Background: Water treatment sometimes needs a coagulation and flocculation process to remove suspended and colloidal materials. Inorganic coagulants used create concerns about pollution of the environment and harmful effects on the human’s health. The studies carried out previously indicated the capability of an active coagulant agent extracted from Descurainia Sophia seed to remove turbidity of water.
Methods: The purpose of this study was to investigate the effect of NaCl (0.05-1 gL^-1), NaOH (0.01-0.1 gL^-1), extraction duration (1-25 min) and the ultrasound frequency (0-45-75 kHz), used in the extraction of Descurainia Sophia seed, on the generation of color in purified water and to provide a model to predict the effects of the studied variables on color generation. Extraction was performed using water as solvent, supplemented with NaCl and NaOH and irradiated by ultrasound. Design of experiments and analysis of results were conducted by the D-optimal method based on the response surface methodology (RSM).
Results: The results demonstrated that only the effect of concentration of NaOH is significant in color generation (with p&It;0.05).
Conclusion: The effect of NaOH on color generation in purified water is predictable by the use of a statistically valid linear model at a confidence level of 95%.