氨基化淀粉螯合材料的制备及其在吸附Zn(Ⅱ)和Co(Ⅱ)中的应用

Synthesis of amino starch chelating material and its application in the adsorption for Zn(Ⅱ) and Co(Ⅱ)

以玉米淀粉为原料,采用酯化-交联-氨解三步反应在淀粉分子中引入氨基配位体,使淀粉具有了螯合重金属离子的能力。对氨解反应机理进行了系统研究,并考察了反应条件对接枝率和反应效率的影响,确定了最佳的反应条件:反应温度为65℃,溶剂中水的质量分数为60%,n(NaOH)/n(己二胺)=0.04,n(己二胺)/n(葡萄糖残基)=1.4,反应时间为6h。对产物采用FTIR、XRD和SEM进行了结构表征,结果显示成功地合成了氨基化淀粉螯合材料(ACSt),淀粉原有的结晶结构被破坏,向无定形态转变。吸附实验表明,ACSt对Zn2+和Co2+的吸附行为为放热反应,在中性环境下具有良好的吸附性,吸附量明显优于无机吸附材料硅藻土和沸石。还进行了ACSt的再生实验,两次再生后吸附量为初始吸附量的80%以上,表明ACSt螯合材料具有良好的可再生性能,可循环使用。该天然基ACSt有望成为处理工业重金属废水的理想吸附剂。

Using the corn starch as raw material,the amino ligands were introduced into the starch molecules by three steps of esterification,where the crosslinking and ammonolysis makes the starch have the ability of chelating heavy metal ions.The ammonolysis reaction mechanism was studied and the effects of reaction conditions on percent grafting(PG)and reaction efficiency(RE)were investigated.When the reaction temperature was 65℃,the water content of reaction solvent was 60%,n(NaOH)∶n(HEDA)was 0.04,n(HEDA)∶n(AGU)was 1.4,and the reaction time was 6h,the ammonolysis reaction was in optimal reaction condition.Structure of the product was confirmed by Fourier transform infrared spectroscopy(FTIR),X-ray powder diffraction(XRD),and scanning electron microscopy(SEM).The analysis showed that ACSt was successfully synthesized,and the original crystalline structure of starch was destroyed and transformed into an amorphous form.The adsorption experiments showed that the adsorption behavior of ACSt on Zn2+and Co2+was exothermic.The ACSt had good adsorption property in neutral environment,and that its adsorption capacity was obviously higher than that of the inorganic adsorbent diatomite and zeolite.In this paper,the regeneration experiment of ACSt was also carried out.It was found that after two regeneration the adsorption capacity was still more than 80%,indicating that the natural based ACSt chelating material with favorable regeneration performance could be reused and was expected to be an ideal adsorbent applying in the treatment of industrial heavy metal wastewater.