Unraveling sorption of nickel from aqueous solution by KMnO₄ and KOH-modified peanut shell biochar: Implicit mechanism

Nickel-containing wastewater is a serious hazard to water environment, so that it is a burning issue to find an efficient and environment-friendly adsorbent. The conventional biochar could not effectively adsorb nickel (Ni(II)), so our study focuses on exploring the adsorption of chemically modified biochar to Ni(II). In this study, the biochar derived from waste peanut shell was modified by KMnO₄ and KOH (MBC). And a series of experiment were carried out to evaluate the sorption ability and explore adsorption mechanism of modified biochar to Ni(II). The results showed the adsorption ability of MBC to Ni(II) reached 87.15 mg g^-1. And the reaction process was spontaneous and endothermic chemisorption. Meanwhile, the analysis of FTIR and XPS visually revealed that the amine groups in the modified biochar could form NH₂Ni with Ni(II) by complexation, while the hydroxyl could form nickel hydroxide and complexed nickel oxide by co-precipitation and complexation. This research showed this novel MBC is a promising adsorbent and has a fantastic prospect in the application of nickel-containing wastewater.