Rapid detoxification of Microcystin-LR by selective catalytic hydrogenation of the Adda moiety using TiO2-supported Pd catalysts.

Abstract The hepatotoxicity of Microcystin-LR (MC-LR) is mainly caused by its Adda moiety. In this study, we used TiO2-supported Pd catalysts to selectively hydrogenate the C C bonds in the Adda moiety, achieving rapid detoxification of MC-LR in water under ambient conditions. MC-LR was removed within 5 min by catalytic hydrogenation on Pd(1.0)/TiO2 with a catalyst dosage normalized rate constant of 1.3 × 10−2 L mgcat−1 min−1, significantly more efficient than other catalytic treatment methods. The reactions proceeded in a highly selective manner towards catalytic hydrogenation at the C C bond of the Mdha moiety and subsequently the conjugated double bond of the Adda moiety, yielding two intermediates and one final product. Upon catalytic hydrogenation for 30 min on Pd(0.07)/TiO2, the toxicity of MC-LR (assessed by protein phosphatase 2A activity assay) drastically decreased by 90.8%, demonstrating effective detoxification. The influence of catalyst support, Pd content, initial MC-LR concentration, reaction pH, and catalytic stability were examined. Surface adsorption and the cationic Pd played a crucial role in the reaction kinetics. Our results suggest that catalytic hydrogenation is a highly effective and safe strategy for detoxifying MC-LR by selective reactions.