Experimental and Molecular Dynamics Simulation Insights into Adsorption of Co(II), Cr(III), and Cu(II) on Chitosan and Chitosan/Tripolyphosphate Nanoparticles.

Chitosan (CS)/tripolyphosphate (TPP) nanoparticles were synthesized using the ionic gelation method based on the mass ratio and volume ratio between CS and TPP and then subsequently characterized using XRD, FT-IR, and SEM. The interaction between the metal ions Co(II), Cr(III), and Cu(II) on CS and 2CS/TPP was simulated using molecular dynamics (MD), and the findings were compared with the experimental data. CS/TPP nanoparticles were more favorable than using pure chitosan at a % removal efficiency of 91.47, 89.11, and 78.11 for Cu(II), Cr(III), and Co(II), respectively. The binding energy between 2CS/TPP and the metals was more favorable than that for CS at -214.95, -106.87, and -58.11 kcal/mol for Cr(III), Co(II), and Cu(II), respectively. The CS/TPP nanoparticles greatly affect metal adsorption and are therefore considered materials for wastewater treatment.

Production of biomaterials from seafood waste for application as vegetable wash disinfectant.

The production of seafood waste was studied by analyzing calcium oxide from the shells of tropical oyster and chitosan from the shells of white shrimp to use as a vegetable wash disinfectant. The preparations used were: natural oyster shell powder (NOSP), calcined tropical oyster shell powder in a programmable furnace for 2 h at 700 °C (OSP700), 800 °C (OSP800) and 900 °C (OSP900) including white shrimp shell chitosan (CS). The physical properties of all biomaterials were analyzed using Thermogravimetric analysis, X-ray diffraction and Fourier-transformed infrared spectrometry. The results showed that NOSP and OSP700 were calcite calcium carbonate crystal, but OSP800 and OSP900 were transformed to calcium oxide and calcium hydroxide. The amino group found in the chitin from white shrimp shell was deacetylated to chitosan. By investigating the qualitative antibacterial activity of OSP900 and CS, the inhibition zone of OSP900 against E. coli was higher than that of CS (p < 0.05); however, the inhibition zone of CS against S. aureus was higher than that of OSP900 (p < 0.05). In addition, OSP900 had significantly higher quantitative antibacterial activity against E. coli than S. aureus. The MIC of OSP900 against E. coli and S. aureus for 15 min were 2.5 and 5 mg/mL, respectively; furthermore, the MBC of OSP900 against E. coli and S. aureus were 5 and 10 mg/mL, respectively. However, the inhibitory activity of CS against S. aureus was higher than against E. coli with MIC and MBC values of 5 and 10 mg/mL, respectively, for 15 min. When testing the biomaterials, OSP900 and CS, to inhibit the bacteria on kale and lettuce, 2.5 mg/mL of OSP900 for a vegetable-washing time of 15 min had the highest E. coli inhibition for both vegetables, while 2.5 mg/mL of CS for the same washing time had the highest S. aureus inhibition for both vegetables. Therefore, this research indicated that biomaterials prepared from tropical oyster shell and white shrimp shell wastes could be used as effective wash disinfectants to eliminate contaminated bacteria on vegetables.