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This work proposes a Mixed Integer Nonlinear Programming (MINLP) model to determine the optimal design of macroalgae based chemicals production plants. The superstructure considers two brown marine macroalgae species (Macrocystis pyrifera and Lessonia vadosa) that are used to produce sorbitol for further transformation. Two additional alternatives are included: corn starch as the traditional feedstock to obtain the corresponding sugars and directly buying sorbitol from market. Sorbitol is transformed into isosorbide, a platform molecule, which can be converted into a drug for heart disease (isosorbide dinitrate), a flame retardant, a biopolymer and a biosolvent (dimethyl isosorbide). The Renewable Process Synthesis Index Metric (RePSIM) is used as objective function to address sustainability. Alternatively, Net Present Value (NPV) is also considered to obtain a detailed economic analysis. In terms of sustainability, the production of isosorbide dinitrate is the optimal pathway, albeit it shows a negative RePSIM of −4.30 million USD/yr. On the other hand, the production of dimethyl isosorbide is the optimal configuration taking into account the economic objective function. Its NPV is 44.31 million USD with a production cost of 6.97 USD/kg. It is worth mentioning that the social and environmental aspect of the dimethyl isosorbide production process is positive. In this sense, this chemical can be obtained from marine macroalgae biomass in a profitable way with a process that is socially and environmentally beneficial.

Bio-chars produced from the pyrolysis of sunflower seed hulls are investigated in the context of adding value to edible oil industry waste. Magnetic bio-chars are obtained to employ them for the aqueous adsorption of guaiacol, which is a model molecule of pollutants in water. Two magnetization methods are followed to get a series of magnetic bio-chars, one based on the pyrolysis of sunflower seed hulls previously washed with FeCl3·6H2O solutions (MBFs) and the other one consisting of magnetization of the bio-char obtained from the pyrolysis of the hulls pretreated with ZnCl2 (MBZ). A full characterization of the samples is carried out by Scanning Electronic Microscopy (SEM), X-Ray Diffraction (XRD), Atomic Absorption (AA), Fourier Transformed Infrared spectroscopy (FTIR), and N2 sorptometry. Selected magnetic bio-chars are tested for the adsorption of guaiacol in water with four models: Langmuir, Freundlich, Sips and Temkin. The best performance is assigned to the sample MBF5 containing 15.2 Fe %wt. with a maximum adsorption capacity of 48.49 mg/g and a heterogeneous surface according to Sips model. Temkin model predicts physisorption as guaiacol surface interaction presenting a b parameter of 15.87 J/mol.