Newly Developed Environmentally Friendly Sustainable Derivatives Based on Chitosan Extracted from Shrimp Shells Grafted with Acrylic Acid and/or Recycled Polyethylene Terephthalate Wastes: Preparation and Characterization

To enhance and widely spread the bioactive sustainable applications of chitosan (CH), three newly developed solid chitosan derivatives were prepared and characterized. Chitosan was obtained from shrimp shell wastes through alkaline deacetylation of its precursor chitin. The obtained CH was reacted with bis-(hydroxyethyl) terephthalate (BHET), which was derived from the recycling of post-consumer PET waste, to create the first derivative, referred to as CBHET. This derivative was then transformed into a second chitosan derivative by grafting with acrylic acid (AA) denoted as CBHET–AAI. The third chitosan derivative was produced by simultaneously reacting CH with both BHET and AA, added at the same time, and this product was designated as CBHET–AAII. The structural characteristics of the three prepared chitosan derivatives were evaluated and confirmed by applying Fourier Transform Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermal analyses (TGA, DTG and DSC), and scanning electron microscopy (SEM). Factors that could affect the properties of the final products were investigated, including treatment temperature, reaction time, and reactant concentrations. The three derivatives were found to be very hard, solid composites, insoluble in most common solvents, acids, bases, and even water. Based on TGA data, CBHET exhibited the highest mass loss at 63.4%, compared to 57.7% for CBHET–AAI and 41% for CBHET–AAII. The crystallinity index (ICR), average crystalline size (D) in ηm, and average interchain spacing <R> in A° were also calculated. According to the data obtained, it can be concluded that these chitosan derivatives are ideal bioactive, sustainable, and newly developed biopolymers based on two waste ingredient materials: namely chitosan from shrimp shell wastes and BHET from glycolysis of post-consumer PET. These novel derivatives can be utilized efficiently and safely as a sustainable biosorbent in the handling of wastewater management, treatment of low- and medium-level radioactive waste effluents, and many other potential applications.