Onion skin–derived sorbent for the sequestration of methylparaben in contaminated aqueous medium

Adedapo O. Adeola, Kabir O. Oyedotun, Ngwako J. Waleng, Bhekie B. Mamba, Philiswa N. Nomngongo

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Carbon-based adsorbents were produced from onion skin waste for the adsorption of methylparaben from contaminated water. The biomass-derived carbon was characterized using various established analytical techniques. The microscopic examinations revealed micro- and mesoporous structures with a partially disordered network of the graphenic carbon-like multilayer structure, confirmed by XPS and Raman spectra. XRD analysis revealed that the biomass-derived carbon is largely amorphous with the graphitic phase also confirmed. Aside from the prominence of sp2 hybridized carbon, FTIR analysis shows the existence of moieties and functional groups that may facilitate the sorption of methylparaben or other organic pollutants if explored. The adsorption isotherm revealed that the multilayer adsorption model (Freundlich) best fits experimental data with an SSE value of 0.454. A complex adsorption process is suspected between methylparaben and OSDC, and the physicochemical properties of the sorbate and sorbent played a huge role in the sorption process. The plausible interactions include van der Waals, hydrophobic bonding, hydrogen bonding, π-π stacking, and pore-filling mechanisms, leading to a hysteretic sorption process. The optimal removal efficiency and adsorption maxima of ~ 100% and ~ 8200 mg/g are obtainable at optimum process conditions. Therefore, waste valorization and adsorption performance achieved in this study suggest a sustainable and cost-effective pathway for pollution remediation.

Original languageEnglish
JournalBiomass Conversion and Biorefinery
Publication statusAccepted/In press - 2023


  • Adsorption
  • Carbon
  • Methylparaben
  • Onion skin
  • Waste valorization
  • Water treatment

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment


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