Effect of branched 1,4-butanediol citrate oligomers with different molecular weights on toughness and aging resistance of glycerol plasticized starch.

The thermoplastic starch with glycerol is easy to retrograde and sensitive to hygroscopicity. In this study, branched 1,4-butanediol citrate oligomers with different molecular weights (P1, P2, and P3) are synthesized, and then mixed with glycerol (G) as the co-plasticizers to prepare thermoplastic starch (CS/PG). The results show that the molecular weight and branching degree of the branched 1,4-butanediol citrate oligomers increase as reaction time prolongs. Compared with glycerol plasticized starch, the thermoplastic starch films with branched 1,4-butanediol citrate oligomers/glycerol (10 wt%/20 wt%) have a better toughness, transmittance, and aging resistance, and have a lower crystallinity, hygroscopicity, and thermal stability. The toughness, transmittance, and aging resistance of CS/PG films are positively correlated with the molecular weight of the branched 1,4-butanediol citrate oligomers. These are due to the fact that the branched 1,4-butanediol citrate oligomer with a high molecular weight could form a stronger hydrogen bond and the more stable cross-linked structure with starch chains than that with a lower molecular weight. The elongation at break of CS/P3G film stored for 3 and 30 d are 98.0 % and 88.1 %, respectively. The mixture of branched butanediol citrate oligomers and glycerol, especially P3/G, has a potential application in the preparation of thermoplastic starch.

Adsorption of cationic dye from water using an iron oxide/activated carbon magnetic composites prepared from sugarcane bagasse by microwave method.

In this work, using an agricultural waste of sugarcane bagasse, new biomass of magnetic sugarcane bagasse activated carbon (MSBAC) has been successfully prepared by a simple microwave method. The composition and structure of MSBAC were characterised by SEM, XRD, BET, and FT-IR. It was found that MSBAC was a mesoporous material with a loose structure and rough surface, and it had a high specific surface area. The pHPZC was 4.1, and MSBAC presented a greater amount of acid functional groups than basic groups, making it efficient for adsorption of cationic dye. To study the adsorption ability of MSBAC, methylene blue (MB) was selected as sample pollutant. Effects of pH, MSBAC dosage, initial MB concentration, temperature, time on the adsorption of MB, and the possibility of regeneration of MSBAC were investigated. The adsorption results showed that the maximum adsorption capacity was 36.14 mg·g-1, and the pH had no significant effect on the MB adsorption in the range of 2-10. The equilibrium data fitted Langmuir isotherm, and the adsorption kinetic data obeyed pseudo-second-order kinetic model. The adsorption process involving the surface diffusion and film diffusion. The positive value of ΔH revealed the adsorption behaviour was an endothermic process. The salt concentration had a negative effect on MB removal. MSBAC had a good magnetic separation performance. The used MSBAC could be regenerated by a simple calcination method under the temperature of 300℃ for 30 min.