Effectiveness of Fucus vesiculosus algae on the removal of Brilliant Cresyl Blue and Methylene Blue from aqueous solutions

Abstract This paper aims to explore the uptake of two basic dyes (methylene blue (MB) and brilliant cresyl blue (BCB)) using the formaldehyde-treated algae Fucus vesiculosus (FV-FORMALD). The modified biomass was characterized by the point of zero-charge (pHpzc), scanning electron microscopy (SEM/EDS), and Fourier-transform infrared spectroscopy (FTIR) analysis before and after dye biosorption. The equilibrium data were best fitted with the Langmuir and Freundlich isotherms for MB and BCB, respectively. The maximum adsorption capacity (Qmax) of MB obtained by the Langmuir isotherm was 791 mg g− 1, whereas the maximum adsorption capacity of BCB obtained experimentally was 966 mg g− 1. Kinetics modeling shows that the adsorption of MB and BCB onto FV-FORMALD was well described by pseudo-second-order. The influence of the pH solution suggests that MB biosorption is increased at basic conditions (pH > 7), while for BCB biosorption, pH does not significantly influence it. The optimum temperatures for maximum adsorption capacity were 330.15 K and 300.15 K for MB and BCB, respectively. The optimum dosage of FV-FORMALD biomass for MB (2 g L− 1) and BCB biosorption (1 g L− 1) were studied. In addition, according to the results, the brown FV-FORMALD could be considered an appropriate waste biosorbent for removing cationic dyes due to its high effectiveness and an environmentally friendly and sustainable approach to water remediation.