Extraction of methylene blue coloring agent from model solutions with a plant-origin sorbent

The production output of dyes and pigments in chemical industry is constantly increasing. Sewage waters, which contain synthetic and organic coloring agents, produce toxic effect, which is preconditioned by their low MAC values - below 0.001 mg/dm ². The most promising method of the pigmented wastewater treatment, which allows reducing the pollutants' content to the regulated permissible amount, is the adsorption method. This work presents research findings concerning sorption purification of test water media, containing methylene blue coloring agent, by using crop farming waste - chopped sunflower (Heliánthus ánnuus) stalks - as a sorption material. It has been determined that the maximum sorption capacity of chopped sunflower stalks biomass for this coloring agent is 0.245 mmol/dm ². The processing of the received data has demonstrated that the obtained adsorption isotherm of methylene blue belongs to Type V isotherms according to classification by Brunauer-Deming-Deming-Teller (BDDT) or to the S-type, according to Giles' classification. This adsorption process is the most accurately described by the Brunauer-Emmett-Teller model (BET), based on the concept of multilayer adsorption.