Concurrent adsorption and reduction of chromium(VI) to chromium(III) using nitrogen-doped porous carbon adsorbent derived from loofah sponge

Feng Chen, Shihao Guo, Yihao Wang, Lulu Ma, Bing Li, Zhimin Song, Lei Huang, Wen Zhang

Research output: Contribution to journalArticlepeer-review

Abstract

To develop highly effective adsorbents for chromium removal, a nitrogen-doped biomass-derived carbon (NHPC) was synthesized via direct carbonation of loofah sponge followed by alkali activation and doping modification. NHPC possessed a hierarchical micro-/mesoporous lamellar structure with nitrogen-containing functional groups (1.33 at%), specific surface area (1792.47 m2/g), and pore volume (1.18 cm3/g). NHPC exhibited a higher Cr(VI) adsorption affinity than the HPC (without nitrogen doping) or the pristine loofah sponge carbon (LSC) did. The influence of process parameters, including pH, dosage, time, temperature, and Cr(VI) concentration, on Cr(VI) adsorption by NHPC were evaluated. The Cr(VI) adsorption kinetics matched with the pseudo-second-order model (R2 ⩾ 0.9983). The Cr(VI) adsorption isotherm was fitted with the Langmuir isotherm model, which indicated the maximum Cr(VI) adsorption capacities: 227.27, 238.10, and 285.71 mg/g at 298K, 308K, and 318K, respectively. The model analysis also indicated that adsorption of Cr(VI) on NHPC was a spontaneous, endothermal, and entropy-increasing process. The Cr(VI) adsorption process potentially involved mixed reductive and adsorbed mechanism. Furthermore, computational chemistry calculations revealed that the adsorption energy between NHPC and Cr(VI) (−0.84 eV) was lower than that of HPC (−0.51 eV), suggesting that nitrogen doping could greatly enhance the interaction between NHPC and Cr(VI). [Figure not available: see fulltext.].

Original languageEnglish (US)
Article number57
JournalFrontiers of Environmental Science and Engineering
Volume16
Issue number5
DOIs
StatePublished - May 2022

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)

Keywords

  • Adsorption
  • Chromium(VI)
  • Loofah sponge
  • Nitrogen-doped porous carbon
  • Reduction

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