Preparation and characteristics of cellulose nanocrystals (CNCs) isolated from Palm empty bunches (PEB) at various temperatures and concentrations of sulfuric acid hydrolysis and their surface modification with aminomethylphosponic acid (AMPA)

Cellulose nanocrystals (CNCs) were successfully prepared from palm empty bunches (PEB) using an alkaline-bleaching-ionic solution method and sulfuric acid hydrolysis. The Fourier transform infra-red (FTIR) spectrum shows the presence of cellulose vibrations and the loss of lignin and hemicellulose vibrations. The hydrolysis temperature and sulfuric acid concentration affect CNC yield and characteristics. At the optimum hydrolysis temperature of 45 degrees C, and 70% H2SO4 produced CNCs with the following characteristics: a yield of 56.63%, a crystallinity index of 83.16%, a crystal size of 1.92 nm, a spherical morphology with an average length of 163.26 nm and an average diameter of 7.84 nm, and a composition consisting of elements C (53.10%) and O (46.23%). CNCs were successfully modified with aminomethylphosphonic acid (AMPA). CNCs and AMPA bond covalently. FTIR analysis showed several vibrations representing amine (554 cm(-1), 789 cm(-1), 1335 cm(-1), 1456 cm(-1), 1592 cm(-1), 1624 cm(-1)) and phosphite groups (1029 cm(-1), 1205 cm(-1)), indicating that AMPA had been grafted onto the surface of the CNCs. Optimum conditions for modification of CNCs were obtained using a 3% AMPA concentration, which produced CNCs/AMPA with a rod-like morphology, an average length of 228.02 nm, an average diameter of 11.34 nm, and a crystallinity index of 80.08% with a crystal size of 3.91 nm. Elemental analysis with energy dispersive x-ray (EDX) showed that CNCs/AMPA 3% consisted of elements C (26.95%), O (44.02%), N (16.95%), and P (10.24%).