Investigation of cascade valorization of Pistia stratiotes L. by hydrothermal treatment

Aquatic plant Pistia stratiotes L. has widely dispersed around the world and is known for rapid reproduction in water system. However, over reproduction could generate serious issues such as clogging the waterways and results in secondary environmental pollution. Therefore, developing an economical and value-added route to valorize aquatic plants not only solves environmental pollution, but also provides novel utilization values. In this study, Pistia stratiotes L. was hydrothermal treated from 200 to 280℃, which can obtain hydrochar, light bio-oil and supernatant fractions. The surprising results showed that a large amount of alkali calcium (5.50 wt%) was enriched on the surface of hydrochar. And the hydrochar could be used as a catalyst for glucose isomerization to fructose after limited oxygen calcination. The yield of light bio-oil increases with the temperature and the composition contains a large amount of cyclopentene derivatives, which can be further refined to chemicals. The hydrothermal supernatant contains a large amount of calcium, magnesium, iron and other nutrients. The seed germination test showed that the supernatant liquid had certain bioactivity and had the potential of developing liquid fertilizer. This study provides basic reference for comprehensive and novel utilization of aquatic plants with abundant yield.