Abstract
Carbon adsorbents for use in the removal of gaseous toluene from the air were prepared from buckwheat (Fagopyrum esculentum Moench) hull. A chemically-activated adsorbent was prepared via the impregnation of raw hull powder with potassium carbonate, followed by thermal decomposition. The chemically-activated adsorbent exhibited improved adsorption capacity for toluene compared to the adsorbent prepared without chemical activation. Toluene concentration in the air decreased from 220 ppm to 160 ppm during 24 h of adsorption using unactivated adsorbent. Only a trace amount of toluene remained after the adsorption under the same conditions using K2CO3-activated adsorbent. This improvement was explained based on experimental results, specifically, iodine adsorption tests, methylene blue adsorption tests, and microscopic observations. Chemical activation dramatically increased the specific surface area of the adsorbent and created mesopores capable of adsorbing toluene. This study revealed that a mesoporous adsorbent for use in volatile toluene removal can be prepared from waste biomass (buckwheat hull) by chemical activation using potassium carbonate.
Highlights
The removal of volatile organic compounds (VOCs) from the air is quite important in industry
The main aim of this work was to evaluate the effect of the K2 CO3 chemical activation of adsorbents derived from buckwheat hull on their gaseous toluene removal capacity
The enhanced toluene removal capacity was explained by the differences in specific surface areas and mesopore structures between the unactivated and K2 CO3 -activated adsorbents
Summary
The removal of volatile organic compounds (VOCs) from the air is quite important in industry. Typical VOCs emitted by processes used in the chemical and petroleum industries contain aromatics, ethers, aldehydes, halogenated compounds, and so on [1]. Toluene is among the most important VOCs emitted by various industrial processes. It has been widely used as a representative solvent in the manufacture of paints, inks, rubbers, adhesives, and various other chemical substances. Toluene is emitted to the atmosphere via vaporization, leakage, and in exhausts. The emission of gaseous toluene is a public health concern because toluene is neurotoxic, and exposure can cause headaches, dizziness, mental depression, cognitive dysfunction, and many other symptoms [2,3]
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