Adamsite is a kind of arsenic-containing hazardous waste, and its harmless and resourceful treatment has been given extensive attention worldwide. This work combined experiment with theoretical computation (DFT) to explore its resource recovery potential in near- and supercritical water and the transformation behavior of arsenic and carbon. The experiment found that high temperature, long residence time, low feedstock concentration and the addition of K 2 CO 3 catalyst all promoted the decomposition and gasification of adamsite and facilitated the stable enrichment of arsenic in the residue. With no catalyst added (400 °C, 5 wt%, 60 min), the maximum molar fraction of H 2 was 19.3%. After reaction at 450 °C for 60 min using K 2 CO 3 catalyst (catalyst-to-feedstock mass ratio = 1:1, loading:10 wt% of feedstock), the molar fraction of H 2 significantly increased to 63.3%, while the highest immobilization rate of arsenic in the residue reached 99.2%. The DFT computation further theoretically revealed the decomposition paths and the migration mechanism of arsenic and carbon, providing an important theoretical basis for the safe disposal and resource recovery of the hazardous waste. • NSCW gasification of adamsite and the degradation mechanism of arsenic-containing waste were studied. • When K 2 CO 3 is added, both theH 2 yield and the fixation rate of arsenic have increased. • The migration paths of carbon and arsenic in the supercritical water treatment process have been revealed. • The reaction mechanism was explained at the atomic level using DFT calculations.
Su et al. (Sun,) studied this question.