生物柴油吸收VOCs的特性及热力学

采用具有高沸点、低粘度特性的生物柴油作为非极性挥发性有机废气（VOCs）的吸收剂，以甲苯为典型VOCs代表，通过吸收实验考察了生物柴油的甲苯吸收特性.结果发现，在同一浓度下生物柴油吸收甲苯容量优于矿物油，且比水提高1个数量级，并且随着初始浓度升高，吸收容量等比例上升.温度是吸收敏感因素，温度上升会导致吸收容量大幅下降.采用UNIFAC模型计算溶解度数据与实验数据吻合较好，平均相对误差为3.37%，可有效预测生物柴油吸收VOCs特性.在此基础上论文也考察了生物柴油对四氯乙烯、苯乙烯、氯苯的吸收特性，并计算了4种VOCs在生物柴油中的无限稀释活度系数、亨利系数及吸收过程的ΔG、ΔH和ΔS.结果表明生物柴油对这4种VOCs的吸收性能排序为：苯乙烯>氯苯>四氯乙烯>甲苯，饱和吸收容量分别为55.17，27.75，20.46，11.93mg/g.

Absorption and thermodynamics of VOCs by biodiesel

Biodiesel with high boiling point and low viscosity was used as the absorbent of non-polar volatile organic compounds (VOCs). In this contribution, toluene, tetrachloroethylene, styrene, and chlorobenzene were taken as the representatives of VOCs, and the absorption experiments were taken under different partial pressures and different absorbtion temperatures. The toluene absorption capacity of biodiesel was increased proportionally as the initial concentration increased. Temperature was a sensitive factor of absorption, and the increased temperature would lead to the decreased absorption capacity. Compared to mineral oil and water for toluene absorption, the toluene capacity of biodiesel was much higher when the absorption performed under the same concentration and temperature. In addition, the results also showed that the capacity order of four VOCs by biodiesel was styrene (55.17mg/g) > chlorobenzene (27.75mg/g) > tetrachloroethylene (29.46mg/g) > toluene (11.93mg/g). The solubility data were calculated according to the UNIFAC model. The average relative error was 3.37%, indicating that this model was not only in good agreement with the experimental data but also could effectively predict the VOCs absorption property of biodiesel. Furthermore, the thermodynamics of four VOCs solubility in biodiesel were also investigated, including infinite dilution activity coefficient, Henry coefficients, ΔG、ΔH and ΔS.