Abstract
Magnetic microalgae-derived biochar (MMBC) is an attractive adsorbent material for the removal of heavy metals (HMs) from wastewater. This study explored removal of single and multiple HMs by MMBC derived from microalgae biomass cultivated in piggery digestate. Results showed that the MMBC prepared with algae powder to K2FeO4 mixing ratio of 1:4 at 200 °C (MMBC2001:4) exhibited excellent adsorption capabilities for HMs. The adsorption capacity of the five HMs increased with pH ≤ 5.0, beyond which precipitation phenomena occurred successively for each HM. In a multi-metal solution, the adsorption capacity for each HM was lower compared to single-metal solutions due to competitive interactions among the HMs. However, the overall adsorption capacity for the mixture of HMs was not significantly affected. The adsorption kinetics followed pseudo-first-order for single metals and pseudo-second-order for multi-metals. The adsorption isotherms of the five HMs followed the Langmuir and Freundlich models, respectively. The magnetic properties of the adsorbed MMBC facilitate easy separation and regeneration. The main mechanisms for the adsorption of HMs by MMBC include physical adsorption, complexation with oxygen functional groups, and cation–π interactions. This research highlights the effectiveness of microalgal biochar in removing HMs from wastewater.
Published Version
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