High-pressure carbon dioxide-hydrothermal enhance yield and methylene blue adsorption performance of banana pseudo-stem activated carbon

In order to reduce environmental risks and fungus disease spread of banana waste, the high-pressure CO2-hydrothermal treatment was developed to produce hydrochar as a precursor of activated carbon from banana pseudo-stem(BP). SEM, BET, XRD, Raman and FTIR was used to investigate the influence mechanism of the high-pressure CO2-hydrothermal pretreatment on the yield and methylene blue(MB) adsorption capacities of the activated carbon. The results show that although the adsorption capacities of BP after high-pressure CO2-hydrothermal pretreatment(BPx) is decrease due to decrease of oxygen-containing functional group and flatter spatial structure, that of BPx after KOH activation(BPx-A) significantly increase and is higher than that of BP by direct KOH activation(BP-A). Because BP-A presents honeycomb porous microstructures and has a higher mesoporous structure(138-472 m2/g), plentiful active sites and rich the abundant influential adsorption group of MB adsorption. In addition, compared to BP-A(0.68%), the total yield of BPx-A(2.42-9.11%) is 356-1340%.