Cationic and Anionic Dye Removal of Modified Ulva lactuca L. and Antioxidant Activity

This study aimed to investigate the removal of fuchsin and nigrosin synthetic dyes using modified Ulva lactuca L. The study used the adsorption process under laboratory conditions to determine the removal effect of initial dye concentration (25, 50, 100 mg L-1) at different exposure times (60, 90, 120 min), constant temperature (26±1 ºC), biomass dosage (1 g dw) and pH (7–8) values on the dried biosorbent chemically treated with magnesium chloride (MgCI2) and potassium hydroxide (KOH). The research also provides information on changes in some biochemical properties of the biosorbent by exposure to MgCI2 and KOH. The adsorption of the dyes on U. lactuca was modeled with the Langmuir and Freundlich isotherms. The study results determined maximum dye removal for fuchsin (70.81%) and nigrosin (61.29%) dyes at 120 min exposure time and 50 mg L-1 dye concentration onto non-modified U. lactuca biomass. The mean dye removal for fuchsin (60.08%, 99.12%) and nigrosin (56.23%, 54.27%) was obtained on U. lactuca biomass treated with MgCI2 and KOH, respectively. The sample prepared at 60 min contact time and 50 mg L-1 dye concentration had the highest adsorption efficiency for fuchsin on U. lactuca biomass treated with KOH (99.40%). These results demonstrated that the KOH exposure onto Ulva is an efficient, non-polluting, and economical process for eliminating fuchsin from aqueous solutions.