Characterization and evaluation of factors influencing microcystin-LR removal by granular activated carbon produced from different raw materials

ABSTRACT

Microcystins (MC), which are among the cyanotoxins more commonly found in cyanobacterial blooms, are not efficiently removed by full-cycle water treatment technologies. As an additional barrier, there is the adsorption process with granular activated carbon (GAC). This research compared the efficiency of MC-LR removal by seven GACs produced from different raw materials, analyzing these samples’ properties: moisture, ash content, pH and textural characteristics. Initially, the results indicated that the GAC properties were influenced by the source material, as well as by the production method. In the adsorption assays, the Langmuir model indicated that in 4h, with 100 mg.L^-1 dosage, the granular activated carbon of lignite (CGLIN) had the highest MC-LR (C_o: 115.1 µg.L^-1) removal capacity (97.2%), with q_e,max of 10.6 mg.g^-1. The volume of mesopores significantly influenced the adsorption capacity of microcystin by the evaluated GACs (r=0.98, Pearson). These results can support the application of the MC-LR adsorption process in water treatment plants to minimize intoxication with contaminated water.

Keywords:
activated carbon; adsorption; microcystin-LR; advanced water treatment