Acidic dye wastewater treatment onto a marine macroalga, Nizamuddina zanardini (Phylum: Ochrophyta)

Biosorption of Acid Black 1 (AB1) onto brown macroalgae, Nizamuddina zanardinii, was investigated. The effects of different parameters including pH, biomass loading, dye concentration, temperature, and salinity on the biosorption capacity were studies. The result at equilibrium was successfully described by the Freundlich model, and the estimated biosorption capacity was 29.79 mg/g. The kinetic of biosorption at different agitation speeds (70–180 rpm) and particle sizes (56–500 μm) were evaluated by pseudo-second-order, pseudo-first-order, and intraparticle diffusion kinetic models. The results showed that the pseudo-second-order model could be used as a successful model for the biosorption kinetics. Thermodynamics of sorption was investigated at different temperatures from 283 to 313 K. The negative values of Gibbs free energy, ΔG0, and positive value of enthalpy, ΔH0, confirm the possibility of the biosorption process and the spontaneous nature of the biosorption. A decrease in particle size of N. zanardinii biomass increased AB1 biosorption capacity. Furthermore, addition of NaCl (0–40 g/L) resulted in minor improvement in the dye biosorption. Role of different functional groups on the surface of biomass for biosorption of AB1 was investigated using FTIR.

► Acid Black 1 biosorption was studied onto marine macroalga.
► The maximum dye removal efficiency was observed at pH 2.0.
► Freundlich isotherm model showed the best fit with the equilibrium data.
► A decrease in particle size of N. zanardini biomass increased AB1 removal capacity.
► Addition of NaCl (0–40 g/L) to the dye solution increased dye removal efficiency.