Synthesis of magnetic activated carbons derived from Artocarpus heterophyllus peel with different magnetization methods: comparative characterizations and hexavalent chromium adsorption study

Magnetic activated carbon has been proved its separation ability to overcome a main drawback of activated carbon powder. However, effect of magnetization method on characterizations and Chromium (VI) adsorption of this adsorbent from Artocarpus Heterophyllus Peel (jackfruit peel) has not been investigated yet. This study magnetized jackfruit peel activated carbon using thermochemical and co-precipitation methods. Magnetic jackfruit activated carbon (MJAC) were examined and compared to jackfruit activated carbon (JAC) for surface chemistry, texture, morphology and crystalline properties. The isotherm/kinetics of Cr(VI) adsorption on these adsorbents were also analyzed. The results showed that all the adsorbents showed a typical peak of -(COO)_n-Fe of iron oxide particles and functional groups but the adsorbent prepared with thermochemical method had the greatest Fe-O-C bond signal. The thermochemical adsorbent also had various particles of Fe₃O₄, Zero Valent Iron, and α-Fe₂O₃ while the co-precipitation absorbents gave a greater mesoporous structure and specific surface area than their JAC precursor; especially the adsorbent produced at mild temperature was covered by the highest iron oxide distribution on the surface and better magnetite property. As a result of the high specific surface area, these co-precipitation adsorbents were more effective for Cr(VI) adsorption than others. The PSO model best describes Cr(VI) adsorption on all absorbents with and without magnetite. Cr(VI) adsorption on JAC was dominated by intra-particle diffusion while multistep processes, including external mass transfer, governed the overall MJAC adsorption process. This work has created jackfruit peel-based magnetic activated carbon for wastewater treatment to remove toxic heavy metals and promote the circular economy that uses solid wastes as raw materials.