VOCs removal by adsorption onto activated carbons from biocollagenic wastes of vegetable tanning

• Characterization and valorization of vegetable-tanned leather wastes.
• Activated carbons prepared by chemical activation with KOH, NaOH and K2CO3.
• The adsorbents obtained are mainly microporous with a certain degree of mesoporosity.
• The activated carbons present specific surface area-SBET of up to 2719 m2 g−1.
• Superior performance for adsorption of VOCs (700 mg of Toluene/g adsorbent).

The objective of this work was to obtain low-cost adsorbent materials in order to remove VOC pollutants. Toluene was chosen as a model of volatile organic compounds for this study. Microporous activated carbons were obtained from vegetable-tanned leather wastes (shavings, trimmings and buffing dust) by means of chemical activation with alkaline agents (KOH, NaOH and K2CO3). A specific BET surface area, total pore volume (VTOT) and total micropore volume (Vtot) of 2719 m2 g−1, 1.184 cm3 g−1 and 0.829 cm3 g−1, respectively, were obtained by KOH-activation, whereas K2CO3-activation yielded values of 1645 m2 g−1, 0.712 cm3 g−1 and 0.536 cm3 g−1, respectively. Low-cost activated carbons with textural properties, chemical functional groups and a capacity for toluene adsorption comparable to that of activated carbons obtained with KOH or NaOH were produced from these wastes by means of K2CO3 chemical activation. Toluene adsorption values at concentrations on the odour threshold-5 ppm (27 mg VOC/g), TLV-TWA-50 ppm (288 mg VOC/g) or TLC-C-100 ppm (700 mg VOC/g) higher than commercial activated carbons such as NORIT RB3, WV-A1100 or Centaur HSV were obtained.

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