氨三乙酸酐改性纤维素对Cd~(2+)的吸附性能

本实验采用氨三乙酸酐改性玉米秸秆纤维素和苎麻纤维素,制备了两种改性纤维素吸附剂NTAA-CS及NTAA-RF,并研究了这两种吸附剂对水中Cd2+的吸附性能.通过元素分析、FTIR及SEM分析发现,纤维材料表面成功引入了氨三乙酸分子中的酯键和氨基基团.在改性纤维素吸附剂投加量为2 g·L-1,Cd2+的初始浓度为200 mg·L-1,p H值为4.0时,NTAA-CS和NTAA-RF对Cd2+的去除率分别为82.6%和90.2%.吸附实验结果表明:改性纤维素吸附剂对Cd2+的吸附是一个快速过程,吸附的最佳p H范围为4.0~7.0.吸附等温线用Langmuir方程的拟合效果优于Freundlich方程.经过5次吸附再生,吸附剂仍可以保持较大的吸附容量.这些结果表明,NTAA-CS和NTAA-RF在去除重金属废水中有较大的应用前景.

Adsorption of Cd2+ by NTA anhydride (NTAA)-modified cellulose materials

Through applying Nitrilotriacetic acid anhydride (NTAA) to modify cornstalk (CS) and ramie fiber (RF), respectively, novel cellulose materials NTAA-CS and NTAA-RF were synthesized and were employed for Cd²⁺ removal from aqueous solution. The materials were characterized through the elemental analysis and by using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Results show that the ester bonds and amine groups were chemically bound to the surface functional groups of the cellulose materials. When the dosage of the two adsorbents were 2 g · L^-1, the removal efficiency of Cd²⁺ reached 82.6% and 90.2%, respectively, under the initial concentration of Cd²⁺ at 200 mg · L^-1 and pH 4.0. Additionally, the fast adsorption of Cd²⁺ took effect in the pH range of 4.0 to 7.0. The Langmuir model fitted the adsorption isotherms curve well. The adsorbents can keep a high metal adsorption capacity even after 5 times of reuse. These results indicate that both NTAA-CS and NTAA-RF are promising adsorbents to remove heavy metals from aqueous solution.