Enhanced substrate suitability of autoclave-assisted acid pre-treated waste sugarcane molasses: Pre-treatment optimization, sequential nano-based detoxification strategies, and bioproduct production

This study modelled and optimised an autoclave-assisted acid pre-treatment of waste sugarcane molasses for the recovery of reducing sugar. Afterwards, the efficiency of removing 5-hydroxymethylfurfural (5-HMF), furfural, and metallic ion inhibitors from the pre-treated hydrolysate was evaluated using a nano-based adsorbent towards bioproduct production. A high coefficient of determination (R² = 0.98) and a maximum reducing sugar concentration of 98.14 g/L were achieved under optimised conditions of 20% (w/v) substrate loading, 0.75% (v/v) sulphuric acid concentration, and 5 min autoclave duration. Furthermore, the application of nano-adsorbent (Fe₃O₄ nanoparticle (0.2% (w/v)) led to a reduction in 5-HMF and furfural concentrations by 29.05% and 53.53%, respectively. Additionally, the concentrations of metal ion contents (Ca, Mg, Na, and S) were reduced by 4.97%, 7.59%, 15.04%, and 7.63%, respectively. Remarkably, surface modification of Fe₃O₄ nanoparticle using poly (ethylene glycol) (PEG), tri sodium citrate (TSC), chitosan-coated and k-carrageenan (k-C) enhanced the removal of metal ion contents up to 42.74-fold. The potential of the optimised pre-treated and detoxified molasses for citric acid (4.04 g/L) and bioethanol production (47.93 g/L) was achieved. The high efficiencies in reducing sugar recovery, inhibitor removal, and bioproduct production demonstrate the potential of a sustainable, cost-effective, and eco-friendly molasses biorefinery concept.

Graphical Abstract