Development of a method for producing carbon sorbents by thermochemical pyrolysis of liquid cellulose waste

Summary

In the process of high-quality cardboard and newsprint production, cellulose is used prepared by thermal treatment of hardwood or softwood with cooking solutions based on alkali metal sulfites or bisulfites. As a result, spent cooking liquors containing lignosulfonates and lignosulfonic acids are generated that are subject to concentration by evaporation. A method is presented for producing carbon sorbent from evaporated liquor in the presence of an activator – potassium hydroxide; the method involves thermochemical pyrolysis of the raw material. It has been established that the developed method provides for one-stage production of carbon sorbents with properties comparable to engineering grades of active carbon. Tertiary treatment of pulping wastes by adsorption to remove lignosulfonates using active carbons of AG-3, BAU grades and carbon sorbents based on liquid lignosulfonates was studied. The obtained adsorption isotherms have allowed to establish that the carbon sorbent samples are applicable for removing organic compounds – lignosulfonates from water. A basic process flow scheme for the utilization of lignin-containing wastes with the production of sorption materials by thermochemical pyrolysis has been developed.

Key words

wastewater treatment , carbonic sorbent , pulp and paper industry , lignin-containing waste , adsorption isotherm