Process for producing heavy-metal-mediated biochar complex cured by using silicate

A process for producing a heavy metal mediated biochar composite, comprising the following steps of:

• step 1, preparing a heavy metal-based biomass by enriching an aquatic plant with heavy metals in sewage water;
• said heavy metal elements comprise lead, manganese and zinc;
• step 2, pyrolyzing said heavy metal-based biomass produced in step 1 together with a silicate-containing composite comprising red mud and bentonite to obtain a pyrolysis product, wherein the pyrolyzing is completed in three stages:
• first stage:
• the pyrolysis temperature is 200-350° C., the heating rate is 6-12° C./min, and the holding time is 0.5-2 h;
• second stage:
• the pyrolysis temperature is 360-450° C., the heating rate is 7-13° C./min, and the holding time is 0.5-3 h;
• third stage:
• the pyrolysis temperature is 460-600° C., the heating rate is 5-10° C./min, and the holding time is 1-4 h;
• and
• step 3, modifying zeolites with a strong acid, and mixing the modified zeolites with the pyrolysis product of step 2 to yield the heavy metal mediated biochar composite.