Sustainable conversion of agro-wastes into valuable products using inexpensive nano-catalyst

Abstract

A systematic investigation employing wasted printed circuit boards (W-PCB) derived silica-alumina based glass fiber (GF) support grafted with molybdenum oxide and gallium oxynitrate catalyst (GaMo-GF) have been synthesized and studied for photocatalytic-hydrolysis of delignified corncob (DCC) to reducing sugars (RS) in a quartz halogen solar batch reactor(QHSR). Corncob was delignified by peroxide-acetic acid treatment. The highest RS yield obtained from DCC (cellulose 75.14%, hemicellulose 22.65% and lignin 2.1%) by using the said catalyst was 72.47% (at 100⁰C for 20 mins of reaction time and 15 wt. % catalyst). On contrary at the same condition the traditionally heated reactor (THR) gave a low yield of 25.58%. The optimum GaMo-GF catalyst was found to have a surface area of 28.008 m2/g, high pore volume (0.04198 cc/g) & high pore diameter (13.5872 nm), respectively, according to BET analysis. Furthermore, MoO3 and GaON crystalline phases were also detected by XRD and the presence of gallium and molybdenum has been confirmed by FTIR analysis. The band gap of the synthesized catalyst was found to be 2.3eV through UV-Vis-NIR spectroscopy. Using the openLCA platform (ecoinvent database v3.8), the process' overall environmental sustainability was evaluated. The QHSR response was significantly more ecologically benign than the THR reaction having over 50% lower harmful environmental impacts. Moreover, the QHSR proved to be more than 90% energy efficient than THR.