Polyhydroxybutyrate (PHB) is a biopolymer of natural origin, one of the suitable alternatives for synthetic plastics. However, pure PHB has a high production cost, is relatively brittle, and has poor processability, hence its limited application. Combining PHB with biomass fillers and plasticizers can significantly improve the properties of the polymer, leading to its commercial usage. In this study, PHB was incorporated with starch (S) as a cheap biomass filler and lauric acid (LA) as a potential plasticizer. The PHB/S/LA composites were prepared using a modified solvent casting method with the incremental addition of LA. The PHB/S ratio was maintained at a ratio of 80/20 (w/w). Physicochemical characterization via EDS, XRD, and FTIR proved that the composite components have blended through nucleation and plasticization processes. The morphology of the PHB/S blends was found to be a heterogeneous matrix, with decreased inhomogeneity upon the addition of LA in the composite. Thermal characterization done by TGA and DSC showed that the thermal properties of PHB/S films improved with the addition of LA. Mechanical tests (UTM) proved that the elastic strain of the films also increased with the addition of LA, although the tensile strength decreased slightly compared to pure PHB/S. Overall, the results of this study provide baseline information on the improvement of PHB-based bioplastics.

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Magnetic citric acid-modified cellulose was successfully produced and tested for the removal of copper in aqueous solution. Initially, the cellulose material was reacted with citric acid solution. The modified cellulose was then attached to the Fe2O3nanoparticle producing an adsorptive magnetic material. Characterization using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy indicated successful binding and chemical modification of the cellulose. Its adsorption was also studied to evaluate its potential in removing heavy metals such as copper. Removal of copper was as high as 84.74% in solution containing 25 mg/L copper. The sorption of copper in the magnetic sorbent follows second-order kinetics and best fits Freundlich isotherm model. The developed material has a strong magnetic response, thus its recovery in the aqueous solution could be easily facilitated using a magnetic field. Regeneration study indicated high recovery efficiency maintaining above 95.7% copper removal efficiency after three cycles of use. Thus, a highly efficient magnetic adsorptive material was produced using simple chemical modification aside from its easy recovery in the water.