多孔氧化镁的制备及其对糖汁的吸附性能研究

Preparation of porous magnesium oxide and its clarification performance in sugar juice industry

采用搅拌-陈化法制备了多孔碱式MgCO_3,在500℃下灼烧3 h,得到了多孔MgO。以赤砂糖回溶糖浆为研究对象,探讨多孔MgO对赤砂糖回溶糖浆的脱色性能,并以脱色率为指标,考察了多孔MgO用量、吸附时间、吸附温度、吸附p H值对赤砂糖回溶糖浆脱色性能的影响。结果表明:在用量为0.1g、吸附时间为60min、吸附温度为60℃、p H值为8.00时,多孔MgO对糖汁的脱色率为84.7%。用多孔MgO进行静态吸附动力学和吸附等温线研究。结果表明,多孔MgO吸附动力学符合准二级反应动力学模型,相关系数R2值最高(R2=0.999),说明其能更好的模拟多孔MgO对糖汁中非糖物质的吸附行为。吸附等温线符合Langmuir吸附等温方程。

Understanding the adsorption properties of the porous magnesium oxide provided a theoretical basis for its application in sugar industry. The porous magnesium oxide was synthesized by hydromagnesite with a stir-ageing method. Brown granulated sugar syrup was used in exploring the feasibility of de-colorization process by the porous magnesium oxide. The de-colorization rate was used as an index to evaluate affecting parameters such as the porous magnesium oxide dosage, pH value, adsorption time and adsorption temperature. The results showed that the optimal process conditions were： the porous magnesium oxide dosage： 0.1 g, adsorption temperature 60℃ , adsorption time： 60 min, and pH value： 8.00. Under these optimal conditions, the de-colorization rate was 84.7%. Further studies show that the adsorption kinetics of the porous magnesium oxide obeys Lagergren equation. Moreover, the adsorption isotherm complied with the Langmuir equation.