煤气化粗渣制多孔吸附材料对亚甲基蓝的吸附研究

Adsorption of Methylene Blue by Porous Adsorbent Made from Coal Gasification Coarse Slag(CGCS)

以煤气化粗渣为原料,分别采用化学法(酸化高温法)和物理法(超声波法)对其进行微观扩孔,并对扩孔后的吸附材料(G1和C1)进行表面改性,制备出改性后的吸附材料G2和C2。利用SEM,BET,XRD和FT-IR对吸附材料的表面形貌、微观结构和官能团组成等进行表征分析,并研究4种吸附材料对水溶液中亚甲基蓝(MB)的吸附特性。结果表明,在同等实验条件下,所制备的4种吸附材料均具有介孔特性,但C1,C2比G1,G2具有更大的比表面积和总孔容,比表面积和总孔容表现为C1>C2>G1>G2。各吸附材料表面均含有以絮状物质形式存在的无定形碳。G1,G2表面粗糙,孔结构丰富,大量的无定形碳阻塞了孔道;而C1,C2表面粗糙且存在明显的断裂层和裂隙孔,孔道结构丰富。MB吸附实验表明,4种吸附材料对MB的吸附效果表现为C1>C2>G1>G2,因材料改性剂影响了样品中Si—O键的含量,阻塞了孔结构,未能明显改善材料的吸附性能。在25℃下,4种吸附材料(用量为100 mg)对浓度为60 mg/L、体积100 mL的MB溶液进行吸附,其吸附过程均符合伪二阶动力学模型和颗粒内扩散模型。在实验条件下,物理法处理后的气化粗渣在孔结构和吸附能力方面均比用化学法处理后的气化粗渣更具有优势。

The pore expansion of CGCS was conducted by chemical method(acidification high temperature method)and physical method(ultrasonic method),respectively,and the surface modification of the expanded adsorbent materials(G1 and C1)was carried out to prepare the modified adsorbent materials G2 and C2.The surface morphology,microstructure and composition of the adsorbent materials were characterized and analyzed by SEM,BET,XRD and FT-IR,and the adsorption properties of the four adsorbent materials on methylene blue(MB)in aqueous solution were investigated.The results show that under the same experimental conditions,the four adsorbent materials have mesoporous properties,but C1 and C2 have larger specific surface area and total pore volume than G1 and G2(C1>C2>G1>G2).The surface of each adsorbent material contains amorphous carbon in the form of flocs.G1 and G2 have rough surfaces and complex pore structures,with a large number of flocculent substances(amorphous carbon)blocking the pores,while C1 and C2 have rough surfaces and obvious fractured layers and fissured holes,with rich pore structures.The MB adsorption experiment shows that the adsorption effect of the four adsorption materials on MB was C1>C2>G1>G2.Due to the influence of the modifier on the Si-O content in the sample and the blockage of the pore structure,it failed to improve the adsorption performance.The adsorption process of the four adsorbents of 100 mg on MB solution with a concentration of 60 mg/L and a volume of 100 mL at 25℃was in accordance with the pseudo-second-order kinetic model and the intra-particle diffusion model.Under the experimental conditions,the gasification coarse slag treated by physical method was superior to that treated by chemical method in terms of both pore structure and adsorption capacity.