Green Synthesis of TiO2 Nanoparticles Using Natural Marine Extracts for Antifouling Activity.

Titanium dioxide (TiO2) nanoparticles were synthesized via a novel eco-friendly green chemistry approach using marine natural extracts of two red algae (Bostrychia tenella and Laurencia obtusa), a green alga (Halimeda tuna), and a brown alga (Sargassum filipendula) along with a marine sponge sample identified as Carteriospongia foliascens. X-ray diffraction (XRD), scanning electron microscope (SEM), UV-Vis, X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR) were employed to characterize the crystal structure, surface morphology, and optical properties of the synthesized nanoparticles. Each of the as-synthesized marine extract based TiO2 nanoparticles was individually incorporated as an antifouling agent to form a newly fabricated marine paint formulation. The newly prepared formulations were applied on unprimed steel panels. A comparative study with a commercial antifouling paint (Sipes Transocean Coatings Optima) was carried out. After 108 days of the coated steel panels' immersion in the Eastern Harbour seawater of Alexandria-Egypt, the prepared paints using B. tenella and C. foliascens extracts demonstrated an excellent antifouling performance toward fouling organisms by inhibiting their settlement and controlling their adhesion onto the immersed panels. In contrast, heavy fouling with barnacles was observed on the surface of the coated panel with the commercial paint. The physicochemical parameters of the seawater surrounding the immersed coated panels were estimated to investigate the influence of the fabricated paint formulations. Interestingly, no effects of the immersed coated panels on the physicochemical characteristics of the surrounding seawater were observed. Based on the obtained results and a comparison with commercially available antifouling products, the marine extract based TiO2 nanoparticle preparations of B. tenella and C. foliascens are promising candidates for eco-friendly antifouling agents. Based on the obtained results and a comparison with commercially available antifouling products, the marine extract based TiO2 nanoparticle preparations of B. tenella and C. foliascens are promising candidates for eco-friendly antifouling agents, which could be attributed to the small crystallite sizes of 22.86 and 8.3 nm, respectively, in addition to the incorporation of carbon in the crystal structure of the nanoparticles.

Mining marine shell wastes for polyelectrolyte chitosan anti-biofoulants: Fabrication of high-performance economic and ecofriendly anti-biofouling coatings.

Banning organotins as antifouling biocides in 2003 was the starting point for many researchers to search for novel economic and environmentally-friendly anti-fouling biocides. In our present contribution, we have successfully functionalized a natural biopolymer, chitosan (CS), isolated from marine wastes with polyelectrolyte brushes akin to ionic liquids. These antifouling biopolymers anchoring polyelectrolyte brushes were in vitro assessed for their ability to eradicate or inhibit the Staphylococcal/Escherichia biofilms. Moreover, these anti-fouling candidates were incorporated into the matrix of commercial paint to formulate antifouling coatings which were subjected to a field static immersion test in the Mediterranean Sea in comparison to a standard antifoulant, Diuron®. The obtained results revealed the prevention of biofilms along with a promising anti-fouling performance. So the new polyelectrolyte chitosan architectures may offer promising anti-foulants additives for biofouling coating applications.