Production, characterization and application of activated carbons derived from local biomass for the removal of emerging water contaminants: linking the circular economy to the blue economy

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Résumé

In Burkina Faso, the increasing presence of emerging contaminants such as cyanide and dyes from water resources is a major environmental concern related to sanitary diseases. To mitigate this problem, water treatment based on adsorption with local materials offers promising and sustainable alternatives instead to conventional treatment. This work investigated the adsorption potential of activated carbons to remove cyanide and methylene blue (MB)for water purification. The multi-scale methodological approach has combined the production and characterization of activated carbons, experimental applications, and chemical modeling of the retention of emerging pollutants. Activated carbons (AC) were produced by pyrolysis of rice husks at 650°C followed by chemical and physical activation. Batch experiments were carried out using synthetic solutions of cyanide and MB and operating conditions were optimized. Results of characterization of AC indicated their carbonaceous and microporous structure. The cyanide removal rate achieved 97% at pH ≥ 11 while 98.32% of MB was removed for 60 min of contact. Monolayer chemisorption was the mechanism governing the removal of the targeted contaminants, following a pseudo-second-order kinetic. Consequently, these remediation methods contribute to the prevention of health risks, the valorization of agricultural wastes and the development of innovative solutions.

Mots-clés

Adsorption, Activated carbons; Circular economy; Cyanide; Methylene blue