Ferric chloride assisted plasma pretreatment of lignocellulose

In this study, a novel pretreatment for spent coffee waste (SCW) has been proposed which combines two techniques viz. atmospheric air plasma and FeCl₃ to create a superior pretreatment that involves Fenton chemistry. The pretreatment was optimised employing Taguchi Design of Experiments, and five parameters were taken into consideration viz. biomass loading, FeCl₃ concentration, H₂SO₄ concentration, plasma discharge voltage and treatment time. The composition analysis of the pretreated SCW revealed substantial amounts of lignin removal, with a maximum for process conditions of 70kV for 2min in an acidic environment containing 1% H₂SO₄. FTIR, XRD and DSC were performed to characterise the samples. The pretreated SCW after enzymatic hydrolysis yielded 0.496g of reducing sugar/g of SCW. The hydrolysate was subjected to fermentation by S. cerevisiae and led to the production of 18.642g/l of ethanol with a fermentation efficiency of 74%, which was a two fold increase in yield compared to the control.