retardation using commercial ion exchange resins was further proved when a battery acid solution was put through the column and sulphuric acid was recovered.
Separating sulfuric acid from ammonium sulphate allows for capital generation from the waste. Using water for regeneration reduces the amount of regeneration chemicals being used; dropping the amount of effluent produced as well as chemical costs. Moreover, using commercial instead of specialized resins reduces the costs of recovering acid by acid retardation.