Applications of algae for environmental sustainability: Novel bioplastic formulation method from marine green alga

Abstract

BackgroundChemical plastics cause global environmental pollution and can take hundreds of years to be naturally removed from the environment; therefore, eco-friendly alternatives are sought. In that regard, marine algae are considered a promising source for bioplastics. However, macroscopic algae from the Arabian Gulf, despite being produced in massive quantities every year, have never been exploited for this purpose. Moreover, most of the available studies have been primarily based on the extraction of specific components of algae to prepare algal bioplastics, which is laborious and costly and does not allow the use of all biological products of algae. Therefore, the present study aimed at generating biodegradable bioplastic from the whole biomass of a marine green macroscopic alga from the Arabian Gulf, Saudi Arabia, using a simplified method.Materials and methodsThe identity of this green alga was investigated using both morphological characteristics and molecular analysis. Different treatments from the literature were initially tried to yield a bioplastic blend, but did not work. The successful method included drying the green macroalgal biomass and grinding it until it becomes a fine powder, followed by sieving. The powder was placed in 100 ml water with other reagents and then autoclaved. The resulting mixture was further treated with glycerin. Several reagents were tested, but successful treatment was achieved with the combination of the ground seeds of Plantago ovata and the chemical plasticizer polyethylene glycol (PEG; Mw = 3,350). The algal biocomposite was effective in forming a tensile polymer whose properties were further enhanced by adding glycerin 1 day after making the blend. Spectrophotometric, thermal, and mechanical analyses of the blend were conducted, including Fourier transform infrared (FTIR) spectroscopy, dynamic mechanical analysis (DMA) for the mechanical properties, and thermogravimetric analysis (TGA) for thermal stability. The biodegradability of the blend was also examined in sandy soil for 3 months.ResultsThe green alga was identified as macroscopic green alga Ulva sp., which was confirmed by both morphological and molecular analyses. The combination of a plant-based plasticizer and algal biomass formed a polymer with excellent tensile properties and thermal stability. FTIR confirmed the formation of a starch-based blend whose functional groups, O–H, C–H, C=O, and C–O, indicate the formation of a starch bioplastic derived from both starch and cellulose in the green alga and in P. ovata. Biodegradability was proven as the blend lost nearly 40% of its biomass after the soil burial test.DiscussionUlva sp. is a marine alga that is widespread in marine habitats. This particular alga is highly rich in carbohydrates including cellulose, hemicelluloses, starch, and ulvan, among other carbohydrates that constitute the major part of its dry weight. This alga and the plant plasticizer both contain starch as reserve food material. Both natural polysaccharides are excellent precursors for the formation of bioplastics and are completely biodegradable by soil microorganisms. PEG is also biodegradable by bacterial action. Therefore, the whole blend is not only biodegradable but also has suitable tensile strength and thermal stability.ConclusionThe present study describes an eco-friendly novel method that is mostly based on using the whole algal biomass in addition to a natural plant material as a plasticizer, thereby providing a sustainable blend for the manufacturing of bioplastics for use in a number of applications, including agriculture, as it is biodegradable and can be utilized for composting and fertilizing plants.

Algal-based bioplastics: global trends in applied research, technologies, and commercialization

“…However, there have been considerable amounts of research and pilot-scale projects conducted on this topic, and several commercial companies are currently successfully producing these bioplastics, which highlights that algal-based bioplastic production is a promising alternative. Breakthroughs in algae-based bioplastics include advancements in genetic modification for increased biopolymer yields (Kamravamanesh et al 2018 ; Kim et al 2020 ; Katayama et al 2018 ; Roh et al 2021 ), engineering for enhanced mechanical properties (Semary et al 2022 ; Zhu et al 2017 ), and novel applications in 3D printing (Mandal et al 2023 ; Vo et al 2022 ), highlighting the dynamic progress and multidisciplinary nature of research in this field.…”

3D-Printed Bioreceptive Tiles of Reaction–Diffusion (Gierer–Meinhardt Model) for Multi-Scale Algal Strains’ Passive Immobilization

“…This chemical interaction can range from adjusting the pH level of the used material composition to catalysis and ion exchange with the hosted strains. Another possibility for active immobilization is to employ algae-based biopolymers such as bioplastics for the immobilization of various algal strains [5], given that microalgae and marine algae are employed to synthesize bioplastic materials [6][7][8]. Optimally, both the chemical and geometrical compositions of a material should be customized to create an optimized bioreceptive surface.…”