Adsorption of methyl violet from aqueous solution using brown algae Padina sanctae-crucis

Objective: The presence of dyes in the water is toxic and harmful to human body so, it must be removed from the water. In the present study, the removal of methyl violet (MV) from aqueous solutions using brown algae Padina sanctae-crucis was investigated. Materials and methods: The rate of adsorption was investigated under various parameters such as contact time (5200), pH (2-11), dye concentration (10-60 mg/L), amount of adsorbent (0.25-5 g/L) and temperature (25-45 degrees C). Results: The maximum adsorption was achieved in 10 mg/L, pH= 8 and adsorbent dose 2 g/L and 80 min contact time for removal of MV from aqueous solutions. Kinetic studies showed that the pseudo second-order model describes adsorbent kinetic behavior better. Besides, experimental data have been modeled using Langmuir and Freundlich isotherms and the results showed that both models are proper to describe adsorption isotherm behavior. In addition, the equilibrium study shows that the adsorption was physical and favorable. Moreover, a thermodynamic study revealed that the adsorption process is exothermic and spontaneously in nature. Furthermore, Maximum adsorption capacity using adsorbent was 10.02 mg/g. Conclusions: It could be concluded that the P. sanctae-crucis biomass is a good adsorbent for removing MV dyes from aqueous solutions.