Facile Green\nProduction of Chitin Nanomaterials from\nShrimp Shell Chitin Using Recyclable Maleic Acid and Microwave Irradiation

This study presents a facile, green, and sustainable\nmethod for\nthe integrated production of chitin nanocrystals (ChNCs) and nanofibers\n(ChNFs) from shrimp shell chitin using recyclable maleic acid and\nmicrowave irradiation. Maleic acid, a mild organic acid, is employed\nfor hydrolysis and functionalization, with 88.5% recovery for reuse,\ncontributing to the sustainability of the process. Optimal production\nconditions, determined using response surface methodology (RSM), were\nan 85% acid concentration, 26.63 min of reaction time, and 315.41\nW microwave power, yielding 26.28% ChNCs and 64.04% ChNFs. Transmission\nelectron microscopy (TEM) revealed rod-like ChNCs (543.71 nm length,\n48.70 nm width) and web-like ChNFs (61.15 nm width). Fourier-transform\ninfrared spectroscopy (FTIR) confirmed successful surface carboxylation,\nwith degrees of substitution of 0.32 for ChNCs and 0.28 for ChNFs.\nBoth nanomaterials exhibited high crystallinity (91.55% for ChNCs,\n87.65% for ChNFs), negative zeta potential values (−44.56 mV\nfor ChNCs, −16.93 mV for ChNFs), and enhanced thermal stability\ncompared to raw chitin. The process, evaluated using sustainability\nmetrics, yielded an E-factor of 3.317, highlighting significant waste\nreduction over conventional acid hydrolysis. This eco-friendly approach\naligns with green chemistry principles and offers a sustainable, scalable\nsolution for chitin nanomaterial production, suitable for diverse\nindustrial applications.