Treatment method for forming a dye sorbent

Treatment method for forming a sorbent comprising:

• treating sawdust with sulfuric acid in a 4:3 weight ratio to form a sulfonating mixture,
• heating the sulfonating mixture at 100 to 200° C. to form a sulfonated sawdust,
• exposing the sulfonated sawdust to vacuum for at least 24 hours, then
• washing and drying the sulfonated sawdust at 50 to 150° C. to form a dried sawdust,
• treating the dried sawdust with a hydrogen peroxide solution to form a peroxide-treated sawdust,
• washing and drying the peroxide-treated sawdust at 50 to 150° C. to form a sulfonated and oxidized sawdust, and
• milling and sieving the sulfonated and oxidized sawdust to form the sorbent,
• wherein the sorbent has a dye adsorption capacity of 20 to 25 mg of dye per g of sorbent at 25 to 45° C.