Abstract:

As a typical harmful VOC pollutant, benzene vapor is of great significance for its efficient purification treatment. Benzene vapor is a typical contaminant of VOCs which is the culprit of various diseases, so it is very meaningful to research how to purify the benzene vapor efficiently. Paper material is a kind of porous material with low density, high porosity and high mechanical strength. In this paper, two different kinds of paper, WFP (wood fiber paper) and CFP (ceramic fiber paper), are used as the porous substrates. Paper based silica gel adsorbent was made by gluing repeatedly, immersing the paper porous substrate in JN-30 silica sol and then drying them in oven several times. The surface morphology and structure of two kinds of paper materials were observed by the scanning electron microscopy (SEM). The adsorption properties of the samples which are made from WFP and CPF are tested by using the multi station absorption apparatus. The results show that the two porous substrates are of strong adhesive ability of silica, and the silica adhesive rate of the WFP and CFP reaches 3.38 g/g and 8.66 g/g after 6 times gluing. With the increase of gluing times, the silica adhesive rate of both materials is increasing, but after the gluing times reaches 4 times, growth of silica adhesive rate becomes significantly lower. The adsorption performance test results show the strong adsorption ability of the paper-based silica adsorbents on benzene vapor, both a good adsorption rate and adsorption capacity: it takes less than 30 min to achieve 80% of maximum adsorption capacity under 0.1 benzene vapor partial pressure, and the maximum adsorption capacity reaches 100 mg/g under 0.8 benzene vapor partial pressure. With the increase of the gluing times, the paper-based silica gel adsorbents’ adsorption capacity of benzene vapor first rises and then drop. In addition, the dynamic adsorption model of the paper-based silica gel adsorbents was fitted by the piecewise dynamic adsorption model. It was found that the dynamic adsorption process under the low pressure was divided into 2 stages: the early stage and later stage. In the early stage of adsorption, the adsorption capacity of materials is strong and adsorption quantity increases rapidly; in the later stage of adsorption, adsorption quantity increases much slower and gradually reaches saturation. By comparing isothermal adsorption curves of two different paper-based silica gel adsorbents, it can be found that, with the increase of gluing times, adsorption capacity of the WFP based silica gel adsorbents increases first and then decreases and it reaches the maximum at 4 times gluing. In contrast, the isothermal adsorption ability of CFP based silica gel adsorbents is basically unchanged after 4 times of gluing. Based on the fitting study of the adsorption isotherm with the Langmuir equation and the D-R equation, it was found that the adsorption isotherm was also divided into 2 parts: the low-pressure area and the high-pressure area. In addition, the adsorption characteristic curve is obtained by segmentation fitting the experimental results.

Key words: benzene, silica, porous material, adsorbents, kinetic adsorption, adsorption isotherm

摘要：

苯蒸气作为一种典型的有害VOC污染物，研究对其的高效净化处理具有重要意义。纸基材料是一种密度小、孔隙率高、机械强度高的多孔材料，分析以木浆纤维纸、陶瓷纤维纸作为多孔基材，通过多次硅溶胶浸泡的方法制得硅胶嵌入多孔纸基吸附材料样片。通过扫描电镜SEM研究两种纸基材料表面的形貌及结构，采用重量法蒸气吸附仪对不同上胶次数的两种基材样片进行吸附性能测试。测试结果表明：木浆纤维纸和陶瓷纤维纸6次上胶率高达3.38 g/g和8.66 g/g; 0.1分压苯蒸气下30 min样片吸附量即可达到最大吸附量的80%；两种硅胶嵌入多孔纸基样片吸附容量在0.8分压苯蒸气下均超过100 mg/g；在4次上胶时样片表现出最佳的苯蒸气吸附性能。此外，通过对实验结果进行分段拟合得到吸附特征曲线。

关键词: 苯, 二氧化硅, 多孔材料, 吸附剂, 动态吸附, 吸附等温线