Conversion of palm oil sludge was studied by esterification and transesterification which used methanol as a reactant. The esterification of palm oil sludge was performed by variation of molar ratios of methanol to palm oil sludge (5:1, 10:1, 15:1, 20:1, and 25:1) and percentages of alum catalyst (3–7 wt%) at 60 °C for 3 h with stirring rate 300 rpm. Transesterification was also carried out by variation of KOH (0.5–2.5 wt%) at 60 °C and stirring rate 300 rpm for 1 h. The optimum molar ratio of methanol to palm oil sludge was 20:1 (6% alum catalyst). Meanwhile, the optimum concentration for transesterification was 1.5% of KOH. The yield of biodiesel production was 93%, the density and kinematic viscosity were 0.864 g mL−1 and 12.8 mm2 s−1, respectively. The existence of ester compounds in the product was shown by Fourier Transform Infrared Spectrometry spectrum data of carbonyl group (CO) at 1744 cm−1 and CO of ester at 1234; 1119 and 1026 cm−1. Gas Chromatograph-Mass Spectrometry analysis showed the biodiesel product contains palmitic acid methyl ester (23.4%), trans-methyl oleate (75.5%), cis-methyl oleate (< 0.1%), and methyl stearate (1.2%)

Surface functionalization of bacterial cellulose (BC) nanofibrils with aminated magnetite nanoparticles (MH) was carried out by one-pot solvothermal reaction of 1,6-hexanediamine, FeCl₃·6H₂O and BC pellicle in ethylene glycol at 200 °C for 6 h. The presence of amine surface-functionalized magnetite nanoparticles on the surface of cellulose nanofibrils not only significantly enhanced the thermal and mechanical properties but also the amine content of the nanostructured bacterial cellulose pellicle. Approximately 10.5 mmol g⁻¹ of amine was measured in the aminated magnetite-BC nanocomposite (BC@MH) which is about 14.3 fold higher than its counterpart (MH) prepared in the absence of BC pellicle. The never-dried BC@MH nanocomposite demonstrated a high adsorption capacity towards As(V) ions because of its high iron-oxide and amine content. Approximately 90 mg of As(V) can be adsorbed per gram of BC@MH.