Comparative assessment of the interface between poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and fish scales in composites: Preparation, characterization, and applications

Study on the Compressive Strength and Reaction Mechanism of Alkali-Activated Geopolymer Materials Using Coal Gangue and Ground Granulated Blast Furnace Slag

By reutilizing industrial byproducts, inorganic cementitious alkali-activated materials (AAMs) contribute to reduced energy consumption and carbon dioxide (CO2) emissions. In this study, coal gangue (CG) blended with ground granulated blast furnace slag (GGBFS) was used to prepare AAMs. The research focused on analyzing the effects of the GGBFS content and alkali activator (i.e., Na2O mass ratio and alkali modulus [SiO2/Na2O]) on the mechanical properties and microstructures of the AAMs. Through a series of spectroscopic and microscopic tests, the results showed that the GGBFS content had a significant influence on AAM compressive strength and paste fluidity; the optimal replacement of CG by GGBFS was 40-50%, and the optimal Na2O mass ratio and alkali modulus were 7% and 1.3, respectively. AAMs with a 50% GGBFS content exhibited a compact microstructure with a 28 d compressive strength of 54.59 MPa. Increasing the Na2O mass ratio from 6% to 8% promoted the hardening process and facilitated the formation of AAM gels; however, a 9% Na2O mass ratio inhibited the condensation of SiO4 and AlO4 ions, which decreased the compressive strength. Increasing the alkali modulus facilitated geopolymerization, which increased the compressive strength. Microscopic analysis showed that pore size and volume increased due to lower Na2O concentrations or alkali modulus. The results provide an experimental and theoretical basis for the large-scale utilization of AAMs in construction.

Eco-friendly preparation and characterization of bioplastic films made from marine fish-scale wastes

Synthetic plastics are becoming hazardous wastes, posing a threat to environmental sustainable health; hence, they must be replaced with alternatives. This study aimed to prepare corn starch-based bioplastics using fish scale through film casting technique as an alternative to synthetic plastics. In this work, four types of bioplastic films (CSF, CSFSF1, CSFSF2, FSF) containing different percentages of fish-scale powder and corn starch were prepared. Physical and chemical properties such as texture, color, solubility in hot water, tensile strength, functional groups, and morphology of all the four types of the prepared bioplastics were analyzed. The mixture of fish-scale powder and corn starch powder in the ratio of 1:3 (CSFSF1) yielded the best results. Its average thickness is 0.0420 ± 0.001 mm, water absorption range is 55-60%, tensile strength is 6.06 ± 0.05 MPa, and thermal stability is 278.741 °C. In the biodegradability test, degradation was noticed after 7 days of treatment with organic waste. The degradation was confirmed by surface changes in the morphology and the development of Aspergillus sp. Corn starch film (CSF) exhibited the highest degradation (60%), while the fish-scales film (FSF) underwent the least degradation (28%). The produced bioplastics were prepared from eco-friendly, inexpensive, and natural materials. Thus, the present research has provided a viable alternative to synthetic plastics.

Recent Applications of Biopolymers Derived from Fish Industry Waste in Food Packaging

Fish waste is attracting growing interest as a new raw material for biopolymer production in different application fields, mainly in food packaging, with significant economic and environmental advantages. This review paper summarizes the recent advances in the valorization of fish waste for the preparation of biopolymers for food packaging applications. The issues related to fishery industry waste and fish by-catch and the potential for re-using these by-products in a circular economy approach have been presented in detail. Then, all the biopolymer typologies derived from fish waste with potential applications in food packaging, such as muscle proteins, collagen, gelatin, chitin/chitosan, have been described. For each of them, the recent applications in food packaging, in the last five years, have been overviewed with an emphasis on smart packaging applications. Despite the huge industrial potential of fish industry by-products, most of the reviewed applications are still at lab-scale. Therefore, the technological challenges for a reliable exploitation and recovery of several potentially valuable molecules and the strategies to improve the barrier, mechanical and thermal performance of each kind of biopolymer have been analyzed.

Biodegradable Composite Nanofiber Containing Fish-Scale Extracts

A biodegradable composite nanofiber containing polyhydroxyalkanoate (PHA) or modified PHA (MPHA) and treated fish-scale powder (TFSP) was prepared and characterized. The powder (20-80 nm) was prepared by grinding after treating FSP with water, acid, and heat (450 °C) to yield the TFSP. Composite nanofibers (100-500 nm long) of TFSP/PHA and TFSP/MPHA were fabricated by electrospinning using a biaxial feed method. The TFSP, which had a high hydroxyapatite content, was suitable as a filler for composites. The Ca/P ratio of the TFSP was similar to that of the human bone. Particle size analysis and analysis of scanning electron microscopy images indicated that, compared with the PHA/TFSP composite, the MPHA/TFSP nanofibers were more uniform and bonded more strongly in the matrix. The tensile strength at failure of the MPHA/TFSP specimens was enhanced and increased with increasing TFSP content. The elongation at failure was lower and decreased with increasing TFSP concentration. The water contact angle decreased with increasing TFSP content in PHA/TFSP and MPHA/TFSP nanofiber membranes. The TFSP enhanced the hydrophilic effect of the PHA/TFSP and MPHA/TFSP nanofiber membranes and provided a more suitable environment for cell growth. This composite nanofiber has potential in many biomedical applications.

Antibacterial properties and cytocompatibility of biobased nanofibers of fish scale gelatine, modified polylactide, and freshwater clam shell

We report herein new nanofibers prepared from fish scale gelatine (FSG), modified polylactide (MPLA), and a natural antibacterial agent of freshwater clam (Corbicula fluminea Estefanía) shell powder (FCSP). A preparation of FSG from Mullet scales is also described. To improve the biocompatibility and antibacterial activity of the non-woven nanofibers, MPLA/FCSP was added to enhance their antibacterial properties. FSG was then combined with MPLA/FCSP using an electrospinning technique to improve the biocompatibility of the as-fabricated 100-500-nm-diameter non-woven MPLA/FCSP/FSG nanofibers. The resulting tensile properties and morphological characteristics indicated enhanced adhesion among FSG, FCSP, and MPLA in the MPLA/FCSP/FSG nanofibers, as well as improved water resistance and tensile strength, compared with the PLA/FSG nanofibers. MTT assay, cell-cycle, and apoptosis analyses showed that both PLA/FSG and MPLA/FCSP/FSG nanofibers had good biocompatibility. Increasing the FSG content in PLA/FSG and MPLA/FCSP/FSG nanofibers enhanced cell proliferation and free-radical scavenging ability, but did not affect cell viability. Quantitative analysis of bacteria inhibition revealed that FCSP imparts antibacterial activity.