优化多孔蜂窝状硅镁胶的制备及其对弱酸性红的吸附性能

为了研究开发经济、高吸附量、可再生的吸附剂,以Na₂SiO₃、MgCl₂为原料,通过溶胶-凝胶法制备出一系列优化蜂窝状硅镁胶,并分析制备硅镁胶的最佳焙烧条件,采用热重分析(TG)、红外光谱(FT-IR)、X射线衍射光谱(XRD)、比表面及孔隙度分析、电镜扫描(SEM)等手段对硅镁胶进行结构表征和性质测定,研究硅镁胶对印染废水中弱酸性红的吸附行为. 结果表明:经500 ℃焙烧4 h后镁硅配比〔n(Mg2+)∶n(SO2-₃)〕为3∶1的硅镁胶对弱酸性红具有最好的吸附效果,硅镁胶对弱酸性红的吸附符合Langmuir模型,吸附过程符合伪二级动力学模型,在吸附温度为25 ℃、投加量为0.5 g/L、ρ(弱酸性红)初始值为200 mg/L时,硅镁胶对弱酸性红的饱和吸附量可达到199.51 mg/g,脱除率达到99.34%；经过5次再生之后对弱酸性红依然具有较高的吸附量,可达到192.12 mg/g,脱除率为95.60%. 研究显示,以Na₂SiO₃、MgCl₂为原料制备的优化多孔蜂窝状硅镁胶对弱酸性红具备良好的吸附性能,并且具有较好的再生能力,是一种廉价高效的吸附材料. 

Preparation of Optimized Porous Honeycomb Magnesium Silica Gels and Their Adsorption Properties for Weak Acid Red

Many magnesium brine resources, including huge magnesium chloride reserves, exist in China. However, development and deep processing of magnesium chloride were once considered to have low value-add, and have been neglected for a long time. In order to study and develop new adsorbents' economic, high adsorption capacity and renewable ability, sodium silicate and magnesium chloride were taken as raw materials, and a series of optimized porous honeycomb magnesium silica gels were synthesized by the sol-gel method. The optimum calcination conditions of the magnesium silica gel were studied as well. Structural characterization and property determination of the samples were obtained through a series of observations and analysis, including TG analysis, infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), specific surface and porosity analysis and SEM. The behaviour of magnesium silica gel adsorbing weak acid red in an aqueous solution was studied subsequently. After calcinating for 4 h at 500 ℃, the magnesium silica gel with a ratio of magnesium to silicon (n(Mg2+)∶n(SO2-₃)) of 3∶1 had the best adsorption capacity for weak acid red. The adsorption of weak acid red conformed to the Langmuir isothermal adsorption model and secondary dynamic equation. At 25 ℃, dosage 0.5 g/L, and initial ρ(weak acid red) 200 mg/L, the saturated adsorption quantity of weak acid red by magnesium silica gel reached 199.51 mg/g, representing a removal rate of 99.34%. After five replications of regeneration, the magnesium silica gel still had a high adsorption capacity of 192.12 mg/g, and the removal rate was 95.60%. The results showed that optimized porous honeycomb magnesium silica gel synthesized by sodium silicate and magnesium chloride has high adsorption capacity and renewable ability to weak acid red. It is an optimized low cost and efficient adsorption material.