Evaluation and modelling of continuous flow sub-critical water hydrolysis of biomass derived components; lipids and carbohydrates

• Demonstration of the utility of sub-critical water (SCW) as a catalytic medium for processing lipids and carbohydrates.
• Feasibility and process advantages of continual flow SCW mediated hydrolysis of lignocellulosic biomass demonstrated.
• Applied and validated RSM to assist process optimisation related to multi product biorefining development.
• Efficient (>90%) sub-critical water mediated hydrolysis of sunflower TAGs within 60 min.

Sub-critical water is widely accepted as an environmentally benign solvent, for extraction but also as a catalytic medium therefore has the potential to support processing of multiple components found in biomass. The manuscript demonstrates the versatility of sub-critical water as a generic medium to support hydrolysis of rice bran (carbohydrates) and sunflower oil (lipid substrates), substrates that possess very different physio-chemically properties within a continuous flow process configuration. Response surface methodologies (RSM) were used to assist modelling the multiple process parameters that impact sub-critical water mediate hydrolysis of sunflower oil. Successful validation, of the models illustrate that 100% FFA yield would be achieved at temperature 385 °C; pressure 20 MPa; residence time of 35 min; oil to water ratio 1:1.8 (v/v) represents 65% water. Experiments conducted under these conditions yielded 93.5%, thereby confirming the utility of the RSM as a tool to assist in process development.