Magnetic modification of microporous carbon for dye adsorption

• Microporous activated carbon was effectively impregnated with magnetite by co-precipitation.
• NH4OH as precipitating agent causes a collapse in the texture of activated carbon.
• The adsorption behavior of magnetic activated carbon was evaluated for the Reactive Black 5.
• The dye-loaded activated carbon can be thermally re-activated.

In this study, impregnation of microporous activated carbon with magnetite was achieved by co-precipitation of iron salts onto activated carbon. The evaluation of the adsorption ability of this material was examined using the anionic dye Reactive Black 5 as model dye pollutant (adsorbate). The effect of pH, ionic strength, contact time and initial dye concentration were also studied. It was found that high pH and high ionic strength favor the adsorption of Reactive Black 5. The adsorption kinetics and isotherms were well fitted by the fractal BS model and Langmuir model, respectively. The impregnation with magnetite decreases the adsorption capacity of activated carbon. Thermal re-activation of dye-loaded activated carbons was also succeeded. The characterization of the magnetic carbons was investigated by various techniques (SEM/EDAX, VSM, BET, FTIR, XRD, DTG) revealing many possible interactions in the carbon-dye system.

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