Removal of Volatile Toluene Using K2CO3-Activated Carbon Adsorbents Prepared from Buckwheat Hull

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.

Tobacco Waste Biomass for Electrochemical Energy Storage Application

A large amount of industrial and agricultural wastes are generated in the tobacco industry, such as tobacco steams, tobacco stalks, and tobacco leaves. How to increase the economic added value of industrial and agricultural wastes is an important issue. It is a promising value-added way that these biological wastes are recycled into carbon materials with excellent electrochemical properties. Herein, biochar were prepared from tobacco waste biomass (mainly tobacco stems, tobacco stalks and tobacco leaves) through one-step carbonization. The as-obtained biochar exhibited high specific capacitance of 305.92 F·g−1 (tobacco stems), 328.07 F·g−1 (tobacco stalks), and 272.48 F·g−1 (tobacco leaves) at 1 A·g−1, when tested in a three-electrode system with 6 M KOH electrolyte. This study highlights the possibility of reusing tobacco waste to produce low-cost, green and high-performance carbon-based electrode materials for sustainable electrochemical energy storage systems.