Reaction coupling separation systems using calcium fumarate as a substrate can break the reaction equilibrium and promote the production of l-malate. However, the low reusability and stability of fumarase limit its further application. In this study, partially purified fumarase of Thermus thermophilus (87.0 U mg−1) was immobilized within konjac-κ-carrageenan beads. An amalgamation of konjac and carrageenan gum (2%) was used to form the beads, and polyethylene polyamine (0.2%) and glutaraldehyde (0.1%) were used as the cross-linking agents. The pH and temperature profiles of free and immobilized fumarases were remarkably similar. The diffusion limit of immobilized fumarase caused a decline in the maximal velocity (Vmax), whereas the kinetic constant (Km) value increased. Optimization of the parameters for biotransformation by immobilized fumarase showed that 88.3% conversion of 200 mM calcium fumarate could be achieved at 55 °C within 8 h. The beads were stored for 30 days at 4 °C with minimal loss in activity and were reusable for up to 20 cycles with 78.1% relative activity. By recycling the reaction supernatant, a total amount of 3.98 M calcium fumarate was obtained with a conversion of 99.5%, which is the highest value ever reported.

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A high effective P/N-containing flame retardant additive CDD was triumphantly synthesized with nitrogen-rich 3,5-Diamino-1,2,4-triazole, DOPO and cinnamaldehyde. With the help of 4 wt% CDD, Epoxy resin (EP) sample succeeded in UL-94 V-0 test, and improved its LOI value to 33.5%. EP/4 wt%CDD sample also performed very well in cone calorimeter (CC) test. For example, the peak of heat release rate of EP/4 wt%CDD decreased to 603 kW/m2, which was 56.8% of EP sample without flame retardants. All these details showed that CDD was highly effective in fire resistance. Besides, the addition of CDD also drastically improved mechanical strength of EP. Tensile strength, flexural strength and izod iMPact strength of EP/4 wt%CDD sample was increased to 102 MPa, 124 MPa and 38 kJ m−2, which was 118.6%, 129.2% and 126.7% of control group. At last, the flame-retardant mechanism of CDD was studied by FTIR, XPS, Raman spectra, and SEM. The results showed that CDD’s perfect performance in fire resistance was ascribed to the generation of phosphorus-rich char layer in condensed phase.