Surface modified and activated waste bone char for rapid and efficient VOCs adsorption

Abstract

In this work, very efficient VOCs adsorbent was developed from waste bovine bone. After pyrolysis at 450 °C, the bone char was treated by H₃PO₄ for surface modification and activated by K₂CO₃ respectively. The prepared materials were characterized by N₂ adsorption isotherms, SEM, FT-IR, and XPS. Adsorption/desorption and regeneration behavior of VOCs were also studied. Results showed that H₃PO₄ modification can effectively accelerate the adsorption process and after K₂CO₃ activation, a new hierarchical pore structure was found with an ultrahigh total pore volume of 2.807 cm³/g. The specific adsorption capacity for typical VOC reached ∼13.03 mmol/g which is much higher than literature data under the same condition. Static toluene adsorption test on the prepared activated bone-char revealed that the hierarchical structure has provided abundant adsorption sites and the adsorption behavior can be well described by the pseudo-second-order model. The dynamic/static adsorption ratio increased from 70.31% to 78.62% due to less mass transfer resistance by surface modification.

Keywords: Adsorption; Biochar; Surface modification; Waste bone.