Sustainable biosorption of Methylthioninium Chloride in wastewaters using new Cystoseira barbata seaweed: Equilibrium isotherm, kinetic modeling and mechanism analysis

Due to its climatic diversity and geographical position, Morocco is one of the most productive countries of seaweed in the world. This work aims to study the Methylthioninium Chloride (referred to as Methylene Blue) adsorption from wastewater using raw marine seaweed C.barbata that are considered as one of the important algae that are responsible for pollution in the Mediterranean Sea. different factors such as biomass dose, pH, and contact time were examined to demonstrate their impact on the biosorption process. The contact time studied revealed that biosorption of Methylene Blue reached equilibrium in 55 min. The biosorption data was subjected to the kinetic models Pseudo-first and pseudo-second order. Pseudo second order model was aligned with the adsorption data, whereas data didn't fit pseudo first order model. Adsorption data were modelled with Freundlich and Langmuir isotherm equations at room temperature. The maximum adsorption capacity estimated was 29.56 mg/g based on Langmuir isotherm model. Thus, C. barbata can be regarded as a valuable natural biosorbent for the treatment of wastewaters containing toxic dyes.