Method for the production of a material of plant origin that is rich in phenolic acids, comprising at least one metal, for carrying out organic synthesis reactions

Method for preparing a material of plant origin rich in phenolic acids, comprising at least one metal, said method comprising the following steps:

• a. preparation of a material of plant origin from a dead plant chosen from:
• aquatic plants;
• materials rich in tannins;
• materials rich in lignin;
• and
• obtaining a material of plant origin, rich in phenolic acids, in which the ratio of the intensity of the vibration band of the C═O bond of the COOH group and the intensity of each of the vibration bands the aromatic ring determined in FT-IR is between 0.5 and 4;
• b. bringing into contact the material of plant origin obtained at the end of step a) with an effluent comprising from 0.1 to 1000 mg/l of at least one metal;
• and
• c. obtaining a material of plant origin rich in phenolic acids comprising from 1 to 30% by weight of at least one metal relative to the total weight of the material.