氨基酸在微波辅助钙改性SBA-15上的吸附性能

Adsorption Properties of Amino Acids on Ca/SBA-15 Prepared by Calcium Modification under Microwave Radiation

采用微波辐射固相法制备了钙改性SBA-15材料Ca/SBA-15(MW),借助小角XRD、N2吸附-脱附实验及TEM表征了Ca/SBA-15(MW)的结构,研究了4种典型的氨基酸在Ca/SBA-15(MW)上的吸附性能,并考察了钙负载量和pH值对其吸附性能的影响.结果表明,制备的钙改性材料仍具有与SBA-15相似的结构特点,且钙物种均匀地分散在介孔材料孔道内.在pH=2.0～10的范围内,Ca/SBA-15(MW)材料对酸性谷氨酸的吸附比纯硅SBA-15更好,且钙含量越高,吸附能力也越强;对碱性赖氨酸而言,在pH<10时,Ca/SBA-15(MW)样品的吸附能力比SBA-15载体要弱,但当pH=10时,其吸附能力要比SBA-15强;对中性苯丙氨酸和丙氨酸而言,在pH=2.0～6.0和pH=6.0～10范围内,SBA-15的吸附能力较弱;而在pH=6.0时,其吸附量最大且分别达到0.34和0.17mmol.g-1,但Ca/SBA-15(MW)对丙氨酸吸附较弱,对苯丙氨酸则几乎没有吸附,这可能是钙改性SBA-15表面亲水性增强,对疏水性较强的丙氨酸尤其是苯丙氨酸的吸附能力较差.

The calcium modified SBA-15 materials, denoted as Ca / SBA-15 （ MW ）, were prepared by sol- id-phase method under microwave radiation. The structure of the materials was characterized by small angle XRD, N2 adsorption-desorption, and TEM. Adsorption performance of four typical amino acids on Ca/SBA-15 （MW） was studied. Effects of the calcium loading and pH of amino acid solution on the adsorption performance were investigated. The results show that the calcium modified materials prepared by this method still retain similar structural characteristics of SBA-15, and calcium species are uniformly dispersed in the mesoporous material pore channel. Ca/ SBA-15 （MW） displays better adsorption ability to the adsorption of acidic glutamic acid at pH = 2.0 -10 as compared to pure silicon SBA-15. Moreover, their adsorption capacity is proportional to calcium content of the samples. For the adsorption of basic amino acid lysine（ Lys）, Ca/SBA-15 （MW） shows the weaker adsorption ability at pH 〈 10 compared with SBA-15, whereas its adsorption ability is stronger than that of SBA-15 when the oH value ofadsorption solution was adjusted to 10. For the adsorption ot some neutral amino aclos SUCh as pnenylatamne,u alanine on SBA-15, their adsorption amount was low at pH = 2.0 - 6.0 and pH = 6.0 - 10. When pH value was ca. 6.0, the maximum adsorption amount of phenylalanine and alanine over SBA-15 was up to 0.34 and 0. 17 mmol/g, respectively. Ca/SBA-15 （MW） exhibits a weak adsorption capacity to alanine, and hardly adsorbed phenylalanine. This is likely due to the surface hydrophilicity of the calcium-containing samples, which can lead to a poor adsorption interaction with hydrophobic alanine and especially phenylalanine.