Thermochemical Liquefaction of Pomace Using Sub/Supercritical Ethanol: an Integrated Experimental and Preliminary Economic Feasibility Study

Fossil sourced chemicals such as aromatics, are widely employed in the chemical industry for the production of commodity items. Recognizing the un-sustainability of existing approaches in the production of these chemicals, the current study investigated the valorization of apple pomace (AP) for their production. The present study assessed AP valorization by imposing variations in processing conditions of temperature (100–260 °C), time (0.5–12 h), alcohol/water ratio v/v (0:1–1:0), and Fe(3+)/H(2)O(2) molar ratio (10:1–100-1), in accordance to the Box-Behnken experimental design. The optimal yield of the oil was 24.6 wt.%, at the temperature, time, alcohol/water ratio v/v, and Fe(3+)/H(2)O(2) molar ratio of 260 °C, 4.7 h, 1, and 100, respectively. Notably, the application of gas chromatography-mass spectroscopy showed that the oil product contained mainly aromatics and interestingly also alkanes, indicating that the experimental conditions imposed promoted secondary hydrogenation reactions of oxygen-containing species during AP valorization. A consideration of the comparative economics of the proposed AP valorization and the existing AP management approach, using approximate estimation techniques, highlighted the potential of a ~ 59% reduction in the unit cost of AP management. The study therefore presents a compelling basis for future investigations into AP waste management using the thermochemical liquefaction technology. GRAPHICAL ABSTRACT: [Image: see text]