壳聚糖基大孔炭质整体材料的制备及其对痕量二氧化硫的吸附性能

以壳聚糖为碳源,综合采用冰模板技术和低温热解炭化技术,制备出具有蜂窝状孔结构特征的大孔炭质整体材料,研究了此类新材料对痕量二氧化硫的吸附性能及再生能力。结果表明,大孔炭质整体材料蜂窝状孔结构的形成及其规整程度与冰模板过程的冷冻时间等因素密切相关;200℃下低温热处理可得到具有丰富表面含氮官能团的大孔炭质整体材料;经氨水溶液中的离子交换功能化处理后,该大孔炭质整体材料对低浓度SO₂的吸附容量显著提高,可达到57 mg·g^-1;吸附饱和后,经空气简单吹扫处理,大孔炭质整体材料即可大部分再生,少数不可再生部分是由于质子化的氨基与亚硫酸根和硫酸根在吸附过程中形成了不可逆化学吸附产物季铵盐所致。壳聚糖基大孔炭质整体吸附剂材料有望在污染空气的脱硫净化,特别是在质子交换膜燃料电池的阴极空气脱硫净化方面发挥重要作用。

Preparation of carbon-based monolith with macro-pore from chitosan and its adsorption performance for trace SO2

Chitosan-based monolithic carbon materials (CBMCMs) with three-dimensional macro-porous honeycomb structure have been prepared by coupling ice templating process with a low-temperature heat treatment one,of which the adsorption and regeneration performance for trace SO₂ in air were evaluated.It is found that formation of macro-porous structure can be tuned by varying the freezing time,and low temperature pyrolysis,such as 200℃,favors the retain of abundant surface nitrogen functional group in as-made CBMCMs.After ion-exchange treatment in ammonia solution,the adsorption capacity for trace SO₂ of the CBMCMs is greatly enhanced,as high as 57 mg·g^-1.The exhausted CBMCMs can be partially regenerated simply by air purge at room temperature.The unrecoverable part is due to the formation of ammonium salts from protonated amine group and sulfite and sulfate ions,as the product of irreversible adsorption.It is believed that after further optimization,the CBMCM materials reported here will be of potential in air cleaning for efficient removal of SO_x species,especially for cathode air desulfurization in proton exchange membrane fuel cells.