Co-hydrothermal carbonization of water hyacinth and polyvinyl chloride: Optimization of process parameters and characterization of hydrochar

Abstract The co-hydrothermal carbonization (co-HTC) of water hyacinth (WH) and polyvinyl chloride (PVC) was investigated and the response surface methodology, which could deduce the interactions among process parameters and establish reliable mathematical models forecasting the behavior of output variables, was implemented to optimized process parameters, including reaction temperature (200-260 °C), residence time (30-90 min) and WH/PVC mixing ratios (0.5-2). Statistical analysis revealed that reaction temperature was the predominant parameter affecting hydrochar dechlorination efficiency, yield, calorific value, energetic recovery efficiency and electricity consumption. The predicted condition of 200-30-0.5 could simultaneously acquire the optimal energetic recovery efficiency and electricity consumption for producing unit HHV, corresponding to 94.96% and 13.81. The characterization results identified that hydrochar could harvest lower H/C and O/C ratios as well as superior inorganics removal ability. Overall, the co-HTC of WH and PVC could definitely be a promising alternative to bridge the gap from solid wastes to renewable fuels.